*Professor Maurice Smith has invited Reza Shadmehr to Speak at a Seminar entitled "Motor Adaptation and the Timescales of Memory " in G135 MD -- Thursday, 5/17 -- 4 PM and invites you to attend. The abstract is below. * Motor Adaptation and the Timescales of Memory Abstract When the brain generates a motor command, it also predicts the sensory consequences of that command via an "internal model". The reliance on a model appears to make the brain able to sense the world better than is possible from the sensors alone. However, this happens only when the models are accurate. To keep the models accurate, the brain must constantly learn from prediction errors. Here I use examples from saccade and reach adaptation to demonstrate that learning is guided by multiple timescales: a fast system that strongly responds to error but rapidly forgets, and a slow system that weakly responds to error but has good retention. Why should learning be guided by multiple timescales? The response of the motor apparatus to neural commands varies due to many causes. Fast timescale disturbances occur when muscles fatigue. Disturbances with a slow timescale occur when muscles are damaged, or limb dynamics change due to development. To maintain performance, motor commands need to adapt. Computing the best adaptation in response to any performance error results in a credit assignment problem: what timescale is responsible for this disturbance? I show that a Bayesian solution to this problem accounts for numerous behaviors of animals during both short and long-term training. Our analysis focuses on characteristics of the oculomotor system during learning, including effects of time passage. However, I suggest that learning and memory in other paradigms, such as reach adaptation, the adaptation of visual neurons, and retrieval of declarative memories, largely follow similar rules. _______________________________________________ Colloquium mailing list Colloquium(a)deas.harvard.edu https://lists.deas.harvard.edu/mailman/listinfo/colloquium _______________________________________________ iic-seminars mailing list iic-seminars(a)calists.harvard.edu http://calists.harvard.edu/mailman/listinfo/iic-seminars