Biophysical modeling of thalamocortical circuit dynamics: species-specific insights into neural synchrony, sleep spindles, and circuit mechanisms.

Thalamocortical circuits play a central role in sensory processing, attention, and sleep spindles. Here, we used a biophysically-grounded computational model with single-compartment neurons and species-inspired thalamocortical architectures to investigate how core and matrix pathways, thalamic interneurons, and open, closed, or hybrid thalamic reticular nucleus-thalamic loop configurations influence synchrony, spatiotemporal signal propagation, and spindle-like activity. The model incorporated both core versus matrix thalamocortical projections, with core pathways providing focal, driving input to middle cortical layers and matrix pathways providing more widespread, modulatory signaling across superficial layers, along with pathway-specific receptor dynamics and rodent-like versus primate-like circuit configurations that differed primarily in the presence of thalamic interneurons, as these cells are sparse in rodents but comprise up to a third of the thalamic neurons in primates. Across the tested conditions, the rodent-like circuits were more sensitive to parameter changes in core and matrix thalamocortical connectivity strength, while primate-like circuits maintained relatively stable spatiotemporal patterns across parameter variations, exhibiting greater stability and synchrony. Spindle analyses further suggested greater variability in event structure and timing in rodent-like networks and more regular spindles in primate-like networks. These findings provide insights into how species-inspired architectural differences may shape thalamocortical dynamics, thereby affecting spindle generation and network synchronization.