1. learning vs plasticity 2. reinforcement learning vs supervised learning 3. circuits: VOR & OKR 4. open vs. closed loop controllers 6. plasticity: cerebellar LTD 5. learning: adjusting the FF controller

frequency EE H LRMR abducens nucl. vestibular nucl. oculomotor nucl. semicircular canals. MLF VOR Circuit contraipsi PPRF

Motor Neurons R m = eye position (deg) From Fuchs & Leschei 1970 From Robinson & Keller eye velocity (deg/s) r / k =  = 0.25 s viscoelastic time constant R o = 100 sp/s RoRo r  1 (sp/s) / (deg/s) + rĖ k  4 (sp/s) / deg + kE firing frequency (spikes/s)

E Pursuit System (Gaze Velocity Purkinje Cell) EpEp Motor Neuron E + Ė Neural Integrator (NPH for H INC for V) E out Extra- Ocular Muscle -H Vestibulo-Ocular Reflex (VOR) Saccade System (Burst Neurons in PPRF) ErEr Final Motor Pathway E in ?

Integrator Lesion: Effects Cannon & Robinson 1987

Planes of the Semi-Circular Canals horizontalanteriorposterior Excitatory Motions for the SCC’s on the left. from Carpenter, fig. 2.7 from KS&J, fig cochlear n. vestibular n. vestibulo- chochlear n. foramen magnum Angle at which the plane of the anterior semicircular duct crosses the midsagittal line cochlea semicircular ducts: anterior horizontal posterior internal acoustic meatus leftright

DTN/NOTLTNMTN D+antU+postH ipsiversive E I Rabbit OK (Afferents) stimulus speed (deg/sec) direction selectivity inferior posterior anterior superior canal:horizontalanteriorposterior Accessory Optic System data from Simpson 1984

VN NPH INC Ė E MN E I + AOS/NOT Inferior Olive Cerebellum climbing fibers mossy fibers SCC error signal Rabbit OK (adjusting VOR gain) Final Motor Pathway

The normal VOR

Spectacles to change VOR gain Steve Lisberger

VOR before and after learning Miles & Fuller, Brain Res. 80:512-6, 1974

Learning in the feedforward controller for saccades Time during adaptation experiment Straube et al. J. Neurophysiol. 77: , 1997.

Double steps of target speed for studying learning in the feedforward controller for pursuit Kahlon & Lisberger, J. Neurosci. 16: , 1996.

Sequence of a pursuit learning experiment Kahlon & Lisberger, J. Neurosci. 16: , 1996.

LEARNING Feedback Controller ~100 ms retinal inputs Goal Feedforward Controller Eyeball + eye movement I. G. Sensed Variable VOR Saccades Pursuit HIIHII -E  I I VN SC, PPRF MT, DLPN FMP General Scheme for Motor Learning e.g. AOS

to eye muscle motor neurons VRN FTN inferior olive GC inhibitory interneurons HGVP parallel fibers climbing fiber inhibition excitation mossy fibers after Lisberger 1998 sites of learning I. H. Cerebellar Circuit (ipsi) (contra)

The learning rule: “Marr-Albus-Ito” or “Floccular” Hypothesis Version 1: operational retinal slip vestibular information + contra I.. ipsi H gain CF + PF LTD Version 2: synaptic plasticity

after Linden & Connor 1995 heterosynaptic LTD associative LTD homosynaptic LTD PC CF PF cerebellar LTD Long Term Depression

PLC PIP 2 DAG IP 3 NO cGMP LTD Induction PKC* after Linden & Connor 1995 Parallel Fiber: H (glutamate). Ca ++ Climbing Fiber: I (PC depolarization). AMPA Na + mGluR1 Na + Ca ++ HGVP Cerebellar LTD