Publications

The auditory system has the most extensive subcortical component of all sensory systems. Starting from the cochlear nucleus, multiple information streams can be identified by their anatomical sources and targets, by the cellular morphology of the participating neurons, and by their physiological properties (Smith and Spirou 2002). Some of this extensive subcortical processing can be attributed to specific processing requirements of the auditory system, such as the computations of binaural disparities in the superior olive. However, compared with the visual system, the shortest path from the sensory receptors (hair cells) to the cortex has one additional synapse, and most of the parallel pathways starting at the cochlear nucleus are even longer. Furthermore, even in the cochlear nucleus there are neurons with highly complex response properties (Nelken and Young 1994; Spirou and Young 1991). In consequence, any response property described in the auditory cortex could be generated subcortically. Very few studies have compared responses to complex sounds in auditory cortex and in subcortical stations (Ehret and Merzenich 1988; Ehret and Schreiner 1997; Fitzpatrick, Kuwada, Kim, Parham, and Batra 1999; Miller, Escabi, Read, and Schreiner 2002; Ulanovsky, Las, and Nelken 2003). The purpose of the study presented here was to identify a set of interesting cortical response properties, and study their development along the ascending auditory system. Three stations were chosen: the inferior colliculus (IC), since all lower processing streams converge there; the medial geniculate body (MGB), which is the main thalamic auditory station; and primary auditory cortex (A1). All the results described here were collected in gas-anesthetized cats. Detailed description of the methods is found in Bar-Yosef, Rotman, and Nelken (2002).