Single modeled neuron selective for interaural phase differences (IPD) across low-frequency carrier waveforms. The neuron’s log-normal selectivity function is similar to neurons in the midbrain nucleus of the inferior colliculus. Selectivity also resembles the first cycle of a low-frequency auditory filter’s impulse response.

Modeled neuron populations are equally spaced so that activity maxima are achieved at IPDs ranging from 0.0 to 0.3 cycles in the left hemisphere and from -0.3 to 0.0 cycles in the right hemisphere. IPDs corresponding to activity maxima therefore span a range of values consistent with published reports (μ = 0.15, σ = 0.08). Note, however, that sub-maximal activities along the medial edges of the neurons correspond to IPDs in both hemispheres.

Activity patterns obtained across a sub-population of five modeled neurons by recurrent IPD values:  -0.2,  -0.1,  0.0,  0.1,  or 0.2 cycles.

• • Individual neurons are defined by the log-normal function: exp(-(ln((L+(1/X))*2)*2.0)^2), where L is the IPD value and ‘label’ along each curve's medial edge at an activity level of 0.5 and X is approximated as: 0.730867+1.291527*exp(-((-L)+0.129749)/0.082556)+2.970719*exp(-((-L)+0.129749)/0.342301).
• • McAlpine, D., Jiang, D., & Palmer, A. (2001) A neural code for low-frequency sound localization in mammals. Nature Neuroscience.
• • Joris PX, Yin TCT. (2007) A matter of time: internal delays in binaural processing. Trends in Neuroscience.
• • Grothe B, Pecka M, McAlpine D. (2010) Mechanisms of sound localization in mammals. Physiological Reviews.
• • An activity level of 0.5 is achieved at IPDs ranging from approximately -0.17 to 0.13 along the medial ‘edges’ of neurons in the left hemisphere and from -0.13 to 0.17 in the right hemisphere. An alternative (often preferable) spacing is for IPD to range, at an activity level of 0.5, from approximately -0.2 to 2.0 in both hemispheres.