Top Neuroscience Technology Quotes
Since 2011, there has been an estimated 25,000+ new articles published in Pubmed.gov pertaining to the words "neuron". As the list of articles continues to grow, compiling all this data into one final brain map seems like a daunting task. However, each new article typically covers the past history of the topic, so in a sense there may be thousands of research papers that are summed up in a later paper taking into account all that past research. I would like to personally thank all the researchers for all their efforts in compiling all this data that I was able to freely access and compile. Here are some of the quotes I found most interesting in all the research papers I have reviewed.last modified 10/25/24
Favorite Quotes:
In a single cubic millimeter of brain
tissue, there are some one hundred million synaptic connections between
neurons. Pg. 173
Incognito: The Secret Lives of The Brain.
“It has been argued that it is in the period from early childhood to
kindergarten in which the PFC forms the basic neural circuitry that will
later underlie higher cognitive functions. Experiences early in life can
therefore lay down the basic circuitry that is modified in adolescence.
Early experiences (aversive or other) set up the PFC trajectories and have
lifelong consequences on behavioral regulation.” pg 17187
Experience and the developing prefrontal cortex
"Parent–infant relationships therefore can initiate long-term developmental effects that persist into adulthood"
"both studies show that a negative manipulation of parent–infant relations changes the development of PFC circuits"
"In sum, one of the most intriguing questions in behavioral neuroscience concerns the manner in which the brain, and especially the cerebral cortex, modifies its structure and function in response to experience in development. As this review has suggested, the PFC can be changed dramatically by events beginning prenatally and throughout the life span. The plasticity and prolonged development of the PFC provide an opportunity for continual modification of cognitive function but, in addition, create a potential susceptibility to the formation of abnormal circuitry, leading to compromised behavioral function"
Experience and the developing prefrontal cortex
"Consequently, neurons responding to visual motion in a direction-selective
way are found in almost all species that see. However, directional
information is not explicitly encoded at the level of a single
photoreceptor. Rather, it has to be computed from the spatio-temporal
excitation level of at least two photoreceptors. How this computation is
done and how this computation is implemented in terms of neural circuitry
and membrane biophysics have remained the focus of intense research over
many decades. Here, we review recent progress made in this area with an
emphasis on insects and the vertebrate retina." pg 1 "As a result, the
individual dendritic sectors can be considered as largely independent
processing units" pg 985
Seeing Things in Motion: Models,Circuits, and Mechanisms
"Visual object recognition is essential for most everyday tasks, including
reading, navigation, and face identification. In a small fraction of a
second (approximately 150 ms), we can recognize complex shapes and
categorize objects and scenes"
How cortical neurons help us see: visual recognition in the human brain
"There is a distinct possibility that we haven't yet understood what the retina is for. What if it
is not merely a sharpening filter for a cable to the visual cortex? Perhaps each of the many ganglion cell types already
computes something rather specific about the visual scene... Indeed, there is a well-known example of this kind of processing:
the direction-selective ganglion cell."
Eye Smarter than Scientists Believed: Neural Computations in the Circuits of the Retina
The detailed circuitry of the LGN, its connections, and the fact that the stimulus preferences of geniculate neurons seem identical to those of their retinal inputs make it clear that this nucleus is concerned with regulating the way in which visual information gains access to the cortex rather than with performing visual processing. The elaborate layout of the nucleus, particularly the precise segregation of different types of information and of information from different parts of the visual field suggests that the LGN is designed to perform its regulatory function extremely selectively.
Cell: Current Biology Vol 11 No 16
The transmission of visual information from the retina to the visual cortex through the lateral geniculate nucleus (LGN) is a complex process, which involves several neuronal mechanisms, elements, and circuits.
-Brainstem Input Modulates Globally the Transmission Through the Lateral Geniculate Nucleus
"fMRI studies have reported three regions in human ventral visual cortex
that respond selectively to faces: the occipital face area (OFA), the
fusiform face area (FFA), and a face-selective region in the superior
temporal sulcus (fSTS)", "Finally, our finding that all three face-selective
regions are sensitive to the external contours of faces suggests that this aspect of
faces is also used for constructing the representation of faces at different
stages of face processing."
Perception of Face Parts and Face Configurations
"the very fact that the FFA lands in roughly the same location across
subjects, along with its predominant lateralization to the right hemisphere,
suggests some constraints on its development. Second, neuropsychological
patients who selectively lose face-recognition abilities as a result of
focal brain damage are rarely, if ever, able to relearn this ability,
suggesting that the remaining visual cortex (which is adequate for visual
recognition of non-face objects) cannot be trained on face recognition in
adulthood"
The fusiform face area: a cortical region specialized for the perception of faces
One of the greatest mysteries in cognitive science is the human ability to reconize visually-presented objects with high accuracy and lightening speed"
The lateral occipital complex and its role in object recognition
"Velocity is the temporal derivative of distance. Its measurement should
therefore be localized in space and time. Unsurprisingly, visual neurons are
well suited to estimate motion parameters in a relatively localized manner.
For instance, in macaque monkeys directionally selective neurons in cortical
area V1 with foveal receptive fields perform their computations in less than
about 100 ms and across about 30 arcmin"
Can spatial and temporal motion integration compensate for deficits in local motion mechanisms?
"Face representation, which is believed to be processed in the temporal
visual pathway, has been extensively investigated in humans and monkeys
through neuroimaging and electroneurophysiology. Lesion studies in monkeys
indicate that simple facial features are processed in the caudal regions,
and that the combined and integrated features of the face are stored in the
perirhinal cortex (PRC)."pg 1, 2012.
Distinct human face representations in the perirhinal cortex and fusiform gyrus,
"Evidence from functional neuroimaging indicates that visual perception of
human faces and bodies is carried out by distributed networks of face and
body-sensitive areas in the occipito-temporal cortex." pg1,2013, "The visual
perception of faces and bodies is crucial for successful social interaction
between human beings as these two biological stimuli convey vital
information on the gender, age, identity, mood, emotions, actions, and
intentions of the other person."
Different Cortical Dynamics in Face and Body Perception: An MEG study
"What does seem pretty clear is that the development of normal adult face
processing (and thus by hypothesis the development of the FFA) is
constrained both anatomically and chronologically. First, the very fact that
the FFA lands in roughly the same location across subjects, along with its
predominant lateralization to the right hemisphere, suggests some
constraints on its development. Second, neuropsychological patients who
selectively lose face-recognition abilities as a result of focal brain
damage are rarely, if ever, able to relearn this ability, suggesting that
the remaining visual cortex (which is adequate for visual recognition of
non-face objects) cannot be trained on face recognition in adulthood" pg 2121, 2006
The fusiform face area: a cortical region specialized for the perception of faces
"One of the greatest mysteries in cognitive science is the human ability to
recognize visually-presented objects with high accuracy and lightening
speed. Interest in how human object recognition works is heightened by the
fact that efforts to duplicate this ability in machines have not met with
extraordinary success. What secrets does the brain hold that underline its
virtuosity in object recognition? Here, we review recent findings from
functional brain imaging research that provide important clues from a region of the brain that appears to play a
central role in human object recognition, the lateral occipital complex. "
The lateral occipital complex and its role in object recognition
"Functional neuroimaging studies have identified an interconnected
occipitotemporal neural network which shows face-selective response
properties and high level of specialization in processing of the facial image"
"We found that the N170 amplitude was larger to opposite and same-sex nude
vs. clothed bodies. Moreover, the N170 amplitude increased linearly as the
amount of clothing decreased from full clothing via swimsuits to nude
bodies. Strikingly, the N170 response to nude bodies was even greater than
that to faces, and the N170 amplitude to bodies was independent of whether
the face of the bodies was visible or not...We conclude that the early
visual processing of human bodies is sensitive to the visibility of the
sex-related features of human bodies and that the visual processing of other
people’s nude bodies is enhanced in the brain. This enhancement is likely to
reflect affective arousal elicited by nude bodies. Such facilitated visual
processing of other people’s nude bodies is possibly beneficial in
identifying potential mating partners and competitors, and for triggering
sexual behavior." pg1, 2011"Our results thus confirm that nudity of human bodies is detected early on during
visual processing, and that the human brain exhibits enhanced visual
processing to other people’s nude bodies. Interestingly, the N170 response
to nude bodies was even greater than that to faces, even though the N170
response to faces was at its largest on the chosen T5/T6 channels. The
amplitude difference between swimsuit bodies and faces was not statistically
significant. Given the sheer number of studies showing that faces elicit the
most pronounced N170 amplitude, our findings showing the largest N170
amplitudes to nude bodies is somewhat surprising. Experiment 1 involved only
male participants, and their N170 amplitude was greater to nude female
bodies than to nude male bodies. This fits with prior findings showing that
male participant’s evaluative and looking-time responses are different for
same vs. opposite-sex nude bodies. We extended these findings to early
visual cortical responses to body stimuli. On the contrary, stimulus sex had
no effect on N170 to faces, which is compatible with previous results
showing no difference in N170 responses to same-sex vs. opposite-sex faces."
pg 5"We conclude that the human brain is tuned to detect sexual signals from human bodies rapidly, and
that this categorization process is reflected in the face- and
body-sensitive N170 component of the ERP wave. Such a perceptual ‘highway’
for processing of sexual cues is highly beneficial for triggering sexual
behavior, and subsequently ensuring mating and reproduction." pg 10
The Naked Truth: The Face and Body Sensitive N170
Response Is Enhanced for Nude Bodies,
“A science of the mind must reduce complexities (of behavior) to their
elements. A science of the brain must point out the functions of its
elements. A science of the relations of mind and brain must show how the
elementary ingredients of the former correspond to the elementary functions
of the latter.”
William James, The Principles of Psychology, 1890
“One cubic millimeter of cerebral cortex
contains roughly 50,000 neurons, each of which establishes approximately
6,000 synapses with neighboring cells. These 300 million interconnections
are highly specific: Neurons innervate some target cells but avoid others.
The complexity is further amplified by the fact that neurons come in many
kinds. For example, some neurons make excitatory connections, while others
establish inhibitory ones. It is thought that there are well over 100 types
of neurons, differing in shape, neurochemistry, and function. In action,
each neuron integrates the signals from hundreds or thousands of synaptic
signals, and this history determines whether or not it will send an
electrical signal to its target cells. A cubic millimeter is but a minuscule
part of the full circuitry, which is estimated to contain 60×1012
synaptic connections.”
Harvard University
https://rc.fas.harvard.edu/case-studies/connections-in-the-brain/
Total surface area of the cerebral cortex = 2,500 cm2 (250,000 mm2 )(2.5 ft2; A. Peters, and E.G. Jones, Cerebral Cortex, 1984)
“People who believe in God are less
anxious and have less reactivity in the ACC (Inzlicht 2009). A strong belief
in God acts as a buffer against anxiety and minimizes the experience of
error. Religion has been shown to provide better mental and physical health
and lower mortality rates. Studies show that the ACC is a critical cortical
structure for the inhibition of response that is seen in anxiety. This area
signals every time when some behavioral modification is needed in response
to an anxiety-producing event (commission of an error, detection of conflict
or the experience of uncertainty). Religious conviction acts like an
anxiolytic, reducing emotional reactions to errors or uncertainty, providing
people with a meaningful system helping them to understand the complex and
uncertain word that we live in (Peterson, 1999). Religion gives motivation,
purpose, and meaning, providing people with standards upon which to act in
life. In physiological terms, it reduces ACC activity and consequently
distress.”
THE ANTERIOR CINGULATE CORTEX
Researchers have discovered a sophisticated neural computer, buried deep in the cerebellum,
that performs inertial navigation calculations to figure out a person's
movement through space.
"These calculations are
no mean feat, emphasized the researchers. The vestibular system in the inner
ear provides the primary source of input to the brain about the body's
movement and orientation in space. However, the vestibular sensors in the
inner ear yield information about head position only. Also, the vestibular
system's detection of head acceleration cannot distinguish between the
effect of movement and that of gravitational force"
"After analyzing the
electrical signals measured from the Purkinje cells during these movements,
the researchers concluded that the specialized Purkinje cells were, indeed,
computing earth-referenced motion from head-centered vestibular
information."
"The researchers
concluded that the output of the Purkinje cells indicates an "elegant
solution" to the computational problems involved in inertial navigation."
Brain's Inertial Navigation System Pinpointed Date: June 21, 2007 Source: Cell Press
The ability to orient and navigate through the terrestrial environment
represents a computational challenge common to all
vertebrates ... Here we show that cerebellar cortical neuron activity in
vermal lobules 9 and 10 reflects the critical computations of transforming
head-centered vestibular afferent information into earth-referenced
selfmotion and spatial orientation signals."
Purkinje Cells in Posterior Cerebellar Vermis Encode Motion in an Inertial Reference Frame
Della Santina has built a vestibular prosthesis that he hopes can someday be implanted in humans
much like cochlear implants are now used to restore hearing. Instead of
using a microphone to pick up sound, his system uses gyroscopes to measure
movement in three dimensions. The measurements, translated to electrical
impulses, would be delivered to the three vestibular nerves that emanate
from the three semicircular canals, much like audio signals are delivered to
the auditory nerve in cochlear implants.
"Neurons receiving such inputs effectively function as adaptive processors
that are able to assume different functional states according to the task being executed."
Top-down influences on visual processing
“Parallel processing of visual information begins at the first synapse in
the retina between the photoreceptors and bipolar cells.”
Characterization of a novel large-field cone bipolar cell type in the
primate retina: Evidence for selective cone connections
“The smooth-pursuit system must interact with the vestibular system to
maintain the accuracy of eye move- ments in space during head movement.
Maintenance of a target image on the foveae is required not only during head
rotation which activates primarily semi-circular canals but also during head
translation which activates otolith organs. The caudal part of the frontal
eye Welds (FEF) contains pur- suit neurons. The majority of them receive
vestibular inputs induced by whole body rotation.”
Otolith inputs to pursuit neurons in the frontal eye fields of alert monkeys
“Here we present for the mouse inner plexiform layer—the main computational neuropil
region in the mammalian retina—the dense reconstruction of 950 neurons and
their mutual contacts… We characterize a new type of retinal bipolar
interneuron and show that we can sub divide a known type based on
connectivity. Circuit motifs that emerge from our data indicate a functional
mechanism for a known cellular response in a ganglion cell that detects
localized motion, and predict that another ganglion cell is motion
sensitive.”
Connectomic reconstruction of theinner plexiform layer in the mouse retina.
“Conclusion: Internal models provide a firm computational foundation from
which theories of the cerebellum can be considered. We have reviewed the
evidence that the cerebellum contains inverse or forward models of the motor
system. By considering the possibility that the cerebellum contains multiple
pairs of forward and inverse models, we believe that the benefits of both
views can be retained and integrated. Such a paired system would results in
computational advantages in both motor learning and control.”
Internal models in the cerebellum
“kinaesthesia, the senses of limb position and limb movement, has been
prompted by recent new observations on the role of motor commands in
position sense. Peripheral receptors which contribute to kinaesthesia are
muscle spindles and skin stretch receptors. Joint receptors do not appear to
play a major role at most joints. The evidence supports the existence of two
separate senses, the sense of limb position and the sense of limb movement.
Receptors such as muscle spindle primary endings are able to contribute to
both senses. While limb position and movement can be signaled by both skin
and muscle receptors, new evidence has shown that if limb muscles are
contracting, an additional cue is provided by centrally generated motor
command signals. Observations using neuroimaging techniques indicate the
involvement of both the cerebellum and parietal cortex in a multi-sensory
comparison, involving operation of a forward model between the feedback
during a movement and its expected profile, based on past experience.
Involvement of motor command signals in kinaesthesia has implications for
interpretations of certain clinical conditions.”
The kinaesthetic senses.
"Vision is an active process, where higher order cognitive influences affect
the operations performed by cortical neurons.."
Top-down influences on visual processing
“Brain circuits process information through specialized neuronal subclasses
interacting within a network. Revealing their interplay requires activating
specific cells while monitoring others in a functioning circuit." pg1
“By triggering inhibition and measuring its effects on connected
cells in the functioning cortex, we have shown the computational impact of
different forms of inhibition on sensory processing.” pg 2
Division and subtraction by distinct cortical inhibitory networks in vivo
“Understanding the structure and function of the neocortical microcircuit
requires a description of the synaptic connectivity between identified
neuronal populations."
"The neocortex is a 6-layered structure which is functionally organized into
columns. Understanding the wiring diagram of a cortical column has received
much attention in recent years” Pg1
Specificity of Synaptic Connectivity between Layer 1 Inhibitory Interneurons and Layer
2/3 Pyramidal Neurons in the Rat Neocortex
"Visual and vestibular signals converge onto the dorsal medial superior
temporal area (MSTd) of the macaque extrastriate visual cortex, which is
thought to be involved in multisensory heading perception for spatial navigation...MSTdneurons respond selectively
to heading and not to changes in orientation relative to gravity. In support
of a role in heading perception, MSTdvestibular responses are also dominated
by velocity-like temporal dynamics, which might optimize sensory integration
with visual motion information. Unlike the cerebellar vermis, however, MSTd
neurons also carry a spatial orientation-independent rotation signal from
the semicircular canals, which could be useful in compensating for the
effects of head rotation on the processing of optic flow"
Vestibular Signals in Macaque Extrastriate Visual Cortex Are Functionally Appropriate for Heading
Perception
"Area MST was the first area reported to have large-field,
complex-motion-sensitive responses. It remains the most studied area in the
context of self-motion.", pg 394, " When VIP is electrically activated with
pulse trains of fairly long duration and moderately large intensities,
stereotyped face, shoulder, and arm movements result, which strongly
resemble normal defensive movements"
Mechanisms of Self-Motion Perception
The deep and intermediate layers of the superior colliculus (DLSC) integrate multimodal sensory information about environmental stimuli to allow for rapid reflex-like responses to potential threats (Stein et al., 2009). DLSC functions in a larger network that includes the periaqueductal gray (PAG), inferior colliculus (IC), amygdala, and hypothalamus. This network has been well characterized in rodents, and has been referred to as the “brain aversion system.” Activation of this network can evoke defense-like behaviors (e.g., freezing, cringing, cowering and escape) -Defense-Like Behaviors Evoked by Pharmacological Disinhibition of the Superior Colliculus in the Primate
The
Human Connectome Project is hard at work producing images such as this,
using an MRI technique known as diffusion tensor imaging. With 100 billion
neurons, each with around 10,000 connections, mapping the human brain will
be no easy feat, and charting every single connection could take decades.
The HCP will tackle the lowest hanging fruit first: charting the major
highways between different brain regions, and showing how these connections
vary between individuals. To do this they will combine several imaging tools
including something called diffusion MRI, which maps the structure of the
white matter that insulates the "wires" of the brain, and also resting-state
MRI, which measures how brain regions oscillate in unison as a result of
shared connections.
NewScientist
"Through a series of complex transformations, the pixel-like input to the
retina is converted into rich visual perceptions that constitute an integral
part of visual recognition... We discuss how neurophysiological recordings
in the macaque monkey and in humans can help us understand the computations
performed by the visual cortex" pg 1
How cortical neurons help us see: visual recognition in the human brain
"Combining systematic studies of the neurophysiology and neuroanatomy of the
visual system in human and non-human animal models is providing new
understanding of some of the computations performed in the visual cortex."
pg 1
How cortical neurons help us see: visual recognition in the human brain
"Initially working in cats, and subsequently in monkeys, they discovered
that neurons in V1 typically respond to bars shown at a specific orientation within their receptive fields (17, 76,
77). The receptive field size for V1 neurons is typically below one degree
of visual angle. Their responses are tuned to the orientation of the bar;
this type of response is similar to the type of operations used in computer
vision to extract the edges of an image "
How cortical neurons help us see: visual recognition in the human brain
"Figure 2 shows another
single unit located in the right anterior hippocampus of a different
patient. This unit was selectively activated by pictures of the actress Halle Berry as well as by a drawing of her (but not by other drawings; for example,
picture no. 87). This unit was also activated by several pictures of Halle
Berry dressed as Catwoman, her character in a recent film, but not by other
images of Catwoman that were not her (data not shown). Notably, the unit was
selectively activated by the letter string ‘Halle Berry’. Such an invariant pattern
of activation goes beyond common visual features of the different stimuli"
Invariant visual representation by single neurons in the human brain
The recognition process likely entails a
sequence of computations across visual cortex, starting from local
computations in early visual cortex related to low-level properties of the
visual stimulus, such as disparity, motion, or orientation, conveying little
sense of the global object shape, then proceeding to more global
computations in higher levels of the hierarchy of visual processing."
Representation of Shapes, Edges, and Surfaces Across Multiple Cues in the Human Visual Cortex
Human visual cortex comprises 6 billion neurons that are organized into more
than a dozen distinct functional areas. The entirety of human cortex occupies a surface area on the order of 1000 cm2
and ranges between 2 and 4mm in thickness. Each cubic millimeter of cortex contains approximately 50 000
neurons so that neocortex in the two hemispheres contain on the order of 30
billion neurons. Human visual cortex includes the entire occipital lobe and
extends significantly into the temporal and parietal lobes. Visual cortex
contains on the order of 4.
There are 1.5 million optic nerve fibers from
each eye in macaque and only 1 million such fibers in humans. The large size
of human visual cortex is likely not a result of an increase in the supply
of information but, rather, due to an increase in visual processing and the
organization and delivery of information to other parts of cortex, such as
those devoted to language and reading. Given these differences in visual
cortex size, it would not be surprising that many features of human visual
cortex are not present in closely related primate systems."
Visual Cortex in Humans
The number of neurons in human visual cortex
far exceeds the number in many other species that depend on vision. For
example, the surface area of macaque monkey visual cortex is probably no
more than 20% that of human visual cortex"
Visual Cortex in Humans
"The dominant thinking for
the past 30 years assumes that each extrastriate map represents a
computational specialization"
Visual Cortex in Humans
Our findings do lend support to the
hypothesis that visual cortex is organized at a large scale into a number of
clusters that share common functional response properties"... "Importantly,
maps that belong to a cluster are characterized by
similar functional computations to mediate common perceptual processes."
Retinotopic Organization of Human Ventral Visual Cortex
"While many areas of the brain have demonstrated roles in trans- mitting and
integrating energy balance signals, the hypothalamus is pivotal. This small
region of the limbic system also has a central role in mediating stress
responses, regulating body temperature, thirst and sleep, and establishing
circadian rhythms. It is bordered by the third ventricle and the highly
vascularized median emi- nence, an area with a porous blood-brain barrier.
This makes it ideally positioned to sense and respond to a myriad of
circulating hormones and nutrients."
Serotonin and the regulation of mammalian energy balance
"Most connections between visual areas consist of both feedforward and
feedback connections, indicating that there is a high degree of interactive processing.
PRIMARY VISUAL CORTEX AND VISUAL AWARENESS
"Virtually all information that reaches the cerebral cortex must first pass
through the thalamus, and yet the thalamus is often seen as a simple
machine-like relay. This suggests that nothing would be lost if information
were passed directly from peripheral receptors, such as the retina, to the
neocortex. However, the known complexity of thalamic circuitry points
strongly to a significant role for thalamic processing, and details about
that role have emerged during the past decade or so, showing that the
thalamus can dynamically alter the information relayed in a manner that
reflects various behavioural states, such as attention and drowsiness."
The role of the thalamus in the flow of information to the cortex pg 1, 2002,
"Our findings do lend support to the hypothesis that visual cortex is
organized at a large scale into a number of clusters that share common
functional response properties"
Retinotopic Organization of Human Ventral Visual Cortex
MT adds little to the raw direction and
speed tuning already found in V1, but researchers still think it plays a
role in computing the motion of whole objects or patterns." pg 168, "The
idea that MTdeals only with segmentation and integration might have sufficed
up until the mid 1990s, but since then, a series of remarkable studies has made it clear that MT is
involved in the computation of structure (although the first evidence for
this fact dates back to Siegel & Andersen 1988). The sensitivity of MT
neurons to speed gradients; the correlation between MT responses and the
perception of 3D cylinders; and the remarkable integration of direction, speed, and disparity gradients
all make a compelling case that MTis processing motion but doing more than
computing the direction and speed of motion."pg 180
Structure and Function of Visual Area MT
Figure 2 shows another single unit located in the right anterior hippocampus
of a different patient. This unit was selectively activated by pictures of the actress Halle Berry as
well as by a drawing of her (but not by other drawings), This unit was also
activated by several pictures of Halley Berry dressed as Cat woman, her
character in a recent film, but not by other images of Cat woman that were
not her. Notably, the unit was selectively activated by the letter string “Halle Berry”.
Invariant visual representation by single neurons in the human brain (test on real humans with epilepsy who had been implanted with depth electrodes)
"The deep and intermediate layers of the superior colliculus (DLSC)
integrate multimodal sensory information about environmental stimuli to
allow for rapid reflex-like responses to potential threats. DLSC functions
in a larger network that includes the periaqueductal grey (PAG), inferior
colliculus (IC), amygdala, and hypothalamus. This network has been
well-characterized in rodents, and has been referred to as the “brain
aversion system”. Activation of this network can evoke defense-like
behaviors (e.g., freezing, cringing, cowering and escape) that include
increased sympathetic arousal (e.g., increase in blood pressure, heart rate,
and respiration)"
Defense-like behaviors evoked by pharmacological disinhibition of the superior colliculus in the primate
The apparent capacity of DA neurones to signal events that are “better” or “worse” than expected(reward prediction errors) has captured the imagination of both the neuroscience and computational communities pg 6
Interactions between the midbrain superior colliculus and the basal ganglia
1 Neuroscience Research Unit, Department of Psychology, University of Sheffield Sheffield UK,
Joseph Fourier University Grenoble France3 Department of Physiology, School of Medicine of Ribeirão
Preto, University of São Paulo, São Paulo, Brazil, Department of Neurobiology and Anatomy, Wake Forest University School of Medicine
In order to see clearly when a target is moving slowly, primates with high acuity foveae use smoothpursuit and vergence eye movements. The former rotates both eyes in the same direction to track target motion in frontal
planes, while the latter rotates left and right eyes in opposite directions
to track target motion in depth. Together, these two systems pursue targets
precisely and maintain their images on the foveae of both eyes. During head
movements, both systems must interact with the vestibular system to minimize
slip of the retinal images" pg 1, "The goal of the pursuit system is to keep the retinal target
image on the fovea by matching the eye velocity in space (i.e., gaze velocity) to target velocity" pg 2
The vestibular-related frontal cortex
and its role in smooth-pursuit eye movements and vestibular-pursuit
interactions
Projections from the peripheral field representation of V2 to parietal areas
could provide a direct route for rapid activation of circuits serving spatial vision and spatial
attention." pg 1
Cortical Projections of Area V2 in the Macaque
"Here we report functional magnetic resonance
imaging (fMRI) evidence that the EBA is strongly modulated by limb (arm,
foot) movements to a visual target stimulus, even in the absence of visual
feedback from the movement. Therefore, the EBA responds not only during the
perception of other people’s body parts, but also during goal-directed
movements of the observer’s body parts." pg 1
Extrastriate body area in human occipital cortex responds to the performance of motor actions
"Finally, aside from dorsal V4, the retinotopic organization of macaque early
visual cortex (V1, V2, V3, V3A, and ventral V4) is remarkably similar to that observed in human fMRI studies. This finding indicates that early visual cortex is mostly conserved throughout hominid evolution." pg 1
So far, however, not a single human fMRI study has provided
any evidence of a robust retinotopic organization within the topological
human equivalent of monkey V4d. Our experiments exclude technique-related
explanations for this functional interspecies difference. Furthermore, in
New World monkeys, which diverged from the Hominidae much earlier than the
Old World monkeys, both dorsal and ventral V4 have a similar
retinotopic organization compared with that of V4v in humans and monkeys.
Together with the present data, this suggests that human and macaque V4d,
but not the remainder of early visual cortex, have evolved differently
during about 25 million years of separation." pg 7404
The Retinotopic Organization of Primate Dorsal V4 and Surrounding Areas: A
Functional Magnetic Resonance Imaging Study in Awake Monkeys,
Proprioception: The sense or perception,
usually at a subconscious level, of the movements and posture of the body
and especially its limbs, independent of vision. This sense is mediated by
sensory nerve terminals in muscles and tendons (muscle spindles) and the
fibrous capsule of joints combined with input from the vestibular
apparatus."
Dorsal and Ventral Streams in the Sense of Touch
"The posterior parietal cortex (PPC), historically believed
to be a sensory structure, is now viewed as an area important for
sensory-motor integration. Among its functions is the forming of intentions,
that is, high-level cognitive plans for movement. There is a map of
intentions within the PPC, with different subregions dedicated to the
planning of eye movements, reaching movements, and grasping movements. These
areas appear to be specialized for the multisensory integration and
coordinate transformations required to convert sensory input to motor
output"
INTENTIONALMAPS IN POSTERIOR PARIETAL CORTEX,
"The classical view that there are only two motor areas is wrong... Motor
and parietal areas are reciprocally connected and form a series of
specialized circuits working in parallel. These circuits transform sensory
information into action. They are the basic elements of the motor system."
pg 283,"The most effective stimuli for many PE neurons are specific combinations of multiple joint
positions or combinations of joint and skin stimuli. Recently, Lacquaniti et
al. (1995) provided evidence that many neurons in area PE encode the
location of the arm in space in a body-centered coordinate system. The main
role of PE-F1 (M1) circuits (Fig. 2A) appears to be that of providing F1
with information on the location of body parts necessary for the control of
movement of limbs and other body parts." pg 286
The organization of the cortical motor system: new concepts
"The posterior parietal cortex of the macaque contains a multiplicity of
areas involved in the analysis of visual information necessary for motor
planning and execution of eye, limb, and body movements", "The rich
parietofrontal connections of these areas mediate the transformation of
visual information into action, and a series of parietofrontal circuits has
been so far identified, linking visually related areas of the caudal
superior parietal lobule (SPL) and of the intraparietal sulcus (IPS) with
different sectors of the agranular frontal cortex or with the frontal eye
fields. These circuits are involved in the visual guidance of reaching,
grasping, or eye movements"
Cortical Connections of the Inferior Parietal Cortical Convexity of the Macaque Monkey
"There is overwhelming evidence that areas in the IPS are involved in complex
hand use, reaching, grasping, matching visual and body centered frames of
references for reaching and grasping, and programming intentional hand
movements.", 2011, pg 1,
Topographic Maps within Brodmann’s Area 5 of Macaque Monkeys
"Although recent findings support the existence of functionally distinct
parietal regions for controlling reach-to-grasp movements, the overlap
between these parietal regions may also reflect the different functional and
computational constraints that need to be satisfied when planning
reach-to-grasp movements."2011, pg 7
Specialization of reach function in human posterior parietal cortex
“Mirror neurons are a particular class of visuomotor neurons,originally
discovered in area F5 of the monkey premotor cortex, that discharge both
when the monkey does a particular action and when it observes another
individual (monkey or human) doing a similar action” pg169
“In the case of humans, there is another faculty that depends on the
observation of others’ actions: imitation learning. Unlike most species, we
are able to learn by imitation, and this faculty is at the basis of human
culture.” pg169
“There are two classes of visuomotor neurons in monkey area F5: canonical
neurons, which respond to the presentation of an object, and mirror neurons,
which respond when the monkey sees object-directed action. In order to be
triggered by visual stimuli, mirror neurons require an interaction between a
biological effector (hand or mouth) and an object.” Pg170
“Thus, the mirror system transforms visual information into knowledge” pg172
THE MIRROR-NEURON SYSTEM
"The confluence of these properties at this particular apex of the “what”
and “where” pathways support the hypothesis that STPa plays a crucial
function in the integration of spatial and form information and its transfer
onto motor planning regions to guide or plan grasping and other reaching
movements to moving objects in the environment." pg9, 2007
Three-dimensional structure-from-motion selectivity in the anterior
superior temporal polysensory area, STPa, of the behaving monkey,
"Optic flow provides an important visual cue to the estimation of
self-motion (egomotion; Gibson 1950; Warren et al. 1988). However, in the
mammalian brain, vestibular and somatosensory signals are integrated with
visual information to compute egomotion parameters. In macaques, there is
much evidence that areas MST and VIP are involved in encoding visual cues
for egomotion and are also sensitive to vestibular and somatosensory cues"
pg1, 2009
Sensitivity of Human Visual and Vestibular Cortical Regions to Egomotion-Compatible, Visual Stimulation,
"Increased activation in the area of the VTA was also seen during cocaine
and heroin rush. The finding that heroin addicts experience orgasmic
pleasure with heroin usage fits with the notion that the VTA is the key
element in both heroin and sexual orgasm. The present findings may represent
an anatomical substrate for the strongly reinforcing nature of sexual
activity in humans. Because ejaculation introduces sperm into the female
reproductive tract, it would be critical for reproduction of the species to
favor ejaculation as a most rewarding behavior."
Brain Activation during Human Male Ejaculation,
“The visibility of sex-related human body features changes the affective and
motivational significance of the stimulus and would thus result in enhanced
engagement of the fronto-insular-temporal network, particularly of the IC
(Insular Cortex) which has been implicated in the integration of internal
motivational drives with external stimuli.” Pg 108
“Female stimuli elicited greater N1 responses than male stimuli across both
genders”… Considering that the enhancement in the processing of nude vs.
clothed bodies can be accounted for by affective arousal, subsequent
triggering of sexual behavior, and the ultimate purpose of reproduction.”
“We conclude that the visibility of sexual features strongly facilitates the
early cortical processing of human bodies, and that this is reflected in
enhanced activity in a distributed network, including body processing areas,
such as the EBA and FBA, as well as affective-motivational areas, such as
the IC and ACC. The purpose of such a neural boost is presumably to trigger
sexual behavior and ultimately ensure reproduction.” Pg 109
Facilitated early cortical processing of nude human bodies
"The sensation of taste originating from receptors distributed on the tongue
and oral cavity of rodents is first carried to the rostral portion of the
nucleus of the solitary tract (NST) by axons of the VIIth, IXth, and Xth
cranial nerves. From the NST, ascending gustatory fibers project to
third-order cells within the parabrachial nuclei (PbN) of the and in turn to
multiple forebrain nuclei, including the ventrobasal thalamus (VPMpc),
insular cortex (IC), lateral hypothalamus (LH), central nucleus of the
amygdala (CeA), and the bed nucleus of the stria terminalis (BST) "2004, pg1
Modulation of Parabrachial Taste Neurons by Electrical and
Chemical Stimulation of the Lateral Hypothalamus and Amygdala.
This representation of face part information is consistent with the OFA
acting as the Wrst stage in a distributed network for face perception in which face
computations of increasing complexity, such as identity and facial
expression discrimination, are performed at higher levels of cortex" - 2011 pg 1.
The role of the occipital face area in the cortical face perception network
"Our ability to perceive the visual environment is remarkable: we can
recognize a scene within a fraction of a second, and use that information to
seamlessly navigate. Given the ecological importance of scene perception and
navigation, it is perhaps not surprising then that particular regions of the
human brain are specialized for processing visual information about scenes,
including the parahippocampal place area (PPA), the retrosplenial complex
(RSC), and a region near the transverse occipital sulcus, formerly referred
to as “TOS”, but for reasons outlined in the Discussion, henceforth called
the “occipital place area” (OPA)." 2013, pg1
The Occipital Place Area Is Causally and Selectively Involved in Scene Perception
"The results of a conjunction analysis
of brain activity showed that, of the several areas that were active with
each type of stimulus, only one cortical area, located in the medial
orbito-frontal cortex (mOFC), was active during the experience of musical
and visual beauty, with the activity produced by the experience of beauty
derived from either source overlapping almost completely within it. The
strength of activation in this part of the mOFC was proportional to the
strength of the declared intensity of the experience of beauty. We conclude
that, as far as activity in the brain is concerned, there is a faculty of
beauty that is not dependent on the modality through which it is conveyed
but which can be activated by at least two sources–musical and visual–and
probably by other sources as well. This has led us to formulate a
brain-based theory of beauty
Toward A Brain-Based Theory of Beauty
"Attractive faces that were more consistently rated by subjects as displaying a happy expression,
produced stronger responses in the region compared to faces that were
displaying a neutral expression.. Given that medial orbitofrontal cortex is
associated with representing stimulus-reward value, it may be that the
reward value of a face is much enhanced when that face is smiling at the
observer (even if subtly as is the case with the stimulus set used here).
The presence of a smile may provide an important signal that a reward is or
is not attainable." 2003, pg 153,
Beauty in a smile: the role of medial orbitofrontal cortex in facial attractiveness
"As recipient of diverse signals, the AM nucleus is in a key position to
link pathways associated with emotions, and may be an important interface
for systems associated with retrieval of information from long-term memory
in the process of solving problems within working memory. Finally, the
internal segment of the globus pallidus (GPi) issued projections to AM,
suggesting direct linkage with executive systems through the basal ganglia.
The diverse connections of the AM nucleus may help explain the varied
deficits in memory and emotions seen in neurodegenerative and psychiatric
diseases affecting the anterior thalamic nuclei."
Pathways for emotions and memory II. Afferent input to the anterior thalamic nuclei from prefrontal, temporal, hypothalamic areas and the basal ganglia in the rhesus monkey
Turning to prefrontal regions, among adults, the OFC and ACC circuitry
modulates behavior by influencing attention to emotional stimuli,
including fearful or other negative facial expressions. Across development,
the OFC and ACC show functional, anatomical, and physiological changes in
adolescence and by early adulthood, and these regions have been implicated
in the maturation of attentional and emotional processes, such as
goal-directed attention to emotionally evocative stimuli found greater OFC
and ACC activation in adolescents than in adults when passively viewing
fearful versus neutral faces, as well as greater OFC activation in adults
than in adolescents when focusing on emotional versus nonemotional aspects
of fearful faces. As a whole, the literature indicates that, like the
amygdala, the fusiform gyrus, the hippocampus, the ACC, and the OFC are
involved in facial emotion processing and the limited developmental studies
of these regions suggest possible age-related changes in fearful-face
processing.Recent work indicates that between-group differences in amygdala response to facial
emotions are associated with between-group differences in functional
connectivity among specific brain regions in adolescent anxiety patients as
well as healthy adults. A recurrent theme in theories of brain development is that adolescence is a
time of neural refinement via synaptic pruning, myelination, and regulatory
processes that may strengthen interconnections among brain circuits. In
theory, behavior is the net result of functional interactions among a highly
integrated network of subcortical–subcortical and subcortical–cortical
regions associated with the human response to emotional stimuli. Because
this is the first study of developmental differences in functional
connectivity during face processing, we viewed these analyses as
exploratory. However, we were particularly interested in amygdala
connectivity with cortical and subcortical temporal regions, such as the
fusiform gyrus and the hippocampus, given their associations with face
processing. Pg4.
A Developmental Examination of Amygdala Response to Facial Expressions
"Patients with strokes in the territory of the middle cerebral artery (primary motor and premotor areas) cannot produce a symmetrical, voluntary smile, nevertheless can smile normally in response to jokes (Monrad-Krohn, 1924; Hopf et al., 1992; Dawson et al., 1994; Töpper et al., 1995; Trepel et al., 1996). These findings suggest the existence of an alternative “limbic” pathway that controls facial expressions. Indeed, patients with strokes in the territory of the anterior cerebral artery, affecting the midcingulate area, are able to make voluntary facial movements but are unable to produce spontaneous emotional expressions (amimia) (Wilson, 1924; Feiling, 1927; Karnosh, 1945).
"
"The amygdalo-motor pathways and the control of facial expressions"
“These results suggest that specific orbitofrontal and medial prefrontal
areas exert a direct influence on the hypothalamus and may be important for
the autonomic responses evoked by complex emotional situations”
Topographic Organization of Connections Between the Hypothalamus and
Prefrontal Cortex in the Rhesus Monkey, pg1
“The human face is an engineering marvel. Underneath our skin, a large
number of muscles allow us to produce many configurations. The face muscles
can be summarized as Action Unit defining positions characteristic of facial
expressions of emotion. These face muscles are connected to the motor
neurons in the cerebral cortex through the corticobulbar track.” Pg 1591
A Model of the Perception of Facial Expressions of Emotion by Humans:Research Overview and Perspectives
(Spirit/Flesh Network)
“It is pretty safe to suggest that if early experiences dramatically alter
PFC circuitry and behavior in laboratory animals, such as rats, the
experiences are likely to have even larger effects in a more complexly
organized PFC, such as in humans.” Pg 17186
“It has been argued that it is in the period from early childhood to
kindergarten in which the PFC forms the basic neural circuitry that will
later underlie higher cognitive functions (12). Experiences early in life
can therefore lay down the basic circuitry that is modified in adolescence.
Early experiences (aversive or other) set up the PFC trajectories and have
lifelong consequences on behavioral regulation.”
“It is now clear that even fairly innocuous-looking experiences can
profoundly affect brain development and that the range of experiences that
can alter brain development is much larger than had once been believed” Pg 17187
Experience and the developing prefrontal cortex,
"Moreover, orbitofrontal and medial prefrontal cortices target the ventral
pallidum and the extended amygdala, through which high-order association
areas may activate motor autonomic structures for the expression of
emotions." -pg1, 2001,
NEURAL INTERACTION BETWEEN THE BASAL FOREBRAIN AND FUNCTIONALLY DISTINCT PREFRONTAL
CORTICES IN THE RHESUS MONKEY
"Hence, the amygdala and orbital prefrontal cortex act as part of an
integrated neural system guiding decision-making and adaptive response
selection." pg 1, 2000, -pg 4317"As mentioned at the outset, humans with
damage to either of these areas are impaired in using information about the
likely consequences of their actions to guide their behavior. This is true
not only in their personal lives in which they often make disastrous social
and financial decisions, but also as indexed by performance in a
laboratory-based “gambling task”
Control of Response Selection by Reinforcer Value
Requires Interaction of Amygdala and Orbital Prefrontal Cortex,
(Renewal)
"The major effect of Ach upon neurons of the cerebral cortex is... a
prolonged reduction of potassium conductance so as to make cortical neurons
more receptive to other excitatory inputs. Cortical cholinergic pathways also promote long-term potentiation and
experience-induced synaptic remodelling."pg 2255, 1998,
Trajectories of cholinergic pathways within the cerebral
hemispheres of the human brain
"It can now be recognized that the region (Orbital and Medial Prefrontal
Cortex) as a whole recieves highly processed sensory afferents, provides for
cortical influence over visceral functions, and participates in high-level
cognitive and emotional processes." pg 1, 2000.
The Organization of Networks within the Orbital and Medial Prefrontal
Cortex of Rats, Monkeys and Humans.
"The visceral nervous system, in turn, is composed of sensors for internal
conditions and effectors controlling body homeostasis. These viscerosensory neurons are
located in the blood vessels, airways or digestive tract monitoring the
internal partial pressurn (pO2es of oxyge) and carbon dioxide (pCO2), blood
pH, organ stretch and, last but not least, taste, and produce
cardiovascular, respiratory and digestive responses." pg1, 2013
Somatic and Visceral nervous systems- an ancient duality
"Given the complexity and diversity of necessary computations, it is perhaps
not surprising that many cortical and subcortical areas in the brain are
involved in decision making. In addition, there is a substantial variability
in the decision-making strategies displayed by different individuals, and
many psychiatric disorders, including mood disorders and substance abuse,
are thought to result from decision-making abilities impaired in some
aspects." pg 1, 2011,
"In the last decade, substantial progress has been
made in uncovering the basic mechanisms of decision making, including how
the brain synthesizes incoming sensory information and the decision maker’s
previous reward history to select the action that is most beneficial to the
subject (3–9).
This knowledge is essential for understanding the precise
nature of dysfunctions in the decision-making circuitries in the brain,
including those responsible for impulsive choice behaviors. This review
first describes the range of computations required for optimal decision
making." pg 2
"Many of our actions are habitual and they are often
generated automatically and rapidly without much deliberation. Often, in
order to produce most appropriate behaviors, such automatic and habitual behaviors must be
first suppressed."
Prefrontal Cortex and Impulsive Decision Making,
“Decision-making is a complex human behavior, dependent on the integrity of
frontal networks. As noted, three frontal circuits have been associated with
decision making: 1) the OFC and limbic pathways, directed toward reward and
affective-based decisions; 2) the DLPFC, specialized for integrating
multiple sources of information; and 3) the ACC, important in sorting among
conflicting options, as well as outcome-processing.” Pg 267
The Functional Neuroanatomy of Decision-Making
"The subcortical brain region most often
associated with the neural processing of anxiety and threat is the amygdala.
It is essential for initial processing of emotional memory and arousal, fast
evaluation of novel stimuli and threat perception. Electrical stimulation of
the amygdala has been shown to elicit fear, anxiety and social withdrawal
and to increase the stress response via cortisol release. Lesions within the
amygdala compromise face processing and judgment of trustworthiness in
social context, impair the recognition of fear and increase social anxiety",
pg 1, 2011,
"Receiving input from higher-order sensory cortices, the
amygdala appears to have a centre or gate function in a hub of connections
associated with the perception, evaluation and response to threatening and
socially relevant stimuli", pg2
"Hyperactivation of the amygdala in response to facial expressions is one of the most
reproduced findings in patients with social anxiety disorder", pg 3
"Anxiety disorder patients had a significantly lower functional connectivity between
the left amygdala and left medial orbitofrontal cortex as well as the left
posterior cingulate cortex/precuneus (PCC/precuneus," pg 4
The OFC is involved in the engagement of interpersonal relationships, moral behavior and social aggression. Lesions
within the medial orbitofrontal cortex enhance the response to stressors or
fear conditions stimuli resulting in severe impairments in social behavior
and difficulties in identifying social signals from facial and voice expressions"
Reduced resting-state functional connectivity between amygdala and orbitofrontal
cortex in social anxiety disorder
"Research in animals and adult humans implicates a circuit connecting the
amygdala and ventral prefrontal cortex (vPFC) in social-threat processing.7,8 Animal studies have
shown that this fear circuitry is shaped by developmental experiences that may chronically
affect social-threat perception.",pg2, 2008,
Amygdala and Ventrolateral Prefrontal Cortex Function During Anticipated Peer Evaluation in Pediatric
Social Anxiety
"Key components of fear circuitry including the amygdala (and its
subnuclei), nucleus accumbens (including bed nucleus of stria terminalis
BNST), hippocampus, ventromedial hypothalamus, periaqueductal gray, a number
of brain stem nuclei, thalamic nuclei, insular cortex, and some prefrontal
regions"pg 1, 2010,
"Extinction learning occurs when a CS that previously
predicted a US no longer does so, and over time, the conditioned response
(eg, freezing or elevated skin conductance responses) decreases. Extinction learning or, more likely, the
later recall of this learning involves the ventromedial prefrontal cortex
(vmPFC)",pg3
The Neurocircuitry of Fear, Stress, and Anxiety Disorders
"The maturing brain during fetal life and infancy may be
particularly susceptible to adverse influences. For instance, early
separation from caregivers, abuse, neglect, or social deprivation in infancy
or early childhood can produce enduring behavioral and neurocognitive
deficits"... In the cerebral cortex, functional domains such as visual processing,
attention, memory, and cognitive control rely on the development of distinct
yet interconnected sets of anatomically distributed cortical and subcortical
regions. The developmental organization of these circuits is a remarkably
complex process that is influenced by genetic predispositions, environmental
events, and neuroplastic responses to experiential demand that modulates
connectivity and communication among neurons, within individual brain
regions and circuits, and across neural pathways." .. "Similarly, animal
studies have shown that maternal care influences behavior and future
parenting of offspring"..."Similarly, a growing body of longitudinal
neuroimaging data describes age-related changes in morphological features
and functional organization of the brain throughout childhood and
adolescence, although the precise correlates of these observations at the
cellular and molecular level are largely speculative." ... "MRI findings in
attention deficit/hyperactivity disorder (ADHD) reveal delays in the time
course of cortical maturational, with peak cortical thickness attained later
than in typically developing children, particularly in anterior temporal and
prefrontal cortices" ..."Children with OCD, for example, perform poorly on
tasks of inhibitory control, and these deficits correlate with clinical
symptoms (Maia et al, 2008). Anatomical and functional neuroimaging studies
suggest that abnormalities in orbitofrontal cortex, striatum, and anterior
cingulate cortex disrupt the functioning of frontostriatal circuits"
Normal Development of Brain Circuits
“Our laminar SST mRNA measurements showed greatest reduction in layer II in
people with schizophrenia, consistent with previous studies showing reduced
gamma-aminobutyric acid (GABA)ergic neuron density in layer II in other
cortical areas in schizophrenia”(Inhibitory neurons) pg 5
Relationship between somatostatin and death receptor expression in the
orbital frontal cortex in schizophrenia: a postmortem brain mRNA study
"There are now substantial data indicating that structural, cellular and
molecular differences exist between the male and female brains in regions
that are important for cognition, memory and affect, such as the
hippocampus, amygdala and prefrontal cortex. Some of these differences may
have clinical relevance, as marked disparities in disease incidence,
manifestation, prognosis and treatment have been observed between the
sexes."
Sex differences, gonadal hormones and the fear extinction network:
implications for anxiety disorders
“Human imaging studies have reported that activity in several brain areas
represents the values of both rewards and punishments…The lateral habenula,
a brain structure located in the epithalamus, is in a good position to
represent emotional and motivational events. It receives inputs from
forebrain limbic regions and projects to midbrain structures, such as the
substantia nigra pars compacta and ventral tegmental area which contain
dopamine neurons, and the raphe nuclei which contain serotonin neurons.
Thus, the lateral habenula could control the monoaminergic (especially
dopaminergic and serotonergic) systems which influence emotion and
motivation. Indeed, electrical stimulation of the lateral habenula inhibits
dopamine and serotonin neurons. Consistent with this view, the lateral
habenula has been implicated in many emotional and cognitive functions
including anxiety, stress, pain, learning and attention. In a recent study,
we showed that neurons in the lateral habenula respond to rewards and
sensory stimuli predicting rewards, and that they send these reward-related
signals to dopamine neurons in the substantia nigra by inhibiting them.” Pg1
Representation of negative motivational value in the primate
lateral habenula
Several studies have investigated the brain areas associated with emotional aspects of pain. Baliki et al. showed that patients with persistent back pain had greater functional connectivity between the medial PFC (mPFC) and NAc [27]. Since the mPFC and NAc are involved in emotion, motivation, and reward-related behaviors, this suggests that the processing of pain perception can be influenced by changes in these functional connections. Hashmi et al. also suggested that regions involved in processing emotions, such as the mPFC and amygdala, are associated with the chronification of pain [28]. Changes in emotion, motivation, and reward-related circuits of the brain (which encode emotional features of pain) may cause disorders associated with emotion in chronic pain conditions.
Chronic Pain: Structural and Functional Changes in Brain Structures and Associated Negative Affective States
“We've all heard the saying "you can't teach an old dog
new tricks." Now neuroscientists are beginning to explain the science behind
the adage.”
“The brain is made up of two types of cells -- inhibitory and excitatory
neurons. Networks of these two kinds of neurons are responsible for
processing sensory information like images, sounds and smells, and for
cognitive functioning. About 80 percent of neurons are excitatory.
Traditional scientific tools only allowed scientists to study the excitatory
neurons.”
Researchers discover how inhibitory neurons behave during critical periods of learning-
http://www.eurekalert.org/pub_releases/2013-08/cmu-rdh082313.php
“Acetylcholine is known to have effects on a person's memory. For example, drugs such as scopolamine, an anticholinergic that works primarily at M1 receptors, prevent the learning of new information. Also, studies have shown that acetylcholine is essential in the neocortex to learn simple tasks of discrimination. In the hippocampus, the absence of acetylcholine causes forgetfulness. ”
Physiology, Acetylcholin
https://www.ncbi.nlm.nih.gov/books/NBK557825/
“Throughout the neocortex, form and function of neural circuitry are shaped
by experience. This sensitivity to experience is most pronounced during
adolescence, and has been studied most extensively in the primary visual
cortex”pg 1.
A disinhibitory microcircuit initiates critical-period plasticity in the
visual cortex
Differences sexes
“Sex differences in typical developmental brain trajectories are highly
relevant for studies of pathology. Robust sex differences in developmental
trajectories were noted for nearly all structures, with GM volume peaks
generally occurring 1–3 years earlier in females” pg 339
“Cerebellum volume peaks about 2 years later than cerebral volume and is the
only structure we have quantified that remains significantly larger in males
after covarying for total cerebral volume” pg 336
“The amygdala is a key component of circuitry involved in assessing
salience, or the importance of environmental stimuli to survival. The
hippocampus is involved in memory storage and retrieval. Connections between
the amygdala and hippocampus result in enhanced memory for stimuli with high
salience” pg 338
The Teen Brain: Insights from Neuroimaging
“Although diabetic ketoacidosis is a pathological condition, mild ketonemia (nutritional ketosis) resulting from fasting, a KD, or other dietary interventions including calorie restriction (CR) has been demonstrated to be beneficial, improving metabolic profiles and extending healthy lifespan [13,14,15,16]. In addition to serving as energy fuel for extrahepatic tissues, KBs exert multifaceted beneficial effects by functioning as signaling molecules, protein post-translational modifiers, regulators of inflammation, oxidative stress, cellular senescence and aging [3,12,17,18]. KBs and KDs are of increasing interest due to their therapeutic potentials for various diseases including metabolic disorders, neurological and cardiovascular diseases, and cancer [3,19,20,21,22,23,24,25,26]
Molecular Mechanisms for Ketone Body Metabolism, Signaling Functions, and Therapeutic Potential in Cancer
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9694619/pdf/nutrients-14-04932.pdf
"Depression and anxiety are more common among females than males and represent a leading cause of disease-related disability in women"
“Analysis of signaling pathways revealed that the sex difference in D1-D2
heteromer expression led to differences in basal and heteromer-stimulated activities of two important signaling
pathways, BDNF/TrkB and Akt/GSK3/β-catenin.
These results suggest that the higher D1-D2 heteromer expression in female may significantly increase
predisposition to depressive-like and anxiety-like behavior in female animals.
Sex difference in dopamine D1-D2 receptor complex
expression and signaling affects depression- and anxiety-like behaviors
http://doi.org/10.1186/s13293-020-00285-9
"Acute stress
has been shown to decrease KNDy neuronal activity and sup
press pulsatile LH secretion (1, 2). Increased HPA axis activity
is strongly linked to impaired reproductive function"
Hypothalamic PVN CRH Neurons Signal Through PVN GABA
Neurons to Suppress GnRH Pulse Generator Frequency in Female Mice
https://academic.oup.com/endo/article/164/6/bqad075/7183901
