Perceptual and nonperceptual components of implicit memory for pictures.

The transfer appropriate processing (TAP) framework posits that in data-driven tasks, such as picture naming (PN) or picture perceptual identification, repetition priming is greater when perceptual processes engaged at study are recapitulated at test. Thus, priming with pictures is greater after study-phase exposure to pictures than to words (picture names). A. S. Brown, D. R. Neblett, T. C. Jones, and D. B. Mitchell (see record 1991-26453-001) reported that a pure-list format eliminated perceptual priming: Participants who saw either pictures or words in a study phase showed equal priming in a PN task. In the present study, participants showed greater priming after exposure to pure lists of pictures than to pure lists of words in 3 PN and 1 picture perceptual identification experiments. Thus, perceptual priming occurred in 4 pure-list picture priming tasks, as predicted by the TAP framework. Priming also was found after exposure to words. In PN and picture perceptual identification tasks, implicit memory for pictures includes perceptual and nonperceptual components. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact acquisition and long-term retention of mirror-tracing skill in Alzheimer's disease and in global amnesia.

The ability of patients with Alzheimer's disease (AD) or global amnesia (AMN) to acquire skill for tracing a pattern seen in mirror-reversed view and to retain that skill over 24-hr intervals was examined. Both patient groups had poor recall and recognition of their mirror-tracing experience, but they acquired and retained mirror-tracing skill as well as normal control Ss. One AMN patient retained the skill over a year-long interval. Furthermore, the patients transferred their skill normally to an alternate pattern. These results indicate that the memory system underlying mirror-tracing skill learning is separable from medial-temporal structures compromised in AMN and AD and from neocortical areas compromised in AD. Brain regions relatively spared in early AD, such as the basal ganglia or cerebellum, may mediate critical aspects of the learning of novel sensorimotor associations that underlie skilled mirror tracing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual and conceptual memory processes in global amnesia.

To determine whether global amnesia reflects a selective deficit in conceptual processing, amnesic and control Ss performed 4 memory tasks that varied processing and retrieval requirements. A study-phase modality (auditory/visual) manipulation validated the nature of processing (perceptual and conceptual) engaged by each task. Amnesic patients were impaired on perceptual and conceptual explicit memory tasks (word-fragment and word-associate cued recall) and were intact on perceptual and conceptual implicit memory tasks (word-fragment completion and word association). These results are consistent with the view that limbic-diencephalic structures damaged in amnesia mediate, in part, processes typically engaged during explicit retrieval. The results are inconsistent, however, with the characterization of that deficit as being one of conceptual processing per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective effects of methylphenidate in attention deficit hyperactivity disorder: a functional magnetic resonance study

Functional MRI revealed differences between children with Attention Deficit Hyperactivity Disorder (ADHD) and healthy controls in their frontal-striatal function and its modulation by methylphenidate during response inhibition. Children performed two go/no-go tasks with and without drug. ADHD children had impaired inhibitory control on both tasks. Off-drug frontal-striatal activation during response inhibition differed between ADHD and healthy children: ADHD children had greater frontal activation on one task and reduced striatal activation on the other task. Drug effects differed between ADHD and healthy children: The drug improved response inhibition in both groups on one task and only in ADHD children on the other task. The drug modulated brain activation during response inhibition on only one task: It increased frontal activation to an equal extent in both groups. In contrast, it increased striatal activation in ADHD children but reduced it in healthy children. These results suggest that ADHD is characterized by atypical frontal-striatal function and that methylphenidate affects striatal activation differently in ADHD than in healthy children.     

Repetition Priming and Recognition Memory in Younger and Older Persons: Temporal Stability and Performance.

The dissociation between intact priming and reduced explicit memory in aging has been called into question on the basis of limited information that suggests that priming measures are less reliable than explicit memory measures. No aging study to date, however, has offered a comprehensive examination of the reliability of these measures. Age-related performance and test-retest stability coefficients for multiple priming and explicit memory tasks were compared. Age effects were found on some tasks but not others, and stability was not related to task performance. Stability was similar for implicit versus explicit task instructions, younger versus older persons, and studied versus unstudied items. Results indicate that dissociations between priming and explicit memory performances cannot be accounted for by differential reliability of the measures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Striatal activation during acquisition of a cognitive skill.

The striatum is thought to play an essential role in the acquisition of a wide range of motor, perceptual, and cognitive skills, but neuroimaging has not yet demonstrated striatal activation during nonmotor skill learning. Functional magnetic resonance imaging was performed while participants learned probabilistic classification, a cognitive task known to rely on procedural memory early in learning and declarative memory later in learning. Multiple brain regions were active during probabilistic classification compared with a perceptual-motor control task, including bilateral frontal cortices, occipital cortex, and the right caudate nucleus in the striatum. The left hippocampus was less active bilaterally during probabilistic classification than during the control task, and the time course of this hippocampal deactivation paralleled the expected involvement of medial temporal structures based on behavioral studies of amnesic patients. Findings provide initial evidence for the role of frontostriatal systems in normal cognitive skill learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Convergent behavioral and neuropsychological evidence for a distinction between identification and production forms of repetition priming.

Four experiments examined a distinction between kinds of repetition priming which involve either the identification of the form or meaning of a stimulus or the production of a response on the basis of a cue. Patients with Alzheimer's disease had intact priming on picture-naming and category-exemplar identification tasks and impaired priming on word-stem completion and category-exemplar production tasks. Division of study-phase attention in healthy participants reduced priming on word-stem completion and category-exemplar production tasks but not on picture-naming and category-exemplar identification tasks. The parallel dissociations in normal and abnormal memory cannot be explained by implicit-explicit or perceptual-conceptual distinctions but are explained by an identification-production distinction. There may be separable cognitive and neural bases for implicit modulation of identification and production forms of knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential Associations Between Entorhinal and Hippocampal Volumes and Memory Performance in Older Adults.

Magnetic resonance imaging-derived entorhinal and hippocampal volumes were measured in 14 nondemented, community-dwelling older adults. Participants were selected so that memory scores from 2 years prior to scanning varied widely but were not deficient relative to age-appropriate norms. A median split of these memory scores defined high-memory and low-memory groups. Verbal memory scores at the time of imaging were lower, and entorhinal and hippocampal volumes were smaller, in the low-memory group than in the high-memory group. Left entorhinal cortex volume showed the strongest correlation (r=.79) with immediate recall of word lists. Left hippocampal volume showed the strongest correlation (r=.57) with delayed paragraph recall. These results suggest that entorhinal and hippocampal volumes are related to individual differences in dissociable kinds of memory performance among healthy older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)