Development of and proposed applications for tetrodes in functional mapping of rodent sensorimotor striatum

Abstract

The Wilson-McNaughton tetrode preparation for awake, behaving rodents was adapted by a group of investigators for use in dorsolateral striatum. Measures were taken to improve the reliability of reaching the target area in the brain and the stability of the implanted tetrode drive over several weeks of recording. Novel methods were developed to confirm the dorsoventral level of tetrodes at intermediate stages of advancement during recording, and to reconstruct estimated directions and distances of recorded sources from tetrodes by post-hoc analysis. Alternative methods of source separation and data visualization were implemented. Additional refinements to improve unit separation within and across recording sessions are proposed. The resulting recording technique is expected to have considerable potential in clarifying behavioral and other functional correlates of systems of striatal anatomical compartmentalization. A set of experiments is proposed to investigate how dorsolateral striatal neuronal activity changes in correlation with learning of three stimulus-response tasks relative to three control tasks with similar sensory, motor and motivational aspects but different learning and memory requirements, and to localize task-responsive units with respect to striosomes and body part areas identified by neuronal responses to cutaneous stimulation/passive manipulation and anterograde anatomical tracers from primary motor cortex. Neuronal activity in the globus pallidus and substantia nigra pars reticulata, output areas of the basal ganglia, is also to be examined over the course of acquisition of the three stimulus-response tasks.

(cont.) The proposed investigations will begin to empirically anchor learning and memory functions of the striatum and basal ganglia to patterns of neuronal activity in the context of the intricate anatomical organization of these areas.