Retrograde amnesia and remote memory impairment.
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Remote memory performance was assessed in a carefully matched sample of temporal lobectomy subjects and normal controls. Left temporal lobectomy subjects exhibited a consistent pattern of remote memory disturbance. Right temporal lobectomy subjects performed at the same level as normal controls. The pattern of impairment observed in left temporal lobectomy subjects was characterized by deficits in recall of chronological information from the past decade and extended to deficits in recall in some aspects of factual knowledge. The disorder could not be attributed solely to language deficits and was at least as severe as accompanying deficits in recent memory. These findings suggest that the left medial temporal region may play a significant role in recall of remote information in addition to its role in recent memory functions.
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A series of experiments was performed to test the reliability of previous reports which indicated that cholinergic blockade of the caudate-putamen produces memory deficits of passive avoidance, and to determine whether overtraining of this task protects against such deficits. In the first experiment the effects of different doses of atropine injected into the caudate-putamen of rats shortly after training were assessed, and a dose-dependent retention deficit was found. In two additional experiments it was observed that by increasing the magnitude of the negative reinforcer used in training, a protection against such retention deficit was produced. These results support the hypotheses that (a) cholinergic activity of the caudate-putamen is critically involved in memory processes that mediate passive avoidance behavior, and (b) after overtraining the control of this behavior is transferred from the striatal cholinergic system to other neurochemical systems within, or outside, the striatum.
This single case study describes our investigations of the retrograde memory deficit of a patient who became severely and selectively amnesic after an encephalitic illness. On clinical assessment his retrograde deficit for both personal and public events appeared to encompass his entire adult life. However, he retained knowledge of words introduced into the vocabulary during the retrograde period. The experimental investigation documented his inability to recall, recognize, and place in temporal order the names and faces of famous people for all time periods sampled. By contrast, his recall of either a famous face or a famous name was significantly facilitated by the verbal cue of the person's first name and initial of the surname (i.e., Margaret T...). His performance on a test of "familiarity" that required him to select the famous name or the famous face from two distractors (unknown) was within normal limits. It is argued that names and faces of famous people are represented in more than one system: both in a vocabulary-like fact memory system that is preserved and also in a congnitively mediated schemata that in this case is functionally inoperative.
We describe a patient who presented with apparent human Klüver-Bucy syndrome. After pharmacological treatment, his problems gradually resolved, with the exception of some unconcern about this present situation, a mild naming and word list generation deficit, a severe remote memory loss and, in comparison, a minimal anterograde memory disturbance. He has been able to relearn certain details of his personal past. These relearned memories are independent of a sense of personal intimacy. The "relearned memory" was frequently associated with a memory of how and when the information had been reacquired. The results suggest that anterograde and retrograde memory functions may, in at least certain patients, be dissociable. The apparently absolute loss of personal memories indicates that either a retrieval deficit or storage depletion are plausible hypotheses of the remote memory loss in this patient.
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Amnesic patients' ability to acquire generic, semantic information was assessed relative to their own level of episodic memory. Patients studied a list of words in which some items were presented twice and others once. Upon each presentation, the words were tagged episodically by presenting them in a unique color. Recall of the colors in which words were presented suggested that individual presentations of repeated items were less likely to be recalled than presentations of nonrepeated items; however, actual recall of repeated items exceeded that of nonrepeated items. This outcome demonstrated that amnesics can recall some items generically without recalling either of their individual presentations. However, amnesics' recall of twice-presented items remained far below that of the control group, even when their recall of once-presented items was matched by testing the control group after a delay. This finding suggests that amnesic patients can acquire new generic knowledge but do so much less efficiently than do normal individuals. Furthermore, this deficit occurs independently of the amnesics' episodic memory impairments, reflecting instead a disruption in semantic learning per se.
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