1. learning vs plasticity
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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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
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frequencyfrequency
E E
H
LRMR
abducens nucl.
vestibular nucl.
oculomotor nucl.
semicircularcanals.
MLF
VORCircuit contraipsi
PPRF
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Motor NeuronsRm =
eye position (deg)
From Fuchs & Leschei 1970 From Robinson & Keller 1972
0-75-150 75 1500
100
200
300
eye velocity (deg/s)
r / k = = 0.25 sviscoelastic time constant
Ro = 100 sp/s
Ro
r 1 (sp/s) / (deg/s)
+ rĖ
k 4 (sp/s) / deg
+ kE
-45 -30 -15 0 +15 +30 +45
350
300
250
200
150
100
50
0
firi
ng f
requ
ency
(sp
ikes
/s)
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E
Pursuit System(Gaze Velocity Purkinje Cell)
EpMotor
NeuronE + Ė
NeuralIntegrator
(NPH for H INC for V)
Eout
Extra-OcularMuscle
-H
Vestibulo-OcularReflex (VOR)
Saccade System(Burst Neurons in PPRF)
Er
Final Motor Pathway
Ein
?
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Integrator Lesion: Effects
Cannon & Robinson 1987
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Planes of the Semi-Circular Canals
horizontal anterior posterior
Excitatory Motions for the SCC’s on the left.
from Carpenter, fig. 2.7
from KS&J, fig. 33-9
cochlear n.
vestibular n.
vestibulo-chochlear n.
foramen magnum
Angle at which the plane ofthe anterior semicircular ductcrosses the midsagittal line
cochlea
semicircular ducts:
anteriorhorizontalposterior
internal acousticmeatus
left right
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DTN/NOT LTNMTN
D+antU+postH ipsiversive
EIRabbit OK (Afferents)
stimulus speed (deg/sec)
direction selectivity
1010.10.01 inferior
posterioranterior
superior
canal: horizontal anterior posterior
Accessory Optic System
data from Simpson 1984
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VN
NPHINC
Ė
E
MN
E
I+
AOS/NOT
InferiorOlive
Cerebellum
climbing fibers
mossyfibers
SCC
errorsignal
Rabbit OK(adjusting VOR gain)
Final Motor Pathway
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The normal VOR
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Spectacles to change VOR gain
Steve Lisberger
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VOR before and after learning
Miles & Fuller, Brain Res. 80:512-6, 1974
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Learning in the feedforward controller for saccades
Tim
e du
ring
ada
ptat
ion
expe
rim
ent
Straube et al. J. Neurophysiol. 77: 874-895, 1997.
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Double steps of target speed for studying learning in the feedforward controller for pursuit
Kahlon & Lisberger, J. Neurosci. 16: 7270-7283, 1996.
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Sequence of a pursuit learning experiment
Kahlon & Lisberger, J. Neurosci. 16: 7270-7283, 1996.
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LEARNING
FeedbackController
~100 msretinalinputs
GoalFeedforward
Controller Eyeball+ eyemovement
I.
G.
SensedVariable
VORSaccadesPursuit
HII
•
•
-EII
•
•
VNSC, PPRF
MT, DLPNFMP
General Scheme for Motor Learning
e.g. AOS
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to eye musclemotor neurons
VRN
FTN
inferiorolive
GCGC
inhibitoryinterneurons
HGVP
parallel fibers
climbingfiber
inhibitionexcitation
mossy fibers
after Lisberger 1998
sites oflearning
I.
H.
Cerebellar Circuit
(ipsi)
(contra)
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The learning rule:“Marr-Albus-Ito” or “Floccular” Hypothesis
Version 1: operational
retinal slip
vestibularinformation + contra I
.. ipsi H gain
CF + PF LTD
Version 2: synaptic plasticity
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after Linden & Connor 1995
heterosynaptic LTD
associative LTD
homosynaptic LTD
PC
CF
PF
cerebellar LTD
Long Term Depression
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PLC
PIP2
DAG
IP3
NO
cGMP
LTDInduction
PKC*
after Linden & Connor 1995
Parallel Fiber: H(glutamate)
.
Ca++
Ca++
Climbing Fiber: I(PC depolarization)
.
AMPA Na+
mGluR1
Na+
Ca++ Ca++
HGVP
Cerebellar LTD