Basilar membrane mechanics in the hook region of cat and guinea-pig cochleae: Sharp tuning and nonlinearity in the absence of baseline position shifts

Cooper, Nigel P.; Rhode, William S.

doi:10.1016/0378-5955(92)90083-y

Cited by 170 publications

(142 citation statements)

References 44 publications

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“…These findings improve on previous recordings, which were made under relatively poor physiological conditions (e.g. Cooper & Rhode, 1992), and bring the data from the hook region BM into closer agreement with those observed in other regions of the cochlea and/or in other species (e.g. Nuttall et al 1996;Ruggero et al 1997).…”

Section: Department Of Physiology University Of Bristol Bristol Bs81tdsupporting

confidence: 89%

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Cellular Neurophysiology

1998

The Journal of Physiology

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Section: Department Of Physiology University Of Bristol Bristol Bs81tdsupporting

confidence: 89%

“…; each millilitre of Hypnorm contains 10 mg fluanisone and 0'315 mg fentanyl citrate), and were overdosed with pentobarbitone on completion of the in vivo measurements. Other experimental details were similar to those described by Cooper & Rhode (1992).…”

Section: Department Of Physiology University Of Bristol Bristol Bs81tdmentioning

confidence: 96%

Cellular Neurophysiology

1998

The Journal of Physiology

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“…Post-mortem phase changes for responses to 10-kHz (CF) and 9-kHz tones were similar but somewhat smaller in another, less-sensitive, cochlea (L33; see Ruggero et al, 1992a andRuggero, 1994). Cooper and Rhode (1992) have described an artifact that must be taken into account in interpreting basilar-membrane recordings obtained using laser velocimetry. These authors noted that a laser velocimeter cannot distinguish Doppler shifts caused by motion of the laser-beam target (the beads on the basilar membrane) from frequency shifts caused by changes of the path length of the laser beam due to alterations in the depth of the fluid in scala tympani.…”

Section: F Variation Of Response Phases As a Function Of Stimulus Frmentioning

confidence: 99%

“…Rhode showed that, in relatively healthy cochleae, basilar-membrane responses to characteristicfrequency (CF) tones grow at compressive rates (less than 1 dB/dB) at moderate-to-intense stimulus levels. This discovery met with much initial skepticism, but the central findings have been subsequently replicated and refined in several laboratories (Sellick et al, 1982;Robles et al, 1986;Cooper and Rhode, 1992;Nuttall and Dolan, 1993;Murugasu and Russell, 1995). Nevertheless, there are many aspects of basilar-membrane responses to tones which, although already addressed by previous studies, could be usefully documented with greater quantitative detail in healthy cochleae.…”

Section: Introductionmentioning

confidence: 99%

Basilar-membrane responses to tones at the base of the chinchilla cochlea

Ruggero

Rich

Recio

et al. 1997

The Journal of the Acoustical Society of America

665

527

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Basilar-membrane responses to single tones were measured, using laser velocimetry, at a site of the chinchilla cochlea located 3.5 mm from its basal end. Responses to low-level (<10-20 dB SPL) characteristic-frequency (CF) tones (9-10 kHz) grow linearly with stimulus intensity and exhibit gains of 66-76 dB relative to stapes motion. At higher levels, CF responses grow monotonically at compressive rates, with input-output slopes as low as 0.2 dB/dB in the intensity range 40-80 dB. Compressive growth, which is significantly correlated with response sensitivity, is evident even at stimulus levels higher than 100 dB. Responses become rapidly linear as stimulus frequency departs from CF. As a result, at stimulus levels >80 dB the largest responses are elicited by tones with frequency about 0.4-0.5 octave below CF. For stimulus frequencies well above CF, responses stop decreasing with increasing frequency: A plateau is reached. The compressive growth of responses to tones with frequency near CF is accompanied by intensity-dependent phase shifts. Death abolishes all nonlinearities, reduces sensitivity at CF by as much as 60-81 dB, and causes a relative phase lead at CF.

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“…This explanation would not apply to barn owls, because the tuning curves of barn owls' primary auditory neurons do not expand asymmetrically (C. Köppl, personal communication). At any rate, this type of phase shift in the auditory nerve and higher-order neurons is likely to originate in the inner ear, because phase shifts of similar nature occur in inner hair cell potentials and basilar membrane mechanics (Rhode and Robles, 1974;Sellick et al, 1982;Dallos, 1986;Cooper and Rhode, 1992;Rhode and Cooper;.…”

Section: Effects Of Iid On the Mean Interaural Phasementioning

confidence: 99%

Effects of Interaural Intensity Difference on the Processing of Interaural Time Difference in the Owl’s Nucleus Laminaris

1997

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Interaural time and intensity differences (ITD and IID) are processed independently in the owl's auditory system. This paper examines whether this independence is established in nucleus laminaris (NL), the first site of ITD processing. A plot of discharge rate against time difference (ITD curve) is sinusoidal in NL. The ITDs that produce the peaks are called the most favorable ITDs, and those that produce the troughs are called the least favorable ITDs. IID had little effect on the discharge rates of laminaris neurons for the most and least favorable ITDs. The degree of peak-trough modulation changed slightly with variation in IID. In contrast, IID in tonal stimuli affected the temporal aspect of ITD curves depending on the difference between the stimulus frequency and the neuron's best frequency (BF). For frequencies below BF, IID caused large and systematic shifts in ITD toward the ear in which the sound was louder, whereas for frequencies above BF, IID caused small shifts in ITD toward the opposite ear. IID had little effect on ITD curves taken with BF or broadband noise. These results can be largely accounted for by the effects of frequency and intensity on the timing of impulses at the level of the cochlear nuclei. Thus, the processing of ITD by NL neurons is independent of IID for behaviorally relevant stimuli, because the timing of impulses is insensitive to sound level when the signal is broadband. Key words: owl; sound localization; nucleus laminaris; interaural time difference; interaural intensity difference; parallel pathwaysParallel processing of information is an important operation in many sensory systems (see, for example, owl's auditory system: Takahashi et al., 1984; monkey visual system: Maunsell et al., 1990;Merigan and Maunsell, 1993; fish electrosensory system: Heiligenberg, 1991). The barn owl's auditory brainstem offers a relatively simple system in which to analyze the relationship between parallel pathways. The owl uses interaural time and intensity differences (ITD and IID) for sound localization (Moiseff, 1989b). The independence of these cues is important for the species, because they code for different spatial coordinate axes, ITD mainly for azimuth and IID mainly for elevation. ITD and IID are processed in separate parallel pathways that start at the level of the cochlear nucleus. The avian auditory system has two anatomically and physiologically distinct cochlear nuclei, nucleus magnocellularis (NM) and nucleus angularis (NA). NM neurons lack dendrites and contain end bulbs of Held, whereas NA neurons have dendrites and bouton-type synapses (Parks, 1981;Jhaveri and Morest, 1982;Takahashi and Konishi, 1988a;Carr and Boudreau, 1993). NM neurons show phase locking, whereas NA neurons do not except for very low frequencies (Sachs and Sinnott, 1978;Sullivan and Konishi, 1984a;Konishi et al., 1985;Warchol and Dallos, 1990). The time-and intensity-processing pathways converge in the inferior colliculus, where neurons selective for combinations of ITD and IID are found. Partial inactivat...

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Basilar membrane mechanics in the hook region of cat and guinea-pig cochleae: Sharp tuning and nonlinearity in the absence of baseline position shifts

Cited by 170 publications

References 44 publications

Cellular Neurophysiology

Cellular Neurophysiology

Basilar-membrane responses to tones at the base of the chinchilla cochlea

Effects of Interaural Intensity Difference on the Processing of Interaural Time Difference in the Owl’s Nucleus Laminaris

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