Amplitude Normalization of Dendritic EPSPs at the Soma of Binaural Coincidence Detector Neurons of the Medial Superior Olive
| Autor: | Kenneth R. Ledford, Shan-Xue Jin, Nace L. Golding, Bradley D. Winters |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Sound localization Male Sensory Receptor Cells Interaural time difference Biology Synapse 03 medical and health sciences 0302 clinical medicine medicine Animals Sound Localization Cells Cultured Research Articles Dendritic spike General Neuroscience Excitatory Postsynaptic Potentials Superior Olivary Complex Dendrites 030104 developmental biology medicine.anatomical_structure nervous system Superior olivary complex Synapses Excitatory postsynaptic potential Soma Female Gerbillinae Neuroscience 030217 neurology & neurosurgery Coincidence detection in neurobiology |
| Zdroj: | The Journal of neuroscience : the official journal of the Society for Neuroscience. 37(12) |
| ISSN: | 1529-2401 |
| Popis: | The principal neurons of the medial superior olive (MSO) encode cues for horizontal sound localization through comparisons of the relative timing of EPSPs. To understand how the timing and amplitude of EPSPs are maintained during propagation in the dendrites, we made dendritic and somatic whole-cell recordings from MSO principal neurons in brain slices from Mongolian gerbils. In somatic recordings, EPSP amplitudes were largely uniform following minimal stimulation of excitatory synapses at visualized locations along the dendrites. Similar results were obtained when excitatory synaptic transmission was eliminated in a low calcium solution and then restored at specific dendritic sites by pairing input stimulation and focal application of a higher calcium solution. We performed dual dendritic and somatic whole-cell recordings to measure spontaneous EPSPs using a dual-channel template-matching algorithm to separate out those events initiated at or distal to the dendritic recording location. Local dendritic spontaneous EPSP amplitudes increased sharply in the dendrite with distance from the soma (length constant, 53.6 μm), but their attenuation during propagation resulted in a uniform amplitude of ∼0.2 mV at the soma. The amplitude gradient of dendritic EPSPs was also apparent in responses to injections of identical simulated excitatory synaptic currents in the dendrites. Compartmental models support the view that these results extensively reflect the influence of dendritic cable properties. With relatively few excitatory axons innervating MSO neurons, the normalization of dendritic EPSPs at the soma would increase the importance of input timing versus location during the processing of interaural time difference cuesin vivo.SIGNIFICANCE STATEMENTThe neurons of the medial superior olive analyze cues for sound localization by detecting the coincidence of binaural excitatory synaptic inputs distributed along the dendrites. Previous studies have shown that dendritic voltages undergo severe attenuation as they propagate to the soma, potentially reducing the influence of distal inputs. However, using dendritic and somatic patch recordings, we found that dendritic EPSP amplitude increased with distance from the soma, compensating for dendritic attenuation and normalizing EPSP amplitude at the soma. Much of this normalization reflected the influence of dendritic morphology. As different combinations of presynaptic axons may be active during consecutive cycles of sound stimuli, somatic EPSP normalization renders spike initiation more sensitive to synapse timing than dendritic location. |
| Databáze: | OpenAIRE |
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