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Project

Causal inferences on the role for dopamine neurons of the ventral midbrain in the modulation of sensory representations in visual cortex: effect of VTA microstimulation investigated with fMRI in monkeys.

The dopamine neurons of the ventral tegmental area (VTA) play an important role in determining when learning occurs. These neurons have a widespread network of connections. When the VTA increases activity (e.g. due to unexpected rewards) dopamine is released throughout this network. Released dopamine in turn regulates plasticity, remodeling the brain to increase the chance of obtaining future rewards. We plan to artificially increase VTA activity through electrical stimulation in monkeys. Because VTA is located deep within the brain, we developed an MRI-guided technique to position an electrode within VTA. We have seen that stimulation of these electrodes reinforcing behavior. For instance, subjects prefer visual symbols associated with stimulation. In addition to behavioral tests, we will administer dopamine increasing or decreasing drugs to test whether dopamine signaling regulates the reinforcing effects of stimulation. We will then perform functional MRI (fMRI) during VTA stimulation. Importantly, fMRI allows us to look at changes in activity throughout the entire brain. We hypothesize stimulation during fMRI will provide evidence for the widespread connections of the VTA via functional changes in brain activity. Furthermore, we will examine whether VTA is responsible for changes in activity in visual regions found previously during juice rewards. Lastly we will test whether pavlovian association of stimulation and a visual symbol improves symbol discrimination.

Date:1 Oct 2013 →  30 Sep 2019
Keywords:Dopamine neurons, fMRI in monkeys
Disciplines:Neurosciences, Biological and physiological psychology, Cognitive science and intelligent systems, Developmental psychology and ageing