Format

Send to

Choose Destination
Neuron. 2019 Jun 19;102(6):1249-1258.e10. doi: 10.1016/j.neuron.2019.04.031. Epub 2019 May 23.

Discrete Stepping and Nonlinear Ramping Dynamics Underlie Spiking Responses of LIP Neurons during Decision-Making.

Author information

1
Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08540, USA. Electronic address: zoltowski@princeton.edu.
2
Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA.
3
Center for Visual Science, University of Rochester, Rochester, NY 14627, USA.
4
Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA; Department of Psychology, The University of Texas at Austin, Austin, TX 78712, USA; Center for Perceptual Systems, The University of Texas at Austin, Austin, TX 78712, USA.
5
Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08540, USA; Department of Psychology, Princeton University, Princeton, NJ 08540, USA.

Abstract

Neurons in LIP exhibit ramping trial-averaged responses during decision-making. Recent work sparked debate over whether single-trial LIP spike trains are better described by discrete "stepping" or continuous "ramping" dynamics. We extended latent dynamical spike train models and used Bayesian model comparison to address this controversy. First, we incorporated non-Poisson spiking into both models and found that more neurons were better described by stepping than ramping, even when conditioned on evidence or choice. Second, we extended the ramping model to include a non-zero baseline and compressive output nonlinearity. This model accounted for roughly as many neurons as the stepping model. However, latent dynamics inferred under this model exhibited high diffusion variance for many neurons, softening the distinction between continuous and discrete dynamics. Results generalized to additional datasets, demonstrating that substantial fractions of neurons are well described by either stepping or nonlinear ramping, which may be less categorically distinct than the original labels implied.

KEYWORDS:

LIP; decision-making; drift-diffusion model; lateral intraparietal area; neural dynamics; stepping

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center