Ventral Tegmental Dopamine Neurons Control the Impulse Vector during Motivated Behavior

Abstract

Highlights d Three populations of VTA DA neurons control the impulse vector d DA populations differ in associated force direction, magnitude, and time course d Optogenetic excitation and inhibition produce opposite directions of force exertion d Optogenetic stimulation regulates anticipatory licking

Dopamine: The Neuromodulator of Long-Term Synaptic Plasticity, Reward and Movement Control

“…Engelhard et al, using 2-photon calcium imaging through an implanted lens to record the activity of >300 mDAergic neurons in the VTA during a complex decision-making task demonstrated that DAergic neurons were functionally clustered and the subpopulations of neurons transmitted information about a subset of behavioral variables, in addition to encoding reward [ 104 ]. Furthermore, Hughes et al [ 129 ], using in-vivo electrophysiology and optogenetics, identified three populations of VTA DAergic neurons that control the force exerted over time. These populations differ in magnitude, direction, and duration of force used by the animal during motivated behavior.…”

Protocol for Recording from Ventral Tegmental Area Dopamine Neurons in Mice while Measuring Force during Head-Fixation

“… Once laser stimulation is completed, stop recording the neural signals and remove the mouse. See ( Hughes et al., 2020b ) for examples of optically tagged neurons. CRITICAL: Save any spiking evoked by optical tagging in the same file that contains the neural activity recorded during the behavioral session.…”

“…Various devices that combine recording and light delivery are also available commercially ( http://www.inphysiology.com/optogenetic-applications/ ). To express ChR2 in DA neurons, one can inject a viral vector containing Cre-dependent ChR2 into the VTA of DAT-Cre mice ( Cohen et al., 2012 ), or by cross-breeding DAT-Cre mice with mice genetically modified to express ChR2 in any neuron also expressing Cre ( Hughes et al., 2020b , Madisen et al., 2012 ). The latter approach ensures more uniform expression of ChR2 in DA neurons, as it eliminates variability due to virus injection.…”

“…The relationships between neural activity and the continuous forces produced by miceare still poorly understood. We have recently demonstrated that DA neurons in the ventral tegmental area (VTA) are responsible for controlling the impulse vector (force exerted in a certain direction over time) in a fixed-time task ( Hughes et al., 2020b ). It is therefore predicted that neural activity in regions innervated by DA neurons are also related to forces exerted by the head and body.…”

“…For complete details on the use and execution of this protocol, please refer to Hughes et al. (2020a , 2020b) …”