Organization of auditory cortex in the albino rat: sound frequency

Abstract

1. Responses of neurons in the auditory cortex of the albino rat were examined using microelectrode mapping techniques. Characteristic frequencies were determined for numerous electrode penetrations across the cortical surface in individual animals. A primary auditory area was identified in the posterolateral neocortex that was characterized by short latency responses to tone bursts and tonotopic organization with high frequencies represented rostrally and low frequencies, caudally. Within this area cells with similar characteristic frequencies were aligned in a dorsoventral orientation to form isofrequency contours. 2. Tuning curves obtained from primary auditory cortex were characteristically "V" shaped with Q10's ranging from 0.97 to 28.4. Maximum Q10 values increased monotonically with characteristic frequency (CF). The lowest thresholds at CF closely approximated the behavioral audiogram for the albino rat. Many neurons, however, had CF thresholds well above the behavioral limit. 3. Areas were found dorsal and ventral to the primary auditory cortex in which CF's were clearly discontinuous with the neighboring isofrequency contours. These data suggest the presence of other auditory fields, the detailed characteristics of which have yet to be examined.

Involvement of auditory cortical and hippocampal neurons in auditory working memory and reference memory in the rat

“…Concerning the AC, the distribution of units with sensory correlates was not related to the functional anatomy or known subdivisions in AC (e.g., Sally and Kelly, 1988). Figure 6 shows the proportions of the units with sensory correlates in each of the four regions.…”

“…The distribution of locations of the units with sensory correlates in the AC was not related to the known functional anatomy of AC (e.g., Sally and Kelly, 1988). This suggests that intrinsic properties of AC neurons shown in the strictly controlled anesthetized rat, narrowly tuned to frequencies of tones and more largely responsive to higher tones (1 O-40 kHz) (Sally and Kelly, 1988), did not affect the sensory correlates of the AC units during freely moving performance of the tasks in this study.…”

Learning strategy determines auditory cortical plasticity

“…Primary auditory cortex (A1) was characterized as the cortical area within a general progression from low to high CFs along the posterior to anterior axis (i.e., tonotopic gradient). Anterior sites that constituted a reversal in the CF progression were considered to be a part of the anterior auditory field (AAF) and were excluded from A1 analysis (Rutkowski, Miasnikov, & Weinberger, 2003;Sally & Kelly, 1988). The remaining borders of A1 were outlined by sites that were more responsive to noise (lower threshold) than to tones which were considered to be outside A1.…”

Representation of Sounds in Auditory Cortex of Awake Rats (Dissertation)

“…Rats are another well-established established group of experimental animals in auditory research (Doron et al, 2002;Kelly and Sally, 1988;Sally and Kelly, 1988), used successfully in both anesthetized (DeWeese et al, 2003;DeWeese and Zador, 2006;Kilgard and Merzenich, 1998a,b;Zador, 2003, 2005, and many others) and awake experiments (Gaese and Ostwald, 2003; and others).…”