Showing papers on "Superior frontal gyrus published in 1995"

Cytoarchitectonic Definition of Prefrontal Areas in the Normal Human Cortex: II. Variability in Locations of Areas 9 and 46 and Relationship to the Talairach Coordinate System

Abstract: The human prefrontal cortex can be divided into structurally and functionally distinct cytoarchitectonic areas, but the extent of individual variation in the position, size, and shape of these areas is unknown. Using criteria described in the preceding companion article (Rajkowska and Goldman-Rakic, 1995), as well as visual inspection, we have mapped areas 9 and 46 in the frontal lobe of seven postmortem human brains, and completely reconstructed these dorsolateral regions in five of the seven cases. The lateral reconstructions in these five cases were analyzed and superimposed on the lateral view of the Talairach and Tournoux (1988) coordinate system in such a way as to render both the variability and the regions of overlap for the two prefrontal areas in the five different brains. Based on this exercise, we developed a set of conservative Talairach coordinates to define area 9 and 46. Area 9 is located on the dorsal, lateral, and dorsomedial surfaces of the frontal lobe extending along the middle third of the superior frontal gyrus and adjacent portions of the middle frontal gyrus in all cases examined. Area 46 lies on the dorsolateral convexity and is either partially or completely surrounded by area 9. It is consistently found on one or more convolutions of the middle frontal gyrus. The superior border of area 46 with adjacent cortex is also variable within the middle and superior frontal sulci, as is the inferior border within the upper wall of the inferior frontal sulcus. The genuine variability in the morphology of the human frontal lobe indicated by our findings suggests that the differences among the classical maps of Brodmann, von Economo and Koskinas, and Sarkissov and others may have been due to normal variation among the brains they analyzed. Such variation may underlie individual differences in the visuospatial and cognitive capacities subserved by these areas.

Nerve growth factor in Alzheimer's disease: increased levels throughout the brain coupled with declines in nucleus basalis

Abstract: The current study analyzed NGF protein levels in the brains of patients with Alzheimer9s disease (AD) as compared with aged neurologically normal individuals An established two-site ELISA was used to measure NGF-like immunoreactivity in the hippocampus, superior temporal gyrus, superior frontal gyrus, inferior parietal lobule, frontal and occipital cortical poles, cerebellum, amygdala, putamen, and nucleus basalis of Meynert (nbM) ChAT activity was assayed in adjacent tissue samples NGF levels were also evaluated in Parkinson9s disease for comparison with both AD and age-matched control cases Regardless of the brain bank (University of Cincinnati, Rush Presbyterian St Luke9s Medical Center in Chicago, or University of Alabama at Birmingham), NGF-like activity was at least moderately increased with AD in virtually every brain region examined except for the nbM, in which significant declines were observed NGF levels were also increased when compared with age- matched Parkinson9s cases (frontal cortex) NGF-like activity was not related to age at onset or disease duration in AD cases, nor did NGF levels correlate with age at death in the control or AD groups Correlations between ChAT and NGF-like activity across brains varied considerably and were generally not significant The present findings indicate that AD is characterized by a widespread increase in cortical and subcortical NGF Although a correlation with ChAT activity was not observed in cortex, the AD-related decline in NGF found in nbM is consistent with the possibility of impaired retrograde transport of NGF to this region

Functional Anatomy of Reaching and Visuomotor Learning: A Positron Emission Tomography Study

Abstract: The purpose of this study was to identify the functional cortical fields involved in reaching for targets in extrapersonal space, and to identify the specific fields representing visual target information in long-term memory. Ten healthy subjects were asked to learn the positions of seven circular targets that were repeatedly projected on a screen. The regional cerebral blood flow was measured with positron emission tomography during a rest state, at an early learning stage, at a later learning stage, and finally at 30 min after the course of learning had been completed. Mean rCBF change images for each task minus rest were calculated and fields of significant rCBF changes were identified. In all three task states, cortical fields were consistently activated in the left motor and premotor areas, the posterior part of the superior parietal lobule, and the right angular gyrus. When learning of the target positions had been achieved, additional fields appeared bilaterally in the posterior part of the superior parietal lobule, the right superior occipital gyrus, the left motor and premotor areas, the medial aspect of the superior frontal gyrus, the postcentral gyrus, the superior part of the cuneus, the inferior part of the angular gyrus, and the anterior part of the insula. The results indicate that there are at least two different types of functional fields in the posterior part of the superior parietal lobule; one is active during reaching for the targets when guided by internal representations of target positions; the other likely represents the storage sites of visual target information that is addressed in long-term memory.

[An autopsy case of corticobasal degeneration clinically misdiagnosed as Pick's disease].

Abstract: We report a 69-year-old woman who was clinically diagnosed as having a frontal lobe-type of Pick's disease. The initial symptoms were personality changes and problematic behaviors. The patient showed intellectual decline, "stehende Redensarten" and abnormal attitude in interpersonal situations such as inattentiveness and indifference in the course of the disease. Brain CT revealed a marked atrophy of the frontal lobes. In the terminal stage the patient had severe dementia, mutism, parkinsonism and cervical dystonia. Neuropathologically, there was a marked atrophy of the frontal lobes. The superior frontal gyrus was most severely atrophic. Histological study revealed mild to moderate loss of neurons, hyperplasia of protoplasmic astrocytes and many balooned neurons in the deep layers of the atrophied cerebral cortex. Severe neuronal loss was even seen only in a part of the superior frontal gyrus. The cerebral white manner showed marked diffuse fibrillary gliosis. There was neuronal loss with gliosis in the thalamus, lentiform nucleus, subthalamic nucleus, substantia nigra and inferior olivary nucleus. Marked gliosis was seen in the midbrain and pontine tegmentum. Sections from several levels of the spinal cord also showed marked gliosis of the gray matter. Antibodies against human tau stained massive argyrophilic thread-like structures and oligodendroglial microtubular masses in the affected lesions. Neurofibrillary tangles were localized in the hippocampus and parahippocampal region. Neither Pick's body nor senile plaque were observed. Corticobasal degeneration (CBD) is a neurodegenerative disease initially presenting with unilateral motor disturbances. Typical initial symptoms are rigidity, akinesia and apraxia of an affected arm. The clinical phenotype might depend upon the affected areas of the cerebral cortex. Our patient initially exhibited personality changes and was clinically diagnosed as having Pick's disease. Although our case had unusual distribution pattern of the cerebral atrophy, it was pathologically diagnosed as CBD. The review of the literature suggests the presence of clinical varieties in CBD.

Benzodiazepine binding sites in alcoholic cirrhotics: evidence for gender differences.

Abstract: Synaptic plasma membranes were prepared from superior frontal gyrus and motor cortex obtained at autopsy from 17 chronic alcoholics not differentiated on thiamine status, of whom 8 had pathologically confirmed cirrhosis of the liver, and 10 controls. Three of the cirrhotic alcoholic cases were female, as was one control. Cases were closely matched for age at death and post-mortem delay. The affinity of “central-type” benzodiazepine sites for [3H]diazepam tended to be lower in both brain regions of both groups of alcoholics ofcf controls, but the reverse was true for [3H]flunitrazepam, especially in cirrhotic cases. [3H]Diazepam affinity was invariant across all males and the female control, but lower in the female cirrhotic alcoholics. Affinity for [3H]flunitrazepam tended to be the reverse of that for [3H]diazepam. [3H]Diazepam Bmax was markedly lower in female cirrhotic alcoholics, especially in superior frontal gyrus, whereas this region showed a much higher Bmax in the female control case. A small regional difference in [3H]flunitrazepam Bmax was the reverse of that for [3H]diazepam Bmax and was seen in all groups. GABA-mediated neurotransmission may be selectively altered in a pathologically abnormal region of cerebral cortex in cirrhotic alcoholics, and the sexes may show differing susceptibilities to change.

Auditory comprehension in transcortical motor aphasia due to a medial lesions of the left frontal lobe

Abstract: We assessed the anatomical findings and auditory comprehension of six patients with transcortical motor aphasia due to medical lesions of the left frontal lobe. All patients were right-handed and were initially mute for several hours after the onset, and they exhibited mild paresis of the right lower extremity. Their spontaneous speech was sparse and not fluent, and sometimes accompanied by echolalia, but their articulation was normal and repetition was excellent. They had difficulty in recalling words. A diagnosis of transcortical motor aphasia was made on the basis of their clinical symptoms. All patients were found to have an infarct in the left medial frontal region by MRI and/or CT. We administered the Western Aphasia Battery and 50 line drawing pointing task in order to evaluate auditory comprehension. Based on the results we concluded that there is no impairment of auditory comprehension of single words when lesions are limited to the superior frontal gyrus, but that lesions extending to the middle frontal gyrus interfere with auditory comprehension of single words. Our observations indicate that the middle frontal gyrus plays an important role in auditory comprehension of single words. All of the patients displayed impaired auditory comprehension of sentences even when their lesions were strictly limited to the medial frontal lobe. This suggests that the medial frontal lobe plays some role in the auditory comprehension of sentences.