Is the Prefrontal Cortex Necessary for Establishing Cognitive Sets?

Abstract

There is evidence from neuroimaging that the prefrontal cortex may be involved in establishing task set activity in advance of presentation of the task itself. To find out whether it plays an essential role, we examined patients with unilateral lesions of the rostral prefrontal cortex. They were first instructed as to whether to perform a spatial or a verbal working memory task and then given spatial and verbal items after a delay of 4 -12 s. The patients showed an increase in switch costs, making more errors by repeating what they had done on the previous trial. They were able to establish regional task set activity during the instruction delay, as evidenced by sustained changes in the blood oxygenation level-dependent signal in caudal frontal regions. However, in contrast to healthy controls, they were less able to maintain functional connectivity among the surviving task-related brain regions, as evidenced by reduced correlations between them during instruction delays. The results suggest that the left rostral prefrontal cortex is indeed required for establishing a cognitive set but that the essential function is to support the functional connectivity among the task-related regions.

Altered connectivity between prefrontal and sensorimotor cortex in conversion paralysis

“…Taken together, this pattern of functional connectivity suggests that although these PFC clusters exibit similar local responses during motor imagery of the affected hand, they differ in terms of the long-range couplings to these local responses. More precisely, the dlPFC is coupled with parts of the motor system, in line with its presumed role in the selection of action plans (Frith et al, 2000b;Passingham, 1993;Rowe et al, 2007) (Fig. 2).…”

Decoding the Content of Delayed Intentions

“…The role of RLPFC in PM is therefore unclear. As hypothesized above, one possibility is that RLPFC supports PM via its interactions with other brain regions, rather than itself representing the content of delayed intentions (Sakai and Passingham, 2003;Rowe et al, 2007). To test this hypothesis, a PPI analysis was conducted, to search for brain regions showing greater functional coupling with RLPFC during PM store periods than baseline store periods, defining a seed region as all those voxels within Brodmann area 10 that were activated by the contrast of PM store periods versus baseline periods at a threshold of p Ͻ 0.001, uncorrected, in the group-level analysis.…”

“…Alternatively, RLPFC might be thought to support a state promoting the ability of environmental events to act as retrieval cues for intended behaviors, analogous to "retrieval mode" (Tulving, 1983). According to this latter model, RLPFC might play a noncontent-specific role via its interactions with distinct brain regions that themselves represent the content of intentions (Sakai and Passingham, 2003;Rowe et al, 2007).…”

The Role of Rostral Prefrontal Cortex in Establishing Cognitive Sets: Preparation or Coordination?: Figure 1.

“…Recently, Rowe et al (2007) scrutinized whether rostral PFC is essential for initiating context-dependent processes in caudal brain regions (including more posterior PFC areas). Patients with lesions to left rostrolateral PFC [Rowe et al (2007), their Fig.…”

“…Patients with lesions to left rostrolateral PFC [Rowe et al (2007), their Fig. 2 (http://www.jneurosci.org/ cgi/content/full/27/48/13303/F2), Table 1 (http://www.jneurosci.org/cgi/content/ full/27/48/13303/T1)] and healthy controls engaged in a working memory task while being scanned by functional magnetic resonance imaging (fMRI) (Fig.…”