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Workshop on the Auditory Basis of Speech PerceptionKeele University, UK |
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Workshop on the Auditory Basis of Speech PerceptionKeele University, UK |
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The hair cells of the organ of Corti transduce vibrations within the cochlea into neural signals which are transmitted by the afferent fibres of the cochlear nerve to the auditory brainstem. Here the fibres bifurcate, projecting to the dorsal and ventral nuclei of the cochlear nuclear complex, a divergence continued in the two main routes taken by the ascending pathways to the midbrain. One runs from the ventral cochlear nucleus to the superior olivary complex and thence to the inferior colliculus whilst the other runs from the dorsal cochlear nucleus direct to the inferior colliculus. Fibres running from the brainstem to the inferior colliculus form a tract, the lateral lemniscus, and may make contact with one of the nuclei within it. The ascending auditory pathway continues via the medial geniculate bodies in the thalamus to the auditory areas in the temporal lobe of the cortex, preserving cochleotopicity within the central auditory regions at all levels. The presence of commissural and decussating connections from the brainstem onwards provides the anatomical substrate for the analysis of binaural information whilst both the descending system which parallels the ascending system throughout, and the intrinsic circuitry at each level, provide the basis for feature extraction from the neural output of the cochlea.
Bibliographic reference. Hackney, Carole M. (1996): "From cochlea to cortex: a simple anatomical description", In ABSP-1996, 9-16.