Biology subjects

Paton, J. J.

Publications and source records attributed to Paton, J. J..

3 recordsLinked to original sources

bioRxiv2020

Manipulation of striatal population dynamics using temperature warps judgment of time

The basal ganglia (BG) are thought to contribute to decision-making and motor control by influencing action selection based on consequences. These functions are critically dependent on timing information that can be extracted from the evolving state of neural populations in the striatum, the major input area of the BG. However, it is debated whether striatal activity underlies latent, dynamic decision processes or kinematics of overt movement. Here, we measured the impact of temperature on striatal population activity and the behavior of rats and compared the observed effects to neural activity and behavior collected in multiple versions of a temporal categorization task. Cooler temperatures caused dilation, and warmer temperatures contraction, of both neural activity and patterns of judgment in time, mimicking endogenous decision-related variability in striatal activity. However, temperature did not similarly affect movement kinematics. These data provide compelling evidence that the time course of evolving striatal population activity dictates the speed of a latent process that is used to guide choices, but not moment by moment kinematics. More broadly, they establish temporal scaling of population activity as a likely cause and not simply a correlate of timing behavior in the brain.

neuroscience↗

bioRxiv2020

Dorsolateral striatal circuits support broadly opponent aspects of action suppression and production

Imbalance between action suppression and production characterizes several neurological disorders of the basal ganglia (BG)1. Relatedly, two major circuits of the BG, the direct and indirect pathways, are hypothesized to function in opposition, promoting and suppressing actions, respectively2. Yet activity of neurons initiating the two pathways, striatal direct (dMSNs) and indirect (iMSNs) medium spiny neurons, appears to be positively correlated around movement, apparently contradicting direct-indirect functional opponency3. Here we show that while coactivation occurs during movement, action suppression produces systematic features of functional opponency between the two pathways. First, suppression produced elevated iMSN activity and diminished dMSN activity in dorsolateral striatum of mice. Second, as the need to suppress movements to one or the other side of the body evolved over time, so too did the relative levels of activity in the two hemispheres, and in opposite patterns in the two pathways. Lastly, optogenetic inhibition of dMSNs, but not iMSNs, slowed movements without affecting their likelihood, whereas inhibition of iMSNs, but not dMSNs, disrupted whether and when mice suppressed or produced particular actions. These data demonstrate large-scale opponency in the activity of neurons that initiate the direct and indirect pathways of the BG, but suggest distinct action-related functions of each pathway. Specifically, the data support a novel model of sensorimotor striatum wherein the direct pathway appears to be necessary for augmenting generalized movement vigor, and the indirect pathway for the proactive suppression of specific behaviors.

neuroscience↗

bioRxiv2020

Dopamine responses reveal efficient coding of cognitive variables

Reward expectations based on internal knowledge of the external environment are a core component of adaptive behavior. However, internal knowledge may be inaccurate or incomplete due to errors in sensory measurements. Some features of the environment may also be encoded inaccurately to minimise representational costs associated with their processing. We investigate how reward expectations are affected by differences in internal representations by studying rodents behaviour and dopaminergic activity while they make time based decisions. Several possible representations allow a reinforcement learning agent to model animals choices during the task. However, only a small subset of highly compressed representations simultaneously reproduce, both, animals behaviour and dopaminergic activity. Strikingly, these representations predict an unusual distribution of response times that closely matches animals behaviour. These results can inform how constraints of representational efficiency may be expressed in encoding representations of dynamic cognitive variables used for reward based computations.

neuroscience↗