Word repetition in amnesia: Electrophysiological measures of impaired and spared memory

J. M. Olichney
2000 Brain  
Amnesic patients often show improved performance when showed a large N400 for incongruous relative to congruous words. Similarly, when incongruous trials were repeated stimuli are repeated, even in the absence of conscious after 0-13 intervening trials, N400s were reduced in both memory for those stimuli. Although these performance groups. When congruous trials were repeated, a late changes are typically attributed to perceptual or motor positive repetition effect was observed, but only in the
more » ... d, but only in the systems, in some cases they may be related to basic control group. Furthermore, the amplitude of the late language processing. We examined two neurophysiological positive repetition effect was highly correlated with later measures that vary with word repetition in 12 amnesic word recall in both patients and controls. In the patients, patients and 12 control subjects: (i) a late positive the correlation was also observed with memory scores component of the event-related potential (ERP) linked to from standardized neuropsychological tests. These data conscious memory and (ii) the N400 component that are consistent with a proposed link between the late varies with language comprehension. In each trial, the positive repetition effect and conscious memory. On the subject heard a category name, then viewed a word, other hand, the N400 repetition effect was not correlated and then decided whether the word was semantically with episodic memory abilities, but instead indexed an congruous or incongruous (e.g. 'yes' for 'baby animal: aspect of memory that was intact in the amnesic patients. cub'; 'no' for 'water sport: kitchen'). Recall and The preserved N400 repetition effect is an example of recognition testing at the end of the experiment showed preserved memory in amnesia that does not easily fit into that control subjects had better memory for congruous the categories of low-level perceptual processing or of than for incongruous words, as did the amnesic patients, motor learning. Instead, the sensitivity of the N400 to who performed less well overall. In contrast, amnesic both semantic context and repetition may reflect a shortpatients were unimpaired on the category decisions term memory process that serves language comprehension in realtime. required in each trial and, like the control subjects,
doi:10.1093/brain/123.9.1948 pmid:10960058 fatcat:xy33csd7zraujf3leshfj4qd4i