Search results for "frontal lobe"
showing 10 items of 158 documents
Reduced oscillatory gamma-band responses in unmedicated schizophrenic patients indicate impaired frontal network processing
2004
Abstract Objective Integration of sensory information by cortical network binding appears to be crucially involved in target detection. Studies in schizophrenia using functional and diffusion tensor neuroimaging, event-related potentials and EEG coherence indicate an impairment of cortical network coupling in this disorder. Previous electrophysiological investigations in animals and humans suggested that gamma activity (oscillations at around 40 Hz) is essential for cortical network binding. Studies in medicated schizophrenia provide evidence for a reduced gamma activity in the context of auditory stimulus processing. This is the first investigation of oscillatory activations in the gamma-b…
Emotional words induce enhanced brain activity in schizophrenic patients with auditory hallucinations.
2005
Neuroimaging studies of emotional response in schizophrenia have mainly used visual (faces) paradigms and shown globally reduced brain activity. None of these studies have used an auditory paradigm. Our principal aim is to evaluate the emotional response of patients with schizophrenia to neutral and emotional words. An auditory emotional paradigm based on the most frequent words heard by psychotic patients with auditory hallucinations was designed. This paradigm was applied to evaluate cerebral activation with functional magnetic resonance imaging (fMRI) in 11 patients with schizophrenia with persistent hallucinations and 10 healthy subjects. We found a clear enhanced activity of the fronta…
ErbB4 genotype predicts left frontotemporal structural connectivity in human brain.
2008
Diminished left frontotemporal connectivity is among the most frequently reported findings in schizophrenia and there is evidence that altered neuronal myelination may in part account for this deficit. Several investigations have suggested that variations of the genes that encode the Neuregulin 1 (NRG1)-ErbB4 receptor complex are associated with schizophrenia illness. As NRG1--ErbB4 has been implicated in neuronal myelination, we investigated with diffusion tensor imaging (DTI) whether fractional anisotropy (FA)--a putative measure of neuronal myelination--is predicted by a risk haplotype of the ErbB4 gene. The effects of the ErbB4 genotype were investigated in healthy subjects (N=59; mean …
Left orbitofrontal and superior temporal gyrus structural changes associated to suicidal behavior in patients with schizophrenia.
2008
Suicidal attempts are relatively frequent and clinically relevant in patients with schizophrenia. Recent studies have found gray matter differences in suicidal and non-suicidal depressive patients. However, no previous neuroimaging study has investigated possible structural abnormalities associated to suicidal behaviors in patients with schizophrenia. A whole-brain magnetic resonance voxel-based morphometric examination was performed on 37 male patients meeting the DSM-IV criteria for schizophrenia. Thirteen (35.14%) patients had attempted suicide. A non-parametric permutation test was computed to perform the comparability between groups. An analysis of covariance (AnCova) model was constru…
Cognitive and social impairments in patients with superficial siderosis
2005
Superficial siderosis of the CNS is a rare condition, caused by deposition of haemosiderin in the superficial layers of the CNS due to repeated chronic subarachnoid or intraventricular haemorrhage. Typically, the hindbrain structures, especially the cerebellum, are most affected. There is a surprising lack of studies investigating in detail the behavioural functioning of patients with such a condition. In this study, we document for the first time the cognitive, social and emotional processing of six patients with a confirmed clinical diagnosis of superficial siderosis. They were aged between 40 and 62 years, with a mean age of 50.2 years; four were male. We administered a comprehensive bat…
Localization of emotional and volitional facial paresis.
1992
Emotional facial paresis is characterized by impaired activation of face muscles with emotion but normal voluntary activation. We report seven patients with this sign. Their lesions involved the frontal lobe white matter, the striatocapsular territory, the anterolateral thalamus and insula, the posterior thalamus and operculum, and the mesial temporal lobe and insula each in one patient, and the posterior thalamus in two patients. Volitional facial paresis affects facial movements with voluntary effort, sparing activation on emotion. We report four such patients, with lesions involving the motor cortex in one and the pyramidal tract in the cerebral hemisphere in three.
The Doors and People Test: The Effect of Frontal Lobe Lesions on Recall and Recognition Memory Performance
2016
Objective: Memory deficits in patients with frontal lobe lesions are most apparent on free recall tasks that require the selection, initiation, and implementation of retrieval strategies. The effect of frontal lesions on recognition memory performance is less clear with some studies reporting recognition memory impairments but others not. The majority of these studies do not directly compare recall and recognition within the same group of frontal patients, assessing only recall or recognition memory performance. Other studies that do compare recall and recognition in the same frontal group do not consider recall or recognition tests that are comparable for difficulty. Recognition memory imp…
Parieto-frontal interactions in visual-object and visual-spatial working memory: Evidence from transcranial magnetic stimulation
2001
This study aimed to investigate whether transcranial magnetic stimulation (TMS) can induce selective working memory (WM) deficits of visual-object versus visual-spatial information in normal humans. Thirty-five healthy subjects performed two computerized visual n-back tasks, in which they were required to memorize spatial locations or abstract patterns. In a first series of experiments, unilateral or bilateral TMS was delivered on posterior parietal and middle temporal regions of both hemispheres after various delays during the WM task. Bilateral temporal TMS increased reaction times (RTs) in the visual-object, whereas bilateral parietal TMS selectively increased RTs in the visual-spatial W…
Direction‐dependent visual cortex activation during horizontal optokinetic stimulation (fMRI study)
2005
Looking at a moving pattern induces optokinetic nystagmus (OKN) and activates an assembly of cortical areas in the visual cortex, including lateral occipitotemporal (motion‐sensitive area MT/V5) and adjacent occipitoparietal areas as well as ocular motor areas such as the prefrontal cortex, frontal, supplementary, and parietal eye fields. The aim of this functional MRI (fMRI) study was to investigate (1) whether stimulus direction‐dependent effects can be found, especially in the cortical eye fields, and (2) whether there is a hemispheric dominance of ocular motor areas. In a group of 15 healthy subjects, OKN in rightward and leftward directions was visually elicited and statistically compa…
fMRI signal increases and decreases in cortical areas during small-field optokinetic stimulation and central fixation
2001
Small-field optokinetic nystagmus (OKN) was performed in seven healthy volunteers in order to analyze the activation and deactivation patterns of visual motion, ocular motor, and multisensory vestibular cortex areas by means of fMRI during coherent visual motion stimulation. BOLD signal decreases (deactivations) were found in the first and second long insular gyri and retroinsular areas (the human homologue of the parietoinsular vestibular cortex and the visual posterior sylvian area in the monkey) of both hemispheres, extending into the transverse temporal gyrus and inferior-anterior parts of the superior temporal gyrus (BA 22), and the precentral gyri at two separate sites (BA 4 and 6). F…