Evidence for the role of serotonin in the inhibition of specific motor responses.
Two behavioural paradigms were used to test the effects of serotonin depletion on a specific form of response inhibition. Treatment with both p-chlorophenylalanine (p-CPA) at 200 mg/kg and lesions of the medial raphe nucleus impaired the acquisition of a step-off passive-avoidance response. The experimental design allowed the elimination of alternative interpretations in terms of increased sensitivity to shock and increased responsiveness to stimuli. p-CPA also impaired response inhibition during an omission-training schedule. The results of the three studies support a general role of serotonin in withholding specific instrumental (reinforced) motor actions. The results contrast with those of studies supporting a role of noradrenaline in response inhibition. A tentative conclusion supports Konorski's (1967) suggestion for differentiation of various types of response inhibition that are mediated by different neurochemical systems.
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D005260:Female; D010134:Fenclonine / Q000494:pharmacology; D009043:Motor Activity / Q000502:physiology*; D051381:Rats; D012701:Serotonin / Q000502:physiology*
D012701:Serotonin; D010134:Fenclonine