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Confusion about the brain regions - temporal cortex, hippocampus and and white matter

Confusion about the brain regions - temporal cortex, hippocampus and and white matter


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I am a computer scientist working with brain data. I have some data from different brain regions, and the regions are called temporal cortex, parietal cortex, hippocampus and forebrain white matter. I want to show those regions on a brain image in a presentation.

The problem is, when I search the brain images online, I cannot find the regions my data mentions. The regions in the search results are usually called "lobe" rather than "cortex". And when I search for "forebrain white matter", the results are usually about "cerebral white matter". I am totally confused. Here are a few questions:

  1. Are "cortex" and "lobe" the same thing? Or does cortex means gray matter while lobe contains both gray and white matter?

  2. Does hippocampus contain gray and white matter? Or does it reside in the inner side of the temporal lobe, meaning it is in the white matter part of the temporal lobe?

  3. Are "forebrain" and "cerebrum" the same thing?

  4. Why is hippocampus considered part of the temporal lobe although it has the long side of it outside of the temporal lobe?


  1. "Lobe" refers to a section of the cerebral cortex, which is the outer part of the cerebrum. The cerebrum contains several structures, but the one that most people care about is the cerebral cortex, which is the 2-4 mm thick layer on the surface of the cerebrum. The cerebral cortex (or "cortex") is divided into several lobes, e.g. temporal lobe, occipital lobe. So, cortex and lobe are not the same thing, as the lobes subdivisions of the cortex as a whole. (See https://en.wikipedia.org/wiki/Cerebral_cortex)
  2. The hippocampus is a region of the cortex in the temporal lobe. Therefore, it consists of gray matter. However, it is connected to several other structures by white matter (e.g. the fornix), and these structures are related to the hippocampus. (See https://en.wikipedia.org/wiki/Hippocampus#Anatomy)
  3. Forebrain refers to the cerebrum as well as other structures, such as the thalamus and hypothalamus. The forebrain is defined as the telencephalon (which is basically the cerebrum) and the diencephalon (which contains the thalamus and hypothalamus). (See https://en.wikipedia.org/wiki/Forebrain and https://en.wikipedia.org/wiki/Diencephalon)
  4. I don't know what you mean by the temporal cortex having "the long side of it outside the temporal lobe", but the temporal cortex and temporal lobe are basically the same thing.

A Critical Role for the Hippocampus in the Valuation of Imagined Outcomes

Affiliations Motivation, Brain and Behavior (MBB) Team, Institut du Cerveau et de la Moelle Epinière (ICM), Paris, France, Service de Neuroradiologie, Hôpital Pitie-Salpetriere, Centre de NeuroImagerie de Recherche (CENIR), Institut du Cerveau et de la Moelle épinière (ICM), Paris, France, INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC – Paris 6), Paris, France

Affiliation Institut de la Mémoire et de la Maladie d'Alzheimer, Hôpital Pitié-Salpêtrière, Paris, France

Affiliations Service de Neuroradiologie, Hôpital Pitie-Salpetriere, Centre de NeuroImagerie de Recherche (CENIR), Institut du Cerveau et de la Moelle épinière (ICM), Paris, France, INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC – Paris 6), Paris, France

Affiliations Service de Neuroradiologie, Hôpital Pitie-Salpetriere, Centre de NeuroImagerie de Recherche (CENIR), Institut du Cerveau et de la Moelle épinière (ICM), Paris, France, INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC – Paris 6), Paris, France

Affiliations INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC – Paris 6), Paris, France, Institut de la Mémoire et de la Maladie d'Alzheimer, Hôpital Pitié-Salpêtrière, Paris, France

Affiliations INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC – Paris 6), Paris, France, Centre Emotion, CNRS USR 3246, Hôpital Pitié-Salpêtrière, Paris, France

Affiliations Motivation, Brain and Behavior (MBB) Team, Institut du Cerveau et de la Moelle Epinière (ICM), Paris, France, Service de Neuroradiologie, Hôpital Pitie-Salpetriere, Centre de NeuroImagerie de Recherche (CENIR), Institut du Cerveau et de la Moelle épinière (ICM), Paris, France, INSERM UMRS 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC – Paris 6), Paris, France


Faith and gray matter: New study finds no relationship between brain structure and religiosity

Religion and neurology often seem at odds an extension of the questionable chasm separating spirituality and science. Indeed, in attempting to explain religious faith, neuroscientists have often sought to highlight subtle differences in brain structure that might confirm a deficiency here or reduction there.

A new, preregistered study out of the Netherlands, published in the European Journal of Neuroscience, sought to test prominent hypotheses in the literature relating brain structure to religious experience by way of a high-powered (i.e., having a large sample size), methodologically robust study on religiosity and structural brain differences.

The need for this, according to the authors, stems from myriad methodological inconsistencies in previous research, including small sample sizes, improperly validated testing tasks, and conceptual confusion regarding the structures being measured.

Thus, while the authors readily admit that brain connectivity measures may provide a more nuanced and accurate picture of the brain-religion relation, their primary aim was to “establish the (absence of the) relation between religiosity and structural brain differences at a level of methodological and statistical rigor that we hope will set a new standard for future studies.”

In other words: to dispel notions of the most basic and simplistic relations between brain structure and religious experience, paving the way for more sophisticated approaches.

Three theories were put to test.

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First, the orbitofrontal cortex (OFC) has been implicated in religiosity for its role in error monitoring, which theorists claim must be impaired to accept religious doctrines. Previous results have been mixed, some finding the OFC to be reduced in volume, others enlarged.

Next, temporal lobe atrophy or dysfunction has been associated with hyper-religiosity, perceived communication with God, and life-changing religious experiences. The authors thus tested whether experiential aspects of religion related to reduced volume in temporal regions, including the hippocampus.

Finally, structural differences in superior and inferior parietal lobes are suspected to relate to increased likelihood of mystical experiences, on the grounds that reduced blood flow to the superior parietal lobe has been found in relation to “experiences of absolute unity” during meditation, among others.

In the study, 211 participants answered a series of questions on religiosity and religious experiences, and then underwent voxel-wise, Region of Interest (ROI) brain scans. Such scans divide the brain into three-dimensional “pixels” (voxel = volume + pixel), which can then be compared between subjects for a particular region. This allows for robust confirmatory testing of hypotheses and provides a simple fashion of quantifying differences in brain matter.

Ultimately, the authors found no relation between structural brain differences in relation to self-reported religiosity or mystical experiences, whether using ROI analysis or whole-brain analysis. To conclude, they recommend that future research forgo such attempts, and instead focus on functional and multivariate approaches.

The need to understand religious and mystical experiences runs deep, and has led to a rich and varied scientific literature. Debate continues on the best method to approach the question neurologically, and the present study should help lead to more appropriate testing methods.


2. Myelin Alterations and Related Functions in the Brain

Myelin is composed of compacted lipid membranes that wrap around the axons of many neurons, providing electrical insulation and trophic support. Myelin allows action potentials to propagate along an axon in a saltatory fashion with higher speed and less energy consumption. Whereas Schwann cells are myelinating glia in the peripheral nervous system (PNS), myelin in the central nervous system (CNS) is formed from oligodendrocyte progenitor cells (OPCs) that differentiate into oligodendrocytes (OLs) and form myelin sheaths surrounding axons. Bundles of myelinated axons give rise to the appearance of the white matter. The mechanism and function of myelin in the white matter have been extensively studied. However, many axons in the gray matter that contains neuronal cell bodies and dendrites are also myelinated. A recent study showed that a large fraction of neocortical myelin ensheathes axons of local inhibitory neurons [18]. Gray matter myelination is much less understood and may be regulated differently due to the distinct microenvironments of the white and gray matter.

Myelination is important in establishing connectivity in the growing brain by facilitating rapid and synchronized information transfer across the nervous system, which is essential to higher-order cognitive functions. Once thought of as solely a passive insulator, myelin alteration is now known to be actively involved in the function and development of the CNS (see review [19]). Disruption of myelin can lead to the dysregulation of various neural circuits and give rise to disease symptoms. Uncovering the regulators of myelination has become increasingly important for the diagnosis and treatment of these diseases.


How kids' brain structures grow as memory develops

Our ability to store memories improves during childhood, associated with structural changes in the hippocampus and its connections with prefrontal and parietal cortices. New research from UC Davis is exploring how these brain regions develop at this crucial time. Eventually, that could give insights into disorders that typically emerge in the transition into and during adolescence and affect memory, such as schizophrenia and depression.

https://old.sciencedaily.com/cms/Located deep in the middle of the brain, the hippocampus plays a key role in forming memories. It looks something like two curving fingers branching forward from a common root. Each branch is a folded-over structure, with distinct areas in the upper and lower fold.

"For a long time it was assumed that the hippocampus didn't develop at all after the first couple of years of life," said Joshua Lee, a graduate student at the UC Davis Department of Psychology and Center for Mind and Brain. Improvements in memory were thought to be due entirely to changes in the brain's outer layers, or cortex, that manage attention and stretagies. But that picture has begun to change in the past five years.

Recently, Lee, Professor Simona Ghetti at the Center for Mind and Brain and Arne Ekstrom, assistant professor in the UC Davis Center for Neuroscience, used magnetic resonance imaging to map the hippocampus in 39 children aged eight to 14 years.

While subfields of the hippocampus have been mapped in adult humans and animal studies, it's the first time that they have been measured in children, Ghetti said.

"This is really important to us, because it allows us to understand the heterogeneity along the hippocampus, which has been examined in human adults and other species" Ghetti said.

Looking at three subregions -- the cornu ammonis (CA) 1, CA3/dentate gyrus and subiculum -- they found that the first two expanded with age, with the most pronounced growth in the right hippocampus. Only in the oldest 25 percent of the children, within a few months either side of 14, did the sizes of all three regions decrease.

When they tested the children for memory performance, children with a larger CA3/dentate gyrus tended to perform better, they found. The work was published online March 15 by the journal Neuroimage.

In a related study in collaboration with the laboratory of Professor Silvia Bunge at UC Berkeley, published March 27 in Cerebral Cortex, the researchers also demonstrated how white matter connections projecting from the hippocampus to the brain cortex are related to memory function in children.

"White matter" tracts connect the prefrontal and parietal regions of the brain cortex, which control how we pay attention to things and engage in memory strategies, with the media-temporal lobe, the area that includes the hippocampus.

In the study, children performed a memory test that prompted them either to actively memorize an item -- and therefore engage the prefrontal and parietal cortices -- or to view an image passively. The ability to successfully modulate attention was linked to development of white matter tracts linking the prefrontal and parietal cortex tothe mediatemporal lobe, Ghetti said, but not to fronto-parietal connections.


Meaning of the Limbic System

The meaning of the term “limbic system” has changed since Broca’s time. It is still meant to include structures between the cortex and the hypothalamus and brainstem, but different specialists have included different structures as part of the limbic system. The amygdala and hippocampus are widely included, as is the olfactory cortex. From there, however, opinions diverge as to what is considered part of the limbic system, and what is paralimbic, meaning a structure that interacts closely with the limbic system but is not truly part of it.


The Central Nervous System

Figure 4 the central nervous system and its components

The central nervous system is divided into a number of important parts (see Figure 4), including the spinal cord, each specialized to perform a set of specific functions. Telencephalon or cerebrum is a newer development in the evolution of the mammalian nervous system. In humans, it is about the size of a large napkin and when crumpled into the skull, it forms furrows called sulci (singular form, sulcus). The bulges between sulci are called gyri (singular form, gyrus). The cortex is divided into two hemispheres, and each hemisphere is further divided into four lobes (Figure 5a), which have specific functions. The division of these lobes is based on two delineating sulci: the central sulcus divides the hemisphere into frontal and parietal-occipital lobes and the lateral sulcus marks the temporal lobe, which lies below.

Figure 5a The lobes of the brain

Just in front of the central sulcus lies an area called the primary motor cortex (precentral gyrus), which connects to the muscles of the body, and on volitional command moves them. From mastication to movements in the genitalia, the body map is represented on this strip (Figure 5b).

Some body parts, like fingers, thumbs, and lips, occupy a greater representation on the strip than, say, the trunk. This disproportionate representation of the body on the primary motor cortex is called the magnification factor (Rolls & Cowey, 1970) and is seen in other motor and sensory areas. At the lower end of the central sulcus, close to the lateral sulcus, lies the Broca’s area (Figure 6b) in the left frontal lobe, which is involved with language production. Damage to this part of the brain led Pierre Paul Broca, a French neuroscientist in 1861, to document many different forms of aphasias, in which his patients would lose the ability to speak or would retain partial speech impoverished in syntax and grammar (AAAS, 1880). It is no wonder that others have found subvocal rehearsal and central executive processes of working memory in this frontal lobe (Smith & Jonides, 1997, 1999).

Figure 5b. Specific body parts like the tongue or fingers are mapped onto certain areas of the brain including the primary motor cortex.

Just behind the central gyrus, in the parietal lobe, lies the primary somatosensory cortex (Figure 6a) on the postcentral gyrus, which represents the whole body receiving inputs from the skin and muscles. The primary somatosensory cortex parallels, abuts, and connects heavily to the primary motor cortex and resembles it in terms of areas devoted to bodily representation. All spinal and some cranial nerves (e.g., the facial nerve) send sensory signals from skin (e.g., touch) and muscles to the primary somatosensory cortex. Close to the lower (ventral) end of this strip, curved inside the parietal lobe, is the taste area (secondary somatosensory cortex), which is involved with taste experiences that originate from the tongue, pharynx, epiglottis, and so forth.

Figure 6a The Primary Somatosensory Cortex

Just below the parietal lobe, and under the caudal end of the lateral fissure, in the temporal lobe, lies the Wernicke’s area (Demonet et al., 1992). This area is involved with language comprehension and is connected to the Broca’s area through the arcuate fasciculus, nerve fibers that connect these two regions. Damage to the Wernicke’s area (Figure 6b) results in many kinds of agnosias agnosia is defined as an inability to know or understand language and speech-related behaviors. So an individual may show word deafness, which is an inability to recognize spoken language, or word blindness, which is an inability to recognize written or printed language. Close in proximity to the Wernicke’s area is the primary auditory cortex, which is involved with audition, and finally the brain region devoted to smell (olfaction) is tucked away inside the primary olfactory cortex (prepyriform cortex).

Figure 6b Wernicke's area

At the very back of the cerebral cortex lies the occipital lobe housing the primary visual cortex. Optic nerves travel all the way to the thalamus (lateral geniculate nucleus, LGN) and then to visual cortex, where images that are received on the retina are projected (Hubel, 1995).

In the past 50 to 60 years, visual sense and visual pathways have been studied extensively, and our understanding about them has increased manifold. We now understand that all objects that form images on the retina are transformed (transduction) in neural language handed down to the visual cortex for further processing. In the visual cortex, all attributes (features) of the image, such as the color, texture, and orientation, are decomposed and processed by different visual cortical modules (Van Essen, Anderson & Felleman, 1992) and then recombined to give rise to singular perception of the image in question.

If we cut the cerebral hemispheres in the middle, a new set of structures come into view. Many of these perform different functions vital to our being. For example, the limbic system contains a number of nuclei that process memory (hippocampus and fornix) and attention and emotions (cingulate gyrus) the globus pallidus is involved with motor movements and their coordination the hypothalamus and thalamus are involved with drives, motivations, and trafficking of sensory and motor throughputs. The hypothalamus plays a key role in regulating endocrine hormones in conjunction with the pituitary gland that extends from the hypothalamus through a stalk (infundibulum).

Figure 7 The interior of the brain

As we descend down the thalamus, the midbrain comes into view with superior and inferior colliculi, which process visual and auditory information, as does the substantia nigra, which is involved with notorious Parkinson’s disease, and the reticular formation regulating arousal, sleep, and temperature. A little lower, the hindbrain with the pons processes sensory and motor information employing the cranial nerves, works as a bridge that connects the cerebral cortex with the medulla, and reciprocally transfers information back and forth between the brain and the spinal cord. The medulla oblongata processes breathing, digestion, heart and blood vessel function, swallowing, and sneezing. The cerebellum controls motor movement coordination, balance, equilibrium, and muscle tone.

The midbrain and the hindbrain, which make up the brain stem, culminate in the spinal cord. Whereas inside the cerebral cortex, the gray matter (neuronal cell bodies) lies outside and white matter (myelinated axons) inside in the spinal cord this arrangement reverses, as the gray matter resides inside and the white matter outside. Paired nerves (ganglia) exit the spinal cord, some closer in direction towards the back (dorsal) and others towards the front (ventral). The dorsal nerves (afferent) receive sensory information from skin and muscles, and ventral nerves (efferent) send signals to muscles and organs to respond.


Publications

Key publications below highlight biological findings by researchers at the Allen Institute for Brain Science. These also include detailed descriptions of methods and analysis protocols. A full list of publications from the Allen Institute is available here. Publications related to single cell and single nucleus transcriptomics can be found in the Cell Taxonomies “Explore” page.

Genome-wide atlas of gene expression in the adult mouse brain

For more than a decade, this highly standardized atlas of the adult mouse brain has provided an open, primary data resource for a wide variety of studies involving brain structure and function. Unbiased fine-resolution analysis has identified highly specific gene expression patterns showing remarkable diversity.

Genomic Anatomy of the Hippocampus

Unbiased analysis of hippocampal gene expression data in the Allen Mouse Brain Atlas revealed a large cohort of genes with robust regionalized hippocampal expression. The CA3 compartment can be divided into a set of nine expression domains in the septal/temporal and proximal/distal axes with reciprocal, nonoverlapping boundaries, and evidence of differential connectivity.

Correlated Gene Expression and Target Specificity Demonstrate Excitatory Projection Neuron Diversity

This study describes a systematic approach to identify molecular correlates of specific projection neuron classes in mouse primary somatosensory cortex using existing ISH data mining, marker gene colocalization, and additional retrograde labeling. The combination of gene expression and target specificity imply a great diversity of projection neuron classes matching or surpassing that of GABAergic interneurons.

An anatomically comprehensive atlas of the adult human transcriptome

Brain-wide variation in gene expression strongly reflects the distributions of major cell classes such as neurons, oligodendrocytes, astrocytes, and microglia. The spatial topography of neocortex is strongly reflected in its molecular topography - the closer two cortical regions, the more similar their transcriptomes.

Large-scale cellular-resolution gene profiling in human neocortex reveals species-specific molecular signatures

Roughly 80% of genes show consistent expression patterning in mouse and human cortex. Distinct molecular signatures span all major cell types, but primarily suggest a shift from corticosubcortical to more predominant corticocortical communications in the human brain.

Canonical genetic signatures of the adult human brain

Genes with the most reproducible patterns between adult human brains are highly biologically relevant, with enrichment for brain-related annotations such as disease associations. Furthermore, most genes are expressed in one of a relatively few patterns, corresponding to cell types and cellular functions. Research-grade code to reproduce figures is included as supplemental software.

A High-Resolution Spatiotemporal Atlas of Gene Expression of the Developing Mouse Brain

The timing of peak gene expression patterns corresponds to distinct developmental phenomena associated with a specific brain structures, with midbrain preceding cortical structures. In addition, a transcription factor code of 83 genes uniquely identifies age and brain region.

Transcriptional landscape of the prenatal human brain

This atlas gives a comprehensive view of when and where genes are expressed while the brain is developing, providing insight into dynamic changes in gene expression over time. For example, genes associated with autism are enriched in newly generated excitatory neurons in the cortex.

A comprehensive transcriptional map of primate brain development

Prenatal development is a time of rapid change reflected in gene usage, yet many of the molecular characteristics of the mature brain are achieved surprisingly late in postnatal development. The vast majority -- but not all -- of these patterns are conserved between primate species.

Transcriptional Architecture of the Primate Neocortex

Microarray analysis of individual cortical layers across cortex identified specific molecular signatures for individual cortical layers and areas. Overall, transcriptome-based relationships were related to spatial proximity, being strongest between neighboring cortical areas and between proximal layers. Laminar patterns were more similar between macaque and human compared to mouse.

An anatomic transcriptional atlas of human glioblastoma

Histologically-defined anatomic regions of glioblastoma are shown here to have highly distinct molecular signatures. This, and other yet-to-be-discovered insights in the Ivy Glioblastoma Atlas Project (GAP) could provide new insights into the pathogenesis, diagnosis, and treatment of glioblastoma.

Neuropathological and transcriptomic characteristics of the aged brain

At the transcriptional level, the aging brain shows remarkable person-to-person variability between dementia and associated pathologies, including examples of resilience to pathology. This study also highlights the importance of controlling for RNA quality when studying the normal and diseased human brain.


DISCUSSION

The results of this study support our hypothesis that FMS is associated with significant changes in the cerebral microstructure of brain areas known to be functionally linked to core symptoms of FMS. Furthermore, correlational analyses showed an association between the degree of microstructural tissue changes and the intensity of several major FMS symptoms.

One of the most prominent symptoms reported by patients with FMS is chronic widespread pain and diffuse tenderness. Although the clinical diagnosis of FMS requires the presence of 11 of 18 tender points, the increased sensitivity to pressure in FMS extends beyond tender points and involves the entire body ( 25 ). A study using functional MR imaging in patients with FMS demonstrated that the application of mild pressure could result in subjective pain reports and brain activation that were qualitatively and quantitatively similar to many of the effects produced by application of at least twice the pressure in healthy controls ( 26 ). These findings are corroborated by many of the results from our study.

The primary somatosensory cortex as part of the postcentral gyrus, which receives the bulk of thalamocortical projections from the sensory input fields, showed bilateral and significant increases in FA. In contrast, FA in the right and left thalamic regions was significantly lower. These findings are in partial agreement with those from 2 recent studies of patients with FMS, one of which demonstrated an isolated decrease in FA of the right thalamus using DTI ( 17 ), and the second showing a decrease in GM values in the left posterior thalamus using voxel-based morphometry ( 20 ). These disparities in comparison with the present results could be due to different locations of the ROIs within the thalamus.

The lateral structures, including the venterolateral thalamic nuclei, are thought to encode pain intensity, whereas the medial structures, including the dorsal medial thalamus, are thought to encode emotional aspects of pain ( 17 , 27-30 ). In our study, the ROI was located more in the posterior (primarily in the lateral and dorsal posterior nuclei and the pulvinar) thalamic structures, which project nociceptive, thermoreceptive, and pressure sensations to the primary somatosensory cortex. One could speculate that a reduced FA and a decrease in GM volumes within the thalamus are suggestive of dysfunctional changes. This brain area serves as a critical relay and filter between spinal and cortical structures, and thalamic dysfunction may therefore result in an increase of “unfiltered” sensory input to the primary somatosensory cortex, which, in turn, responds with an increase in FA that is probably indicative of increased plasticity.

We found no relationship between subjective pain intensity and our indicators of microstructural changes in the primary somatosensory cortex or the selected nuclei of the thalamus. Instead, enhanced pain intensity was associated with increased FA of the right superior frontal gyrus, a brain area shown by functional MR imaging to be activated by the affective components of pain ( 31 ). When compared with healthy control subjects, our patients had significantly higher FA values in this area. In addition, parts of the right superior frontal gyrus have also been implicated in emotional self-regulation ( 32 ) and pain catastrophizing in FMS ( 33 ). Pain catastrophizing is defined as the experience of pain as being unbearable, horrible, and awful and is known to be an important factor in chronification ( 34 ).

In addition to chronic widespread pain, debilitating fatigue and nonrestorative sleep are 2 of the most prominent features of FMS ( 35 ), and there is considerable overlap with another, common stress-related disorder, namely CFS. In our study, the degree of fatigue was correlated significantly with microstructural changes in the left frontal gyrus and anterior cingulate gyrus, and both of these brain areas showed significant differences in microcircuitry when compared with that in healthy, nonfatigued controls. Other reports have shown differences in brain morphology between patients with CFS and controls ( 36 ). A recent study using functional MR imaging in patients with CFS showed significant increases in activity in the cingulate and frontal brain areas during a fatiguing cognitive task ( 37 ). In addition, the attention to and processing of information from the inside world of an individual has been mapped to structures of the medial frontal lobes, including the superior frontal gyrus and cingulate gyrus ( 38 ). This could indicate that morphologic changes in these brain areas can lead to increased attention to physical changes and symptoms, including fatigue and pain, and to more pronounced emotional reactions to physical symptoms. This tendency is commonly seen in patients with FMS.

FMS is, however, not a homogeneous diagnosis but shows varying proportions of comorbid anxiety and depression that are dependent on the psychosocial characteristics of the patients ( 39 ). Major depression was excluded as a criterion in our patients, but anxiety was common in our FMS sample, as illustrated by the anxiety subscore of the FIQ. Patients with FMS showed bilateral microstructural changes in the amygdala, a brain area critical for the processing of fear and emotion ( 40 ). In addition, the degree of anxiety was related to ADC and FA values from the right superior frontal gyrus and the right anterior cingulate, and both brain areas in these patients showed significant differences in microstructure when compared with healthy controls.

The prominent role of morphologic changes in the anterior cingulate in stress-related disorders has also been illustrated by a recent study in patients with PTSD in which DTI was used ( 41 ). Comparable with our findings, patients with PTSD had significantly higher FA values in the right anterior cingulate, and the symptom intensity of PTSD tended to correlate with FA in this brain area. PTSD symptoms as a comorbidity were common in our patient sample, and the mean PTSD scores measured with the PTSS-10 instrument exceeded the threshold of 35 points that is required for PTSD diagnosis with this questionnaire ( 10 ). This again suggests that there is a considerable overlap of symptoms in stress-related disorders.

Similarly, our patients had structural changes in the amygdala, which has also been demonstrated in patients with PTSD ( 42 ). There is evidence, from functional MR imaging studies in PTSD, of a direct influence of the amygdala on the medial frontal regions, particularly the anterior cingulate ( 42 ). PTSD has also been conceptualized as a disorder in the encoding and retrieval of traumatic memories, with a particularly important role of the amygdala and the hippocampus, and microstructural changes in these brain areas have been reported in patients with PTSD ( 43 , 44 ), in patients with chronic pain ( 14 ), in patients with fibromyalgia ( 19 ), and in our patients as well.

Likewise, our patients had significantly lower hippocampal volumes, as has been described frequently in individuals with PTSD ( 44 ). It is of interest to note that ADC values in the hippocampus of our patients correlated negatively with the number of traumatic memories reported on the standardized questionnaire, including memories of pain. This suggests an increased microstructural complexity (reduced water diffusivity) of the hippocampus with an increase in traumatic memories.

A further important structure with documented involvement in both PTSD and FMS is the thalamus. A deactivation of this brain area has been shown in patients with PTSD during recall of traumatic information ( 45 , 46 ). In our study, we found weak, but statistically significant, correlations between PTSD stress-symptom intensity scores and ADC values in this brain area. The important role of the thalamus in FMS has been demonstrated in several other imaging studies, which have shown a decrease in GM in the left dorsal thalamus, a decrease in regional cerebral blood flow ( 47 ) by single-photon–emission computed tomography in the right thalamus, and significantly lower FA values in the right thalamus as measured by DTI ( 20 ).

In our patients, the decrease in FA was bilateral, and the posterior thalamus was the only brain area, besides the anterior part of the insular cortex, with a significant reduction in FA, whereas all other ROIs showed increases in FA. In this regard, several studies have shown that the anterior insula is related to olfactory, gustatory, and autonomic functions, as well as the experience of temperature and pain ( 48 ). The anterior insular cortex receives inputs from the venteromedial nucleus (posterior part) of the thalamus, which is highly specialized to convey emotional/homeostatic information such as pain, temperature, itch, and sensual touch. Furthermore, the insula is believed to play an important role in body representation and subjective emotional experience and processes convergent information to produce an emotionally relevant context for sensory experience. This is also illustrated by the fact that painful thermal stimuli resulted in bilateral activation of the insula in patients with PTSD, but not in comparable subjects without PTSD ( 49 ). These findings from PTSD and FMS studies suggest that a structural reorganization of the brain is taking place, possibly as a result of a continuous nociceptive input ( 50 ), a severe stress exposure ( 51 ), or a combination of these effects ( 49 ).

Our study, as well as other investigations using different modes of brain imaging in different stress-induced disorders, has demonstrated comparable structural changes in brain areas that are active in pain and sensory perception, introspection and body awareness, the coordination of sensory input with emotions, including emotional responses to pain, the regulation of fear and anxiety states, and the encoding and retrieval of traumatic memories. These findings point to the fact that the complex neuromatrices of stress and pain overlap at these brain structures. This could help to explain, on a microstructural level of the brain, how a sustained activation of the stress-regulation system, with its complex, delicately balanced interactions, can give rise to chronic pain.

In summary, our study provides evidence of alterations in brain microcircuitry, as measured by MR-DTI, that are correlated with FMS symptom intensity. MR-DTI could serve as an additive diagnostic technique in FMS and probably other functional somatic syndromes. This could also help to resolve the longstanding debate regarding the legitimacy of FMS ( 52 ), which originated from the subjective nature of FMS symptoms in the absence of an objective diagnostic approach.


Confusion about the brain regions - temporal cortex, hippocampus and and white matter - Biology

The brain is constantly adapting throughout a lifetime, though sometimes over critical, genetically determined periods of time. Neuroplasticity is the brain’s ability to create new neural pathways based on new experiences. It refers to changes in neural pathways and synapses that result from changes in behavior, environmental and neural processes, and changes resulting from bodily injury. Neuroplasticity has replaced the formerly held theory that the brain is a physiologically static organ, and explores how the brain changes throughout life.

Neuroplasticity occurs on a variety of levels, ranging from minute cellular changes resulting from learning to large-scale cortical remapping in response to injury. The role of neuroplasticity is widely recognized in healthy development, learning, memory, and recovery from brain damage. During most of the 20th century, the consensus among neuroscientists was that brain structure is relatively immutable after a critical period during early childhood. It is true that the brain is especially ” plastic ” during childhood’s critical period, with new neural connections forming constantly. However, recent findings show that many aspects of the brain remain plastic even into adulthood.

Plasticity can be demonstrated over the course of virtually any form of learning. For one to remember an experience, the circuitry of the brain must change. Learning takes place when there is either a change in the internal structure of neurons or a heightened number of synapses between neurons. Studies conducted using rats illustrate how the brain changes in response to experience: rats who lived in more enriched environments had larger neurons, more DNA and RNA, heavier cerebral cortices, and larger synapses compared to rats who lived in sparse environments.

A surprising consequence of neuroplasticity is that the brain activity associated with a given function can move to a different location this can result from normal experience, and also occurs in the process of recovery from brain injury. In fact, neuroplasticity is the basis of goal-directed experiential therapeutic programs in rehabilitation after brain injury. For example, after a person is blinded in one eye, the part of the brain associated with processing input from that eye doesn’t simply sit idle it takes on new functions, perhaps processing visual input from the remaining eye or doing something else entirely. This is because while certain parts of the brain have a typical function, the brain can be “rewired”—all because of plasticity.

Synaptic Pruning

“Synaptic (or neuronal or axon ) pruning” refers to neurological regulatory processes that facilitate changes in neural structure by reducing the overall number of neurons and synapses, leaving more efficient synaptic configurations. At birth, there are approximately 2,500 synapses in the cerebral cortex of a human baby. By three years old, the cerebral cortex has about 15,000 synapses. Since the infant brain has such a large capacity for growth, it must eventually be pruned down to remove unnecessary neuronal structures from the brain. This process of pruning is referred to as apoptosis, or programmed cell death. As the human brain develops, the need for more complex neuronal associations becomes much more pertinent, and simpler associations formed at childhood are replaced by more intricately interconnected structures.

Pruning removes axons from synaptic connections that are not functionally appropriate. This process strengthens important connections and eliminates weaker ones, creating more effective neural communication. Generally, the number of neurons in the cerebral cortex increases until adolescence. Apoptosis occurs during early childhood and adolescence, after which there is a decrease in the number of synapses. Approximately 50% of neurons present at birth do not survive until adulthood. The selection of the pruned neurons follows the “use it or lose it” principle, meaning that synapses that are frequently used have strong connections, while the rarely used synapses are eliminated.

Neuron growth: Neurons grow throughout adolescence and then are pruned down based on the connections that get the most use.

Synaptic pruning is distinct from the regressive events seen during older age. While developmental pruning is experience-dependent, the deteriorating connections that occur with old age are not. Synaptic pruning is like carving a statue: getting the unformed stone into its best form. Once the statue is complete, the weather will begin to erode the statue, which represents the lost connections that occur with old age.