Noise-Driven Adaptation : and Mathematical Analysis

Fairhall et al. (2001) recently reported on variance adaptation processes in cells of the fly visual system, and qualitatively similar effects have been observed in various vertebrate preparations. To better understand the contributions of somatic mechanisms to this kind of adaptation, we recorded intracellularly from neurons of rat sensorimotor cortex while stimulating with a noise current whose standard deviation was varied parametrically. We observed systematic variance-dependent adaptation (where adaptation is defined as a scaling of a nonlinear transfer function), similar in many respects to the effects observed The fact that similar adaptive phenomena could be observed in such different preparations led us to investigate a simple model of stochastic stimulus-driven neural activity. The simplest such model, the leaky integrate-and-fire (LIF) cell driven by noise current, permits us to analytically compute many quantities relevant to our observations on adaptation; we show that the LIF model displays "adaptive" behavior which is quite similar to the effects observed and