Heterogeneity of Thalamic Input Landscapes

Abstract

Abstract Unlike cortical neurons, thalamocortical neurons are not connected to each other via a rich recurrant collateral system. As a consequence, thalamic computation is dominated by the integration of extrinsic inputs, not by the interactions among intrinsic elements. The thalamus represents a critical bottleneck in the communication between the cortex and the rest of the brain. The cortex provides by far the most numerous inputs to the thalamus but a variety of other afferents arise from almost the entire neuraxis. Axon terminals in the thalamus display substantial morphological heterogeneity and associated variability in short-term dynamics of neurotransmission. Axon terminals having different origins, transmitters, and synapse numbers can be integrated in many distinct ways in different thalamic territories. Thus there is no canonical input integration in the thalamus. Instead, a rich complexity of uni- and multisynaptic terminals in the thalamus suggests that a core feature of thalamic afferents is the heterogeneous dynamics of synaptic transmission associated with inputs having different number of synapses.