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Amee J. Hall, Jeffrey G Mellott, Stephen G Lomber; Audiovisual interactions in the Cat: Direct cortical projections from the posterior auditory field to primary visual cortex. Journal of Vision 2007;7(9):867. doi: 10.1167/7.9.867.
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© ARVO (1962-2015); The Authors (2016-present)
Sensory systems do not operate in isolation and must have the ability to influence each other. On a behavioral level, we have been examining the influence of auditory cortex on basic visual functions. Therefore, we are interested in identifying possible pathways that may serve to mediate these interactions. In adult cats ([[gt]]6 months), sources of auditory cortical projections to primary visual cortex (areas 17 & 18) were studied using injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into areas 17 & 18. In each animal, multiple injections were made into representations of both the central and peripheral visual fields. In agreement with previous studies, characteristic patterns of cell body labeling were identified in extrastriate visual cortex (areas PMLS, PLLS, AMLS, 19, 20, & 21) and the visual thalamus (LGN, MIN, & LPl), thus confirming the efficacy of the tracer injections. Labeled neurons were also identified in the visual area of the anterior ectosylvian sulcus (area AEV). In auditory cortex, of the four tonotopically-organized regions, labeling was identified in the supragranular layers of the posterior auditory field (PAF). Little or no labeling was evident in the primary auditory cortex (AI), the anterior auditory field (AAF), or the ventral posterior auditory field (VPAF). Furthermore, little or no labeling was identified in the remaining nine generally-recognized regions of auditory cortex. Therefore, while no projections originating in AI could be found to terminate in primary visual cortex, projections were identified from non-primary PAF. Interestingly, PAF has been recently identified to play a significant role in the spatial localization of a sound source. Therefore, we propose that the PAF to primary visual cortex audio-visual pathway may serve to enhance or inhibit accurate spatial localization functions in primary visual cortex.
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