Servan-Schreiber D, Blackburn JR. Neuroleptic effects on acquisition and performance of learned behaviors: a reinterpretation.
Life Sci 1995;
56:2239-45. [PMID:
7791511 DOI:
10.1016/0024-3205(95)00213-p]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
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.
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