Synaptic plasticity can produce and enhance direction selectivity (Carver et al, 2008)

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Accession:116901
" ... We propose a parsimonious model of motion processing that generates direction selective responses using short-term synaptic depression and can reproduce salient features of direction selectivity found in a population of neurons in the midbrain of the weakly electric fish Eigenmannia virescens. The model achieves direction selectivity with an elementary Reichardt motion detector: information from spatially separated receptive fields converges onto a neuron via dynamically different pathways. In the model, these differences arise from convergence of information through distinct synapses that either exhibit or do not exhibit short-term synaptic depression—short-term depression produces phase-advances relative to nondepressing synapses. ..."
Reference:
1 . Carver S, Roth E, Cowan NJ, Fortune ES (2008) Synaptic plasticity can produce and enhance direction selectivity. PLoS Comput Biol 4:e32 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism:
Cell Type(s): Electric fish midbrain torus semicircularis neuron;
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: MATLAB;
Model Concept(s): Oscillations; Depression; Direction Selectivity; Synaptic Convergence;
Implementer(s): Carver, Sean [sean.carver at jhu.edu];
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carver
stimuli
Igamma.m
Igrey.m
Ipreinitseq.m
Isequence.m
Isine.m
                            
function I = Isine(varargin) 
% ISINEGRATING Returns sine-grating-intensity as a function of time and space 
%
% I = ISINE(x,t,f,lambda,phi,sigma), with 5 args, returns intensity I(x,t) 
%     for position range x, time range t, temporal frequency f
%     spatial wavelegth lamba, sigma (1 = right to left, -1 reverse)
%
% PERIOD = ISINE(f,lambda,phi,sigma), with 3 args, returns period = 1/f 
%          The PERIOD function was used in our implementation of
%          the original Chance model to save memory (so that the intensity
%          of only one cycle of the need be handled).
%          It is not used for the present model.
%
% STRING = ISINE(), with 0 args, returns string of params 
%                  '{f,lambda,phi,sigma}' 
%
% Code written by SEAN CARVER, last modified 12-5-2007

if nargin==0
  I = '{f,lambda,phi,sigma}';
elseif nargin < 6 
  f = varargin{1};
  I = 1/f; 
else
  x = varargin{1};
  t = varargin{2};
  f = varargin{3};
  lambda = varargin{4};	
  phi = varargin{5};
  sigma = varargin{6};

  I = sin(2*pi*x.'*ones(1,length(t))/lambda ...
         -sigma*2*pi*ones(length(x),1)*f*t ...
         +phi*pi/180);
end