Functional organization of posterior parietal cortex circuitry based on inferred information flow.

Many studies infer the role of neurons by asking what information can be decoded from their activity or by observing the consequences of perturbing their activity. An alternative approach is to consider information flow between neurons. We applied this approach to the parietal reach region (PRR) and the lateral intraparietal area (LIP) in posterior parietal cortex. Two complementary methods imply that across a range of reaching tasks, information flows primarily from PRR to LIP. This indicates that during a coordinated reach task, LIP has minimal influence on PRR and rules out the idea that LIP forms a general purpose spatial processing hub for action and cognition. Instead, we conclude that PRR and LIP operate in parallel to plan arm and eye movements, respectively, with asymmetric interactions that likely support eye-hand coordination. Similar methods can be applied to other areas to infer their functional relationships based on inferred information flow.

Information processing in the dorsal pathway: from "where" to "what we do with it".

Visual processing in the brain has been understood as the ventral and dorsal pathways processing "what" and "where" information, respectively. Mocz et al. (Mocz V, Vaziri-Pashkam M, Chun M, Xu Y. J Cogn Neurosci 34: 2406-2435, 2022), however, report that the two pathways code object features in a parallel manner. These results support that information processing in the dorsal pathway is not strictly limited to "where" and that the two pathways work in parallel to process task-relevant information ("what we do with it").