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Titolo:
Enhanced responsiveness of human extravisual areas to photic stimulation in patients with severely reduced vision
Autore:
Rausch, M; Widdig, W; Eysel, UT; Penner, IK; Tegenthoff, M;
Indirizzi:
Kantonsspital, Dept Neuroradiol, CH-4031 Basel, Switzerland KantonsspitalBasel Switzerland CH-4031 diol, CH-4031 Basel, Switzerland Univ Klinikum Bergmannsheil, Dept Neurol, D-44789 Bochum, Germany Univ Klinikum Bergmannsheil Bochum Germany D-44789 44789 Bochum, Germany Ruhr Univ Bochum, Dept Neurophysiol, D-44780 Bochum, Germany Ruhr Univ Bochum Bochum Germany D-44780 physiol, D-44780 Bochum, Germany
Titolo Testata:
EXPERIMENTAL BRAIN RESEARCH
fascicolo: 1, volume: 135, anno: 2000,
pagine: 34 - 40
SICI:
0014-4819(200011)135:1<34:EROHEA>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
FRONTAL EYE-FIELD; DIRECTING ATTENTION; FUNCTIONAL-ANATOMY; CORTICAL BLINDNESS; NEURAL SYSTEMS; LOCATIONS; FMRI;
Keywords:
brain imaging; visual system; cortical lesion; frontal cortex; attention; human;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
23
Recensione:
Indirizzi per estratti:
Indirizzo: Rausch, M Kantonsspital, Dept Neuroradiol, CH-4031 Basel, Switzerland Kantonsspital Basel Switzerland CH-4031 031 Basel, Switzerland
Citazione:
M. Rausch et al., "Enhanced responsiveness of human extravisual areas to photic stimulation in patients with severely reduced vision", EXP BRAIN R, 135(1), 2000, pp. 34-40

Abstract

Lesions in the primary visual cortex induce severe loss of visual perception. Depending on the size of the lesion, the visual field might be affectedby small scotomas, hemianopia, or complete loss of vision (cortical blindness). In many cases, the whole visual field of the patient is affected by the lesion, but diffuse light-dark discrimination remains (residual rudimentary vision, RRV). In other cases, a sparing of a few degrees can be found (severely reduced vision, SRV). In a follow-up study, we mapped visually induced cerebral activation of three subjects with SRV using functional magnetic resonance imaging. We were especially interested in the visual areas that would be activated if subjects could perceive the stimulus consciously although information flow from V1 to higher visual areas was strongly reducedor virtually absent. Because subjects were only able to discriminate strong light from darkness, we used goggles flashing intense red light at a frequency of 3 Hz for full visual field stimulation. Besides reduced activationin V1, we found activation in the parietal cortex, the frontal eye fields (FEF), and the supplementary eye fields (SEF). In all patients, FEF activation was pronounced in the right hemisphere. These patterns were never seen in healthy volunteers. In a patient who recovered completely, we observed that extrastriate activation disappeared in parallel with the visual field restitution. This result suggests that damage to the primary visual cortex changes the responsiveness of parietal and extra-visual frontal areas in patients with SRV. This unexpected result might be explained by increased stimulus-related activation of attention-related networks.

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Documento generato il 05/04/20 alle ore 09:37:53