Ventral Medial Nucleus Neurons Send Thalamocortical Afferents More Widely and More Preferentially to Layer 1 than Neurons of the Ventral Anterior–Ventral Lateral Nuclear Complex in the Rat

Abstract

Not only inhibitory afferent-dominant zone (IZ) of the ventral anterior-ventral lateral thalamic complex (VA-VL) but also the ventral medial nucleus (VM) is known to receive strong inputs from the basal ganglia and send axons to motor areas. We previously reported differences in axonal arborization between IZ neurons and the other VA-VL neurons in rats by single-neuron tracing with viral vectors. In the present study, the axonal arborization of single VM neurons was visualized by the same method, and compared with that of IZ neurons. VM neurons formed fewer axon collaterals in the striatum, but sent axon fibers more widely and more preferentially (79% of fibers) to layer 1 of cortical areas than IZ neurons. Furthermore, the VM seemed to contain at least 2 types of neurons; a major population of VM neurons sent axon fibers principally to motor-associated areas as VA-VL neurons did, and the other population projected mainly to orbital or cingulate areas. Although both VM and IZ neurons receive strong basal ganglia inputs, these results suggest that VM neurons, at a single neuron level, innervate the apical dendrites of cortical pyramidal neurons more intensely and more widely than IZ neurons.

Different cortical projections from three subdivisions of the rat lateral posterior thalamic nucleus: a single‐neuron tracing study with viral vectors

“…We have developed Sindbis virus vectors (Furuta et al ., ; Nishino et al ., ) that strongly express reporter protein under control of the powerful viral subgenomic promoter, and that are considered to be suitable for visualising entire structures of a few neurons or single neurons. Using the vectors, we have clearly demonstrated the axonal arborisations of single mesencephalic dopamine neurons (Matsuda et al ., ) and thalamic neurons (Kuramoto et al ., , ; Ohno et al ., ). In the present study, we applied this technique to reveal the axonal arborisations of single LP neurons, and demonstrated that LP neurons in each subdivision had different characteristics in the cortical target areas and layers.…”

Super-wide-field two-photon imaging with a micro-optical device moving in post-objective space

“…Trial-to-trial correlations between neurons are thought to reflect patterns of synaptic inputs that are common to both and the reciprocal connections between them 33–35 . In fact, RFA and CFA possess reciprocal connections 27,36 and receive common inputs from the thalamus 37 . The four behavioral properties and the net motor cortical activity were less related to the similarity of the population activity in the RFA (or CFA) within trial clusters than the population activity in the CFA (or RFA) was.…”

Differential Inputs to the Perisomatic and Distal-Dendritic Compartments of VIP-Positive Neurons in Layer 2/3 of the Mouse Barrel Cortex

“…Furthermore, the motor thalamic nuclei provide axon fibers to the S1. The caudolateral portion of the ventral anterior-ventral lateral motor thalamic nuclei (VA/VL) sends axons to the middle layer of the S1, whereas the rostromedial portion of the VA/VL and the ventral medial nucleus (VM) have widespread projections to L1 of the S1 (Kuramoto et al, 2009, 2015). It is therefore assumed that the apical and basal branches of L2/3 VIP+ neurons receive synaptic inputs from different thalamic nuclei.…”