Neural representation of head motion in the vestibulo-cerebellum of the macaque
Event details
| Date | 22.04.2013 |
| Hour | 14:00 › 15:00 |
| Speaker |
Dr. Jean Laurens, Washington University School of Medicine (Saint Louis, Missouri) & EPFL. |
| Location | |
| Category | Conferences - Seminars |
Spatial orientation, locomotion and equilibrium rely on the brain’s ability to estimate head orientation relative to gravity. Studying this function provides an excellent model of how the brain tracks the motion of more complex body parts such as the arms, a process in which the cerebellum plays a key role.
The otoliths, which are gravity sensors located in the inner ear, are also sensitive to head translations: 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 decades have suggested that the brain resolves this ambiguity by using an internal model of head motion. This model integrates over time head rotation signals provided by the semi-circular canals. This allows maintaining an internal estimate of the orientation of the gravity vector relative to the head (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-cerebellum of macaques which selectively respond to tilt and translation. Through a simple decoding scheme, we compute signals carried by these neurons and we demonstrate that they obey the equation F=G+A. We conclude that these neurons encode internal estimates of tilt and translation whose calculation relies on the long-postulated theoretical concept of internal model.
The otoliths, which are gravity sensors located in the inner ear, are also sensitive to head translations: 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 decades have suggested that the brain resolves this ambiguity by using an internal model of head motion. This model integrates over time head rotation signals provided by the semi-circular canals. This allows maintaining an internal estimate of the orientation of the gravity vector relative to the head (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-cerebellum of macaques which selectively respond to tilt and translation. Through a simple decoding scheme, we compute signals carried by these neurons and we demonstrate that they obey the equation F=G+A. We conclude that these neurons encode internal estimates of tilt and translation whose calculation relies on the long-postulated theoretical concept of internal model.
Practical information
- Informed public
- Free
Organizer
- Prof. G.Courtine
Contact
- Center for Neuroprosthetics, [email protected]