Biomedical subjects

S Bentin

Publications and source records attributed to S Bentin.

59 records · Page 4Linked to original sources

PubMed1978

Correlation between regional cerebral blood flow and brain atrophy in dementia. Combined study with 133Xenon inhalation and computerised tomography.

Measurement of the regional cerebral blood flow (rCBF) by the 133Xenon inhalation method and computerised tomography were performed in 25 patients with presenile and senile dementia. Reduction of rCBF and various degrees of ventricular enlargement and cortical sulcal widening were demonstrated in the majority of demented subjects. However, there was no correlation between rCBF values and the severity of ventricular dilatation or cortical atrophy. These findings suggest that loss of brain substance is not an important factor in the reduction of rCBF in dementia.

Adult↗

PubMedDate not supplied

Unilateral neglect after right-hemisphere damage: contributions from event-related potentials.

Unilateral neglect is a frequent sequel of right-hemisphere damage. Patients suffering from neglect may fail to detect, orient to, acknowledge or respond to stimuli on their contralesional side, even in the absence of primary sensory or motor loss. Despite the major clinical significance of the phenomenon and its potential implications for our understanding of human cognition, the underlying cognitive deficits are not well understood. We review the relatively few event-related potential studies that attempted to assess the different parts of the cognitive system in neglect patients. We suggest that theories of neglect, based primarily on performance data, may be refined by incorporating these results, and that this line of research may provide information that is not available using traditional performance measures.

Attention↗

PubMedDate not supplied

Reduction in regional cerebral blood flow during normal aging in man.

Regional cerebral blood flow (rCBF) was measured by the 133Xenon inhalation method in a selected group of 44 normal non-hospitalized, normotensive subjects aged 19 to 79 years. rCBF was computed as the initial slope index value (ISI). Advancing age was associated with significant reductions in the mean brain and mean hemispheric ISI as well as in individual ISI levels measured from all areas in both hemispheres. Our findings suggest that decline of rCBF is not limited to normal elderly subjects but that it is a progressive phenomenon which begins at an earlier age.

Adult↗

PubMedDate not supplied

Electrophysiological studies of visual word perception, lexical organization, and semantic processing: a tutorial review.

Visual word recognition requires the matching of an orthographic unit to its meaning via a phonological unit in the mental lexicon. The nature and the speed of this process are affected by "bottom-up" factors (e.g., the manner in which the phonology is represented by the orthography) and by "top-down" factors (e.g., network connections between related words in the lexicon, and contextual semantic information). Event-related potentials (ERPs) provide a relatively new tool that complements behavioral measures of word recognition. ERP components recorded during word perception tasks have been found to be sensitive to orthographic, phonological, and semantic manipulations. They go beyond behavioral measures by providing continuous information about the activity of the cognitive system from stimulus onset to the occurrence of the response. In addition, ERPs enable the researcher to examine word perception and reading in more natural situations, without time constraints and overt responses. Finally, intra-cranial ERP recording in humans and modern analytical techniques may shed light on the relations between cognitive linguistic processes and brain structures. Collaboration between cognitive psychologists, linguists, and ERP researchers will be necessary to exploit the great potential of these electrophysiological techniques.

Cognition↗

PubMedDate not supplied

Visual word perception and semantic processing: an electrophysiological perspective.

This paper reports data from three experiments in which semantic priming effects were investigated using the event-related potentials (ERP) technique. In the first experiment, a specific electrophysiological manifestation of semantic priming was demonstrated, and it was related to a previously reported negative component--N400. In the second experiment, it was suggested that the N400 wave does not directly reflect disconfirmation of subjects' expectations, but that it is related to semantic activation and is affected by the amount of lexical processing. In the third experiment, it was demonstrated that priming effects are also evident in natural reading, without any time constraints imposed by the task. It is concluded that the ERP technique provides an important tool in cognitive research in general, and language processing in particular.

Brain↗