ABSTRACT
Visual stimuli produce waves of activity that propagate across the visual cortex of fresh water turtles. This study used a large-scale model of the cortex to examine the roles of specific types of cortical neurons in controlling the formation, speed and duration of these waves. The waves were divided into three components: initial depolarizations, primary propagating waves and secondary waves. The maximal conductances of each receptor type postsynaptic to each population of neurons in the model was systematically varied and the speed of primary waves, durations of primary waves and total wave durations were measured. The analyses indicate that wave formation and speed are controlled principally by feedforward excitation and inhibition, while wave duration is controlled principally by recurrent excitation and feedback inhibition.
Subject(s)
Neural Networks, Computer , Turtles/physiology , Visual Cortex/physiology , Animals , Bayes Theorem , Computer Simulation , Electrophysiology , Feedback/physiology , Geniculate Bodies/cytology , Geniculate Bodies/physiology , Models, Neurological , Neurons/physiology , Photic Stimulation , Pyramidal Cells/physiology , Receptors, AMPA/physiology , Receptors, GABA/physiologyABSTRACT
Visual stimuli evoke waves of electrical activity that propagate across the visual cortex of freshwater turtles. The experimental methods used to demonstrate these waves measure the activity of populations of pyramidal cells. However, turtle visual cortex contains pyramidal cells and at least three populations of inhibitory interneurons. This study uses a large-scale model to characterize the time course of activity of each of the major populations of neurons in turtle visual cortex.
