Different effects of nucleus accumbens and ventrolateral striatal dopamine depletions on instrumental response selection in the rat.
Level 5 - mechanism / opinion, no new human data
Animal research without human data
PubMed 8309975 · doi:10.1016/0091-3057(93)90226-j
What was done
Rats were tested in an operant chamber choice task where they could either press a lever on a fixed ratio 5 (FR5) schedule to obtain a preferred food (Bioserve pellets) or eat a concurrently available, less preferred food (lab chow). 6-hydroxydopamine was injected directly into either the nucleus accumbens, medial striatum, or ventrolateral striatum to examine how site-specific dopamine depletion altered instrumental response selection.
What was found
Nucleus accumbens dopamine depletion significantly decreased lever pressing and significantly increased lab chow consumption, a shift that correlated significantly with decreased spontaneous locomotor activity. Medial striatal dopamine depletion had no significant effect on lever pressing or chow consumption. Ventrolateral striatal dopamine depletion decreased lever pressing, tended to decrease chow consumption, and produced severe home-cage feeding deficits requiring wet mash or tube feeding. No exact numerical values or effect sizes were reported in the abstract.
Why it matters
The findings demonstrate a functional dissociation within the striatum, showing that nucleus accumbens dopamine mediates effort-related choice and work output rather than general primary food motivation.
Limits
This is an animal study in rats. Sample size was not reported, no exact quantitative data or statistical values were provided in the abstract, and the abstract text was truncated at 250 words.
Cited by
- supports Rats with neurochemically ablated mesolimbic dopamine neurons will consume accessible palatable food but will not exert physical effort or work to obtain it.