Information processing in the thalamus

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DESCRIPTION (provided by applicant): An enormous amount of energy has been targeted at elucidating basal ganglia function yet almost nothing is known about the mechanisms that govern the relay of basal-ganglia output through the thalamus. The basic thrust of this research proposal is to explore how information is transferred through a thalamic nucleus, which lies within a basal ganglia loop required for song learning in zebra finches. This problem is interesting because the most substantial input to this thalamic area (DLM), is GABAergic and strongly inhibitory to DLM neurons. How, then, might DLM relay GABAergic inputs? A robust feature of thalamic neurons could render inhibitory post-synaptic potentials (IPSPs) excitatory, namely post-inhibitory rebound. In fact, short barrages of IPSPs have been shown to elicit rebound spikes in DLM neurons. In this study, we plan to systematically explore the capacity of thalamic neurons to translate IPSPs into superthreshold output. These experiments will provide powerful insight into the function of thalamic areas important for motor learning in vertebrates, as well as thalamic-basal ganglia relay. This information is necessary to completely understand basal ganglia circuitry, which is pathological in human disorders such as Parkinson's disease.