Natural Rationality | decision-making in the economy of nature


Just (don't) do it: The neural correlate of the veto process

A study published in the new edition of the Journal of Neuroscience proposes that the dorsal fronto-median cortex (dFMC) is primarily involved in the inhibition of intentional action. Subjects had to inhibit a simple decision: choosing when to execute a simple key press while observing a rotating clock hand (the design is hence analogue to the famous Ben Libet's experiment on free will where he found out that "subjects perceived the intention to press as occurring before a conscious experience of actually moving". The difference being that this time, researchers have fMRI data (and not just EEG recording) and that subjects must choose and then inhibit. So here is that small piece of gray matter that inhibit you behavior:

(from Brass & Haggard, 2007)

Interestingly, their finding also suggest a top-down mechanisms for action inhibition:

Cognitive models of inhibition have focused on inhibition of prepotent responses to external stimuli (Logan et al., 1984; Cohen et al., 1990). An important distinction is made between "lateral" competitive interaction between alternative representations at a single level (Rumelhart and McClelland, 1986) and inhibitory top-down control signals from hierarchically higher brain areas (Norman and Shallice, 1986). The first idea would be consistent with a general decision process being involved. If the dFMC decides between action and inhibition by a competitive interaction process, then representations corresponding to the possibilities of action and to non-action should initially both be active, leading to activation in both action trials and inhibition trials. Our finding of minimal dFMC activation in action trials (...) argues against a view of endogenous inhibition based on competitive interaction between alternatives and thus is also not consistent with the idea of the dFMC being involved in a general decision process. In contrast, our result is consistent with a specific top-down control signal gating the neural pathways linking intention to action. This view is supported by the negative correlation between dFMC activation and primary motor cortex activation.