Temporal Coding of Reward Value in Monkey Ventral Striatal Tonically Active Neurons

Abstract

The rostromedioventral striatum is critical for behavior dependent on evaluating rewards. We asked what contribution tonically active neurons (TANs), the putative striatal cholinergic interneurons, make in coding reward value in this part of the striatum. Two female monkeys were given the option to accept or reject an offered reward in each trial, the value of which was signaled by a visual cue. Forty-five percent of the TANs use temporally modulated activity to encode information about discounted value. These responses were significantly better represented using principal component analysis than by just counting spikes. The temporal coding is straightforward: the spikes are distributed according to a sinusoidal envelope of activity that changes gain, ranging from positive to negative according to discounted value. Our results show that the information about the relative value of an offered reward is temporally encoded in neural spike trains of TANs. This temporal coding may allow well tuned, coordinated behavior to emerge.

Attractor dynamics reflect decision confidence in macaque prefrontal cortex

“…Because reject decisions led to a random draw from the possible offers in the next trial, each trial’s offer could be compared to the average offer and the delay to the next trial. Consistent with previous work on this paradigm 32,36 , we found that offers were consistently accepted or rejected when the utilities were well above or below the average. Offers with intermediate values, however, were sometimes accepted and sometimes rejected.…”

“…Behavioral task, behavior, and recording sites. A. Temporal-discounting task 32 . In each trial, the animals first touched a bar, after which a red dot was presented.…”

Single caudate neurons encode temporally discounted value for formulating motivation for action

“…We exclusively examined the activity of the presumed projection neurons, which are characterized as having a low spontaneous discharge rate (< 2 spikes/s) outside the task context and exhibiting phasic discharges in relation to one or more behavioral task events. The activity of TANs recorded from the CD of monkeys performing a similar task was reported in a previous study (Falcone et al, 2019). The timing of action potentials was recorded together with all task events at millisecond precision.…”

Polysynaptic inhibition between striatal cholinergic interneurons shapes their network activity patterns in a dopamine-dependent manner

“…In primates, synchronized pauses in neighboring ChINs exhibit different patterns with respect to the bursts preceding and following the pause. Some ChINs exhibit a reward-related burst-pause-rebound pattern while others have only a pause-rebound or an isolated pause response 2 , 10 , 19 , 21 . The mechanisms underlying the various pause responses are still unclear 22 .…”