The auditory cortex of the house mouse: left-right differences, tonotopic organization and quantitative analysis of frequency representation.

Multi-unit electrophysiological mapping was used to establish the area of the left- and right-hemisphere auditory cortex (AC) of the mouse and to characterize various fields within the AC. The AC of the left hemisphere covered a significantly larger (factor of 1.30) area compared to that of the right side.

Thresholds of intracranially recorded auditory field potentials in the pigeon compared with compound action potential thresholds.

The compound action potential (CAP) thresholds provide a reliable indicator for cochlear functional integrity during experimentation in birds as well as in mammals. However, if experimental manipulations are necessary in the middle ear/inner ear spaces, the round window electrodes are often inconvenient. In search for an alternative for CAP recordings, intracranial recordings of acoustically evoked field potentials from the nucleus angularis/magnocellularis were made in pigeons using stereotactically placed electrodes.

Temperature-dependence of auditory nerve response properties in the frog.

Response properties of the auditory nerve fibers of the Pacific treefrog, Hyla regilla, were shown to be comparable to other Hylids at a standard temperature of 20 degrees C. This species from a rather variable thermal habitat was compared to the neotropical aboreal species, Eleutherodactylus coqui, in a study of auditory responses under conditions of changing temperatures. We found that as temperature increased: the center frequencies (CFs) of tuning curves remained constant for neurons from the basilar papilla but shifted to higher frequencies for neurons from the amphibian papilla (the amount of frequency shift decreased as CF increased); tone response thresholds decreased; phase-locking became stronger; the phase of the preferred response showed a lag in neurons with CFs below 500 Hz, a lead for CFs above 600 Hz, and almost no changes for CFs between 500 and 600 Hz; the variance of the click response and the average latency of the first spike in the response decreased.

Tone-threshold mapping in the inferior colliculus of the house mouse.

The distribution of lowest tone-response thresholds was examined within 3 different isofrequency planes (10, 20 and 30 kHz) of the inferior colliculus (IC) of the house mouse. Lowest thresholds are located in, or slightly rostrolateral to the center of each isofrequency plane. Thresholds increase centrifugally, although in the rostrolateral direction the increase is less marked.

Inferior colliculus of the house mouse. I. A quantitative study of tonotopic organization, frequency representation, and tone-threshold distribution.

Electrophysiological mapping was used to study frequency representation in the inferior colliculus (IC) of the mouse. In the lateral nucleus (LN) only part of the frequency range of hearing was represented and tonotopicity was separate from that in the rest of the IC. Highest frequencies occupied the medial part (M) of the central nucleus (CN).