A combined electrophysiological and [14C] 2-deoxyglucose study of the frequency organization of the inferior colliculus of the cat.

Single units were recorded in the inferior colliculus of 3 young cats. A tonotopic sequence of characteristic frequencies (CF) was obtained in response to contralateral stimulation. In each cat Pontamine sky blue was deposited from the recording pipette at the site of a unit with a particular CF. [14C] 2-Deoxyglucose was then injected into the cats, each of whom was presented with tone bursts at a frequency identical with the CF recorded at this site. Selective labelling was found in the contralateral inferior colliculus of each cat and the position of the band of marking coincided with the recording position of the chosen unit. These data demonstrated for the first time that cells in the region of [14C] 2-deoxyglucose marking have the differential physiological properties capable of producing the selective functional labelling. The bands of selective labelling found in response to different frequencies are produced by cells tuned to the particular stimulating frequency.