Neurons in the medial superior olive (MSO) enable sound localization by their remarkable sensitivity to submillisecond interaural time differences (ITDs). Each MSO neuron has its own “best ITD” to which it responds optimally. A difference in physical path length of the excitatory inputs from both ears cannot fully account for the ITD tuning of MSO neurons. As a result, it is still debated how these inputs interact and whether the segregation of inputs to opposite dendrites, well-timed synaptic inhibition, or asymmetries in synaptic potentials or cellular morphology further optimize coincidence detection or ITD tuning. Using in vivo juxtacellular and whole-cell recordings, we find that ITD tuning of MSO neurons is determined by the timing of their excitatory inputs. The inputs from both ears sum linearly, whereas spike probability depended nonlinearly on the size of synaptic inputs. This simple coincidence detection scheme thus makes accurate sound localization possible.
37th Congress of IUPS (Birmingham, UK) (2013) Proc 37th IUPS, SA268
Research Symposium: Cellular mechanism of sound localization
M. van der Heijden1, J. A. Lorteije1,3, A. Plauska1, M. T. Roberts2, N. L. Golding2, J. G. Borst1
1. Neuroscience, Erasmus MC, Rotterdam, Netherlands. 2. Section of Neurobiology and Center for Learning and Memory, University of Texas at Austin, Austin, Texas, United States. 3. Vision & Cognition, Netherlands Institute for Neuroscience, Amsterdam, Netherlands.
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