NEURAL CIRCUITS OF THE INFERIOR PARIETAL LOBULE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this proposal is to directly examine Mitchison and Cricks hypothesis in terms of the functional circuit organization of the inferior parietal lobule in behaving monkey. To study the functional circuit organization of inferior parietal lobule in vivo, we have spent the last three years perfecting the ability to perform two-photon imaging of genetically transformed neurons in the behaving monkey. These neurons are virally transfected to express a fluorescent sensor for voltage or calcium. Thus a neuron can be imaged at microscopic resolution along with its neuronal activity. Performing these experiments has demonstrated many advantages for the behaving monkey preparation. We have observed neurons a known depth from the pial surface, observed their precise spatial relationships to each other in the tangential plane, and measured their tuning during a behavioral task. Indeed, we have made stable continuous two-photon microscopic recordings from 15 neurons for 3 hours. These advances support examining specific projective functional circuits in association cortex during behavior. Our working hypothesis is: the inferior parietal lobule is organized into local modules containing neurons with the same projection patterns and the same functions. We will be using these funds to computationally analyze the large imaging data sets collected in the biological experiments.