Antonio Homero Lara - US grants

? DESCRIPTION (provided by applicant): Uncovering the principles behind the generation of voluntary movements is a necessary first step in the development of technologies and treatments aimed at restoring motor abilities lost to neurological disease or trauma. The aim of this project is to shed light on the neural mechanisms of voluntary movement initiation. An essential component of voluntary movement is the choice of when to act. Under normal circumstances this decision can be time consuming usually taking up to a few hundreds of milliseconds, longer that the known delays in the nervous system. The area of the brain most associated with generating movements, the motor cortex, becomes very active just before and during the movement, however what exactly is happening during this time is still not well understood. Indeed, while much is known about the neural basis of generating movements, several open questions remain: does a movement generated deliberately with no time pressure, like a reach made to grab an object from a table, share the same neural underpinnings with a very fast reach to catch a falling object? Will the motor cortex be just as active before a quasi-automatic reach when time is of the essence? Or is pre-movement activity only present when there is enough time to deliberately plan the movement? During movement itself, is motor cortex involved in generating quasi-automatic reaches or is there is some reflex mechanism that bypasses motor cortex to generate urgent reaches? To begin answering these questions we have trained two monkeys to initiate a reach under three very different circumstances: sometimes monkeys move at a time of their own choosing with no imposed time constraints, other times monkeys must intercept a rapidly moving target on a screen, which elicits very short-latency reaches. In yet another set of trials monkeys must withhold a reach until given a go cue. The first aim of this project is to determine if these three movements (self-initiated, quasi-automatic and cue-initiated) share a common neural mechanism that does not depend on how the movement is initiated. To do this we will record the responses from a number of neurons in two key regions of the motor cortex: the primary motor and dorsal premotor cortex. In order to understand and interpret these responses, we will employ cutting edge machine learning techniques that will allow us to visualize and quantify the how neural activity evolves in time. Being able to visualize the evolution of neural activity is a key component in understanding the principles that govern how the neural activity translates to movement. The second aim of this project is to elucidate the role that higher cortical areas play in the generation of voluntar movements. We will record neural activity from areas upstream of motor cortex (supplementary motor area), which is heavily interconnected with the motor cortex and is suspected to play crucial a role in determining when a movement should be initiated. We will test record neural activity from this area and characterize its properties using the same cutting edge techniques developed in the first part of this project.