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Barn owls use interaural level differences for vertical sound source localization: their feathers on their head are asymmetric leading to differences in their ears' sensitivities to sounds from above and below.

Sensory maps and their registration across modalities has been demonstrated in mice, cats, monkeys, guinea pigs, hamsters, barn owls, and iguanas.

Rucci et al. present an algorithm which performs auditory localization and combines auditory and visual localization in a common SC map. The mapping between the representations is learned using value-dependent learning.

Bergan et al. offer four factors which might explain the increase in shift of the auditory space maps in owls with shifted visual spatial perception:

  • Hunting represents a task in which accurate map alignment is important (owls which do not hunt presumably do not face such tasks),
  • more cross-modal experience (visual and auditory stimuli from the mice),
  • cross-modal experiences in phases of increased attention and arousal,
  • increased importance of accurate map alignment (important for feeding).

If increased importance of accurate map alignment is what causes stronger map alignment in the optic tectum of owls that hunt than in those of owls that do not hunt (with visually displacing prisms), then that could point either

  • to value-based learning in the OT
  • or to a role of cognitive input to the OT (hunting owls pay more attention/are more interested in audio-visual stimuli than resting or feeding owls).

Rucci et al. model learning of audio-visual map alignment in the barn owl SC. In their model, projections from the retina to the SC are fixed (and visual RFs are therefore static) and connections from ICx are adapted through value-dependent learning.

It is interesting that Rucci et al. modeled map alignment in barn owls using value-based learning so long before value based learning was demonstrated in map alignment in barn owls.

Rearing barn owls in darkness results in mis-alignment of auditory and visual receptive fields in the owls' optic tectum.

Rearing barn owls in darkness results in discontinuities in the map of auditory space of the owls' optic tectum.

The superficial SC of the owl is strongly audio-visual.