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The Italian Journal of Neurological Sciences

, Volume 13, Issue 8, pp 649–655 | Cite as

Interhemispheric communication following unilateral cerebrovascular lesions

  • Anzola G. P. 
  • Vignolo L. A. 
Original Articles

Abstract

39 patients with a single small cerebrovascular lesion (20 in the right, 19 in the left hemisphere) were subjected to a simple reaction time (RT) task with visual stimuli flashed to the visual field either ipsilateral or contralateral to the cerebral lesion. The subject responded always with the ipsilateral hand. The crossed-uncrossed difference (CUD), i.e. the RT when both stimulus and response occur on the same side minus the RT when stimulus and response occur on opposite sides, is assumed to assess the transit time of information through callosal fibers, and in normal people is about 3–5 msec. In our patients the mean CUD, expressed as the difference between contralateral and ipsilateral responses, was 20 msec. Patients with parietal lesions had still longer CUDs, 37 msec on the average. There was no statistical difference in CUDs between right and left brain-damaged patients. The CUD in brain-damaged patients was of the same order of magnitude as that found in acallosal or split-brain patients. Nonetheless, the present findings are interpreted as reflecting the intrahemispheric rather than the interhemispheric delay in information transmission, with the possible additive effect of an asymmetrical orienting of attention.

Key Words

Interhemispheric communication reaction time cerebrovascular diseases 

Sommario

In 39 pazienti portatori di una singola lesione cerebrovascolare emisferica (in 20 all'emisfero destro, in 19 all'emisfero sinistro), è stato effettuato un test di tempi di reazione semplici a uno stimolo visivo non strutturato presentato nel campo visivo ipsilaterale o controlaterale alla lesione. Le risposte erano effettuate sempre con la mano ipsilaterale.

La differenza fra tempi di reazione crociati (cioè stimolo e risposta su lati opposti) e tempi di reazione non-crociati (cioè stimolo e risposta dallo stesso lato) rappresenta il tempo di transito callosale dell'informazione e nei soggetti normali è dell'ordine di 3–5 msec.

Nei pazienti con lesione cerebrale tale valore era allungato a 20 msec di media, con un ulteriore ritardo a 37 msec. nei pazienti con lesione parietale. Non vi era nessuna differenza, significativa fra pazienti con lesione dell'emisfero destro e pazienti con lesione dell'emisfero sinistro. La differenza fra risposte crociate e risposte dirette da noi trovata nei cerebrolesi è dello stesso ordine di grandezza di quella che presentano i soggetti con agenesia del calloso o i pazienti sottoposti a callosotomia. Tuttavia, è verosimile che nei nostri pazienti il ritardo trovato rifletta piuttosto la somma di un'anomala conduzione intraemisferica e di possibili disturbi attenzionali.

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Copyright information

© Masson Italia Periodici S.r.l. 1992

Authors and Affiliations

  • Anzola G. P. 
    • 1
  • Vignolo L. A. 
    • 1
  1. 1.II Divisione di NeurologiaClinical Neurologica dell'UniversitàBrescia

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