Data from: Transitions in dynamical regime and neural mode underlie perceptual decision-making

Perceptual decision-making is the process by which an animal uses sensory
stimuli to choose an action or mental proposition. This process is thought
to be mediated by neurons organized as attractor networks. However,
whether attractor dynamics underlie decision behavior and the complex
neuronal responses remains unclear. Here we use simultaneous recordings
from hundreds of neurons, together with an unsupervised, deep
learning-based method, to discover decision-related neural dynamics in
frontal cortex and striatum of rats while the subjects accumulate
pulsatile auditory evidence. The data set consists of spike times from
simultaneously recorded neurons, along with the timing of the sensory
stimuli and the rat's actions for each trial. Recordings were made
from 12 rats across 115 daily sessions, 84-663 units recorded per session
(median: 327) and 157 to 854 trials completed per session (median: 455).
We found that trajectories evolved along two sequential regimes, the first
dominated by sensory inputs, and the second dominated by the autonomous
dynamics, with flow in a direction (i.e., “neural mode”) largely
orthogonal to that in the first regime. We propose that the second regime
corresponds to decision commitment. We developed a simplified model that
approximates the coupled transition in dynamics and neural mode and allows
precise inference, from each trial’s large-scale neural population
activity, of a putative internal decision commitment time in that trial.
The simplified model captures diverse and complex single-neuron temporal
profiles, such as ramping and stepping. It also captures trial-averaged
curved trajectories, and reveals distinctions between brain regions. The
putative neurally-inferred commitment times (“nTc”) occurred at times
broadly distributed across trials, and not time-locked to stimulus onset,
offset, or response onset. Nevertheless, when trials were aligned to nTc,
behavioral analysis showed that, as predicted by a decision commitment
time, sensory evidence before nTc affected the subjects’ decision, but
evidence after nTc did not. Our results show that the formation of a
perceptual choice involves a rapid, coordinated transition in both the
dynamical regime and the neural mode of the decision process, and suggest
the moment of commitment to be a useful entry point for dissecting
mechanisms underlying rapid changes in internal state.