Dr. Ross Williamson
Ahrens et al. (2008a) introduced a multilinear framework, which captures neuron-specific nonlinear effects of stimulus context on spiking responses to complex sounds. In such a framework, contextual effects are interpreted as non-linear stimulus interactions that modulate the input to a subsequent STRF-like linear filter. We derive various extensions to this framework, and demonstrate that the nonlinear effects of stimulus context are largely in- separable, and fundamentally different for near-simultaneous and delayed non-simultaneous sound energy. In two populations of neurons, recorded from the mouse auditory cortex and thalamus, we show that simultane- ous sound energy provides a nonlinear positive (amplifying) gain to the subsequent linear filter, while non-simultaneous sound energy provides a negative (dampening) gain. We demonstrate that this structure is largely responsible for providing a significant increase in the predicitve capabili- ties of the model.
Using this framework, we show that nonlinear context dependence dif- fers between cortical fields, consistent with previous studies (Linden et al., 2003). Furthermore, we illustrate how such a model can be used to probe the nonlinear mechanisms that underly the ability of the auditory system to operate in diverse acoustic environements. These results provide a novel extension to the study of receptive fields in multiple brain areas, and ex- tend existing understanding of the way in which stimulus context drives complex auditory responses.
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