Liam Paninski, 10/21/03

Maximum likelihood estimation of cascade point-process neural encoding models

Recent work has examined the estimation of models of stimulus-driven neural activity in which some linear filtering process is followed by a nonlinear, probabilistic spiking stage. We analyze the estimation of one such model for which this nonlinear step is implemented by a known parametric function. The assumption that this function is known can speed up the estimation process considerably, albeit at the cost of significantly less generality. We investigate the shape of the likelihood function for this model, give a simple condition on the nonlinearity ensuring that no local maxima exist in the likelihood (leading, in turn, to an efficient algorithm for the computation of the maximum likelihood estimator), and discuss some of the implications of this condition for the form of the allowed nonlinearities.