Which part of the brain generates freewill?
Focus, issue 272, September 2014, p. 72, www.sciencefocus.com
The Focus magazine’s reply to this question leaves considerable gaps in terms of the present century’s neuroscience. Benjamin Libet’s experiment from the 1980s is once again confidently quoted as a refutation of the concept of freewill. This veteran
experiment showed that brain activity could be detected before the conscious awareness of the intention to perform an action, and has ever after been trundled out as a refutation of freewill. It has to be stressed that the Libet experiment and subsequent similar experiments involved trivial and pre-decided actions, such as moving a finger or flexing a wrist. All that subjects of this laboratory experiment had to actually decide was the exact timing of the trivial movement.
Since the period of the Libet experiment, it has been discovered that the brain’s dorsal stream, which is responsible for movement, is unconscious. Consciousness is not usually involved in the type of actions tested by Libet. Really, this should have been obvious from the beginning, as we are all familiar with performing actions, sometimes unintended ones, on autopilot, but we don’t take this as evidence that we perform our whole life on autopilot.
The Ventral Stream
A separate brain system, the ventral stream is responsible for developing conscious images that are projected to the brain’s reward circuit. The brain regions involved in the reward circuit are upstream of those initiating action and behaviour, and are also connected to our reasoning/thought processes. This refers to more deliberative decisions and actions rather than the trivial movements studied by Libet.
The curious nature of the short piece discussed here is compounded by a hang over from the Cartesian belief system suggesting that the process of thought is somehow separate from the physical universe or non-material, thus supposedly rendering any influence of thought on action ‘magical’. Of course modern neuroscience has for a good time identified the physical processes involved in thought within the prefrontal areas of the brain, and these, like the reward stream, lie upstream of the more deliberative decisions and actions.
The concept of free will is problematic as it proposes something outside the cause and effect sequences described by science. It is perhaps more relevant to talk of conscious will, in terms of influence of the subjectively experienced reward circuit. The conscious experience itself could be identified with a fundamental aspect of the universe, such as spacetime, simply because of the lack of any place for it in the rest of physics.
Such an influence might be deterministic, in the same way that the execution of the physical law is deterministic, but might at the same time be blended with other more local influences, such as reasoning in the brain. This might leave us with something akin to turbulent or chaotic activity, which is quite distinct from randomness, although for all practical purposes it is also unpredictable.Tags: dorsal stream, free will, freewill, Libet, reward circuit, ventral stream Posted by