Although the location of a sound source is almost certainly represented by the activity of cells in the auditory cortex, the exact nature of this representation is far from clear. Early expectations were for a systematic distribution of spatially tuned cells across the cortical surface which, as a population, would produce a coherent map of auditory space. In contrast, studies have consistently demonstrated that the spatial tuning of cortical cells is quite broad, with receptive fields often encompassing a hemifield or more of space, and have failed to identify a cortical map of auditory space. This has lead to the alternative suggestion that cortical neurons represent space 'panoramically' with the activity of individual cells providing information about much of auditory space. One limitation of most of these studies, however, is that they have been conducted in anesthetized animals. If their ultimate goal is to demonstrate how auditory space is represented in the cortex of normal animals, including humans, it follows that the use of global anesthesia should be avoided whenever possible. Presently, cats will be trained to perform a number of behavioral tasks including sound localization while neural activity is recorded from the auditory cortex. In addition to allowing for the comparison of spatial coding in awake and anesthetized animals (Specific Aim 1), the proposed studies will also address the possible task dependence of cortical responses (Specific Aim 2). Studies like these will contribute greatly to our understanding of the role of the cortex in sound localization and to the relationship between brain and behavior.
| Harrington, Ian A; Stecker, G Christopher; Macpherson, Ewan A et al. (2008) Spatial sensitivity of neurons in the anterior, posterior, and primary fields of cat auditory cortex. Hear Res 240:22-41 |
| Stecker, G Christopher; Harrington, Ian A; Middlebrooks, John C (2005) Location coding by opponent neural populations in the auditory cortex. PLoS Biol 3:e78 |
| Stecker, G Christopher; Harrington, Ian A; Macpherson, Ewan A et al. (2005) Spatial sensitivity in the dorsal zone (area DZ) of cat auditory cortex. J Neurophysiol 94:1267-80 |
