NUMERICAL SENSORIMOTOR TRANSFORMATION IN THE PARIETAL CORTEX OF RHESUS MACAQUES

How the brain converts perceived numerical information into an appropriate sequence of self-generated actions remains poorly understood. Here, we investigated this transformation in the parietal cortex of rhesus macaques performing a manual counting task, in which visual numerical cues instructed the animals to produce a corresponding number of hand movements. Single-neuron recordings from the ventral intraparietal area (VIP), a region implicated in numerosity processing, revealed robust numerical selectivity that extended beyond a simple representation of a learned motor plan. Number-selective activity emerged during the sensory instruction phase, persisted through motor preparation, and generalized across sensory and motor task epochs. Neurons exhibited both sustained and transient response patterns, indicating the presence of stable and dynamic coding mechanisms supporting numerical sensorimotor transformation. Population decoding further confirmed that VIP encoded the intended number of actions and captured systematic over- and underestimation biases. Together, these findings identify a neural mechanism by which abstract numerical information is transformed into goal-directed motor output, providing insight into the sensorimotor foundations of numerical cognition in primates.