Maps versus clusters: different representations of auditory space in the midbrain and forebrain

The auditory system determines the location of stimuli based on the evaluat ion of specific cues, The analysis begins in the tonotopic pathway, where t hese cues are processed in parallel, frequency-specific channels. This freq uency-specific information is processed further in the midbrain and in the forebrain by specialized, space-processing pathways that integrate informat ion across frequency channels, creating high-order neurons tuned to specifi c locations in space. Remarkably, the results of this integrative step are represent-ed very differently in the midbrain and forebrain: in the midbrai n, space is represented in maps, whereas, in the forebrain, space is repres ented in clusters of similarly tuned neurons. We propose that these differe nt representations reflect the different roles that these two brain areas h ave in guiding behavior.