?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=DYNAMICS+OF+A+RECURRENT+NETWORK+OF+SPIKING+NEURONS+BEFORE+AND+FOLLOWING+LEARNING&rft.creator=Amit%2C+Daniel+J.&rft.creator=Brunel%2C+Nicolas&rft.subject=Computational+Neuroscience&rft.subject=Statistical+Models&rft.subject=Neural+Modelling&rft.subject=Neuropsychology&rft.description=Extensive+simulations+of+large+recurrent+networks+of+integrate-and-fire+excitatory+and+inhibitory+neurons+in+realistic+cortical+conditions+(before+and+after+Hebbian+unsupervised+learning+of+uncorrelated+stimuli)+exhibit+a+rich+phenomenology+of+stochastic+neural+spike+dynamics%2C+and+in+particular%2C+coexistence+between+two+types+of+stable+states%3A+spontaneous+activity%2C+upon+stimulation+by+an+unlearned+stimulus%3B+and+%60working+memory'+states+strongly+correlated+with+learned+stimuli.+Firing+rates+have+very+wide+distributions%2C+due+to+the+variability+in+the+connectivity+from+neuron+to+neuron.+ISI+histograms+are+exponential%2C+except+for+small+intervals.+Thus+the+spike+emission+processes+are+well+approximated+by+a+Poisson+process.+The+variability+of+the+spike+emission+process+is+effectively+controlled+by+the+magnitude+of+the+post-spike+reset+potential+relative+to+the+mean+depolarization+of+the+cell.+Cross-correlations+(CC)+exhibit+a+central+peak+near+zero+delay%2C+flanked+by+damped+oscillations.+The+magnitude+of+the+central+peak+in+the+CCs+depends+both+on+the+probability+that+a+spike+emitted+by+a+neuron+affects+another+randomly+chosen+neuron+and+on+firing+rates.+It+increases+when+average+rates+decrease.+Individual+CCs+depend+very+weakly+on+the+synaptic+interactions+between+the+pairs+of+neurons.+The+dependence+of+individual+CCs+on+the+rates+of+the+pair+of+neurons+is+in+agreement+with+experimental+data.+The+distribution+of+firing+rates+among+neurons+is+in+very+good+agreement+with+a+simple+theory%2C+indicating+that+correlations+between+spike+emission+processes+in+the+network+are+effectively+small.&rft.date=1997&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=application%2Fpostscript&rft.identifier=http%3A%2F%2Fcogprints.org%2F59%2F2%2Fspikemn.ps&rft.identifier=++Amit%2C+Daniel+J.+and+Brunel%2C+Nicolas++(1997)+DYNAMICS+OF+A+RECURRENT+NETWORK+OF+SPIKING+NEURONS+BEFORE+AND+FOLLOWING+LEARNING.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F59%2F