PARIETAL Stim Human Movement Intention Desmurget Lyon Science 2009
<p>Jul 15, 2012 04:32 PM
<b> </b>
<b>title: Movement Intention After Parietal Cortex Stimulation in Humans</b>...
 
authors:  Michel 
Desmurget,  Karen Reilly, Nathalie Richard... Angela Sirigu  all
at  Centre de Neuroscience Cognitive  CNRS in Lyon.
 
appeared in SCIENCE   8 May 2009  (in my files, pdf)
 
page 811
 
Parietal and premotor cortex regions are serious contenders for bringing motor intentions and
motor responses into awareness. We used electrical stimulation in <b>seven patients</b> undergoing
awake brain surgery. <b>Stimulating the right inferior parietal regions triggered a strong intention</b>
<b>and desire to move the contralateral hand, arm, or foo</b>t, whereas<b> stimulating the left inferior</b>
<b>parietal region provoked the intention to move the lips and to talk</b>. When stimulation intensity was
increased in parietal areas, participants believed they had really performed these movements,
although no electromyographic activity was detected. Stimulation of the premotor region triggered
overt mouth and contralateral limb movements. Yet, patients firmly denied that they had moved.
Conscious intention and motor awareness thus arise from increased parietal activity before
movement execution.
 
Where is the ORIGIN of WILLED ACTIONS.  page  811
Where in the brain are INTENTIONS FORMED!!!
 
decision to move  LAGS the monset of brain activity.
 
CONSc intention of a mvmt emerges as a <b>CONSEQUENCE of incr neural activity in a </b>
<b>premotor-parietal circuit  which elaborate motor plans before action</b>..
 
We directly stimulate parietal and premotor cortex regions  we shud be able to evoke motor responses
in specific body areas  AND
in areas involved in carrying out ADVANCE COMPUTATIONS
related to consc intention and motor awareness, these mvmts shud be accompanied or preceded by the
SUBJECTIVE EXPERIENCE of willed action.
 
2nd to last para on page 813
 
awareness of initiating and executing a movement is NOT derived from afferent inputs
but rather from the INTERNAL COMPUTATIONS carried out in the posterior parietal cortex
before action.
 
we are unaware of sensory feedback abt ongoing motor actions, as long as intentions are achieved.
Peripheral inputs prob. intervene when we need to compare EXPECTED and ACTUAL MOVVMTS.
 
if premotor strip is stim. directly then (there is no proprioceptice input) with which to compare
to an expected input to estimate mvmt state to construct a veridical motor awareness.
 
 
 
 
 
 
Our study suggests that MOTOR INTENTION and AWARENESS are
conseq. of Incr PARIETAL ACTIVITY before mvmt execution.
The subjective (and potentially illusory) feeling that we are executing a mvmt
does not arise from the mvmt itself, but is gen by PRIOR CONSC INTENTION
and its predicted consequences.
 
 
 
 
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