Stimulation of the cochlear nucleus (CN) has been used on a limited basis f
or rehabilitation of a select group of patients with bilateral acoustic neu
romas, These patients were implanted with an electrode placed on the surfac
e of the CN after resection of their tumors. Animal studies have demonstrat
ed greater efficiency of a penetrating CN electrode in activating the centr
al auditory system than a surface electrode. The objective of this work was
to study the electrically evoked middle latency response generated by stim
ulation through a penetrating multichannel CN electrode in an animal model.
Six pigmented guinea pigs underwent implantation with a penetrating multic
hannel CN electrode. Threshold, latency, and input-output functions of elec
trically evoked middle latency responses with different stimulation pads we
re studied. There were systematic differences in the latency and amplitude
of the input-output functions depending on the site of stimulation within t
he CN. The results support the hypothesis that discrete activation of neuro
nal subpopulations within the CN is possible with a penetrating multichanne
l microelectrode.