File:DA Models Fig1.jpg

Summary

DA / D1R modulation of the single cell input/output (I/O) function. A) In connectionist-like abstract model networks the output (activation) is usually assumed to be a sigmoid function of the weighted sum of ‘presynaptic’ activities (aj). One of the earliest computational proposals was that DA increases the slope (gain) of this sigmoid I/O function (Servan-Schreiber, Printz, Cohen, 1990). B) Simulations of D1R effects in a biophysically and morphologically highly realistic 189-compartment representation of a striatal MSN provided evidence for this idea (Moyer, Wolf and Finkel, 2007), although I/O functions for the simulated MSN were almost linear (schema). C) I/O functions under control and dopamine/ D1R activation in prefrontal cortical pyramidal cells in vitro stimulated with a fluctuating somatic current input (schema; Thurley, Senn and Lüscher, 2008). Note that despite the initial increase in gain the D1R effects on low and high inputs are just opposite from those in A and B. Solid lines = control, dashed lines = D1R activation in all graphs. Reprinted from Durstewitz (2009) with permission from Oxford University Press (Copyright 2009).

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