Cortex In Man Research Articles

The tondo and “The Power of the Center”

The tondo, a circular work of art, comprises a geometry that is said to increase the visual concentration on the picture's centre, a concentration that is enhanced by a picture frame. The present contribution discusses these observations from the perspective of the psychologist and the art historian, notes the perceptual differences between circular and other shapes of pictures, and refers to studies including eye-tracking methods, neurophysiological experiments on the visual cortex in man and macaques, and consideration of ocular factors. These studies provide considerable support for the "Power of the Center" when viewing tondi.

Structural covariance of amygdala subregions is associated with trait aggression and endogenous testosterone in healthy individuals

Many studies point toward volume reductions in the amygdala as a potential neurostructural marker for trait aggression. However, most of these findings stem from clinical samples, rendering unclear whether the findings generalize to non-clinical populations. Furthermore, the notion of neural networks suggests that interregional correlations in gray matter volume (i.e., structural covariance) can explain individual differences in aggressive behavior beyond local univariate associations. Here, we tested whether structural covariance between amygdala subregions and the rest of the brain is associated with self-reported aggression in a large sample of healthy young students (n = 263; 49% women). Salivary testosterone concentrations were measured for a subset of n = 40 male and n = 36 female subjects, allowing us to investigate the influence of endogenous testosterone on structural covariance. Aggressive individuals showed enhanced covariance between left superficial amygdala (SFA) and left dorsal anterior insula (dAI), but lower covariance between right laterobasal amygdala (LBA) and right dorsolateral prefrontal cortex (dlPFC). These structural patterns overlap with functional networks involved in the genesis and regulation of aggressive behavior, respectively. With increasing endogenous testosterone, we observed stronger structural covariance between right centromedial amygdala (CMA) and right medial prefrontal cortex in men and between left CMA and bilateral orbitofrontal cortex in women. These results speak for structural covariance of amygdala subregions as a robust correlate of trait aggression in healthy individuals. Moreover, regions that showed structural covariance with the amygdala modulated by either testosterone or aggression did not overlap, suggesting a complex role of testosterone in human social behavior beyond facilitating aggressiveness.

Cytoarchitectonics of the Superior Parietal Cortex of an Outstanding Russian Scientist-Physiologist

The aim of the study is to identify possible cytoarchitectonic features of the structure of the cortex in the superior parietal region of an outstanding and talented scientist-physiologist.Material and methods. The cortex (area 7) of the superior parietal region of a scientist-physiologist and men of the senile age in the control group (8 hemispheres) was studied on the series of frontal brain slices, 20 μ thick, stained with cresyl purple according to Nissl method. The cortex area thickness, the thickness of the cytoarchitectonics layer III, the area of profile field of pyramidal neurons in layers III and V, the density of neurons surrounded by satellite glia and satellite glia density in layers III and V were measured in the cortex (area 7) of the superior parietal region in the left and right hemispheres of the brain.Results. We have identified several features of the cytoarchitectonics structure of the cortex (area 7) in the brain of the scientist-physiologist that may correlate with his outstanding scientific abilities. The cortex of a scientist-physiologist is characterized by a large thickness of the studied cortex and its cytoarchitectonic layers III and V, and a greater value of the area of the profile field of neurons if compared with the cortex in men of the senile age from the control group. A higher value of the neuron density and satellite glia in the cortex of the superior parietal region of the scientist-physiologist was revealed. There was also a lower severity of age-related changes in the cortex of the scientist-physiologist compared with the control group of men.Conclusion. The structure of the cortex (area 7) of the superior parietal region of the scientistphysiologist is characterized by a greater parameter of the cortical thickness and the thickness of the associative layer III, the size of neurons and the density of satellite glia if compared with those in men of the senile age of the control group. These features distinguish the structure of his cortex from the similar cortex of the control group of men and may be related to the features of the cognitive activity of the outstanding scientist-physiologist.

AGE-RELATED CHANGES OF THE PROFILE FIELD OF NEURONS OF THE AREA 7 OF THE BRAIN OF MEN AND WOMEN IN THE PROCESS OF THE AGING

The aim of the work is to study changes in the profile field of pyramidal neurons in the cortex of field 7 of the brain of men and women in the aging process. A cytoarchitectonic study of the cortex of field 7 of the upper parietal region of the brain of men and women was carried out on a series of frontal paraffin sections stained by the Nissl method. The brain preparations of men and women of three age groups were studied: the groups of mature age (from 20 to 60 years), the elderly group (from 60 to 75 years) and the group of senile age (from 75 years and older). In each age group, 5 preparations of the male brain and 5 preparations of the female brain were studied. Age-related changes in the cytoarchitectonics of the profile field of pyramidal neurons in the cytoarchitectonic layers of the third and fifth cortex fields 7 of the brain of men and women were studied. As a result of the study, it was revealed that in the process of aging of the brain of men and women, changes in similar morphometric indicators of field 7 cortex occur at different age periods, the dynamics of age-related changes in functionally different cytoarchitectonic layers III and V of the cerebral cortex of men and women are also different.

Neuroglial Complex of the Prefrontal Cortex in Men and Women of the Senile Age

The aim of study was to investigate the neuroglial complex of the prefrontal cortex BA10 area in men and women of the senile age in comparison with the similar parameters in the elderly people. Material and methods. The study of the neuroglial complex was carried out on a series of frontal total sections of 5 male and 5 female brains in people of the senile age. Totally 20 male and female brain hemispheres were studied. The material was obtained no later than 24 hours after death and was fixed in 10% formalin solution. 20-micron-thick samples were stained with cresyl violet using Nissl method. The density of neurons, total glia, satellite gliocytes and neurons surrounded by them were investigated. Statistical data processing was performed in STATISTICA 12. Results. The study revealed gender age-related differences of the neuroglial complex morphometric parameters of the prefrontal cortex BA10 area in men and women. The decrease in the density of neurons, the proportion of satellite glia, the increase in the density of total glia were more significantly expressed in senile men than in senile women. These changes were more pronounced in the left hemisphere of the male brain and equally pronounced in both hemispheres in the female brain. Conclusion . Thus, this study detected features of the neuroglial complex of the prefrontal cortex BA10 area in men and women of the senile age. There was revealed the more significant decrease in the density of pyramidal neurons and satellite gliocytes in the cytoarchitectonic layer III of the prefrontal cortex BA10 area of the male brain compared with the similar layer of the female brain.

Altered gray matter volume and disrupted functional connectivity of dorsolateral prefrontal cortex in men with heroin dependence.

Chronic heroin use can cause various neuropathological characteristics that may compromise brain function. The present study evaluated the alteration of gray matter volume (GMV) and its resting-state functional connectivity (rsFC) over the dorsolateral prefrontal cortex (DLPFC) among male heroin users. Thirty heroin-dependent men undergoing methadone maintenance therapy and 30 educational-level- and age-matched male controls were recruited for this study. To assess their GMV and rsFC, the participants were evaluated using spoiled gradient echo and gradient-recalled echo planar imaging sequences with a 3-Tesla General Electric MR scanner under resting state. The heroin-dependent men showed lower GMV over the right DLPFC in comparison with the controls. Further evaluation of the rsFC of the right DLPFC revealed a marked decrease in interhemispheric DLPFC connectivity among those with heroin dependence under control of head movement and GMV of the right DLPFC. Although the mechanism remains unclear, the present study shows that chronic heroin use is associated with alteration of morphology as well as rsFC over the right DLPFC. As the DLPFC plays an imperative role in various domains of cognitive function, service providers for heroin users should consider the impacts of possible DLPFC-related cognitive deficits on treatment effectiveness.

N-Acetyl-Aspartate in the dorsolateral prefrontal cortex in men with schizophrenia and auditory verbal hallucinations: A 1.5\u2009T Magnetic Resonance Spectroscopy Study

Auditory verbal hallucinations (AVH) in patients with schizophrenia are linked to abnormalities within a large cerebral network including frontal and temporal regions. Whilst abnormalities of frontal speech production and temporal speech perception regions have been extensively studied, alterations of the dorsolateral prefrontal cortex (DLPFC), a region critically involved in the pathophysiology of schizophrenia, have rarely been studied in relation to AVH. Using 1.5 T proton magnetic resonance spectroscopy, this study examined the relationship between right and left DLPFCs N-AcetylAspartate (NAA) levels and the severity of AVH in patients with schizophrenia. Twenty-seven male patients with schizophrenia were enrolled in this study, 15 presented daily treatment-resistant AVH (AVH+) and 12 reported no AVH (no-AVH). AVH+ patients displayed higher NAA levels in the right DLPFC than no-AVH patients (p = 0.033). In AVH+ patients, NAA levels were higher in the right DLPFC than in the left (p = 0.024). No difference between the right and left DLPFC was observed in no-AVH patients. There was a positive correlation between NAA levels in the right DLPFC and the severity of AVH (r = 0.404, p = 0.037). Despite limited by magnetic field strength, these results suggest that AVH may be associated with increased NAA levels in the right DLPFC in schizophrenia.

Inattention Predicts Increased Thickness of Left Occipital Cortex in Men with Attention-Deficit/Hyperactivity Disorder.

Attention-deficit/hyperactivity disorder (ADHD) in adulthood is a serious and frequent psychiatric disorder with the core symptoms inattention, impulsivity, and hyperactivity. The principal aim of this study was to investigate associations between brain morphology, i.e., cortical thickness and volumes of subcortical gray matter, and individual symptom severity in adult ADHD. Surface-based brain morphometry was performed in 35 women and 29 men with ADHD using FreeSurfer. Linear regressions were calculated between cortical thickness and the volumes of subcortical gray matter and the inattention, hyperactivity, and impulsivity subscales of the Conners Adult ADHD Rating Scales (CAARS). Two separate analyses were performed. For the first analysis, age was included as additional regressor. For the second analysis, both age and severity of depression were included as additional regressors. Study participants were recruited between June 2012 and January 2014. Linear regression identified an area in the left occipital cortex of men, covering parts of the middle occipital sulcus and gyrus, in which the score on the CAARS inattention subscale predicted increased mean cortical thickness [F(1,27) = 26.27, p < 0.001, adjusted R2 = 0.4744]. No significant associations were found between cortical thickness and the scores on CAARS subscales in women. No significant associations were found between the volumes of subcortical gray matter and the scores on CAARS subscales, neither in men nor in women. These results remained stable when severity of depression was included as additional regressor, together with age. Increased cortical thickness in the left occipital cortex may represent a mechanism to compensate for dysfunctional attentional networks in male adult ADHD patients.

Similarities in trabecular hypertrophy with site-specific differences in cortical morphology between men and women with type 2 diabetes mellitus.

The goal of our study was to investigate interactions between sex and type 2 diabetes mellitus (T2DM) with regard to morphology of the peripheral skeleton. We recruited 85 subjects (mean age, 57±11.4 years): women with and without T2DM (n = 17; n = 16); and men with and without T2DM (n = 26; n = 26). All patients underwent high-resolution, peripheral, quantitative, computed tomography (HR-pQCT) imaging of the ultradistal radius (UR) and tibia (UT). Local bone geometry, bone mineral density (BMD), and bone microarchitecture were obtained by quantitative analysis of HR-pQCT images. To reduce the amount of data and avoid multi-collinearity, we performed a factor-analysis of HR-pQCT parameters. Based on factor weight, trabecular BMD, trabecular number, cortical thickness, cortical BMD, and total area were chosen for post-hoc analyses. At the radius and tibia, diabetic men and women exhibited trabecular hypertrophy, with a significant positive main effect of T2DM on trabecular number. At the radius, cortical thickness was higher in diabetic subjects (+20.1%, p = 0.003). Interestingly, there was a statistical trend that suggested attenuation of tibial cortical hypertrophy in diabetic men (cortical thickness, pinteraction = 0.052). Moreover, we found an expected sexual dichotomy, with higher trabecular BMD, Tb.N, cortical BMD, Ct.Th, and total area in men than in women (p≤ 0.003) at both measurement sites. Our results suggest that skeletal hypertrophy associated with T2DM is present in men and women, but appears attenuated at the tibial cortex in men.

Gendernye osobennosti stroeniya prefrontal'noj kory mozga muzhchin i zhenshchin

Gendernye osobennosti stroeniya prefrontal'noj kory mozga muzhchin i zhenshchin

Age-Related Sex-Specific Changes in Brain Metabolism and Morphology.

With a large database, we aimed to evaluate sex-specific distinctive changes in brain glucose metabolism and morphology during normal aging using MRI and (18)F-FDG PET. A total of 963 cognitively healthy adults were included in this study. All subjects completed a medical questionnaire, took the mini-mental state examination, and underwent brain MRI and whole-body (18)F-FDG PET. The MR and PET images were statistically analyzed using 3-dimensional stereotactic surface projection. All images were corrected for whole-brain pixel value to identify the brain regions with significant changes, and regions of interest were set up with reference to Brodmann areas. We evaluated morphologic and glucose metabolic changes by cross-sectional analysis. The baseline database consisted of subjects from 30 to 40 y old, and the age-step for comparison was 5-y ranges. We also compared sex-specific differences in MR and PET images in each age group. Regarding age-related changes, in both sexes brain atrophy was observed in the lateral frontal and parietal regions and glucose hypometabolism in the medial frontal regions. There were significant differences in these parameters between the sexes; parallel changes in volume and metabolism were manifested in the medial frontal cortex in men and in the lateral and medial temporal cortex in women. By contrast, metabolism-dominant reductions were manifested in the lateral and medial parietal cortex in men and in the ventrolateral prefrontal cortex, including the Broca area, in women. These differences became insignificant in individuals 66 y or older. Our brain mapping study with a large number of reference human brain data demonstrated age-related parallel changes between morphology and metabolism in the medial frontal regions and sex-specific hypometabolism in the parietal (male) and ventrolateral prefrontal (female) cortices. These findings may suggest an aging vulnerability in sex-specific brain regions: the parietal cortex for visuospatial ability in men and the Broca area for speech processing in women.

Relating education, brain structure, and cognition: the role of cardiovascular disease risk factors.

The protective effect of education on cognitive and brain health is well established. While the direct effects of individual cardiovascular disease (CVD) risk factors (i.e., hypertension, smoking, diabetes, and obesity) on cerebral structure have been investigated, little is understood about the possible interaction between the protective effect of education and the deleterious effects of CVD risk factors in predicting brain ageing and cognition. Using data from the PATH Through Life study (N = 266), we investigated the protective effect of education on cerebral structure and function and tested a possible mediating role of CVD risk factors. Higher education was associated with larger regional grey/white matter volumes in the prefrontal cortex in men only. The association between education and cognition was mediated by brain volumes but only for grey matter and only in relation to information processing speed. CVD risk factors did not mediate the association between regional volumes and cognition. This study provides additional evidence in support for a protective effect of education on cerebral structures and cognition. However, it does not provide support for a mediating role of CVD risk factors in these associations.

Intranasal insulin increases regional cerebral blood flow in the insular cortex in men independently of cortisol manipulation

Insulin and cortisol play a key role in the regulation of energy homeostasis, appetite, and satiety. Little is known about the action and interaction of both hormones in brain structures controlling food intake and the processing of neurovisceral signals from the gastrointestinal tract. In this study, we assessed the impact of single and combined application of insulin and cortisol on resting regional cerebral blood flow (rCBF) in the insular cortex. After standardized periods of food restriction, 48 male volunteers were randomly assigned to receive either 40 IU intranasal insulin, 30 mg oral cortisol, both, or neither (placebo). Continuous arterial spin labeling (CASL) sequences were acquired before and after pharmacological treatment. We observed a bilateral, locally distinct rCBF increase after insulin administration in the insular cortex and the putamen. Insulin effects on rCBF were present regardless of whether participants had received cortisol or not. Our results indicate that insulin, but not cortisol, affects blood flow in human brain structures involved in the regulation of eating behavior.

Relationships between mandibular cortical indexes, bone mineral density, and osteoporotic fractures in Brazilian men over 60 years old

The aim of this study was to assess relationships between panoramic indexes, bone mineral density (BMD), and osteoporotic fractures in men >60 years old. Body height and weight, body mass index, lumbar spine and hip BMD, and the presence of osteoporotic fractures were determined in the 127 studied men. Dental panoramic radiographs (DPRs) were used for measuring mandibular cortical indexes. BMDs were lower in patients with thinning and resorption of mandibular cortex. No association was found between mandibular indexes and the presence of osteoporotic fractures. In a forward stepwise logistic regression model, the odds of having a T score ≤-2.5 was increased by 1.97 times for every 1-mm reduction in average mandibular cortical width. DPRs could show pronounced thinning of the inferior mandibular cortices in men >60 years old. However, there was no apparent association between vertebral fragility fractures and the appearance of mandibular cortex in elderly men.

Cytoarchitectonic Characteristics of the Speech Motor Fields of the Cortex in Men and Women

The cytoarchitectonics of the speech motor cortical fields 44 and 45 in the left and right hemispheres were studied in men and women. Serial frontal sections stained with cresyl violet by the Nissl method were examined. The areas of neuron profiles were measured in layer III, along with its thickness and the crosssectional thickness of the cortex. There were no significant differences in these parameters between men and women. However, there were tendencies to larger values in men than in women in the left hemisphere of the brain and in women than in men in the right hemisphere.

Effect of Moxication on the Adrenal Cortex in Man (1)

Effect of Moxication on the Adrenal Cortex in Man (1)

Painful tonic heat stimulation induces GABA accumulation in the prefrontal cortex in man

Relatively little is known on pain-induced neurotransmitter release in the human cerebral cortex. We used proton magnetic resonance spectroscopy ( 1H-MRS) during tonic painful heat stimulation to test the hypothesis of increases in both glutamate and GABA, two neurotransmitters with a key role in pain processing. Using a 3 T MR scanner, we acquired spectra from the rostral anterior cingulate cortex (rACC) in 13 healthy right-handed subjects at rest and during painful heat stimulation. The painful stimulus consisted of a suprathreshold painful tonic heat pulse, which was delivered to the right upper leg via a fMRI-compatible Peltier element. Compared to non-painful stimulation, painful tonic heat was associated with a significant increase in GABA concentrations in the rACC. No changes in glutamate concentrations were detected during noxious stimulation. This study provides the first evidence that GABA is released in the human cerebral cortex during painful stimulation. The results are in line with animal findings on the role of GABA in pain processing and with studies in humans showing analgesic efficacy of GABA-related drugs in clinical pain conditions.

The effects of two different repetitive TMS stimulation protocols on muscle fatigue associated changes in excitability of motor cortex in man

The effects of two different repetitive TMS stimulation protocols on muscle fatigue associated changes in excitability of motor cortex in man

Accurate prediction of V1 location from cortical folds in a surface coordinate system

Previous studies demonstrated substantial variability of the location of primary visual cortex (V1) in stereotaxic coordinates when linear volume-based registration is used to match volumetric image intensities [Amunts, K., Malikovic, A., Mohlberg, H., Schormann, T., and Zilles, K. (2000). Brodmann’s areas 17 and 18 brought into stereotaxic space—where and how variable? Neuroimage, 11(1):66–84]. However, other qualitative reports of V1 location [Smith, G. (1904). The morphology of the occipital region of the cerebral hemisphere in man and the apes. Anatomischer Anzeiger, 24:436–451; Stensaas, S.S., Eddington, D.K., and Dobelle, W.H. (1974). The topography and variability of the primary visual cortex in man. J Neurosurg, 40(6):747–755; Rademacher, J., Caviness, V.S., Steinmetz, H., and Galaburda, A.M. (1993). Topographical variation of the human primary cortices: implications for neuroimaging, brain mapping, and neurobiology. Cereb Cortex, 3(4):313–329] suggested a consistent relationship between V1 and the surrounding cortical folds. Here, the relationship between folds and the location of V1 is quantified using surface-based analysis to generate a probabilistic atlas of human V1. High-resolution (about 200 μm) magnetic resonance imaging (MRI) at 7 T of ex vivo human cerebral hemispheres allowed identification of the full area via the stria of Gennari: a myeloarchitectonic feature specific to V1. Separate, whole-brain scans were acquired using MRI at 1.5 T to allow segmentation and mesh reconstruction of the cortical gray matter. For each individual, V1 was manually identified in the high-resolution volume and projected onto the cortical surface. Surface-based intersubject registration [Fischl, B., Sereno, M.I., Tootell, R.B., and Dale, A.M. (1999b). High-resolution intersubject averaging and a coordinate system for the cortical surface. Hum Brain Mapp, 8(4):272–84] was performed to align the primary cortical folds of individual hemispheres to those of a reference template representing the average folding pattern. An atlas of V1 location was constructed by computing the probability of V1 inclusion for each cortical location in the template space. This probabilistic atlas of V1 exhibits low prediction error compared to previous V1 probabilistic atlases built in volumetric coordinates. The increased predictability observed under surface-based registration suggests that the location of V1 is more accurately predicted by the cortical folds than by the shape of the brain embedded in the volume of the skull. In addition, the high quality of this atlas provides direct evidence that surface-based intersubject registration methods are superior to volume-based methods at superimposing functional areas of cortex and therefore are better suited to support multisubject averaging for functional imaging experiments targeting the cerebral cortex.

Vestibular integration in human cerebral cortex contributes to spatial remapping

The process of visuo-spatial updating is crucial in guiding human behaviour. While the parietal cortex has long been considered a principal candidate for performing spatial transformations, the exact underlying mechanisms are still unclear.In this study, we investigated in a patient with a right occipito-parietal lesion the ability to update the visual space during vestibularly guided saccades. To quantify the possible deficits in visual and vestibular memory processes, we studied the subject's performance in two separate memory tasks, visual (VIS) and vestibular (VES). In the VIS task, a saccade was elicited from a central fixation point to the location of a visual memorized target and in the VEST task, the saccade was elicited after whole-body rotation to the starting position thus compensating for the rotation. Finally, in an updating task (UPD), the subject had to memorize the position of a visual target then after a whole-body rotation he had to produce a saccade to the remembered visual target location in space. Our main findings was a significant hypometria in the final eye position of both VEST and UPD saccades induced during rotation to the left (contralesional) hemispace as compared to saccades induced after right (ipsilesional) rotation. Moreover, these deficits in vestibularly guided saccades correlated with deficits in vestibulo-ocular time constant, reflecting disorders in the inertial vestibular integration path. We conclude that the occipito-parietal cortex in man can provide a first stage in visuo-spatial remapping by encoding inertial head position signals during gaze orientation.