Middle latency responses to acoustical and electrical stimulation of the cochlea in cats

• Published in: Hearing research Vol. 92; no. 1; pp. 63 - 77
• Main Authors: Popelář, Jiří, Hartmann, Rainer, Syka, Josef, Klinke, Rainer
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.1995; Elsevier
• Subjects: Acoustic Stimulation; Acoustical stimulation; Analysis of Variance; Animals; Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - toxicity; Auditory Cortex - physiology; Auditory Threshold - physiology; Biological and medical sciences; Cat; Cats; Cochlea - physiology; Cochlear Implants; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Electric Stimulation; Electrical stimulation; Evoked Potentials, Auditory, Brain Stem - physiology; Fundamental and applied biological sciences. Psychology; Hair Cells, Auditory - cytology; Hair Cells, Auditory - drug effects; Hair Cells, Auditory - pathology; Kanamycin - administration & dosage; Kanamycin - toxicity; Microelectrodes; Middle latency response; Neomycin - administration & dosage; Neomycin - toxicity; Vertebrates: nervous system and sense organs; Vestibulocochlear Nerve - physiology; Middle latency response; Electrical stimulation; Cat; Acoustical stimulation; Fissipedia; Carnivora; Vertebrata; Mammalia; Acoustic stimulus; Auditory evoked potential; Electrical stimulus; Electrophysiology; Cochlea; Inner ear; Organ of hearing
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(95)00199-9

The middle latency responses (MLR) to acoustical stimulation (A-MLR) as well as to electrical stimulation (E-MLR) of the inner ear were recorded in pentobarbital-anaesthetised cats. Monopolar and bipolar MLR recordings were performed with electrodes located at different places on the primary auditory cortex (AI). The cochlea was electrically stimulated (ES) through a single round-window electrode or through a multichannel intracochlear implant. The slope of amplitude-intensity functions of the A-MLR was steeper when the stimulus frequency of the acoustical stimuli corresponded to the tonotopical recording place on the auditory cortex. Other response properties (waveshape, thresholds and latencies) were related to the recording site and stimulus frequency in only two-thirds of animals. Parameters of E-MLRs evoked by high-frequency (> 4 kHz) and low-intensity ES in hearing cats, which produced an electrophonic effect, were similar to parameters of acoustically evoked MLRs. In deafened cats, the properties of responses to extracochlear ES were different from those recorded to acoustical stimulation and they were almost uniform in all cortical places. Variations in thresholds, in latencies and in the slope of the amplitude-intensity functions of the E-MLRs recorded in individual tonotopical cortical places were observed when the auditory nerve was stimulated with different configurations of electrodes through a multichannel intracochlear implant.