Choice-specific sequences in parietal cortex during a virtual-navigation decision task

Abstract

The posterior parietal cortex (PPC) plays an important role in many cognitive behaviors; however, the neural circuit dynamics underlying PPC function are not well understood. Here we optically imaged the spatial and temporal activity patterns of neuronal populations in mice performing a PPC-dependent task that combined a perceptual decision and memory-guided navigation in a virtual environment. Individual neurons had transient activation staggered relative to one another in time, forming a sequence of neuronal activation spanning the entire length of a task trial. Distinct sequences of neurons were triggered on trials with opposite behavioral choices and defined divergent, choice-specific trajectories through a state space of neuronal population activity. Cells participating in the different sequences and at distinct time points in the task were anatomically intermixed over microcircuit length scales (< 100 micrometers). During working memory decision tasks the PPC may therefore perform computations through sequence-based circuit dynamics, rather than long-lived stable states, implemented using anatomically intermingled microcircuits.

Segregated fronto‐cortical and midbrain connections in the mouse and their relation to approach and avoidance orienting behaviors

“…Some of these discrepancies can be resolved. For example the parietal region uncovered to project to SCm by Comoli et al (2012), is likely to be equivalent to the region termed the secondary visual cortex in our work, a consequence of the sometimes variable use of nomenclature in relation to mouse cortical areas (Guo et al, 2014; Harvey, Coen, & Tank, 2012). In addition, we found retrogradely labeled cells in areas, which were not reported by Comoli et al (2012).…”

Distinct timescales of population coding across cortex

“…1; Supplementary Information). In PPC, a substantial fraction of neurons had different activity on trials with opposite behavioral choices 8–10,15–18 (Fig. 1f).…”

“…We developed a sound localization task in which mice reported perceptual decisions by navigating through a visual virtual reality T-maze 10 (Fig. 1a).…”

“…We focused on AC because it is necessary for sound localization tasks 11 and on PPC because it is involved in spatial auditory processing 12 , receives inputs from AC, is a multisensory-motor interface 8–10,13–17 , and is essential for virtual-navigation tasks 10 . In each mouse, we imaged the activity of ~50 neurons simultaneously from AC and PPC on separate days.…”

“…4b–j). In both areas, individual neurons were briefly informative, with subsets of largely distinct neurons providing information at different time points in a trial 10,22 (Fig. 2f–k).…”