A Specific Component of the Evoked Potential Mirrors Phasic XXXX Neuron Activity during Conditioning.

@entity935 @entity19 @entity71529
Midbrain @entity935 (DA) neurons are thought to be a critical node in the circuitry that mediates reward learning. DA neurons receive diverse inputs from regions distributed throughout the neuraxis from frontal neocortex to the mesencephalon. While a great deal is known about changes in the activity of individual DA neurons during learning, much less is known about the functional changes in the microcircuits in which DA neurons are embedded. Here we used local field potentials recorded from the midbrain of behaving @entity19 to show that the midbrain evoked potential ( @entity71529 ) faithfully reflects the temporal and spatial structure of the phasic response of midbrain neuron populations during conditioning. By comparing the @entity71529 to simultaneously recorded single units, we identified specific components of the @entity71529 that corresponded to phasic DA and non-DA responses to salient stimuli. The DA component of the @entity71529 emerged with the acquisition of a conditioned stimulus, was extinguished following changes in reinforcement contingency, and could be inhibited by pharmacological manipulations that attenuate the phasic responses of DA neurons. In contrast to single-unit recordings, the @entity71529 permitted relatively dense sampling of the midbrain circuit during conditioning and thus could be used to reveal the spatiotemporal structure of multiple intermingled midbrain circuits. Finally, the @entity71529 response was stable for months and thus provides a new approach to study long-term changes in the organization of ventral midbrain microcircuits during learning. Significance statement: Neurons that synthesize and release the neurotransmitter @entity935 play a critical role in voluntary reward-seeking behavior. Much of our insight into the function of @entity935 neurons comes from recordings of individual cells in behaving animals; however, it is notoriously difficult to record from @entity935 neurons due to their sparsity and depth, as well as the presence of intermingled non-dopaminergic neurons. Here we show that much of the information that can be learned from recordings of individual @entity935 and non- @entity935 neurons is also revealed by changes in specific components of the local field potential. This technique provides an accessible measurement that could prove critical to our burgeoning understanding of the molecular, functional, and anatomical diversity of neuron populations in the midbrain.
