Biology subjects

Hanks, T. D.

Publications and source records attributed to Hanks, T. D..

5 recordsLinked to original sources

bioRxiv2025

Population-level temporal decoding and dynamical structure in frontostriatal circuits during decision making

Perceptual decisions unfold over time, requiring neural circuits to evaluate sensory evidence, track elapsed time, and commit to an action. To investigate how these computations are distributed across corticostriatal circuits, we recorded large-scale neural population activity using Neuropixels probes in the rat frontal orienting field (FOF) and anterior dorsal striatum (ADS) during a free-response auditory change detection task. Both regions exhibited structured, highly dynamic population activity during task performance. Using single-trial population decoding, we found that both FOF and ADS robustly encoded retrospective time from stimulus onset and prospective time preceding the decision report. Using a new approach to analyze temporal encoding to identify the dynamical structure supporting decoding, we found that time encoding could be decomposed into two primary dynamical motifs: monotonic ramp-like trajectories and transient bump-like trajectories. While these modes were similarly expressed during early evidence evaluation, FOF exhibited more pronounced decision-aligned changes near the time of the decision report, possibly reflecting a state transition at commitment. Population geometry analyses further revealed stable low-dimensional subspaces during evidence evaluation that transitioned at decision commitment, with significantly larger subspace changes in FOF than ADS. Together, these results reveal a common dynamical framework during evidence evaluation across corticostriatal circuits, while identifying a selective reorganization of FOF dynamics associated with decision commitment.

neuroscience↗

bioRxiv2025

Computational characterization of decision making during trans-saccadic visual perception

When viewing the environment, humans execute fast sequential saccadic eye movements that disrupt the flow of visual information, yet still preserve stability in their visual percept. At the time of the saccade subjects often experience saccadic suppression of displacement - a failure to notice changes in the location of visual objects slightly shifted during the eye movement. Although well studied, the weighing of sensory information and the extent to which this integration influences visual perceptual judgments is still poorly characterized and understood. Here we used a drift diffusion modeling (DDM) framework to systematically examine the extent to which sensory information biased perceptual judgments when detecting trans-saccadic shifts of visual targets. Healthy human participants (N = 29, 20 female) completed a visual perception task in which a visual target was shifted following a cued saccadic eye movement (4o or 8o). Trans-saccadic target displacements occurred up to +2.5o along the horizontal axis, and participants reported the shift direction with a button press response. We present a version of the DDM that takes the visual error as input to simulate offsets in evidence accumulation during decision-making. The model provides an explanatory framework for the integration of sensory information, capturing the temporal dynamics of evidence accumulation that explain the range of perceptual biasing and response timing effects observed across participants.

neuroscience↗

bioRxiv2025

Time-adaptive modulation of evidence evaluation in rat posterior parietal cortex

A crucial component of successful decision making is determining the optimal timescale over which to evaluate evidence. For example, when detecting transient changes in the environment, it is best to focus evaluation on the current evidence as opposed to older evidence. However, it is unclear how this adjustment in timescale is achieved in the brain in terms of how the neurons that process evidence adjust their dynamics. To address this question, we used Neuropixel probes to record spiking activity from neurons in the posterior parietal cortex (PPC) of rats performing a free-response auditory change detection task in which subjects evaluate sensory evidence over short timescales to determine when a change occurs in a noisy sensory stream. Consistent with longer timescale temporal integration tasks, we found that PPC neurons modulated their activity by the strength of evidence leading to decisions, were selective for the rats choices, and had opposing populations of neurons that were positively versus negatively modulated by evidence. However, in contrast to temporal integration tasks, responses of neurons to individual pulses of evidence were transient, such that the effect of the evidence on activity tapered off over a timescale corresponding to the subjects behavioral timescale of evidence evaluation. Intriguingly, PPC also exhibited "gain changes" in the influence of evidence as a function of decision time that were consistent with changes in behavioral urgency. In addition, reversible inactivation revealed an important role for PPC in this auditory change detection, such that PPC inactivation altered choice behavior and the timescale over which rats evaluated evidence. Together, our results suggest important contributions of PPC to free-response decisions that involve adjusting timescales of evidence evaluation.

neuroscience↗

bioRxiv2020

Change point detection with multiple alternatives reveals parallel evaluation of the same stream of evidence along distinct timescales

In order to behave appropriately in a rapidly changing world, individuals must be able to detect when changes occur in that environment. However, at any given moment, there are a multitude of potential changes of behavioral significance that could occur. Here we investigate how knowledge about the space of possible changes affects human change point detection. We used a stochastic auditory change point detection task that allowed model-free and model-based characterization of the decision process people employ. We found that subjects can simultaneously apply distinct timescales of evidence evaluation to the same stream of evidence when there are multiple types of changes possible. Informative cues that specified the nature of the change led to improved accuracy for change point detection through mechanisms involving both the timescales of evidence evaluation and adjustments of decision bounds. These results establish three important capacities of information processing for decision making that any proposed neural mechanism of evidence evaluation must be able to support: the ability to simultaneously employ multiple timescales of evidence evaluation, the ability to rapidly adjust those timescales, and the ability to modify the amount of information required to make a decision in the context of flexible timescales.

neuroscience↗

bioRxiv2018

Causal contribution and dynamical encoding in the striatum during evidence accumulation

A broad range of decision-making processes involve gradual accumulation of evidence over time, but the neural circuits responsible for this computation are not yet established. Recent data indicates that cortical regions prominently associated with accumulating evidence, such as posterior parietal cortex and the frontal orienting fields, are not necessary for computing it. Which, then, are the regions responsible? Regions directly involved in evidence accumulation should satisfy the criteria of being necessary for accumulation-based decision-making behavior, having a graded neural encoding of accumulated evidence and causal contributing throughout the accumulation process. Here, we investigated the role of the anterior dorsal striatum (ADS) in a rodent auditory evidence accumulation task using a combination of behavioral, pharmacological, optogenetic, electrophysiological and computational approaches. We find that the ADS is the first brain region known to satisfy these criteria. Thus, the ADS may be the first identified node in the network responsible for evidence accumulation.

neuroscience↗