Modular organization of intrinsic connections associated with spectral tuning in cat auditory cortex

Many response properties in primary auditory cortex (Al) are segregated spatially and organized topographically as those in primary visual cortex. Intensive study has not revealed an intrinsic, anatomical organizing principle related to an Al functional topography, We used retrograde anatomic tracing and topographic physiologic mapping of acoustic response properties to reveal long-range (greater than or equal to1.5 mm) convergent intrinsic horizontal connections between Al subregions with similar bandwidth and characteristic frequency selectivity. This suggests a modular organization for processing spectral bandwidth in Al.