Functional links between sensory representations, choice activity, and sensorimotor associations in parietal cortex

Abstract

Three-dimensional (3D) representations of the environment are often critical for selecting actions that achieve desired goals. The success of these goal-directed actions relies on 3D sensorimotor transformations that are experience-dependent. Here we investigated the relationships between the robustness of 3D visual representations, choice-related activity, and motor-related activity in parietal cortex. Macaque monkeys performed an eight-alternative 3D orientation discrimination task and a visually guided saccade task while we recorded from the caudal intraparietal area using laminar probes. We found that neurons with more robust 3D visual representations preferentially carried choice-related activity. Following the onset of choice-related activity, the robustness of the 3D representations further increased for those neurons. We additionally found that 3D orientation and saccade direction preferences aligned, particularly for neurons with choice-related activity, reflecting an experience-dependent sensorimotor association. These findings reveal previously unrecognized links between the fidelity of ecologically relevant object representations, choice-related activity, and motor-related activity.

Parallel processing, hierarchical transformations, and sensorimotor associations along the ‘where’ pathway

“…Lastly, the distributions of Φ peaked at approximately 90° in both V3A (median Φ = 88°) and CIP (median Φ = 89°), indicating that any anisotropy in the tuning curves generally occurred along the tilt/slant axes ( Figure 3—figure supplement 2E,F ). These findings indicate greater orientation tuning symmetry in CIP than V3A, which may be important for perceptual sensitivity to changes in object orientation to not depend on the axis of rotation (Chang et al, 2020b).…”

“…To quantify the distance-dependence of 3D orientation tuning curve shape, we fit each 3D pose tuning curve with a separable model ( Equation 3 ) and computed a Tolerance index (Chang et al, 2020b). Tolerance values near zero indicate that the shape of the orientation tuning curve changed substantially with distance (as expected for neurons selective for low-level visual features).…”

“…However, the specific functional contributions of areas along this pathway remain elusive due in part to methodological differences across studies. We previously showed that macaque caudal intraparietal (CIP) area neurons possess robust three-dimensional (3D) visual representations, carry choice-related and presaccadic activity, and exhibit experience-dependent sensorimotor associations (Chang et al, 2020b). Here, we used a common experimental design to reveal parallel processing, hierarchical transformations, and the formation of sensorimotor associations along the ‘where’ pathway by extending the investigation to V3A, a major feedforward input to CIP.…”

MRI Compatible, Customizable, and 3D-Printable Microdrive for Neuroscience Research

“…We have used variations of this technique for years (Rosenberg et al, 2013;Laurens et al, 2016;Chang et al, 2020), and have not encountered problems with infection. Meticulous cleaning of the acrylic layer before and after drilling, cleaning and sterilizing components, and covering the implant outside of the experiment (CAD files for a cover are provided but not shown) greatly reduce the risk of infection.…”

“…The penetration grid used in conjunction with a contrast agent is visible in structural scans, providing a fiducial reference for estimating penetration trajectories (Kalwani et al, 2009;Dubowitz & Scadeng, 2011;Glud et al, 2017). The penetration grid further serves as a guide for a micro-drilling technique that replaces conventional craniotomies with small holes through which probes are introduced into the brain (Rosenberg et al, 2013;Laurens et al, 2016;Chang et al, 2020). Compared to conventional craniotomies and chambers, this technique reduces potential artifacts caused by air-filled spaces, the need for periodic debridement of granulation tissue, and potential deformation of the underlying neuronal tissue (Wilson et al, 2005;Spitler & Gothard, 2008;Premereur & Janssen, 2020).…”