Common mechanisms of human perceptual and motor learning

Abstract

The adult mammalian brain has a remarkable capacity to learn in both the perceptual and motor domains through the formation and consolidation of memories. Such practice-enabled procedural learning results in perceptual and motor skill improvements. Here, we examine evidence supporting the notion that perceptual and motor learning in humans exhibit analogous properties, including similarities in temporal dynamics and the interactions between primary cortical and higher-order brain areas. These similarities may point to the existence of a common general mechanism for learning in humans.

Figure 1. Perceptual and motor learning

The texture discrimination and sequential finger-tapping tasks (BOX 1) are commonly used to study visual and motor procedural learning, respectively. Both tasks are characterized by within-session fast learning, which involves rapid improvements in performance^–. Depending on the training conditions, the memory can be susceptible to interference for a limited time window of several hours following its acquisition^,,, and deterioration in performance can develop across wakefulness^,–,,. The memory also undergoes the competing process of consolidation after acquisition, which involves stabilization of the memory (enabling its resistance to interference by competing stimuli or tasks^,–,) and offline gains in performance^,,,,–. Slow wave sleep and rapid eye movement sleep involve memory reactivation, downscaling of synaptic strength and long-term synaptic plasticity-related processes. These processes support recovery from performance deterioration and offline learning^,,, by stabilizing and further enhancing the memory through consolidation. Reactivation of the memory during sleep or wakefulness (for example during re-testing on the task) can lead to memory modification, which involves the integration of new information^,.

Figure 2. Interplay between primary cortical processing and higher-order brain areas

The primary visual cortex (V1) and primary motor cortex (M1) have important roles in perceptual and motor learning, respectively, by contributing to the retention of specific physical properties or features of a task. Learning-induced modulation of tuning curves determines the preferred orientation for responding to lines and bars in V1 cells and the preferred direction for reaching movements in M1 cells. However, higher-order brain areas involved in decision-making and reinforcement are also engaged in between-session performance improvements, enabling rule-based learning and generalization. In the motor domain, frontal regions such as the supplementary motor area (SMA) and premotor cortex (PMC), as well as M1, are involved in intermanual transfer of motor sequence learning^,,,. The striatum and hippocampus, which are involved in offline motor learning, show sleep-dependent increased activity, as measured by functional MRI^,. This engagement of higher-order brain areas, which is well documented in motor learning, has also been shown in learning perceptual tasks that require processing in early visual areas^–. Thus, perceptual learning engages not only areas within the ventral stream (for example, V4) and dorsal stream (for example, the medial temporal area) but also areas involved in decision-making, such as the lateral intraparietal area (LIP) and the anterior cingulate cortex (ACC).