Neurophysiological Effects of Training in Visual Cognitive Tasks

PROJECT SUMMARY The study will investigate the neural mechanisms through which visual information is maintained in working memory. The neural basis of working memory has been a matter of debate in recent years, with competing theories proposing alternative neural correlates for its maintenance. Neurophysiological recordings will target multiple subdivisions of the prefrontal cortex, a brain area implicated in working memory tasks, as well as the anterior cingulate cortex, which has been implicated in learning to perform such tasks. Monkeys will be trained in cognitive tasks that require them to observe and remember the identity of different visual objects, which can be manipulated parametrically. A chronic array of microelectrodes will be implanted, and spike and local field potential recordings will be acquired as the animals are trained to perform the working memory task, and as they learn to perform the task with different stimulus sets. The experiment will allow us to determine the patterns of neuronal activation that determine the behavioral performance in the task and adjudicate between competing models. Analysis will determine changes at the level of single neurons, and neuronal populations, as well as changes evident in the rhythmicity of local field potentials. The experiments will also uncover the nature of changes that take place in the prefrontal cortex during training to perform an object working memory task and uncover what aspects of neural activity are critical for task acquisition. Finally experiments will investigate the flow of information within areas of the prefrontal cortex and between the prefrontal cortex and other cortical areas. Collectively, these experiments will uncover the fundamental mechanisms through which the neural circuits of the prefrontal cortex allow the maintenance of visual object information in working memory.