A Fundamental Micro-circuit Computation in Neocortex and Hippocampus


September 8, 2015 - 12:00pm
NW 243
About the Speaker
Jeffrey Magee (Janelia)

In many cortical microcircuits the integration of two functionally distinct inputs occurs nonlinearly via the generation of active dendritic signals that drive burst firing output and robust plasticity. We have examined the role of this processing in the production of neuronal feature selectivity and network level representations in both the hippocampus (CA1) and barrel cortex (L5). We have found that these conjunctive dendritic signals gain modulate the firing fields of both areas and rapidly induce novel place field formation in CA1. At the network level, the gain modulation produces a nonlinear combination of motor and sensory input that yields a mixed representation of salient object location in layer 5 neurons. This representation was also found to be important for a simple motor adaptation of whisking pattern in behaving mice. These and other studies present evidence that active dendritic integration in pyramidal neuron based cortical microcircuits supports a general microcircuit operation or low-level computation; the nonlinear interaction of long-range and local inputs that leads to firing rate modulation, neuronal plasticity and mixed network representations.