期刊
JOURNAL OF NEUROSCIENCE
卷 37, 期 21, 页码 5319-5333出版社
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.0015-17.2017
关键词
action potential; backpropagation; dendrite; low-threshold spike; thalamic reticular nucleus; thalamocortical
资金
- Wellcome Trust [91882]
- Wellcome Trust (Strategic Award DEFINE)
- Jane Hodge Foundation
Backpropagating action potentials (bAPs) are indispensable in dendritic signaling. Conflicting Ca2+-imaging data and an absence of dendritic recording data means that the extent of backpropagation in thalamocortical (TC) and thalamic reticular nucleus (TRN) neurons remains unknown. Because TRN neurons signal electrically through dendrodendritic gap junctions and possibly via chemical dendritic GABAergic synapses, as well as classical axonal GABA release, this lack of knowledge is problematic. To address this issue, we made two-photon targeted patch-clamp recordings from rat TC and TRN neuron dendrites to measure bAPs directly. These recordings reveal that tonic' and low-threshold-spike (LTS) burst APs in both cell types are always recorded first at the soma before backpropagating into the dendrites while undergoing substantial distance-dependent dendritic amplitude attenuation. In TC neurons, bAP attenuation strength varies according to firing mode. During LTS bursts, somatic AP half-width increases progressively with increasing spike number, allowing late-burst spikes to propagate more efficiently into the dendritic tree compared with spikes occurring at burst onset. Tonic spikes have similar somatic half-widths to late burst spikes and undergo similar dendritic attenuation. In contrast, in TRN neurons, AP properties are unchanged between LTS bursts and tonic firing and, as a result, distance-dependent dendritic attenuation remains consistent across different firing modes. Therefore, unlike LTS-associated global electrical and calcium signals, the spatial influence of bAP signaling in TC and TRN neurons is more restricted, with potentially important behavioral-state-dependent consequences for synaptic integration and plasticity in thalamic neurons.
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