Retrograde amnesia in patients with diencephalic,temporal lobe or frontal lesions

Patients with focal diencephalic, temporal lobe, or frontal lobe lesions were examinedon various measures of remote memory. Korsakoff patients showed a severe impairment with acharacteristic temporal gradient, whereas two patients with focal diencephalic damage (andanterograde amnesia) were virtually unimpaired on remote memory measures. Patients withfrontal lobe pathology were severely impaired in the recall of autobiographical incidents andfamous news events. Patients with temporal lobe pathology showed severe impairment but arelatively flat temporal gradient, largely attributable to herpes encephalitis patients. Fromrecognition and cued recall tasks, it is argued that there is an important retrieval component tothe remote memory deficit across all the lesion groups. In general, the pattern of performance bythe frontal lobe and temporal lobe groups was closely similar, and there was no evidence of anymajor access⧸storage difference between them. However, laterality comparisons across thesegroups indicated that the right temporal and frontal lobe regions may make a greater contributionto the retrieval of past episodic (incident and event) memories, whereas the left temporal regionis more closely involved in the lexical-semantic labelling of remote memories.