The representation of auditory space in the mammalian superior colliculus

Abstract

The superior colliculus (SC) is involved in orienting responses to sensory stimuli¹ and contains detailed sensory and motor maps^1–3. The visual and somatosensory maps have been well documented^4–15 and are topographic representations of the primary receptor surfaces. However, the formation of an ordered map of auditory space is rather more problematic as it requires either reorganization of monaural information or combination of information from both ears^16,17. Nevertheless, such an ordered map has been demonstrated in the midbrain of the barn owl¹⁸ and there have been indications that a similar map occurs in mammals^{7–9,12,13,19–21}, although a recent study suggests that this is not the case in the cat²². Here we report briefly the results of our study, showing that auditory space is precisely represented in the deep layers of the guinea pig SC. This map of auditory space resembles the visual map in that cells responding to sounds in the anterior contralateral field are located rostrally, while those responding to sounds in the posterior contralateral field are located in caudal SC.