While it is well known that repetition can enhance memory in amnesia, little is known about which forms of repetition are most beneficial. This study compared the effect on recognition memory of repetition of words in the same semantic context and in varied semantic contexts. To gain insight into the mechanisms by which these forms of repetition affect performance, participants were asked to make Remember/Know judgments during recognition. These judgments were used to make inferences about the contribution of recollection and familiarity to performance. For individuals with intact memory, the two forms of repetition were equally beneficial to overall recognition, and were associated with both enhanced Remember and Know responses. However, varied repetition was associated with a higher likelihood of Remember responses than was fixed repetition. The two forms of repetition also conferred equivalent benefits on overall recognition in amnesia, but in both cases, this enhancement was manifest exclusively in enhanced Know responses. We conclude that the repetition of information, and especially repetition in varied contexts, enhances recollection in individuals with intact memory, but exclusively affects familiarity in patients with severe amnesia. (JINS, 2008, 14, 365–372.)

This study directly compared how well Korsakoff patients can process spatial and temporal order information in memory under conditions that included presentation of only a single feature (i.e., temporal or spatial information), combined spatiotemporal presentation, and combined spatiotemporal order recall. Korsakoff patients were found to suffer comparable spatial and temporal order recall deficits. Of interest, recall of a single feature was the same when only spatial or temporal information was presented compared to conditions that included combined spatiotemporal presentation and recall. In contrast, control participants performed worse when they have to recall both spatial and temporal order compared to when they have to recall only one of these features. These findings together indicate that spatial and temporal information are not automatically integrated. Korsakoff patients have profound problems in coding the feature at hand. Moreover, their lower recall of both features at the same time suggests that Korsakoff patients are impaired in binding different contextual attributes together in memory. (JINS, 2006, 12, 327–336.)

Alcoholic Korsakoff's syndrome (KS) is marked by remote memory impairment together with characteristic profound anterograde memory deficits. Despite previous studies of memory processes in KS, questions remain regarding the nature and severity of these impairments and identification of brain systems that underlie these different memory impairments. This study examined remote and anterograde memory function in 5 KS patients in comparison with 8 patients with Alzheimer's disease (AD) and 24 normal control subjects (NC). In addition, relationships between memory performance and regional brain volumes were examined in the KS group. Overall, the KS group showed severe impairment on both remote and anterograde memory measures, performing at the level of the AD group on most measures. Differences were observed on the pattern of temporal gradient for verbal recognition, with KS exhibiting a more steeply graded rate of decline over the most recent period examined. Severity of the remote memory deficit in KS was not associated with severity of anterograde memory deficit. Examination of brain structure–function relationships in the KS subjects revealed that photo naming of remote historical information was related to posterior cortical white matter volumes but not hippocampal volumes; sequencing was related to prefrontal but not hippocampal volumes. By contrast, a measure of anterograde memory for nonverbal visual material showed a relationship to hippocampal but not regional cortical white matter volumes. This set of dissociations, which parallels that observed in our earlier study of AD, is now documented in KS and provides further evidence that these separate cortical and limbic brain systems are principal neural substrates of the remote and anterograde memory and sequencing deficits in KS. (JINS, 2004, 10, 427–441.)

We studied time estimation in patients with frontal damage (F) and alcoholic Korsakoff (K) patients in order to differentiate between the contributions of working memory and episodic memory to temporal cognition. In Experiment 1, F and K patients estimated time intervals between 10 and 120 s less accurately than matched normal and alcoholic control subjects. F patients were less accurate than K patients at short (< 1 min) time intervals whereas K patients increasingly underestimated durations as intervals grew longer. F patients overestimated short intervals in inverse proportion to their performance on the Wisconsin Card Sorting Test. As intervals grew longer, overestimation yielded to underestimation for F patients. Experiment 2 involved time estimation while counting at a subjective 1/s rate. F patients' subjective tempo, though relatively rapid, did not fully explain their overestimation of short intervals. In Experiment 3, participants produced predetermined time intervals by depressing a mouse key. K patients underproduced longer intervals. F patients produced comparably to normal participants, but were extremely variable. Findings suggest that both working memory and episodic memory play an individual role in temporal cognition. Turnover within a short-term working memory buffer provides a metric for temporal decisions. The depleted working memory that typically attends frontal dysfunction may result in quicker turnover, and this may inflate subjective duration. On the other hand, temporal estimation beyond 30 s requires episodic remembering, and this puts K patients at a disadvantage. (JINS, 2000, 6, 517–528.)