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

Many response properties in primary auditory cortex (Al) are segregated spa tially and organized topographically as those in primary visual cortex. Int ensive study has not revealed an intrinsic, anatomical organizing principle related to an Al functional topography, We used retrograde anatomic tracin g and topographic physiologic mapping of acoustic response properties to re veal long-range (greater than or equal to1.5 mm) convergent intrinsic horiz ontal connections between Al subregions with similar bandwidth and characte ristic frequency selectivity. This suggests a modular organization for proc essing spectral bandwidth in Al.