Apparatus and method for optical- or optical-and-electrical stimulation of midbrain and/or brainstem tissue (e.g., auditory nerve pathways). Peripheral neural stimulation using infrared lasers has been demonstrated in several systems； however, optical stimulation of the central nervous system (CNS) has not been previously described. In some embodiments of the present invention, radiant energy exposure of the cochlear nucleus using a mid-wavelength infrared laser generates optically-evoked auditory brainstem responses (oABRs). In an experiment, the cochlear nuclei of adult male Sprague-Dawley rats were exposed using a suboccipital craniotomy approach. In one embodiment, different regions of left cochlear nucleus were acutely stimulated with a 200- or 400-micron-diameter optical fiber placed on the surface of the brainstem, using 50- to 750-microsecond pulses of 1849-nm to 1865-nm-wavelength radiation at a rate of 10 to 40 Hz and power levels ranging from 10% to 80% of 5 watts. oABRs were recorded during the period of optical stimulation.
