9410933 Mel This collaborative project between a young theorist and two experienced experimentalist to test a new theory of what happens in the brain during learning.. The theory says that learning in the mammalian cortex is guided by a balance between two distinct mechanisms. One is the continual activity-independent changes in the connections between neurons (called synapses) that tend to randomize the place on a neuron where an incoming afferent neuron establishes its connection. The second is an activity-dependent process in which the connections of afferent neurons that are active at the same time are stabilized if they happen by chance to be close together. This means that groups of frequently co- activated inputs to the brain come together to form neighboring synapses and, therefore, have a more powerful effect on their target neurons. This theory will be tested experimentally by looking anatomically at the spatial arrangement of afferent synapses on target neurons when the afferent neurons are artificially induced to have correlated activity. The theory will also be tested by simulating this type of biological experiment on a computer. The outcome of these studies promises to have a significant impact on the way we think about how the brain does the computations that allow us to learn complicated patterns.
