Dynamical Systems in Neuroscience:

Simple Models 315cells, but mostly LTS cells are of this type.• (STUT) stuttering interneurons fire high-frequency clusters of regular spikesintermingled with unpredictable periods of quiescence. Some FS and LS cellsexhibit this firing type.• (BST) bursting interneurons fire a cluster of 3 to 5 spikes riding on a slowdepolarizing wave followed by a strong slow AHP.• (IS) irregular spiking interneurons fire single spikes randomly with pronouncedfrequency accommodation.NAC and AC are the most common response types found in neocortex. Each groupcan be divided into three subgroups depending on the type of the onset of the responseto a step depolarization:• (c) classical response is when the first spike has the same shape as any otherspike in the response.• (b) burst response is when the first three or more spikes are clustered into a burst.• (d) delayed response is when there is noticeable delay before the onset of spiking.The BST type has a different subdivision: repetitive (r), initial (i), or transient (t)bursting.In Fig. 8.30 we use the simple model (8.5, 8.6) to reproduce all firing patterns of theinterneurons, including the delayed irregular spiking (d-IS) pattern that was omittedin Fig. 8.29. We use one-fit-all set of parameters C = 100, k = 1, v r = −60 mV andv t = −40 mV, and we vary the parameters a, b, c, and d. We do not strive to reproducethe patterns quantitatively, but only qualitatively.The parameters for the NAC and AC cells were similar to those for RS neurons, withan additional passive dendritic compartment for the delayed response. The parametersfor the STUT and IS cells were similar to those of LS interneuron with some minormodifications that affect the initial burstiness and delays. Irregular stuttering in thesetypes results from the co-existence of stable resting equilibrium and spiking limit cycleattractor, as in the case of FS and LS neurons considered above. The level of intrinsicnoise controls the probabilities of transitions between the attractors. The parametersfor the BST cells were similar to those of IB and CH pyramidal cells. Varying theparameters a, b, c, and d, we indeed can get all the firing patterns in Fig. 8.29 plus manyintermediate patterns, thereby creating a continuum of types of inhibitory interneurons.8.3 ThalamusThalamus is the major gateway to the neocortex in the sense that no sensory signal,such as vision, hearing, touch, taste, etc., can reach the neocortex without first passing