Pure topographical disorientation due to a deep-seated lesion with cortical remote effects

Lesions producing pure topographical disorientation syndromes are classically located either in the right parietal region either in the right parahippocampal gyrus. The patient described in the present study was admitted to hospital after sudden onset of a left hemiparesis. The lesion at CT scan was located in the posterior limb of the right internal capsule. Neuropsychological assessment was normal except for the presence of a major topographical disorientation and of mnestic disturbances for visuo-spatial material leading us to attribute topographical disorientation to a specific loss of topographical memory. Regional cerebral blood flow measurements disclosed a right parietal hypoperfusion. This remote cortical effect could account for the presence of the neuropsychological disorders.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

Les rôles respectifs des mains dans la lecture du braille: Une étude exploratoire

info:eu-repo/semantics/publishe

Quantitative EEG in subcortical neglect

Right-sided capsulo-lenticular strokes may cause left visuo-spatial neglect. The neural mechanism most frequently evoked to account for the occurrence of related cognitive disorders is remote cortical dysfunction in the posterior part of the right hemisphere. We studied 33 patients with capsulo-lenticular stroke, with (n = 16) or without (n = 17) associated subcortical neglect. A 20-channel EEG cartography system was used. Four regions of interest were delineated on the topographic map. Absolute delta and theta amplitude peaks were obtained, as well as left-to-right ratios between activities in homologous regions of interest. The population was subdivided into two groups according to the presence or absence of neglect. Delta activity was higher in neglect patients than in patients without neglect, but the magnitude of delta activity differences between the two groups of patients did not depend on the site. The left-to-right ratio of delta activity between posterior homologous regions was lower in neglect patients, suggesting that right posterior dysfunction producing an imbalance between these regions might contribute to the emergence of the attention disorder.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Spatial effects in speech perception in the absence of spatial competition

Two synthetic speech syllables, differing in pitch, were presented over one loudspeaker situated at one of the following azimuths: 0° (in front of the subject); 45°, 90° and 135° to the left or to the right; and at 180°. The subject's task was to report the high-pitch syllable. The pattern of performance can be described in terms of two component effects: a decreasing anterior posterior gradient and right side advantage. Competition between messages from one direction only appears to be as effective in determining auditory spatial effects as competition between spatially distinct sources.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Spatial constraints on focused attention: beyond the right side advantage

The subjects listened to one of two simultaneous synthetic speech syllables delivered independently over two loudspeakers. When the loudspeakers were situated at 90° to the left and to the right, right side advantage was found. When one loudspeaker was situated in front of the subject in the median plane, and the other at one of several azimuthal positions around him, an advantage of the frontal position was observed in all cases. On the other hand, performance on the nonfrontal message was affected significantly by its position. The pattern of performance which is observed can be described in terms of three component factors: a right side advantage, related presumably to cerebral dominance, an advantage of sources situated in front of the subject over those at his back, and possibly an advantage of sources near the median plane over more remote ones.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Functional dissociations following bilateral lesions of auditory cortex

We present true patients with bilateral lesions of the superior temporal cortex who manifested a number of functional dissociations in the auditory domain. The perception of speech and environmental sounds were preserved; yet, the perception of times, prosody and voice was impaired. As the processing of melodic but not rhythmic variations in musical sequences was selectively disturbed, the deficit cannot be attributed to a general impairment in auditory memory or sequential processing. These findings suggest that melody processing is not mediated by a general-purpose auditory architecture bur by specialized cortical subsystems residing within the lesioned areas. Current taxonomies of auditory agnosia and models of normal music cognition are evaluated in light of the functional dissociations manifested by these patients.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

L’air ferait-il la chanson? Analyse de deux cas d’amusie

info:eu-repo/semantics/nonPublishe

L’air ferait-il la chanson? Analyse de deux cas d’amusie

info:eu-repo/semantics/nonPublishe

Spatial constraints on attention to speech in the blind.

When sighted persons try to identify one of two speech utterances coming from different directions, they display both a frontal position advantage, i.e. better recognition of inputs from the front than of those from the rear, and a right-side advantage, better recognition of inputs from the right than of those from the left. The present study demonstrates a dissociation of the two effects in blind subjects (N = 10) who showed no frontal position advantage together with a right-side advantage superior to that of control sighted subjects (N = 16). There was no systematic difference between congenitally blind subjects and noncongenitals. The absence of frontal position advantage in the blind is consistent with the notion that this effect originates in the habit of sighted listeners to orient toward the source of heard speech. The occurrence of at least normal right-side advantage in the blind does not support recent suggestions of reduced lateralization of language functions in such subjects.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe