Tactual extinction without anomia: evidence of attentional factors in a patient with a partial callosal disconnection.
Tactual extinction was examined in a 43-yr-old left-handed male patient (MM) with a hematoma in the trunk of the corpus callosum sparing the genu and the ventral part of the splenium as well as the cerebral hemispheres. Experiments I and II showed no deficit in tactual perception nor in the inter-hemispheric transfer of tactual information. In Experiment III, MM palpated stimuli differing in their association value, and responded vocally or manually. There was no difference in performance between the hands in unimanual control conditions, but in a dichhaptic condition an overall right-hand advantage was observed, depending on the kind of stimulus and on the mode of response: such results were not observed in control subjects. Results showed that MM's left-hand performance reached right-hand levels after specific modifications in the allocation of attention between the hands or the load of information in haptic memory (Experiment IV). Experiment V revealed a major deficit in the matching of left- and right-hand information only for the dichhaptic procedure. The results are discussed with a view of cerebral mechanisms as dynamic rather than structurally determined: it is suggested that extinction phenomena are sensitive to cognitive strategies and attentional factors and that the corpus callosum plays a critical role in the lateral control of attention to tactual as well as to auditory and visual information.
Mayer
E
E
Geneva University Hospital, Department of Neurology, Switzerland.
Koenig
O
O
Panchaud
A
A
D000328:Adult; D000849:Anomia / Q000503:physiopathology*; D001037:Aphasia / Q000503:physiopathology*; D001288:Attention / Q000502:physiology*; D002543:Cerebral Hemorrhage / Q000503:physiopathology*; D003337:Corpus Callosum / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006406:Hematoma / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000502:physiology; D011434:Proprioception / Q000502:physiology; D012684:Sensory Thresholds; D012867:Skin / Q000294:innervation; D013236:Stereognosis / Q000502:physiology; D014110:Touch / Q000502:physiology*