Modeling and investigation of neural activity in the thalamus

Although it is known that electroencephalographic (EEG) spindle oscillations are generated and maintained in the thalamus, the underlying mechanisms are still not clear. In this paper, a physiologically based continuum model is used to explore the role of the thalamus in generation of EEG rhythms, particularly spindle oscillations. Furthermore, local interneurons (LIs) which were not previously included in such modeling are studied. A previous continuum model is extended to incorporate LIs within relay nuclei and self-connections of the reticular (RE) nucleus into investigation of the roles and functions of groups of thalamic neurons. The isolated thalamus is analysed into five distinct classes of substructures. Analysis of the properties of waves generated, leads to the main results that: (1) an isolated RE nucleus cannot generate spindle oscillations, but it is essential to generation of spindle oscillations in cooperation with the relay cells; (2) the LIs can also generate spindle oscillations in conjunction with the relay cells; (3) the self-connection loop within the LI population and the one within the RE nucleus both make spindle oscillations easier to produce than in the absence of these connections; (4) the LIs have similar effects to the RE nucleus, except that they are purely inhibitory, whereas the latter has both direct inhibitory effects on relay cells, and indirect net excitatory effects by inhibiting LIs which inhibit relay cells, and (6) self-connections amongst the LIs have equivalent effects to self-connections within the RE nucleus.