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We have examined the effect of restricted unilateral cochlear lesions on the orderly topographic mapping of sound frequency in the auditory cortex of adult guinea pigs. These lesions, although restricted in spatial extent, resulted in a variety of patterns of histological damage to receptor cells and nerve fibres within the cochlea. Nevertheless, all(More)
Acoustic information in auditory nerve discharges is integrated in the cochlear nuclei, and ascends through several parallel pathways to higher centers. Octopus cells of the posteroventral cochlear nucleus form a pathway known to carry information in the timing of action potentials. Octopus cells have dendrites oriented to receive converging input from many(More)
Plasticity in the adult mammalian brain can occur after damage to peripheral nerves and has also been described in the auditory system. Acoustic trauma, resulting in a loss of cochlear sensitivity, can lead to elevated levels of spontaneous activity, that is hyperactivity, in central nuclei such as the inferior colliculus. The current view is that this(More)
Hearing loss from acoustic trauma is a risk factor for tinnitus. Animal models using acoustic trauma have demonstrated hyperactivity in central auditory pathways, which has been suggested as a substrate for tinnitus. We used a guinea-pig model of unilateral acoustic trauma. Within the same animals, measurements of peripheral hearing loss, spontaneous(More)
Rate-intensity functions at characteristic frequency (CF) were recorded from single fibres in the auditory nerve of anaesthetised guinea pigs. Within the same animal, CF rate-intensity functions, although probably forming a continuum, could be conveniently divided into three groups; (1) Saturating; reach maximum discharge rate within 30 dB of threshold, (2)(More)
In a previous paper (Winter et al., 1990) we demonstrated the existence of a new type of auditory-nerve rate-intensity function, the straight type, as well as a correlation between rate-level type, threshold and spontaneous rate. In this paper we now show that the variation in rate-intensity functions has its origin in the basilar membrane nonlinearity.(More)
We have investigated the morphological relationship between auditory cortex efferents and medial olivocochlear neurones. Using combined retrograde and anterograde tracing we describe close contacts between medial olivocochlear neurones and corticofugal terminals in the ventral nucleus of the trapezoid body. The data indicate a possible direct action of the(More)
Partial hearing loss is known to cause increased spontaneous activity at several stages of the central auditory pathways, and this phenomenon has been suggested as a possible neural substrate for tinnitus, a phantom hearing sensation. One recent study in guinea pig has suggested that approximately 6 weeks after acoustic trauma, the increased spontaneous(More)
Efferent neurones within the intraganglionic spiral bundle of the guinea pig cochlea were characterized in terms of their response properties, and their pattern of termination within the receptor organ revealed by intracellular labelling with horseradish peroxidase. All neurones subsequently identified as efferent neurones had clear features of their(More)
The emergence of hyperactivity in the form of elevated spontaneous firing rates after cochlear trauma has been well documented in a number of central auditory structures, including the auditory cortex, inferior colliculus, and dorsal subdivision of the cochlear nucleus. This hyperactivity is of interest as a possible neural substrate of tinnitus. Whether(More)