Transient activation of inferior prefrontal cortex during cognitive set shifting

Abstract

The Wisconsin Card Sorting Test, which probes the ability to shift attention from one category of stimulus attributes to another (shifting cognitive sets), is the most common paradigm used to detect human frontal lobe pathology. However, the exact relationship of this card test to prefrontal function and the precise anatomical localization of the cognitive shifts involved are controversial. By isolating shift-related signals using the temporal resolution of functional magnetic resonance imaging, we reproducibly found transient activation of the posterior part of the bilateral inferior frontal sulci. This activation was larger as the number of dimensions (relevant stimulus attributes that had to be recognized) were increased. These results suggest that the inferior frontal areas play an essential role in the flexible shifting of cognitive sets.

Brain imaging of the central executive component of working memory

“…A significant transient increase in neural activitywas observed in the right antero-dorsal part (BA 46) of the prefrontal cortex, near the frontal pole, when participants had to shift an attentional set between different perceptual dimensions. Konishi et al [68] used a similar procedure to dissociate the shifting processes from the inhibitory ones in the Wisconsin Card Sorting Test. Transient shift-related signals after each dimensional shift were found in the posterior part of the bilateral inferior frontal sulci (BA 45/44) but foci of activation were also found in the right and left supramarginal gyrus (BA 40) and the anterior cingulate cortex (BA 24/32), although these regions were less reproducibly activated across the participants.…”

Prefrontal mechanisms for executive control over emotional distraction are altered in major depression

“…This region has been associated with mediating conflict between competing responses (Carter et al, 1998, Botvinick et al, 2001, monitoring for the occurrence of response conflict in information processing (Carter et al, 1998, Botvinick et al, 1999, Barch et al, 2000, Botvinick et al, 2001, and error monitoring and detection (Rubia et al, 2003). In addition, a number of studies using Stroop, Go/No Go and other attention-demanding tasks suggest a role of the right inferior frontal gyrus (IFG) in inhibitory processes relevant for successful cognitive performance and executive function (Jonides et al, 1998, Konishi et al, 1998, D'Esposito et al, 1999, Liddle et al, 2001, Rubia et al, 2003, Aron et al, 2004.…”

Wisconsin Card Sorting Test

“…Here, the anomalous absence of the extrastriate N1 component ( Fig. 1) appears to precede in time a signi®-cant reduction in P2 activity over the right frontal region [7]. This explanation is consistent with claims that perseverative errors may result from disruptions in more than one mechanism of visual attention [16], as well as with mounting clinical evidence of increased rates of perseverative responses secondary to lesions in temporo-parietal visual association areas [8,12,15].…”

“…On the one hand, clinical reports suggest that WCST scores alone should not be regarded as markers of frontal dysfunction [10±12], since lesions in posterior brain regions may lead to increased rates of perseveration [8,9,15]. On the other hand, WCST performance is consistently related to bilateral metabolic activation of dorsolateral prefrontal regions [7,18,19]. Evidence from Fig.…”

“…Thus, a nonperseverative error in late WCST trials can be regarded as a distraction, and has not been so often related to dorsolateral prefrontal damage [1,14]. Many neuroimaging studies have shown increased metabolic activation in both frontal and posterior brain areas during WCST performance [7,18,19]. However, no study to date has accomplished a direct measurement of brain activity associated with either type of WCST error.…”