Physiological and psychophysical modeling of the precedence effect

Area of Science:

• Neuroscience
• Computational Auditory Neuroscience
• Acoustic Perception

Background:

• The precedence effect (PE) describes the perception of a sound's location based on the first-arriving sound, even with subsequent sounds from different directions.
• Understanding the neural mechanisms underlying PE is crucial for explaining auditory spatial perception.

Purpose of the Study:

• To develop a computational model of low-frequency inferior colliculus (IC) neurons.
• To account for both physiological and psychophysical responses related to the precedence effect (PE).

Main Methods:

• A computational model simulating IC neuron responses to click stimuli with varying inter-stimulus delays (ISDs) and locations.
• Model inputs included excitation from the medial superior olive (MSO) and inhibition from MSO relayed through the dorsal nucleus of the lateral lemniscus.
• Psychophysical predictions were derived from a simulated population of model neurons.

Main Results:

• The model demonstrated that physiological suppression of lagging sound responses is dependent on ISD and sound locations.
• Predicted lead localization was accurate across all ISDs.
• At short ISDs, the model predicted lag localization near the lead, aligning with perceptual fusion; at longer ISDs, it predicted lag localization closer to the true lag, aligning with sound segregation.

Conclusions:

• Location-dependent suppression within IC neurons provides a plausible neural basis for the precedence effect.
• The model successfully bridges physiological neural mechanisms with psychophysical observations of sound localization.