Graeme Clark Collection

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Author: Burkitt, Anthony × Start date: 1994 × Subject: cochlear nucleus ×

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    Ventral cochlear nucleus coding of voice onset time in naturally spoken syllables
    Clarey, Janine C. ; Paolini, Antonio, G. ; Grayden, David B. ; Burkitt, Anthony, N. ; Clark, Graeme M. ( 2004)
    Unavailable due to copyright.
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    Temporal processing from the auditory nerve to the medial nucleus of the trapezoid body in the rat
    Paolini, AG ; FitzGerald, JV ; Burkitt, AN ; Clark, GM (ELSEVIER SCIENCE BV, 2001-09)
    This investigation examines temporal processing through successive sites in the rat auditory pathway: auditory nerve (AN), anteroventral cochlear nucleus (AVCN) and the medial nucleus of the trapezoid body (MNTB). The degree of phase-locking, measured as vector strength, varied with intensity relative to the cell's threshold, and saturated at a value that depended upon stimulus frequency. A typical pattern showed decline in the saturated vector strength from approximately 0.8 at 400 Hz to about 0.3 at 2000 Hz, with similar profiles in units with a range of characteristic frequencies (480-32,000 Hz). A new expression for temporal dispersion indicates that this variation corresponds to a limiting degree of temporal imprecision, which is relatively consistent between different cells. From AN to AVCN, an increase in vector strength was seen for frequencies below 1000 Hz. At higher frequencies, a decrease in vector strength was observed. From AVCN to MNTB a tendency for temporal coding to be improved below 800 Hz and degraded further above 1500 Hz was seen. This change in temporal processing ability could be attributed to units classified as primary-like with notch (PL(N)). PL(N) MNTB units showed a similar vector strength distribution to PL(N) AVCN units. Our results suggest that AVCN PL(N) units, representing globular bushy cells, are specialised for enhancing the temporal code at low frequencies and relaying this information to principal cells of the MNTB.
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    Intracellular responses of the rat cochlear nucleus to sound and its role in temporal coding
    Paolini, Antonio G. ; Clark, Graeme M. ; Burkitt, Anthony N. ( 1997)
    The anteroventral cochlear nucleus (AVCN), the first centre of the central auditory pathway, contains globular bushy cells, which are unique in their ability to produce fast excitatory post-synaptic potentials (EPSPs). Using in vivo intracellular recordings in the rat AVCN we examined these fast EPSPs in relation to temporal coding. At frequencies up to 2.5 kHz, EPSPs were evoked on successive sine waves of the stimulus with EPSP summation limited. This one-to-one relationship between the EPSPs and the sound wave period was present at higher frequencies and over a greater intensity range than for action potentials. These results suggest that temporal coding is possible in globular bushy neurones by their ability to extract temporal information through fast processing of convergent presynaptic input.