Dhakshin S Ramanathan

• University of California, San Francisco

A remarkable feature of motor control is the ability to coordinate movements across distinct body parts into a consistent, skilled action. To reach and grasp an object, ‘gross’ arm and ‘fine’ dexterous movements must be coordinated as a single action. How the nervous system achieves this coordination is currently unknown. One possibility is that, w...

Recent work has highlighted the importance of transient low-frequency oscillatory (LFO; <4 Hz) activity in the healthy primary motor cortex during skilled upper-limb tasks. These brief bouts of oscillatory activity may establish the timing or sequencing of motor actions. Here, we show that LFOs track motor recovery post-stroke and can be a physiolo...

A fundamental goal of motor learning is to establish the neural patterns that produce a desired behavioral outcome. It remains unclear how and when the nervous system solves this 'credit assignment' problem. Using neuroprosthetic learning, in which we could control the causal relationship between neurons and behavior, we found that sleep-dependent...

Author Summary Sleep has been shown to help in consolidating learned motor tasks. In other words, sleep can induce “offline” gains in a new motor skill even in the absence of further training. However, how sleep induces this change has not been clearly identified. One hypothesis is that consolidation of memories during sleep occurs by “reactivation...

Intracortical brain-machine interfaces (BMIs) may eventually restore function in those with motor disability after stroke. However, current research into the development of intracortical BMIs has focused on subjects with largely intact cortical structures, such as those with spinal cord injury. Although the stroke perilesional cortex (PLC) has been...

Rodent forelimb reaching behaviors are commonly assessed using a single-pellet reach-to-grasp task. While the task is widely recognized as a very sensitive measure of distal limb function, it is also known to be very labor-intensive, both for initial training and the daily assessment of function. Using components developed by open-source electronic...

Previous studies reported that early post-natal cholinergic lesions severely perturb early cortical development, impairing neuronal cortical migration and the formation of cortical dendrites and synapses. These severe effects of early post-natal cholinergic lesions preclude our ability to understand the contribution of cholinergic systems to the la...

Brain-machine interfaces can allow neural control over assistive devices. They also provide an important platform for studying neural plasticity. Recent studies have suggested that optimal engagement of learning is essential for robust neuroprosthetic control. However, little is known about the neural processes that may consolidate a neuroprostheti...

The basal forebrain cholinergic system has been implicated in the reorganization of adult cortical sensory and motor representations under many, but not all, experimental conditions. It is still not fully understood which types of plasticity require the cholinergic system and which do not. In this study, we examine the hypothesis that the basal for...

Selective attention may be flexibly directed toward particular locations in the visual field (spatial attention) or to entire object configurations (object-based attention). A key question is whether spatial attention plays a direct role in the selection of objects, perhaps by spreading its facilitatory influence throughout the boundaries of an obj...

To investigate functional mechanisms underlying cortical motor plasticity in the intact and injured brain, we used “behaviorally relevant,” long-duration intracortical microstimulation. We now report the existence of complex, multijoint movements revealed with a 500-msec duration intracortical stimulation in rat motor cortex. A consistent topograph...