hierarchy of visual cortex models
TRANSCRIPT
Hierarchy of visual cortex models
Preferred direction Null direction
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Experiments:Université Rene Descartes, Paris (rats and cats, visual cortex neurons, in-vivo, dynamic clamp):
Anton V. Chizhov
Ioffe Physico-Technical Institute of RAS,St.-Petersburg
Experiment. Responses of a neuron selective to direction of stimulus movement.
Experiment. Orientation map.
1 mm
Experiment. Responses of a thalamic neuron on 3 repetitions of a movie-stimulus.
Visual cortex
Cortical neurons with similar receptive fields are united in columns.in somatosensory cortex (Mountcastle, 1957);in auditory cortex (Brugge&Merzenich, 1973);in visual cortex (Hubel&Wiesel, 1965).
Hypercolumn is a minimal functional unit, uniting columns with all different orientations.
The pictures of orientation columns in cat and monkey visual cortex, obtained by electrophysiology with deoxyglucose.
Hubel&Wiesel
The PINWHEEL
The pictures of hypercolumns, obtained by voltage sensitivedyes.
Bonhoeffer&Grinvald
Computational costs for simulation of 1 mm2 of cortex
Monte-Carlo simulation(101-102 ODEs for 1 neuron
+ 2-104 ODEs for synapses)X 2-10 synaptic typesX 102 neurons 1 one columnX 101-102 columns in 1 hypercolumnX 101 hypercolumns in 1 mm2
X 102-103 stimulation trialsTotal: 107-1012 ODEs.
CBRD continual model(101 PDEs for 1 neuron
X 2-10 types of neuronsX 101-102 discretization points in t*- space + 101 ODEs for synapses) X (101-102)2 discretization points in (x,y)-space
Total: 105-108 PDEs.
preferred orientation:
Synaptic inputs
Synaptic morphologyIntracortical connections:
Thalamic input:
pinwheel centers:
Synaptic kinetics gS
t
d
fw
Model. Response of 1mm2-area of the cortex on a change of orientation of visual stimulus-bar.
Model. Responses of 2 neurons preferring orthogonal orientations.
[Myme et al. 2003]
AMPA- and NMDA-EPSCs
[Dong et al. 2004]
Synaptic currentsEPSCs and IPSCs
E X P E R I M E N T
M O D E L
Spatiotemporal patterns generated by an electrical stimulus reveal clusters of activity.Scale bars in the experiments are 220μm.
E X P E R I M E N TActivity patterns in visual cortex slices
M O D E L
3.5 ms 6.5 ms [Tucker & Katz, 2003]
3.5 ms 6.5 ms-60
-65
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mV
* -60
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mV
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ms
mV
0 20 40 60 80 100
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weakmoderatestrong
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mV
0 20 40 60 80 100
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weakmoderatestrong
[Tucker & Katz, 2003]PSPs
Responses on electrical stimulationE X P E R I M E N T
M O D E L
PSPs
ms
mV
0 20 40 60 80 100
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controlBic
ms
mV
0 20 40 60 80 100-70
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-62 controlBic
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mV
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2 stimulating electrodesE X P E R I M E N T
M O D E L
S1
S2
[Tucker & Katz, 2003]
S1
S2
ms
mV
0 20 40 60-70
-65
-60
S1+S2
CBRD ring model for
HH-neurons with synaptic kinetics
RDA-based ring model for
LIF-neurons with synaptic kinetics
Kolmogorov-Fokker-Planck (KFP)-based ring model for
LIF-neurons with synaptic kinetics
2-d CBRD model for Hodgkin-Huxley (HH)-neurons with
synaptic kinetics
KFP-based ring model for
LIF-neurons with instantaneous synaptic currents
Firing-Rate (FR) ring model with
instantaneous synaptic currents
=
Hierarchy of visual cortex models20151050
Hz
Threshold-linear approximation of steady-state firing rate of LIF noisy neuron
pA
Hz
0 100 200 300 4000
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2-d RD model
FR-shunt ring KFP-shunt ring
RD ring, cos-profileRD ring, exp-profile
canonical FR ring model
RD ring, nonadaptive
RD ring, 2-comp. LIF
RD ring, 1-comp. LIF