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Posterior parietal cortex is implicated in continuous switching between verbal fluency tasks: an fMRI study with
Jennifer M Gurd1, Katrin Amunts, Peter H Weiss
1Neuropsychology Unit, University Department of Clinical Neurology, Radcliffe Infirmary, Oxford, UK. jenifer.gurd@clinical-neurology-oxford.ac.uk
Brain : a Journal of Neurology
|April 19, 2002
Summary
The superior posterior parietal cortex controls attentional switching, even in tasks without visual or spatial elements. This finding suggests its role in executive functions and potential clinical relevance for parietal lesion patients.
Area of Science:
- Cognitive Neuroscience
- Neuroimaging
- Neuropsychology
Background:
- Attentional switching is a key executive function often linked to frontal lobe activity.
- The role of the posterior parietal cortex in attentional control, particularly in non-spatial and non-visual tasks, remains less understood.
Purpose of the Study:
- To investigate the involvement of the posterior parietal cortex in attentional switching during verbal fluency tasks.
- To determine if the superior posterior parietal cortex acts as a supramodal area for task switching.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to scan healthy volunteers.
- Participants performed verbal fluency tasks involving switching between semantic categories or overlearned sequences versus non-switching conditions.
- A factorial design examined the effects of verbal class (semantic category vs. overlearned sequences) and switching conditions.
Main Results:
- Increased neural activity was observed in the superior posterior parietal cortex bilaterally during switching conditions compared to non-switching conditions.
- Semantic category fluency, compared to overlearned sequence fluency, activated the anterior cingulate cortex, left inferior frontal gyrus, middle frontal gyrus, frontal operculum, and cerebellar vermis.
- No significant activations were found in the posterior parietal cortex for the verbal class factor.
Conclusions:
- The superior posterior parietal cortex plays a crucial role in attentional switching, independent of spatial or visual demands.
- These findings support the hypothesis of the superior posterior parietal cortex as a supramodal region for task switching.
- Task switching research may benefit from considering the superior posterior parietal cortex, with implications for assessing patients with superior posterior parietal lesions.