Dynamics in networks of cortical fast-spiking inhibitory interneurons

University Of California-Davis, Davis CA

Investigators

Abstract

Fast-spiking (FS) inhibitory neurons in the cortex play fundamental roles in setting the response threshold and shaping the response of cortical microcircuits. In particular, the temporal structure and the amplitude of population synchrony in the network of FS neurons strongly influence the response of the full cortical microcircuit. However, while pairs of FS neurons in vivo have been shown to frequently fire in synchrony, the extent of synchrony in the population of FS neurons is not known. To understand cortical information processing, we must know how the FS network is behaving and how the cellular properties and connectivity interact to produce this behavior. We will use mathematical modeling to examine the mechanisms that shape the response of networks of inhibitory neurons in the cortex to sensory input, and thus we will provide insight into the role of inhibition in sensory information processing. Both biophysical-detailed and idealized models of the FS neuron network will be constructed, and the dynamics of the network models will be thoroughly examined using data analysis methods, numerical simulations and analytical mathematical techniques. The responses of the model network to biologically-realistic stochastic input will be studied. In particular, the influence of the correlation structure of the input, the intrinsic properties of FS cells and the connectivity within the FS network will be considered. We hypothesize that certain input to the FS network could trigger waves of activity that propagate through the network via the electrical coupling. These waves would be a novel mechanism for significant amplification of the inhibitory response. Conditions for waves in the FS model networks will be investigated and the likelihood of waves occurring in vivo will be assessed. The behavior in the models will be compared to data from in vivo experimental data, and predictions made from the modeling work will be tested in vitro experiments. A major goal of neuroscience is to understand the mechanisms involved in processing sensory information in the cerebral cortex. This involves understanding how the intrinsic properties of neurons and the connectivity between neurons affect the input-output characteristics of cortical neuronal networks. It is known that inhibitory neurons, such as fast-spiking (FS) neurons, play fundamental roles in determining the response of cortical networks, however the details concerning exactly what they do and how they do it remain unclear. This modeling project will examine the response characteristics of networks of FS neurons and identify the cellular mechanisms underlying these characteristics. Thus, the work will take a step towards understanding the cellular basis of how the brain processes sensory information. The work will be part of a large body of research being done by many neuroscientists that will lead to improved treatments for complex neurological disorders such as epilepsy and attentional disorders.