At attention and intention

Abstract

Attention is so closely bound to eye movement that saying ‘look’ is often tantamount to saying ‘pay attention’. Orienting one's visual attention often involves shifting one's gaze from one thing to another, but it can in the absence of overt eye movement, in other words, covertly. But could we also covertly orient our intentions in the same way that we covertly orient our attention?Recent studies by Rushworth et al., using both event-related fMRI 1xAttention systems and the organization of the human parietal cortex. Rushworth, M.F.S. et al. J. Neurosci. 2001; 21: 5262–5271PubMedSee all References1 and PET imaging 2xThe attentional role of the left parietal cortex: the distinct lateralization and localization of motor attention in the human brain. Rushworth, M.F.S. et al. J. Cogn. Neurosci. 2001; 13: 698–710Crossref | PubMed | Scopus (229)See all References2, support the idea of covert intentional orienting processes, or ‘motor attention’, and their results suggest that covert visual attention and motor attention play similar roles in their respective modalities. Just as covert visuospatial orienting involves a shift of attention from one part of the visual field to another without making any overt eye movements, visuomotor attention can be thought of as involving a shift of intention from one potential limb movement to another before selecting a response. The experiments by Rushworth and colleagues have indicated that motor attentional processes are anatomically distinct from visuospatial attentional processes. Covert visual attention activates regions of the parietal lobe, an area that is responsible for spatial processing and sensorimotor integration; covert motor attention relies on parietal processing as well, but activates different areas from those involved in visual attentional orientation.In the fMRI experiment 1xAttention systems and the organization of the human parietal cortex. Rushworth, M.F.S. et al. J. Neurosci. 2001; 21: 5262–5271PubMedSee all References1, Rushworth et al. used two related tasks that required subjects to shift their attention from one stimulus feature to another. In the first task, subjects were asked to select the appropriate stimulus by simply attending to it visually; in the second, they had to select their response by pressing a button with the right or left hand. The second condition was designed to isolate activity associated with motor attentional shifts – or ‘intention-switching’ – from that associated with visual attentional shifts. The researchers found that the locations of parietal activity associated with the purely visual task coincided very little with those associated with the motor response task, indicating that visual attention and visuomotor attention are subserved by two dissociable processes in the brain.The PET study 2xThe attentional role of the left parietal cortex: the distinct lateralization and localization of motor attention in the human brain. Rushworth, M.F.S. et al. J. Cogn. Neurosci. 2001; 13: 698–710Crossref | PubMed | Scopus (229)See all References2 revealed another contrast between visual attention and motor attentional activity. Visuospatial attentional systems are distributed throughout the right parietal and frontal cortices. The distinct motor attentional activity revealed by these experiments was, on the other hand, restricted to the left hemisphere. In particular, a left parietal area previously implicated in motor preparation showed significant activity. Left prefrontal areas active in action perception, motor imagery and copying tasks were also active in the motor attention tasks. This suggests a specialization for these visuomotor circuits in the left hemisphere. It also emphasizes the close relationship between attention and intention in the selection of actions. Are the two processes more similar than we usually think? These studies suggest that, although the brain mechanisms of visual orienting and motor orienting are distinct, covert attention and intention nevertheless share a functional logic at this level of processing. The authors’ elucidation of motor attention could help to resolve previous confounds between visual and motor attention, and inform future research on the tightly linked systems underlying perception and action, attention and intention.