Sumner, P, Husain, M, Singh, K and Rafal, R (2009-2012). See it, grab it: Control of automatic sensorimotor behaviour in health and disease. Wellcome Trust. £440,665 (Cardiff Funding: £214,913)
Specialist Summary
Our goal is to understand how automatic processes are involved in the flexible, ‘volitional’ control of behaviour . We will integrate different lines of research concerning automatic and unconscious activation and inhibition of motor plans, which together may challenge the traditional view that volitional and automatic behaviours are mediated separately. We will investigate:
• The roles of medial frontal and parietal brain regions in the activation of, competition between, and inhibition of action plans elicited by visual stimuli in the world around us.
• The inability of patients to inhibit stimulus-driven responses following focal damage to these regions, or in corticobasal degeneration.
• The relationship between the activation, conflict and inhibition mechanisms engaged by different sensor imotor paradigms (masked priming; flankers; object affordance).
A key strength of our proposal is the principled combination of experimental domains. Careful behavioural studies will determine performance correlates of activation, conflict and inhibition mechanisms and how they interact . A selected population of lesion patients will allow us to test hypotheses concerning the cortical substrates of these mechanisms, and the outcomes of interfering with them. Imaging will reveal the spatial distribution of implicated areas, and also the dynamics of activation within these cortical networks.
Non-Specialist Summary
Although we normally feel we have ‘voluntary’ control over our actions, in certain contexts we seem driven by automatic ‘reflexive’ responses – for example, a smoker taking a cigarette from a packet placed in front of him, without consciously deciding to. We become aware of such examples because the unintended action is actually carried out, but many more motor plans are initiated in our brains that
remain unconscious and un-executed.
Remarkably, simply looking at an object may be sufficient to automatically and unconsciously activate motor plans to grasp it . Such "priming" is useful when we need to act quickly, but what if we don’t want to do the primed action? Clearly, flexible control over our actions requires the ability to ‘veto’ action priming. This veto can be lost after stroke or in patients with alien limb syndrome who are unable to
stop themselves reaching out and grasping objects around them.
We aim to understand how the brain decides whether to ‘go with’ a primed response, or to veto it and select an alternative action. It appears that actions can be suppressed automatically and subconsciously as well as volitionally. We study how such automatic suppression is integrated with voluntary control.