1 / 19

1. learning vs plasticity

1. learning vs plasticity. 2. reinforcement learning vs supervised learning. 3. circuits: VOR & OKR. 4. open vs. closed loop controllers. 5. learning: adjusting the FF controller. 6. plasticity: cerebellar LTD. VOR Circuit. E. E. H. frequency. frequency. ipsi. contra. MR. LR.

qamra
Télécharger la présentation

1. learning vs plasticity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. VORCircuit E E H frequency frequency ipsi contra MR LR oculomotor nucl. MLF PPRF abducens nucl. vestibular nucl. semicircular canals.

  3. Ro + kE + rĖ 300 350 300 250 200 200 150 k  4 (sp/s) / deg 100 Ro = 100 sp/s 100 r  1 (sp/s) / (deg/s) 50 0 0 -150 -75 0 75 150 -45 -30 -15 0 +15 +30 +45 eye velocity (deg/s) From Robinson & Keller 1972 Rm = Motor Neurons r / k =  = 0.25 s viscoelastic time constant firing frequency (spikes/s) eye position (deg) From Fuchs & Leschei 1970

  4. Final Motor Pathway Saccade System (Burst Neurons in PPRF) Er Ein Pursuit System (Gaze Velocity Purkinje Cell) Eout Ep Neural Integrator (NPH for H INC for V) -H Vestibulo-Ocular Reflex (VOR) Extra- Ocular Muscle E ? Motor Neuron E + Ė

  5. Integrator Lesion: Effects Cannon & Robinson 1987

  6. Excitatory Motions for the SCC’s on the left. horizontal anterior posterior from Carpenter, fig. 2.7 Planes of the Semi-Circular Canals cochlea left right cochlear n. semicircular ducts: vestibular n. anterior horizontal vestibulo- chochlear n. posterior internal acoustic meatus foramen magnum from KS&J, fig. 33-9 Angle at which the plane of the anterior semicircular duct crosses the midsagittal line

  7. Rabbit OK (Afferents) I direction selectivity E superior anterior posterior H ipsiversive U+post D+ant canal: horizontal anterior posterior 0.01 0.1 1 10 inferior stimulus speed (deg/sec) Accessory Optic System DTN/NOT MTN LTN data from Simpson 1984

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

  9. The normal VOR

  10. Spectacles to change VOR gain Steve Lisberger

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

  12. Learning in the feedforward controller for saccades Time during adaptation experiment Straube et al. J. Neurophysiol.77: 874-895, 1997.

  13. Double steps of target speed for studying learning in the feedforward controller for pursuit Kahlon & Lisberger, J. Neurosci.16: 7270-7283, 1996.

  14. Sequence of a pursuit learning experiment Kahlon & Lisberger, J. Neurosci.16: 7270-7283, 1996.

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

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

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

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

  19. Cerebellar LTD . Climbing Fiber: I (PC depolarization) Ca++ NO cGMP Na+ . AMPA Parallel Fiber: H (glutamate) Na+ LTD Induction Ca++ Ca++ Ca++ IP3 PKC* DAG PLC mGluR1 PIP2 HGVP after Linden & Connor 1995

More Related