Human visual evoked potentials during the recognition of facial emotional expression

Visual evoked potentials (VEPs) were recorded in 22 right-handed healthy subjects in the occipital, parietal, central, frontal and posterotemporal cortical areas during recognition and passive viewing of positive, negative, and neutral emotional facial expression. Peak latencies of N90, P150, and N180 VEP components appeared to be significantly shorter in response to the negative emotional expression than during administration of other facial stimuli. The differences were observed both during active recognition and passive viewing. Correct recognition was characterized by involvement of both hemispheres and high level of interhemispheric correlation between the peak latencies of P150 in the posterotemporal and of N180 in the frontal areas. It is suggested that the facial expressions are primarily recognized at the subthreshold level with participation of the posterotemporal areas. The role of the frontal areas is discussed in the completion of this process and making the correct decision about the image.     

Neurochemical asymmetry of human cerebral hemispheres

The study was concerned with cholinesterase activity and acetylcholine content in the cortical tissue of the human brain, obtained in autopsy and during neurosurgery. A symmetry of cholinesterase activity was found in paired cortical zones of the cutaneous analyser, while in the cortical substance of the motor analyser, its activity was asymmetrical. In the parietal cortex the acetylcholine content was almost equal on two sides; a tendency to its asymmetry was noted in the frontal area. These characteristics of interhemispheric transmitter-enzyme relations between symmetrical cortical centres seem to be a link in the mechanism underlying paired and asymmetrical activity of cortical areas of the cerebral hemispheres in humans.     

Lateralization of emotionality in right parietal cortex of the rat.

Lesions of right parietal cortex in the rat increase activity in the open field compared with left parietal lesions, especially after section of the corpus callosum. Left or right motor or medial frontal cortex lesions do not have a lateralized effect. This evidence of a localized asymmetry between the cerebral hemispheres strongly implies that right parietal cortex has a role in emotionality in this species. Our findings suggest a functional similarity to right parietal cortex in man. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies on integrative functions of the human frontal association cortex with MEG

Our MEG studies on the human frontal association cortex are briefly reviewed. (1) The no-go potential was first found at go/no-go reaction-time hand movement task with discrimination between different colour light stimuli in the prefrontal cortex of monkeys. The potential was recorded in human subjects with EEG over the scalp, but its current dipoles could be localized only by use of MEG, in the dorsolateral part of the frontal association cortex in both cerebral hemispheres. The function for no-go decision and subsequent suppressor action was thus substantiated in the human frontal cortex. (2) Utterance of a short noun in Japanese was found to be initially preceded by an activity in the lower lateral part of the frontal lobe and then by that around the central sulcus. The area of the former, often in both hemispheres, appears to correspond to Broca's motor speech centre and that of the latter, always in both hemispheres, to correspond to the motor-somatosensory cortices. (3) Intensive and continuous concentration on mental calculation and some 'abstract' thinking for a few minutes were often associated with magnetic theta (5-7 Hz) wave bursts in the frontal part of the scalp. Dipole fitting suggested that the electrical current dipoles occur successively and scattered in wide areas of the frontal lobe on both sides. They are to be called "frontal mental theta wave", revealing dynamic and active participation of the frontal lobe in mental functions.     

Regional brain activity during tasks devoted to the central executive of working memory

Most previous PET studies investigating the central executive (CE) component of working memory found activation in the prefrontal cortex. However, the tasks used did not always permit to distinguish precisely the functions of the CE from the storage function of the slave systems. The aim of the present study was to isolate brain areas that subserve manipulation of information by the CE when the influence of storage function was removed. A PET activation study was performed with four cognitive tasks, crossing conditions of temporary storage and manipulation of information. The manipulation of information induced an activation in the right (BA 10/46) and left (BA 9/6) middle frontal gyrus and in the left parietal area (BA7). The interaction between the storage and manipulation conditions did not reveal any significant changes in activation. These results are in agreement with the hypothesis that CE functions are distributed between anterior and posterior brain areas, but could also reflect a simultaneous involvement of controlled (frontal) and automatic (parietal) attentional systems. In the other hand, the absence of interaction between the storage and manipulation conditions demonstrates that the CE is not necessarily related to the presence of a memory load.     

Effects of parietal cortex lesions on spatial problem solving in the rat

The Maier 3-table task was used to examine spatial representations in rats with lesions of the parietal cortex. Some animals had anteriorly placed lesions, some posteriorly placed in cortical areas, sometimes regarded as 'parietal' in earlier studies. After 5 days of familiarization, animals were given 18 days of testing on the standard Maier task. Both parietal groups were initially impaired, but reached the same level of performance as controls by the end of the test period. Learning occurred both within and between sessions for the anterior group, but only between sessions for the posterior group. There was no major functional differentiation apparent on this task between the two 'parietal' areas. Rate of exploration increased in both parietal groups across test sessions as task performance improved. It is argued that the change in exploratory activity across sessions in parietal groups may reflect the adoption of a compensatory strategy which improved performance, but that improvement could also have been due to neural changes, as structures, such as the frontal cortex or hippocampus, assume some functions normally mediated by the parietal area.     

The decoding of emotional concepts in patients with focal cerebral lesions

The effects of focal brain lesions on the decoding of emotional concepts in facial expressions were investigated. Facial emotions are hierarchically organized patterns comprising (1) structural surface features, (2) discrete (primary) emotional categories and (3) secondary dimensions, such as valence and arousal. Categorical decoding was measured using (1) selection of category labels and selection of the named emotion category; (2) matching one facial expression with two choice expressions. Dimensional decoding was assessed by matching one face with two different expressions with regard to valence or arousal. 70 patients with well documented cerebral lesions and 15 matched hospital controls participated in the study. 27 had left brain damage (LBD; 10 frontal, 10 temporal, 7 parietal); 37 had right brain damage (RBD; 15 frontal, 11 temporal, 11 parietal). Six additional patients had lesions involving both frontal lobes. Right temporal and parietal lesioned patients were markedly impaired in the decoding of primary emotions. The same patients also showed a reduced arousal decoding. In contrast to several patients with frontal and left hemisphere lesions, emotional conceptualization and face discrimination was not independent in these groups. No group differences were observed in valence decoding. However, right frontal lesions appeared to interfere with the discrimination of negative valence. Moreover, a distraction by structural features was noted in RBD when facial identities were varied across stimulus and response pictures in matching tasks with differing conceptual load. Our results suggest that focal brain lesions differentially affect the comprehension of emotional meaning in faces depending on the level of conceptual load and interference of structural surface features.     

Functional Frontoparietal Connectivity During Short-Term Memory as Revealed by High-Resolution EEG Coherence Analysis.

In this electroencephalographic study, the authors modeled the functional connectivity between frontal and parietal areas during short-term memory (STM) processes by spectral coherence analysis and the directed transfer function, that is, for the estimation of coherence "direction." A no-STM task was used as a reference. STM was characterized by an increased frontoparietal electroencephalograph coherence at high frequencies (beta and gamma, 14-45 Hz). In the control task, parietal-to-frontal flow prevailed at those frequencies. However, the STM task showed a bidirectional frontoparietal flow at the gamma band. In conclusion, frontoparietal connectivity would optimize "representational" memory during STM. In this context, the frontal areas would increase their influence on parietal areas for memory retention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regional differences of cerebral blood flow in the preterm infant

The purpose of our study was to evaluate the regional distribution of the resting cerebral blood flow (CBF) pattern in preterm neonates. Sixty-eight preterm babies with a gestational age of less than 34 weeks and a birth weight of less than 1500 g were enrolled into the study. The CBF was measured by the noninvasive intravenous 133Xenon method at three different times. Depending on the age we classified our measurements into three groups. Group 1: measurement between 2-36 h (n = 46). Group 2: measurement between 36-108 h (n = 39). Group 3: measurement between 108-240 h (n = 41). In all three groups CBF was significantly lower in the occipital region than in the frontal and parietal regions (group 1: frontal region 12.8 +/- 3.5 ml/100 g/min, parietal region 12.8 +/- 3.9 ml/100 mg/min, and occipital region 11.6 +/- 3.18 ml/100 g/min; group 2: frontal region 15.4 +/- 4.2 ml/100 g/min, parietal region 15.3 +/- 4.1 ml/100 g/min, and occipital region 13.4 +/- 3.5 ml/100 g/min; group 3: frontal region 14.6 +/- 3.6 ml/100 g/min, parietal region 14.6 +/- 3.2 ml/100 g/min, and occipital region 12.8 +/- 2.7 ml/100 g/min.). CBF did not differ between the left and the right hemispheres in either of the three measured regions. No gradient was found in infants between 108 h and 240 h of age with periventricular leukomalacia and periventricular haemorrhage. CONCLUSION. In preterm neonates the antero-posterior gradient of CBF is already present. Periventricular leukomalacia as well as periventricular haemorrhage may affect the regional regulation of CBF.     

Ectopic expression of SPARC in Xenopus embryos interferes with tissue morphogenesis: identification of a bioactive sequence in the C-terminal EF hand

A developmental chronometry hypothesis of early brain damage is suggested in which regions of the brain with a protracted course of postnatal development will be more vulnerable than earlier maturing areas to deleterious effects of early insult and, therefore, may become common sites of abnormality across many disorders originating in early childhood. Initial investigations of the cerebellum and frontal lobes are presented using MRI and neuropsychological measures. Planimetric measures of the cerebellar vermis (lobuli I-V and VI-VII) and pons, and neuropsychological frontal lobe measures were obtained from high functioning individuals with autism (A), survivors of acute lymphoblastic leukemia (ALL) with brain sequelae following radiation and chemotherapy, and from rigorously selected healthy controls (C). The neuropsychological results were clustered according to functions commonly related to frontal brain, posterior brain, and left and right hemispheres. The A and ALL groups, as compared to C, yielded modest but consistently reduced MRI measures for vermal lobuli I-V and VI-VII. Hypoplasia of lobuli VI-VII was more marked than I-V. Performance on neuropsychological tests for frontal lobe functions was generally depressed in both groups, with more severe deficits in A. Between-group differences in verbal, visual-spatial, and emotional-social skills are discussed. The cerebellar and frontal brain deficits that are present in both clinical groups (A and ALL) may be common to other developmental and acquired disorders of early childhood. Such joint manifestation of cerebellar and frontal lobe abnormalities is in agreement with the concept of cerebellar significance for the development of higher cognitive functions.     

Verbal fluency deficits in patients with schizophrenia: Semantic fluency is differentially impaired as compared with phonologic fluency.

Patients with schizophrenia show deficits in phonologic (ability to name words that begin with a specific letter, e.g., F) and semantic (ability to name members of a category, e.g., "animals" fluency.) Whereas the former deficit has been presumed to reflect a dysfunction of the frontal lobe, the latter has been linked to frontal and temporoparietal brain areas. These 2 verbal fluency measures were studied in a sample of 27 schizophrenia patients and 24 normal controls who were matched on age and a putative measure of premorbid intellectual ability. A 2-min production task of switching between letters and between categories measured demand for flexibility. On switching and nonswitching tasks controls produced more words during semantic versus phonologic fluency. Conversely, schizophrenia patients produced more words for letters than for categories, suggesting dysfunction of the frontal and temporoparietal areas of the brain. Furthermore, the greater impairment of semantic fluency may be related to a breakdown of semantic information processing beyond "executive" search and retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebral cortical hyperactivation in response to mental stress in patients with coronary artery disease

The central nervous system (CNS) effects of mental stress in patients with coronary artery disease (CAD) are unexplored. The present study used positron emission tomography (PET) to measure brain correlates of mental stress induced by an arithmetic serial subtraction task in CAD and healthy subjects. Mental stress resulted in hyperactivation in CAD patients compared with healthy subjects in several brain areas including the left parietal cortex [angular gyrus/parallel sulcus (area 39)], left anterior cingulate (area 32), right visual association cortex (area 18), left fusiform gyrus, and cerebellum. These same regions were activated within the CAD patient group during mental stress versus control conditions. In the group of healthy subjects, activation was significant only in the left inferior frontal gyrus during mental stress compared with counting control. Decreases in blood flow also were produced by mental stress in CAD versus healthy subjects in right thalamus (lateral dorsal, lateral posterior), right superior frontal gyrus (areas 32, 24, and 10), and right middle temporal gyrus (area 21) (in the region of the auditory association cortex). Of particular interest, a subgroup of CAD patients that developed painless myocardial ischemia during mental stress had hyperactivation in the left hippocampus and inferior parietal lobule (area 40), left middle (area 10) and superior frontal gyrus (area 8), temporal pole, and visual association cortex (area 18), and a concomitant decrease in activation observed in the anterior cingulate bilaterally, right middle and superior frontal gyri, and right visual association cortex (area 18) compared with CAD patients without myocardial ischemia. These findings demonstrate an exaggerated cerebral cortical response and exaggerated asymmetry to mental stress in individuals with CAD.     

Leptomeningeal angiomatosis accompanied by hair follicle nevus

A 5-day-old male infant with leptomeningeal angiomatosis accompanied by hair follicle nevus and congenital alopecia is reported. Admitted for frequent left hemiconvulsions, he had three small papular lesions around his right eye and ipsilateral alopecia from the frontal to parietal areas. Histopathological examination of the papular lesions revealed crowding of hair follicles. There were no other skin lesions and no ophthalmic abnormalities. Ictal EEG showed a theta burst in the right parietal area. Computed tomography of the brain revealed cerebral atrophy and a slightly high intensity lesion in the right parietal and occipital lobes with calcification. Gyriform enhancement was demonstrated by contrast MRI in these areas. The pathogenesis is discussed. This case may represent a previously unknown neurocutaneous syndrome.     

Cortical-hippocampal auditory processing identified by magnetoencephalography

We recorded magnetic and electrical responses simultaneously in an auditory detection task to elucidate the brain areas involved in auditory processing. Target stimuli evoked magnetic fields peaking at approximately the same latency of around about 400 msec (M400) over the anterior temporal, superior temporal, and parietal regions on each hemisphere. Equivalent current dipoles (ECDs) were analyzed with a time-varying multidipole model and superimposed on each subject's magnetic resonance image (MRI). Multiple independent dipoles located in the superior temporal plane, inferior parietal lobe, and mesial temporal region best accounted for the recorded M400 fields. These findings suggest that distributed activity in multiple structures including the mesial temporal, superior temporal, and inferior parietal regions on both hemispheres is engaged during auditory attention and memory updating.     

Chronic administration of a glycine partial agonist alters the expression of N-methyl-D-aspartate receptor subunit mRNAs

Both acute and chronic treatments with the glycine partial agonist 1-aminocyclopropanecarboxylic acid (ACPC) are neuroprotective in animal models of focal, global and spinal ischemia. After a chronic regimen of ACPC, brain and plasma levels were undetectable at the time of ischemic insult, which suggests that the neuroprotective effects of acute and chronic ACPC are mediated by different mechanisms. To investigate the possibility that chronic administration of ACPC alters N-methyl-D-aspartate (NMDA) receptor composition, the levels of mRNAs encoding zeta and epsilon subunits were quantified by in situ hybridization histochemistry with 35S-labeled riboprobes. Chronic ACPC administered to mice (200 mg/kg for 14 days) increased the level of epsilon-1 mRNA in the hippocampus (particularly CA1 and CA2 regions) and cerebral cortex (frontal, parietal and occipital regions), without altering levels in cerebellum. In contrast, this regimen decreased epsilon-3 subunit mRNA levels in the hippocampus (especially CA1 and dentate gyrus) and frontal and occipital cortices. Decreases in epsilon-2 subunit mRNA levels in cerebral cortex (especially frontal and parietal cortices) were also observed without accompanying alterations in the cerebellum, hippocampus or dentate gyrus. The levels of zeta subunit mRNA (determined with a probe that detects all splice variants) were not altered in any brain areas examined. Based on studies in recombinant receptors, these region-specific changes in mRNAs produced by a chronic regimen of ACPC could result in NMDA receptors with reduced affinities for glycine and glutamate. It is hypothesized that such alterations in NMDA receptor subunit composition may explain the neuroprotective effects produced by chronic ACPC.     

Transgenerational effects of abusive violence on the children of Vietnam combat veterans

The present study was aimed at the comparative assessment of electrophysiological and clinical data in persons (155 right-handed men) who took part in the Chernobyl clean-up in different periods after radiation. Dynamic evaluation of psychoneurological disorders revealed the growth of incidence and severity of cerebrovascular disturbances accompanied by the signs of organic symptoms' aggravation and encephalopathy in longer periods after radiation. The results of neuropsychological examination also showed the deterioration of patients' state manifested as growth of fatigue, cognitive defects, and emotional impairments. Analysis of the EEG parameters, including power and coherence mapping and 3-d dipole source localization analysis demonstrated the increasing number of patients with the most severe forms of EEG pathology: the "plane" type in combination with fast paroxysmal (beta-band) and slow forms of activity from 45% in 1990-92 to 63% in 1997. The "hypersynchronization" type of EEG activity was typical for the earlier period accompanied by the dominance of the pathological forms of EEG activity in mediobasal structures of the left hemisphere, and brainstem zones vs. diencephalon and the right hemisphere. The later period was characterized by decreasing coherence in symmetrical frontal and front-temporal areas of the left hemisphere, while in the early period the hypersynchronization prevailed in symmetrical central areas and in the right hemisphere. The evidence were obtained to a disconnection between the brain hemispheres. We suppose that the progressive involvement of structures of the limbic-reticular complex (especially, brainstem, mediobasal structures, and white matter) into the pathological process occurs with time in participants of clean-up of the Chernobyl disaster consequences.     

An assessment of oxidative damage to proteins, lipids, and DNA in brain from patients with Alzheimer's disease

Oxidative stress may contribute to neuronal loss in Alzheimer's disease (AD). The present study compares the levels of oxidative damage to proteins, lipids, and DNA bases from seven different brain areas of AD and matched control tissues by using a range of techniques. No differences in levels of lipid peroxidation were found in any of the brain regions by using two different assay systems. Overall, there was a trend for protein carbonyl levels to be increased in AD in frontal, occipital, parietal, and temporal lobe, middle temporal gyrus, and hippocampus, but a significant difference was found only in the parietal lobe. Gas chromatography-mass spectrometry was used to measure products of damage to all four DNA bases. Increased levels of some (8-hydroxyadenine, 8-hydroxyguanine, thymine glycol, Fapy-guanine, 5-hydroxyuracil, and Fapy-adenine), but not all, oxidized DNA bases were observed in parietal, temporal, occipital, and frontal lobe, superior temporal gyrus, and hippocampus. The baseline level of oxidative DNA damage in the temporal lobe was higher than in other brain regions in both control and AD brain. The finding of increased oxidative damage to protein and DNA strengthens the possibility that oxidative damage may play a role in the pathogenesis of AD in at least some key brain regions.     

Brain biopotential mapping in emotional and cognitive pathology

The EEG rhythms spectral power and intracortical connections were studied in depressive and schizophrenic patients in four schematically outlined main cortical quadrants. In depressive patients two cortical quadrants--right anterior and left posterior ones appeared to be predominantly involved in negative emotions regulation. Alpha-rhythm spectral power and cortical connections in these areas were decreased, pointing to their relative hyperactivation and functional disturbances. Schizophrenics patients were divided into two groups--with the predominance of "positive" and "negative" symptoms. In the first group there was revealed the decrease of the most EEG rhythms spectral power only in parietal areas, on the second one--in all cortical areas. There was also the significant alpha-rhythm spectral power asymmetry, different in the two groups of schizophrenic patients. In "positive" schizophrenics the decrease of alpha-rhythm spectral power was revealed in parietal and occipital areas of the right hemisphere, and in "negative" ones--vice versa, these results pointing of the relatively higher activation of the right posterior quadrant in the former group and of the left posterior quadrant in the latter one. In the anterior cortical quadrants the intracortical connections were however higher in the left hemisphere in "positive" and in the right one--in "negative" schizophrenics. Thus, there are some contradictory results obtained by different methods in anterior and posterior cortical quadrants in each hemisphere, these results being of opposite directions in patients with "positive" and "negative" manifestations. "Region of interest" (ROI) in schizophrenics appeared to be predominantly the frontal and temporal ones, while the "Rhythm of interest"--beta2.     

Expression of neuronal type nitric oxide synthase and renin in the juxtaglomerular apparatus of angiotensin type-1a receptor gene-knockout mice

OBJECTIVE: To determine whether the hypometabolism observed in PET images of patients with Alzheimer's disease (AD) is due entirely to brain atrophy. BACKGROUND: Reduced brain glucose metabolism in AD patients measured using PET has been reported by numerous authors. Actual glucose metabolic values in AD may be reduced artificially because of brain atrophy, which accentuates the partial volume effect (PVE) on data collected by PET. METHODS: Using segmented MR images, we corrected regional cerebral metabolic rates for glucose for PVEs to evaluate the effect of atrophy on uncorrected values for brain metabolism in AD patients and healthy control subjects. RESULTS: Global glucose metabolism was reduced significantly before and after correction in AD patients compared with controls. Before PVE correction, glucose metabolic values in patients were lower than in control subjects in the inferior parietal, frontal, and lateral temporal cortex; in the posterior cingulate; and in the precuneus. These reductions remained significantly lower after PVE correction, although in the posterior cingulate the difference in metabolism between AD patients and control subjects lessened. Regional glucose metabolism of these areas with PVE correction was lower in moderately-severely demented patients than in mildly demented patients. CONCLUSION: Reduced glucose metabolism measured by PET in AD is not simply an artifact due to an increase in CSF space induced by atrophy, but reflects a true metabolic reduction per gram of tissue.     

Effect of acute and chronic hypoxia on the structure of the neural elements of the brain

In rats subjected to the effect of 10 000 m "altitude" for 2 h, numerous nerve cells in different areas of the brain (cortex of both cerebral hemispheres, cerebellum, optic thalamus, hippocamp, pons varolii) had morphological features peculiar to a reversible and irreversible dystrophic process. Similar changes were not observed in the brain of rats subjected to the effect of 9000 m "altitude" for one hour. Nerve cells in all brain areas are rich in substance of Nissl. In the rats adapted to hypoxia, as in the rats from the first experiment, the nerve cells are enlarged in their dimentions, the substnace of Nissl in their cytoplasm is seem increased. The destructive changes in neurons are scarce. Many neurons of the cortex have signs pointing to an increased activity of nucleus and nucleolus. Satallitosis and quantitative augmentation of glial cells is noted.