Activity patterns of cochlear ganglion neurones in the starling

Abstract

Summary. 1. Spontaneous activity and responses to simple tonal stimuli were studied in cochlear ganglion neurones of the starling.2. Both regular and irregular spontaneous activity were recorded (Figs. I to 5). Non-auditory cells have their origin in the macula lagenae. Mean spontaneous rate for auditory cells (all irregularly spiking) was 45 spikes s-1.3. In half the units having characteristic frequencies (CFs) <1.5 kHz, time-interval histograms (TIHs) of spontaneous activity showed regularly-spaced peaks or 'preferred' intervals. The spacing of the peak intervals was, on average, 15% greater than the CF-period interval of the respective units (Fig. 11).4. In TIH of lower-frequency cells without preferred intervals, the modal interval was also on average about 15% longer than the CF-period interval (Fig. 11). Apparently, the resting oscillation frequency of these cells lies below their CF.5. Tuning curves (TCs) of neurones to short tone bursts show no systematic asymmetry as in mammals. Below CF 1 kHz, the low-frequency flanks of the TCs are, on average, steeper than the high-frequency flanks. Above CF 1 kHz, the reverse is true (Fig. 15).6. The cochlear ganglion and nerve are tonotopically organized. Low-frequency fibres arise apically in the papilla basilaris and are found near non-auditory (lagenar) fibres (Figs. 2 and 19).7. Discharge rates to short tones were monotonically related to sound presure level (Fig. 20). Saturation rates often exceeded 300 spikes s-1.8. 'On-off' responses and primary suppression of spontaneous activity were observed (Figs. 22 and 23).Abbreviations." CF characteristic frequency; TC tuning curve; TIH time interval histogram 9. A direct comparison of spontaneous activity and tuning-curve symmetry (Fig. 15b) revealed that, apart from quantative differences, fundamental qualitative differences exist between starling and guinea-pig primary afferents.

Temporal modulation transfer functions in the European starling (Sturnus vulgaris): II. Responses of auditory-nerve fibres

“…Complete tuning and TMTF data for both gated and continuous stimuli were determined in 21 cells. The distribution of thresholds, Qm dB values, slopes of the tuning curve flanks and the spontaneous discharge rates of the fibres in this study resembled those of previous descriptions of starling auditory-nerve fibre characteristics (Manley et al, 1985;Klump and Gleich, 1991;Gleich, 1994). Similar to the results of these previous studies we found a spread of thresholds between 4 and 80dB SPL.…”

Temporal modulation transfer functions in the European starling (Sturnus vulgaris): II. Responses of auditory-nerve fibres

“…Complete tuning and TMTF data for both gated and continuous stimuli were determined in 21 cells. The distribution of thresholds, Qm dB values, slopes of the tuning curve flanks and the spontaneous discharge rates of the fibres in this study resembled those of previous descriptions of starling auditory-nerve fibre characteristics (Manley et al, 1985;Klump and Gleich, 1991;Gleich, 1994). Similar to the results of these previous studies we found a spread of thresholds between 4 and 80dB SPL.…”

Neural correlates of behavioral amplitude modulation sensitivity in the budgerigar midbrain

“…1B), whereas mean Q 10 (CF divided by 10 dB bandwidth) increased from 2.0 at CF of 1 kHz to 3.5 at CF of 4 kHz. These values are similar to Q 10 values reported over the same range of CFs in the auditory periphery of the starling (Manley et al 1985) and both the periphery and IC of cats (Miller et al 1997;Ramachandran et al 1999). Excitatory rate responses were frequently observed at sound levels as low as 15 dB SPL (the lowest stimulus level tested), particularly at recording sites with CFs from 1.5 to 3.5 kHz.…”

Midbrain-Level Neural Correlates of Behavioral Tone-in-Noise Detection: Dependence on Energy and Envelope Cues

“…L. Fan, KS Henry, and LH Carney (unpublished observations) used the same 0.33 octave noise bandwidth used in budgerigars but did not consider off-CF responses. In general, the existence of broadly similar TIN responses between birds and mammals agrees with previous studies highlighting conserved auditory neural-processing mechanisms between these groups, from auditory-nerve fibers to the level of cortical microcircuits (Sachs et al, 1974;Manley et al, 1985;Salvi et al, 1992;Woolley and Portfors, 2013;Calabrese and Woolley, 2015).…”

Temporal modulation transfer functions in the European starling (Sturnus vulgaris): II. Responses of auditory-nerve fibres

“…Complete tuning and TMTF data for both gated and continuous stimuli were determined in 21 cells. The distribution of thresholds, Qm dB values, slopes of the tuning curve flanks and the spontaneous discharge rates of the fibres in this study resembled those of previous descriptions of starling auditory-nerve fibre characteristics (Manley et al, 1985;Klump and Gleich, 1991;Gleich, 1994). Similar to the results of these previous studies we found a spread of thresholds between 4 and 80dB SPL.…”

Neural correlates of behavioral amplitude modulation sensitivity in the budgerigar midbrain

“…1B), whereas mean Q 10 (CF divided by 10 dB bandwidth) increased from 2.0 at CF of 1 kHz to 3.5 at CF of 4 kHz. These values are similar to Q 10 values reported over the same range of CFs in the auditory periphery of the starling (Manley et al 1985) and both the periphery and IC of cats (Miller et al 1997;Ramachandran et al 1999). Excitatory rate responses were frequently observed at sound levels as low as 15 dB SPL (the lowest stimulus level tested), particularly at recording sites with CFs from 1.5 to 3.5 kHz.…”

Midbrain-Level Neural Correlates of Behavioral Tone-in-Noise Detection: Dependence on Energy and Envelope Cues

“…L. Fan, KS Henry, and LH Carney (unpublished observations) used the same 0.33 octave noise bandwidth used in budgerigars but did not consider off-CF responses. In general, the existence of broadly similar TIN responses between birds and mammals agrees with previous studies highlighting conserved auditory neural-processing mechanisms between these groups, from auditory-nerve fibers to the level of cortical microcircuits (Sachs et al, 1974;Manley et al, 1985;Salvi et al, 1992;Woolley and Portfors, 2013;Calabrese and Woolley, 2015).…”

Temporal modulation transfer functions in the European starling (Sturnus vulgaris): II. Responses of auditory-nerve fibres

“…Complete tuning and TMTF data for both gated and continuous stimuli were determined in 21 cells. The distribution of thresholds, Qm dB values, slopes of the tuning curve flanks and the spontaneous discharge rates of the fibres in this study resembled those of previous descriptions of starling auditory-nerve fibre characteristics (Manley et al, 1985;Klump and Gleich, 1991;Gleich, 1994). Similar to the results of these previous studies we found a spread of thresholds between 4 and 80dB SPL.…”

Neural correlates of behavioral amplitude modulation sensitivity in the budgerigar midbrain

“…1B), whereas mean Q 10 (CF divided by 10 dB bandwidth) increased from 2.0 at CF of 1 kHz to 3.5 at CF of 4 kHz. These values are similar to Q 10 values reported over the same range of CFs in the auditory periphery of the starling (Manley et al 1985) and both the periphery and IC of cats (Miller et al 1997;Ramachandran et al 1999). Excitatory rate responses were frequently observed at sound levels as low as 15 dB SPL (the lowest stimulus level tested), particularly at recording sites with CFs from 1.5 to 3.5 kHz.…”

Midbrain-Level Neural Correlates of Behavioral Tone-in-Noise Detection: Dependence on Energy and Envelope Cues

“…L. Fan, KS Henry, and LH Carney (unpublished observations) used the same 0.33 octave noise bandwidth used in budgerigars but did not consider off-CF responses. In general, the existence of broadly similar TIN responses between birds and mammals agrees with previous studies highlighting conserved auditory neural-processing mechanisms between these groups, from auditory-nerve fibers to the level of cortical microcircuits (Sachs et al, 1974;Manley et al, 1985;Salvi et al, 1992;Woolley and Portfors, 2013;Calabrese and Woolley, 2015).…”