Biomedical subjects

I M Winter

Publications and source records attributed to I M Winter.

21 records · Page 2Linked to original sources

PubMed1988

Cochlear nucleus inputs to olivocochlear neurones revealed by combined anterograde and retrograde labelling in the guinea pig.

Injections of the fluorescent tracer, Fast blue (FB), into cochlear nucleus complex in guinea pig produced strong anterograde labelling of ascending projections from this nucleus. When combined with retrograde labelling of olivocochlear efferent neurones by intracochlear injection of a second fluorescent tracer, Diamidino yellow (DY), the synaptic terminals formed on these cells by projections from the cochlear nucleus could be identified. The results provide direct support for the notion that many of the ipsilateral-monaural cochlear efferents identified in physiological studies correspond to the olivocochlear neurones located in brainstem nuclei contralateral to their target cochlea.

Amidines↗

PubMed1986

The representation of steady-state vowel sounds in the temporal discharge patterns of the guinea pig cochlear nerve and primarylike cochlear nucleus neurons.

We have recorded the responses of fibers in the cochlear nerve and cells in the cochlear nucleus of the anesthetized guinea pig to synthetic vowels [i], [a], and [u] at 60 and 80 dB SPL. Histograms synchronized to the pitch period of the vowel were constructed, and locking of the discharge to individual harmonics was estimated from these by Fourier transformation. In cochlear nerve fibers from the guinea pig, the responses were similar in all respects to those previously described for the cat. In particular, the average-localized-synchronized-rate functions (ALSR), computed from pooled data, had well-defined peaks corresponding to the formant frequencies of the three vowels at both sound levels. Analysis of the components dominating the discharge could also be used to determine the voice pitch and the frequency of the first formants. We have computed similar population measures over a sample of primarylike cochlear nucleus neurons. In these primarylike cochlear nucleus cell responses, the locking to the higher-frequency formants of the vowels is weaker than in the nerve. This results in a severe degradation of the peaks in the ALSR function at the second and third formant frequencies at least for [i] and [u]. This result is somewhat surprising in light of the reports that primarylike cochlear nucleus cells phaselock, as well as do cochlear nerve fibers.

Animals↗

PubMedDate not supplied

The temporal window of two-tone facilitation in onset units of the ventral cochlear nucleus.

Effects of a tone, not at the best frequency (BF), on the responses of onset units to BF tones were recorded in the ventral cochlear nucleus of the guinea pig. The off-BF tone was at a fixed non-excitatory sound level. When the two tones were gated simultaneously, a marked threshold facilitation was observed; however, no facilitation was observed if the off-BF tone burst was delayed by 5-10 ms. Facilitation in some units declined and was either absent or only just detectable, when the start of the off-BF tone preceded that of the BF by more than 10 ms. However, the responses of the majority of onset units were facilitated when the off-BF tone preceded the BF tone by as much as 20 ms. Similar results were obtained when the roles of the BF and off-BF tones were reversed. These data suggest that depolarization due to BF inputs is of shorter duration than that due to off-BF inputs.

Animals↗