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- Title
The Parafascicular Thalamic Nucleus Concomitantly Influences Behavioral Flexibility and Dorsomedial Striatal Acetylcholine Output in Rats.
- Authors
Brown, Holden D.; Baker, Philip M.; Ragozzino, Michael E.
- Abstract
Recent evidence suggests that a circuit involving the centromedian-parafascicular (P0 thalamus and basal ganglia is critical for a shift away from biased actions. In particular, excitatory input from the Pf onto striatal cholinergic neurons may facilitate behavioral flexibility. Accumulating evidence indicates that an endogenous increase in dorsomedial striatal acetylcholine (ACh) output enhances behavioral flexibility. The present experiments investigated whether the rat (Rattus norvegicus) Pf supports flexibility during reversal learning, in part, by modifying dorsomedial striatal ACh output. This was determined first by examining the effects of Pf inactivation, through infusion of the GABA agonists baclofen and muscimol, on place acquisition and reversal learning. Additional experiments examined Pf inactivation on dorsomedial striatal ACh outputduring reversal learning and a resting condition. Behavioral testing was performed in a cross-maze. In vivo microdialysis combined with HPLC/electrochemical detection was used to sample ACh from the dorsomedial stria- tum. Pf inactivation selectively impaired reversal learning in a dose-dependent manner. A subsequent study showed that an increase in dorsomedial striatal ACh efflux (---30% above basal levels) during reversal learning was blocked by Pf inactivation, which concomitantly impaired reversal learning. In the resting condition, a dose of baclofen and muscimol that blocked a behaviorally induced increase in dorsomedial striatal ACh output did not reduce basal ACh efflux. Together, the present findings indicate that the Pf is an intralaminar thalamic nucleus critical for behavioral flexibility, in part, by directly affecting striatal ACh output under conditions that require a shift in• choice patterns.
- Subjects
RATTUS norvegicus; ACETYLCHOLINE; NEURAL physiology; CHOLINERGIC mechanisms; ELECTROCHEMICAL sensors; DOSE-response relationship in biochemistry; GABA; BEHAVIOR
- Publication
Journal of Neuroscience, 2010, Vol 30, Issue 43, p14390
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.2167-10.2010