Visual recalibration of auditory spatial perception: two separate neural circuits for perceptual learning

Area of Science:

• Neuroscience
• Perceptual Psychology
• Auditory Neuroscience

Background:

• Auditory spatial perception can be rapidly recalibrated by visual stimuli, leading to biases (ventriloquism after-effect) or improvements (multisensory enhancement).
• These recalibration effects may involve distinct neural pathways: the geniculostriate and the collicular-extrastriate pathways.

Purpose of the Study:

• To investigate whether visual recalibration of auditory spatial perception relies on two separate neural pathways.
• To differentiate the roles of the geniculostriate and collicular-extrastriate pathways in auditory-visual recalibration.

Main Methods:

• Used hemianopic patients (striate cortex lesion) and neglect patients (temporoparietal cortex lesion) to localize sounds.
• Applied auditory-visual stimulation with spatially disparate or coincident stimuli in normal or affected visual fields before and after adaptation.

Main Results:

• Adaptation to spatially disparate stimuli in the normal field caused shifts in auditory localization for all patients.
• When adaptation occurred in the affected field, neglect patients showed shifts, but hemianopic patients did not.
• Adaptation to spatially coincident stimuli improved auditory localization in all patients, regardless of the adaptation field.

Conclusions:

• Findings suggest two distinct recalibration mechanisms for auditory spatial perception.
• The geniculostriate circuit mediates corrective mechanisms for spatially conflicting stimuli.
• The collicular-extrastriate circuit mediates error reduction for spatially aligned auditory-visual inputs.