Sensory information can be used as clue for identifying objects, both rewarding objects and aversive objects. However, to use that information as clue, learning process would be required. And the association between sensory information and rewarding outcome would modify neural circuits that also involving for recognition of objects. For example, most natural rewarding object is food. For learning to recognize the object is food, edible, interactions between components of a taste-reward circuit that include many brain areas are important. Although many brain areas involving eating behavior, it is poorly known which neurons in the circuit mediate the ability to identify edible foods. For this learning, I speculated that adding rewarding value with sensory information is important aspect. One important region that may supply valence information is the insular cortex. The insular cortex is a brain region that integrates incoming sensory information including somatosensory and visceral information and is also known as the taste cortex. Furthermore, recent findings suggest that through the integration of information coming from visceral cues and sensory component of rewarding objects, insular cortex neurons can powerfully modulate appetitive behaviors. Therefore, I hypothesize that neural circuit that involve in cue-reward learning will also be made and refined in the insular cortex during cue-reward association learning training. I have started three experiments this year. Major purpose of this research is to confirm whether synaptic inputs into insular cortex neurons would be potentiated during cue-reward association learning training. To get more precise anatomical information about neuronal connection in the insular cortex, I observed afferent inputs into insular cortex by labeling neurons retrogradely using tracer called Fluorogold. Preliminary data indicates that two thalamic regions that involve to processing taste information and olfactory information project to insular cortex. Moreover, amygdala, the region that involve to salient learning also project to insular cortex. This experiment has been conducting with Dr. Morales group in NIDA IRP. I also needed to establish animal behavior paradigm in this research. Pvlovian conditioning task was used as a model behavior of cue-reward learning. Mice learned association between sensory cue and food reward within one week. To confirm insular cortex is involved to this behavior, pharmacological experiment using Lidocaine has been done with cannula implanted mice. Preliminary data suggests that insular cortex is involving to express conditioned behavior. To measure synaptic inputs into insular cortex neurons, I used slice whole cell recording and compared strength of synaptic inputs between before trained animals and after trained animals. Although preliminary data didnt show clear difference between groups, I am still working on this experiment by choosing neurons in same layer and observing synaptic inputs from specific inputs.
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