Neuroleptic effects on acquisition and performance of learned behaviors: a reinterpretation.
It is well-established that dopamine facilitates motor responsiveness. However, neuroleptics--drugs that block dopaminergic transmission--do not affect equally motor responses to environmental stimuli: responses to some stimuli seem completely preserved while responses to other stimuli are greatly disturbed. For example, escape responses to a noxious stimulus are typically preserved, even when avoidance to a cue predicting the noxious stimulus is absent. In this paper, we propose a connectionist account of this differential effect. We assume that dopamine determines the "gain" of the function relating the activation of a neural ensemble to its excitatory or inhibitory input. Because such a function is necessarily non-linear, we show that the influence of gain on whether a neural ensemble reaches a "threshold" of activation is critically different for low and high excitatory drives. This analysis makes specific predictions about the effect of neuroleptics on motor responses at different stages of training.
Servan-Schreiber
D
D
Clinical Cognitive Neuroscience Laboratory, Western Psychiatric Institute and Clinic, Pittsburgh, PA 15213, USA.
Blackburn
J R
JR
D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects*; D004298:Dopamine / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D007858:Learning; D008954:Models, Biological
D014150:Antipsychotic Agents; D018492:Dopamine Antagonists; D004298:Dopamine