Tuning Neurons to Interaural Intensity Differences Using Spike Timing-Dependent Plasticity

Mammals are known to use Interaural Intensity Difference (IID) to determine azimuthal position of high frequency sounds. In the Lateral Superior Olive (LSO) neurons have firing behaviours which vary systematicaly with IID. Those neurons receive excitatory inputs from the ipsilateral ear and inhibitory inputs from the contralateral one. The IID sensitivity of a LSO neuron is thought to be due to delay differences between both ears, delays due to different synaptic delays and to intensity-dependent delays. In this paper we model the auditory pathway until the LSO. Inputs to LSO neurons are at first numerous and differ in their relative delays. Spike Timing-Dependent Plasticity is then used to prune those connections. We compare the pruned neuron responses with physiological data and analyse the relationship between IID-s of teacher stimuli and IID sensitivities of trained LSO neurons.

• Bertrand Fontaine
• Herbert Peremans

• Interaural difference
• lateral superior olive
• spike time-dependent plasticity.

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[12] The networks have been simulated using the Csim Toolbox available at http://www.lsm.tugraz.at/csim The parameters of the LIF neurons are: Rm=1M╬®, ¤äm=20ms, Vthresh=-0.045V, Vresting=-0.06V, Vreset=- 0.06V, Vinit=-0.06V, Trefract=1ms. The parameters of the synapses are ¤äContra=2ms, ¤äIpsi=0.5ms, Wmax=1e-4. The parameters of the windows are A+=2/3, B+=0.25, ╬À+=50e-6, ¤ä+ 0 =1/10ms, ¤ä+ 1 =1/200ms, ¤ä+ 2 =1/2ms, s*+=-1/800ms, A−=0.7, B−=0.25, ╬À−=50e-6, ¤ä−0 =1/5ms, ¤ä−1 =1/20ms, ¤ä−2 =1/2ms, s*−=-0.1ms.</p>