An integrated microcircuit model of working memory and

An integrated microcircuit model of working memory and decision making Wang TINS 2001 Wang Neuron 2002

Lorente de Nó’s reverberatory circuit

Roitman and Shadlen 2002

Reaction Time Task Roitman and Shadlen 2002

2 -population excitatory and inhibitory neurons (integrate-and-fire or conductance-based Hodgkin-Huxley neurons) • • Biologically realistic synaptic kinetics (AMPA, NMDA and GABAA) • Structured network connectivity

MT output

Reaction Time Simulations

Model Data

Reaction time decreases with increasing coherence Weber's Law Data by J Roitman, J Ditterich and M Shadlen

Integrate-and-Decide (diffusion) Model R Ratcliff (Psychol Rev 1978) J Schall (Nature Rev Neurosci 2001) Mazurek et al (Cereb Cortex 2003)

Kong-Fatt Wong

c’=6. 4% c’=51. 2% c’=100%

But how is threshold-crossing readout by downstream neurons? A bursty neuron in superior colliculus Fixation Target D Munoz and R Wurtz

Bistability: hard threshold detection

Feedback Inhibition: Bursting Chung-Chuan Lo

A Large-scale Network Model of Decision-Making Cortex Caudate SNr SC

SC Network LIP Network

Threshold can be effectively modulated by the cortico-striatal synaptic pathway

Adjusting the threshold to optimize rewards: Speed-accuracy tradeoff

Optimal threshold should be adjustable according to the distribution of coherence levels in the environment

End