NEURAL SUBSTRATES OF LEARNING

大脑如何使人学习新行为的问题

The question of how the brain enables one to learn new behavior based on rewarding feedback is one of neuroscience's greatest challenges. Research in recent decades has produced considerable knowledge about the neurocircuitry that controls motor behavior and about brain structures that are involved in positive sensory experience, but the location of sites in the brain where reward circuits act on motor control circuits to change future behavior remains an enigma. The purpose of this project is to analyze the connections of a part of the brain where a reward circuit and a relatively well-understood motor circuit converge to determine its role in learning new behaviors. Monkeys are taught to perform the simple behavior of moving the eyes back and forth between two target spots out of 25 possible targets on a video screen. They are rewarded with direct brain stimulation for the time-consuming process of finding the correct pair of targets and alternating their gaze bet ween the two. The goals of the research are 1) to identify one or more specific areas in the brain where stimulation is sufficiently rewarding that the animal learns to find and alternate gaze between new targets; 2) to identify the nerve pathways that pass through those areas to an area in frontal cortex where nerve cells are known to be active during the learning of eye movements; and 3) to determine whether direct treatment of that area with neurochemical agents that temporarily disrupt its function prevents the learning of eye movements to new targets. In 1998 one animal was tested for self-stimulation at some 10 brain sites. Equipment was fabricated and installed for monitoring eye movements. An eye coil was implanted in one animal and preliminary testing was conducted to test a protocol for training the animal in alternating eye movements. FUNDING NIH grant RR00166.