alien hand syndrome
what is it
movements which the patient regards as foreign, involuntary (unwilled)
unwilled grasping behaviours mentioned in lecture but other behaviours have been recorded
understand the hand is theres but have lost voluntary control over it
neural correlates
lesions to the medial frontal lobes
lesions to the corpus callosum
increasingly reported in corticobasal degeneration/syndrom which affects the basal ganglia which is linked to movement
more recent reports of a small number of cases following posterior parietal stroke and posterior cerebral artery stroke
control/awaremess of action
forward model of motor control
when the outcome and prediction of the motor command match there is a low sensory discrepancy
if they don't match and there's a discrepancy then we may feel we don't have ownership of the movement
free will (libet et al., 1983)
asked p's to press red button and say clock position at the time of conscious intention
found brain activity occurred a whole second before p's felt they intended to press button
suggests conscious action is after the neural signals prepare the action
this would suggest unconscious processes in the brain are the true initiator of volitional acts and therefore free will plays no part in their initiation
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free won't (brass & haggard, 2007)
voluntary inhibition does seem to exist
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