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Parahippocampal Gyrus (parahippocampal + gyrus)

Distribution by Scientific Domains

Life Sciences	50%
Medical Sciences	42%

Selected Abstracts

Synaptophysin protein and mRNA expression in the human hippocampal formation from birth to old age,

HIPPOCAMPUS, Issue 8 2006
Sharon L. Eastwood
Abstract In the human neocortex, progressive synaptogenesis in early postnatal life is followed by a decline in synaptic density, then stability from adolescence until middle age. No comparable data are available in the hippocampus. In this study, the integral synaptic vesicle protein synaptophysin, measured immunoautoradiographically, was used as an index of synaptic terminal abundance in the hippocampal formation of 37 subjects from 5 weeks to 86 yr old, divided into 4 age groups (10 infants, 15 adolescents/young adults, 6 adults, and 6 elderly). In all hippocampal subfields, synaptophysin was lowest in infancy, but did not differ significantly between the older age groups, except in dentate gyrus (DG) where the rise was delayed until adulthood. A similar developmental profile was found in the rat hippocampus. We also measured synaptophysin mRNA in the human subjects and found no age-related changes, except in parahippocampal gyrus wherein the mRNA declined from infancy to adolescence, and again in old age. The synaptophysin protein data demonstrate a significant presynaptic component to human postnatal hippocampal development. In so far as synaptophysin abundance reflects synaptic density, the findings support an increase in hippocampal and parahippocampal synapse formation during early childhood, but provide no evidence for adolescent synaptic pruning. The mRNA data indicate that the maturational increases in synaptophysin protein are either translational rather than transcriptional in origin, or else are secondary to mRNA increases in neurons, the cell bodies of which lie outside the hippocampal formation. Published 2006 Wiley-Liss, Inc. [source]

Lag-sensitive repetition suppression effects in the anterior parahippocampal gyrus

HIPPOCAMPUS, Issue 5 2005
Craig J. Brozinsky
Abstract Single-unit recording studies of monkeys have shown that neurons in perirhinal and entorhinal cortex exhibit activity reductions following stimulus repetition, and some have suggested that these "repetition suppression" effects may represent neural signals that support recognition memory. Critically, repetition suppression effects are most pronounced at short intervals between stimulus repetitions. Here, we used event-related functional magnetic resonance imaging (fMRI) to identify repetition suppression effects in the human medial temporal lobe and determine whether these effects are sensitive to the length of the interval between repetitions. Twenty-one participants were scanned while performing a continuous recognition memory task in which the interval between item repetitions was parametrically varied from 2 to 32 intervening items. We found evidence of repetition suppression in the anterior parahippocampal gyrus, but only when the repetition interval was relatively short. Moreover, bilateral hippocampal regions showed lag-sensitive repetition effects. Our results demonstrate that activity in the human medial temporal cortex, like that of monkeys, exhibits repetition suppression effects that are sensitive to the length of the interval between repetitions. © 2005 Wiley-Liss, Inc. [source]

Dissociable neural responses in the hippocampus to the retrieval of facial identity and emotion: An event-related fMRI study

HIPPOCAMPUS, Issue 4 2003
Tetsuya Iidaka
Abstract In studies with brain-damaged patients and experimental animals, the medial temporal lobe, including the hippocampus and parahippocampal gyrus, has been found to play a critical role in establishing declarative or episodic memory. We measured the neural response in these structures, using event-related functional magnetic resonance imaging, while six healthy subjects performed the retrieval task for facial identity and emotion, respectively. Under the identity condition, the subjects participated in a yes/no recognition test for neutral faces learned before the scanning. Under the emotion condition, the subjects learned the faces with positive or negative expression and retrieved their expressions from neutral cue faces. The results showed that the left hippocampus is primarily involved in the identification of learned faces, and that the adjacent parahippocampal gyrus responds more to target than to distracter events. These results indicate a specific engagement of the left hippocampal regions in conscious recollection and identification of physiognomic facial features. The activity in the right hippocampus increased under both the identity and emotion conditions. The present results may relate with the functional model of face recognition in which the left hemisphere contributes to the processing of detailed features and the right hemisphere is efficient in the processing of global features. Hippocampus 2003;13:429,436. © 2003 Wiley-Liss, Inc. [source]

Representation of place by monkey hippocampal neurons in real and virtual translocation

HIPPOCAMPUS, Issue 2 2003
Etsuro Hori
Abstract The hippocampal formation (HF) is hypothesized as a neuronal substrate of a cognitive map, which represents environmental spatial information by an ensemble of neural activity. However, the relationships between the hippocampal place cells and the cognitive map have not been clarified in monkeys. The present study was designed to investigate how activity patterns of place-selective neurons encode spatial relationships of various environmental stimuli; to do this, we used multidimensional scaling (MDS) for hippocampal neuronal activity in the monkey during the performance of real and virtual translocation. Of 389 neurons recorded from the monkey HF and parahippocampal gyrus (PH), 166 had place fields that displayed increased activity in a specific area of an experimental field and/or on a monitor (place-selective neurons). The MDS transformed relationships among the 16 places in the experimental field and the monitor, expressed as correlation coefficients between all possible pairs of two places based on the 166 place-selective responses, into geometric relationships in a two-dimensional MDS space. In the real translocation tasks, the 16 places were distributed throughout the MDS space, and their relative positions were well correlated to real positions in the experimental laboratory. However, the correlation between the MDS space and real arrangements was significantly smaller in virtual than real translocation tasks. The present results strongly suggest that activity patterns of the HF and PH neurons represent spatial information and might provide a neurophysiological basis for a cognitive map. Hippocampus 2003;13:190,196. © 2003 Wiley-Liss, Inc. [source]

Genetic influences on human brain structure: A review of brain imaging studies in twins,

HUMAN BRAIN MAPPING, Issue 6 2007
Jiska S. Peper
Abstract Twin studies suggest that variation in human brain volume is genetically influenced. The genes involved in human brain volume variation are still largely unknown, but several candidate genes have been suggested. An overview of structural Magnetic Resonance (brain) Imaging studies in twins is presented, which focuses on the influence of genetic factors on variation in healthy human brain volume. Twin studies have shown that genetic effects varied regionally within the brain, with high heritabilities of frontal lobe volumes (90,95%), moderate estimates in the hippocampus (40,69%), and environmental factors influencing several medial brain areas. High heritability estimates of brain structures were revealed for regional amounts of gray matter (density) in medial frontal cortex, Heschl's gyrus, and postcentral gyrus. In addition, moderate to high heritabilities for densities of Broca's area, anterior cingulate, hippocampus, amygdala, gray matter of the parahippocampal gyrus, and white matter of the superior occipitofrontal fasciculus were reported. The high heritability for (global) brain volumes, including the intracranium, total brain, cerebral gray, and white matter, seems to be present throughout life. Estimates of genetic and environmental influences on age-related changes in brain structure in children and adults await further longitudinal twin-studies. For prefrontal cortex volume, white matter, and hippocampus volumes, a number of candidate genes have been identified, whereas for other brain areas, only a few or even a single candidate gene has been found so far. New techniques such as genome-wide scans may become helpful in the search for genes that are involved in the regulation of human brain volume throughout life. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source]

Neural correlates of verbal episodic memory in patients with MCI and Alzheimer's disease,,a VBM study

INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 11 2008
Dirk T. Leube
Abstract Objective The hippocampus is a key area for episodic memory processes. Hippocampal atrophy is a hallmark feature of Alzheimer's disease (AD). We used a new and automatized morphometric technique to better characterize brain atrophy in subjects with different levels of cognitive deficit. Methods In this study 21 participants with Mild Cognitive Impairment (MCI), 12 patients with early AD and 29 elderly control subjects were subjected to high resolution MRI and a neuropsychological test battery. Brain volume across participants, measured by voxel-based morphometry (VBM), was correlated with verbal memory capacity, measured with a verbal memory test (VLMT). Results Atrophy in the anterior hippocampus, the ento- and perirhinal cortex as well as the parahippocampal gyrus, middle temporal gyrus and anterior cingulate cortex correlated closely with episodic memory performance. Conclusions These brain areas are known to subserve episodic encoding of verbal material. The data contribute to a better understanding of atrophic brain processes in subjects at risk for AD. A combination of neuropsychological testing and voxel-based morphometry may serve as a diagnostic tool in the future. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Primary squamous cell carcinoma of the brain.

NEUROPATHOLOGY, Issue 3 2003
A rare autopsy case
In the present study, a rare autopsy case of primary squamous cell carcinoma of the brain is described. The patient was a 49-year-old man who showed brainstem symptoms and signs. These included oculomotor, abducens and facial palsies, dysphagia, dysarthria, and long tract signs such as quadriplegia with Babinski's signs during the 3-year and 6-month course of his illness. Neuropathologically, poorly differentiated squamous cell carcinoma was seen in the pons, medulla oblongata, part of the midbrain and spinal cord, the base of the cerebellum, the hypothalamus, the optic chiasm, and the left parahippocampal gyrus. The base of the pons and medulla oblongata were extensively destroyed by tumor cells. The relevant literature regarding primary squamous cell carcinomas of the brain was reviewed, and the characteristic features of this rare condition were discussed. [source]

Frontotemporal dementia with motor neuron disease (amyotrophic lateral sclerosis with dementia)

NEUROPATHOLOGY, Issue 1 2000
Imaharu Nakano
Frontotemporal dementia (FTD) with motor neuron disease means amyotrophic lateral sclerosis (ALS) with dementia. In the cerebrum of this condition, the medial cortex of the rostral temporal lobe is constantly and most remarkably involved. Another constant and quite characteristic lesion is neuronal loss localized to the CA1-subiculum transitional area at the level of the pes hippocampi. The rostral portion of the parahippocampal gyrus, and the amygdaloid nucleus are also involved. Ubiquitinated intracytoplasmic inclusions are seen in the dentate granule cells and parahippocampal gyrus neurons. Some cases of ALS without dementia show the identical temporal lobe degeneration as well as the cortical ubiquitinated inclusions, thus raising the possibility of overlooked dementia or premature death of the patients. Similarly, recently proposed motor neuron disease-inclusion dementia may be a forme fruste of ALS with dementia. [source]

Neural activity and diurnal variation of cortisol: Evidence from brain electrical tomography analysis and relevance to anhedonia

PSYCHOPHYSIOLOGY, Issue 6 2008
Katherine M. Putnam
Abstract The medial prefrontal cortex (mPFC), hippocampus, and amygdala are implicated in the regulation of affect and physiological processes, including hypothalamic-pituitary-adrenal (HPA) axis function. Anhedonia is likely associated with dysregulation of these processes. Dense-array resting electroencephalographic and cortisol were obtained from healthy and anhedonic groups. Low-resolution electromagnetic tomography was used to compute intracerebral current density. For the control group, voxelwise analyses found a relationship between current density in beta and gamma bands and steeper cortisol slope (indicative of more adaptive HPA axis functioning) in regions of the hippocampus, parahippocampal gyrus, and mPFC. For the anhedonic group, the mPFC finding was absent. Anhedonia may be characterized by disruptions of mPFC-mediated neuroendocrine regulation, which could constitute a vulnerability to the development of stress-related disorders. [source]

A multicenter, prospective pilot study of gamma knife radiosurgery for mesial temporal lobe epilepsy: Seizure response, adverse events, and verbal memory,

ANNALS OF NEUROLOGY, Issue 2 2009
Nicholas M. Barbaro MD
Objective The safety, efficacy, and morbidity of radiosurgery (RS) must be established before it can be offered as an alternative to open surgery for unilateral mesial temporal lobe epilepsy. We report the 3-year outcomes of a multicenter, prospective pilot study of RS. Methods RS was randomized to 20 or 24Gy targeting the amygdala, hippocampus, and parahippocampal gyrus. Seizure diaries evaluated the final seizure remission between months 24 and 36. Verbal memory was evaluated at baseline and 24m with the Wechsler Memory Scale,Revised (WMS-R) and California Verbal Learning Test (CVLT). Patients were classified as having "significant improvement," "no change," and "significant impairment" based on relative change indices. Results Thirteen high-dose and 17 low-dose patients were treated. Both groups showed significant reductions in seizures by 1 year after treatment. At the 36-month follow-up evaluation, 67% of patients were free of seizures for the prior 12 months (high dose: 10/13, 76.9%; low dose: 10/17, 58.8%). Use of steroids, headaches, and visual field defects did not differ by dose or seizure remission. The prevalence of verbal memory impairment was 15% (4/26 patients); none declined on more than one measure. The prevalence of significant verbal memory improvements was 12% (3/26). Interpretation RS for unilateral mesial temporal lobe epilepsy offers seizure remission rates comparable with those reported previously for open surgery. There were no major safety concerns with high-dose RS compared with low-dose RS. Additional research is required to determine whether RS may be a treatment option for some patients with mesial temporal lobe epilepsy. Ann Neurol 2009 [source]

Medial temporal lobe function and structure in mild cognitive impairment

ANNALS OF NEUROLOGY, Issue 1 2004
Bradford C. Dickerson MD
Functional magnetic resonance imaging (fMRI) was used to study memory-associated activation of medial temporal lobe (MTL) regions in 32 nondemented elderly individuals with mild cognitive impairment (MCI). Subjects performed a visual encoding task during fMRI scanning and were tested for recognition of stimuli afterward. MTL regions of interest were identified from each individual's structural MRI, and activation was quantified within each region. Greater extent of activation within the hippocampal formation and parahippocampal gyrus (PHG) was correlated with better memory performance. There was, however, a paradoxical relationship between extent of activation and clinical status at both baseline and follow-up evaluations. Subjects with greater clinical impairment, based on the Clinical Dementia Rating Sum of Boxes, recruited a larger extent of the right PHG during encoding, even after accounting for atrophy. Moreover, those who subsequently declined over the 2.5 years of clinical follow-up (44% of the subjects) activated a significantly greater extent of the right PHG during encoding, despite equivalent memory performance. We hypothesize that increased activation in MTL regions reflects a compensatory response to accumulating AD pathology and may serve as a marker for impending clinical decline. Ann Neurol 2004;56:27,35 [source]

Trait impulsivity in female patients with borderline personality disorder and matched controls

ACTA NEUROPSYCHIATRICA, Issue 3 2010
Jørgen Assar Mortensen
Mortensen JA, Rasmussen IA, Håberg A. Trait impulsivity in female patients with borderline personality disorder and matched controls. Objective: Impulsivity has been shown to load on two separate factors, rash impulsivity and sensitivity to reward (SR) in several factor analytic studies. The aims of the current study were to explore the nature of impulsivity in women with borderline personality disorder (BPD) and matched controls, and the underlying neuronal correlates for rash impulsivity and SR. Methods: Fifteen females diagnosed with BPD and 15 matched controls were recruited. All completed the impulsiveness-venturesomeness scale (I7), the sensitivity to punishment (SP) - sensitivity to reward (SR) questionnaire, and performed a Go-NoGo block-design functional magnetic resonance imaging (fMRI) paradigm at 3T. Correlation analyses were done with I7, SP and SR scores with the level of activation in different brain areas in the whole group. An independent group t -test was used to explore any differences between the BPD group and the matched controls. Results: I7 scores correlated negatively with activity in the left orbitofrontal cortex, amygdala and precuneus, and bilaterally in the cingulate cortices during response inhibition for the entire sample. SP yielded negative correlations in the right superior frontal gyrus and parahippocampal gyrus. No activity related to response inhibition correlated to SR. The Go-NoGo task gave similar brain activity in BPD and matched controls, but behaviourally the BPD group had significantly more commission errors in the NoGo blocks. The BPD group had increased I7 and SP scores indicating rash impulsiveness combined with heightened SP. Conclusion: These results imply that successful impulse inhibition involves interaction between the impulsive and the emotional systems. Furthermore, impulsivity in BPD is described as rash impulsivity, coexisting with increased SP. [source]