DIFFERENTIAL LATERALIZATION OF MEMORY DISCRIMINATION AND RESPONSE BIAS IN TEMPORAL-LOBE EPILEPSY PATIENTS

Recognition memory for words and designs was assessed in epilepsy pati ents who underwent unilateral anterior temporal lobectomy. Memory was assessed during the intracarotid amobarbital test (IAT) performed prio r to surgery and also following surgery. Memory discrimination and res ponse bias lateralized differently. Memory discrimination, or memory a ccuracy, lateralized as a function of the type of material used in mem ory testing. Left temporal lobe lesions resulted in more impaired disc rimination of verbal materials; right temporal lobe lesions resulted i n more impaired discrimination of visuospatial materials. Response bia s, the decision rule adopted in situations of uncertainty, was more li beral following left temporal lobe lesions for both verbal and visuosp atial materials. Findings suggest that the two cerebral hemispheres ar e differentially specialized for encoding different types of informati on in long term memory, and that this impacts on decision strategies i n situations of memory uncertainty.