Intact implicit habit learning in Alzheimer's disease.

Abstract

Habit learning refers to the incremental implicit learning of associations. Patients with Alzheimer's disease (AD) exhibit deficits in explicit memory and in conceptual implicit memory tasks that rely on the cortical areas damaged in AD. The authors tested patients with AD and controls on a probabilistic classification task in which participants implicitly acquire cue-outcome associations. Both groups showed evidence of learning across 50 trials, and performance did not differ significantly between the groups. In contrast, patients with AD exhibited a profound impairment in explicit memory for the testing episode. These results are consistent with the idea that habit learning relies on subcortical structures, including the basal ganglia, and is independent of the medial temporal and cortical areas damaged in AD.

Learning strategies in amnesia

“…The small number of amnesic participants is not particular to our study. For instance, the experiments of Eldridge et al (2002), Knowlton et al (1994), and Reber et al (1996) all had eight amnesic participants, while Hopkins et al (2004) had nine. Lack of statistical power is common in neuropsychological studies that rely on patient populations (Zaki, 2004).…”

“…It is an established finding that, compared to controls, amnesic individuals show unimpaired early learning (Knowlton et al, 1994Eldridge, Masterman, & Knowlton, 2002;Reber, Knowlton, & Squire, 1996; but see Hopkins, Myers, Shohamy, Grossman, & Gluck, 2004, for a different result). More specifically, what has been found is that categorization performance of amnesic groups does not significantly differ from performance of matched controls in the first 50 trials of the weather prediction task.…”

“…Since the performance of both groups does differ significantly from chance performance, both groups show learning, in an apparently similar manner. However, when asked about certain features of the task, such as where the cards were placed on a computer screen, or the number of elements of the geometric patterns on the cards, amnesic patients show very poor memory of these task features Eldridge et al, 2002). Hence, there appears to be unimpaired learning, but impaired declarative memory in amnesia.…”

Models of probabilistic category learning in Parkinson’s disease: Strategy use and the effects of L-dopa

“…One impetus for the claim of such dissociable learning systems was the finding that amnesic patients showed no (early) impairment in the WPT, whilst unable to recall recall certain aspects of the testing episode (Eldridge et al, 2002;Knowlton et al, 1994Knowlton et al, , 1996. Impaired WPT performance was not accompanied by this lack of declarative memory in PD patients (Knowlton et al, 1996;Sage et al, 2003;Witt et al, 2002).…”

Alzheimer's disease and implicit memory

“…When these patients are repeatedly expose to an object, these patients can process information faster and/ or more accurately compared to baseline 5,40 . The perceptual priming spare in AD patients has been demonstrated using words 38 , objects nonverbal responses to pictorial material 41,42 and a picture fragment task 38,43 .…”