Neural Mechanisms of Expert Skills in Visual Working Memory

Abstract

Expertise can increase working memory (WM) performance, but the cognitive and neural mechanisms of these improvements remain unclear. Here, we used functional magnetic resonance imaging to assess the degree to which expertise acquisition is supported by tuning of occipitotemporal object representations and tuning of prefrontal and parietal networks that may support domain-specific WM skills. We trained subjects to become experts in a novel category of complex visual objects and examined brain activity while they performed a WM task with objects from the expert category and from an untrained category. Visual expertise training resulted in improved recognition of expert, compared with untrained objects, and this effect was eliminated in a behavioral experiment by stimulus inversion. These behavioral changes were accompanied by increased recruitment of bilateral dorsolateral prefrontal, posterior parietal, and occipitotemporal cortices during WM encoding and maintenance. Across subjects, behavioral measures of expertise reliably predicted increased activation during maintenance of expert objects in all three regions. These neural expertise effects could not be attributed to differences in low-level stimulus characteristics between the two categories, familiarity with features of expert-domain objects, or familiarity with the WM task. These results are consistent with the idea that visual expertise improves WM performance through tuning of occipitotemporal object representations and through development of lateral prefrontal and posterior parietal networks that mediate the application of domain-specific mnemonic skills.

The right parietal lobe is critical for visual working memory

“…This view stands in contrast to the interpretations of previous fMRI findings in which PPC activations were associated with maintenance of visual information in WM (Leung, Oh, Ferri, & Yi, 2007;Moore, Cohen, & Ranganath, 2006;Todd & Marois, 2004;Woodward et al, 2006;Xu & Chun, 2006). One explanation for this is that activity during the WM maintenance period reflects an attentional tagging process important for memory retrieval.…”

Functional Coupling of Human Prefrontal and Premotor Areas during Cognitive Manipulation

“…In turn, the segmenting operation should evoke a similar process of LTM reactivation, which is to retrieve chunk contents from LTM. Consistently, these segmenting-related areas overlap with the expertise-related activity in a recent study in which subjects were extensively trained on visual category recognition before fMRI (Moore et al, 2006). During encoding/maintenance, novel stimuli of the trained category more strongly activated bilateral DLPFC and VLPFC than those of untrained categories.…”

Many Faces of Expertise: Fusiform Face Area in Chess Experts and Novices

“…It should be noted, though, that even in face perception, we have a dedicated network of brain structures, which are responsible for different processes (Tovée, 1998). It is thus plausible that we may have similar complex networks for processing other overlearned objects (Moore et al, 2006;Op de Beeck et al, 2006). Which areas of the ventral stream are engaged most likely depends on the nature of the stimuli.…”