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SUMMARY:Neural representation of head motion in the vestibulo-cerebellum o
 f the macaque
DTSTART:20130422T140000
DTEND:20130422T150000
DTSTAMP:20260928T175438Z
UID:bd1c40ba66c849bea93cd0d2261421e7ef8c91d2e40d805c9e8794c6
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Jean Laurens\, Washington University School of Medicine 
 (Saint Louis\, Missouri) & EPFL.\nSpatial orientation\, locomotion and equ
 ilibrium rely on the brain’s ability to estimate head orientation relati
 ve to gravity. Studying this function provides an excellent model of how t
 he brain tracks the motion of more complex body parts such as the arms\, a
  process in which the cerebellum plays a key role.\nThe otoliths\, which a
 re gravity sensors located in the inner ear\, are also sensitive to head t
 ranslations: they detect the gravito-inertial force (F)\, which is the sum
  of gravity (G) and linear acceleration (A)\, i.e. F=G+A. As an analogy\, 
 one can compare them to a pendulum\, swinging relative to the head when it
  tilts or accelerates. Behavioral and theoretical studies in the last deca
 des have suggested that the brain resolves this ambiguity by using an inte
 rnal model of head motion. This model integrates over time head rotation s
 ignals provided by the semi-circular canals. This allows maintaining an in
 ternal estimate of the orientation of the gravity vector relative to the h
 ead (i.e. of G) which is subtracted from the otolith signal to compute an 
 internal estimate of acceleration (A=F-G). In support of this theory\, we 
 have recently identified populations of Purkijne cells in the vestibulo-ce
 rebellum of macaques which selectively respond to tilt and translation. Th
 rough a simple decoding scheme\, we compute signals carried by these neuro
 ns and we demonstrate that they obey the equation F=G+A. We conclude that 
 these neurons encode internal estimates of tilt and translation whose calc
 ulation relies on the long-postulated theoretical concept of internal mode
 l.
LOCATION:SV1717a http://plan.epfl.ch/?room=SV%201717A
STATUS:CONFIRMED
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