Responses of Dorsal Cochlear Nucleus Neurons to Signals in the Presence of Modulated Maskers

Neuert, Veronika; Verhey, Jesko L.; Winter, Ian M.

doi:10.1523/jneurosci.0450-04.2004

Cited by 40 publications

(61 citation statements)

References 40 publications

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“…Together, we suggest that although the detection of the tone could occur in IC, or even lower (Pressnitzer et al, 2001;Neuert et al, 2004), the tone representation is more explicit in MGB and even more so in A1.…”

Section: Locking Suppression By Low-level Tonesmentioning

confidence: 75%

“…A major challenge in auditory neuroscience is to understand how the auditory system segregates low-level signals embedded in masking noise (Phillips and Cynader, 1985;Ramachandran et al, 2000;Neuert et al, 2004). Humans and animals perceive lowlevel signals embedded in slowly fluctuating noise more efficiently than similar signals embedded in unmodulated noise (Schooneveldt and Moore, 1989;Klump and Langemann, 1995;Langemann and Klump, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Representation of Tone in Fluctuating Maskers in the Ascending Auditory System

Las¹,

Stern²,

Nelken³

2005

J. Neurosci.

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Humans and animals detect low-level tones masked by slowly fluctuating noise very efficiently. A possible neuronal correlate of this phenomenon is the ability of low-level tones to suppress neuronal locking to the envelope of the fluctuating noise ("locking suppression"). Using in vivo intracellular and extracellular recordings in cats, we studied neuronal responses to combinations of fluctuating noise and tones in three successive auditory stations: inferior colliculus (IC), medial geniculate body (MGB), and primary auditory cortex (A1). We found that although the most sensitive responses in the IC were approximately isomorphic to the physical structure of the sounds, with only a small perturbation in the responses to the fluctuating noise after the addition of low-level tones, some neurons in the MGBandallA1neuronsdisplayedstrikingsuppressiveeffects.Theseneuronswerehypersensitive,showingsuppressionalreadywithtonelevels lower than the threshold of the neurons in silence. The hypersensitive locking suppression in A1 and MGB had a special timing structure, starting Ͼ75 ms after tone onset. Our findings show a qualitative change in the representation of tone in fluctuating noise along the IC-MGB-A1 axis, suggesting the gradual segregation of signal from noise and the representation of the signal as a separate perceptual object in A1.

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Section: Locking Suppression By Low-level Tonesmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Representation of Tone in Fluctuating Maskers in the Ascending Auditory System

Las¹,

Stern²,

Nelken³

2005

J. Neurosci.

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“…Medial OC neurons are known to have collaterals projecting to the CN (Winter et al, 1989;Benson and Brown, 1990;Benson and Potashner, 1990;Brown, 1993;Benson et al, 1996;Horváth et al, 2000), and we have previously shown direct excitatory effects of these collaterals on CN neurons, in particular onset chopper neurons (Mulders et al, 2002(Mulders et al, , 2003(Mulders et al, , 2007). These neurons are thought to provide wide band inhibition to other CN neurons (Verhey et al, 2003;Arnott et al, 2004;Neuert et al, 2004) and could be responsible for the modulation of spontaneous activity remaining after cochlear strychnine. Further investigations are required to determine the exact cause of the extensive effects on spontaneous rate when the peripheral effects of the OC system are blocked.…”

Section: Discussionmentioning

confidence: 99%

Efferent Pathways Modulate Hyperactivity in Inferior Colliculus

Mulders

Seluakumaran²,

Robertson³

2010

Journal of Neuroscience

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Animal models have demonstrated that mild hearing loss caused by acoustic trauma results in spontaneous hyperactivity in the central auditory pathways. This hyperactivity has been hypothesized to be involved in the generation of tinnitus, a phantom auditory sensation. We have recently shown that such hyperactivity, recorded in the inferior colliculus, is still dependent on cochlear neural output for some time after recovery (up to 6 weeks). We have now studied the capacity of an intrinsic efferent system, i.e., the olivocochlear system, to alter hyperactivity. This system is known to modulate cochlear neural output. Anesthetized guinea pigs were exposed to a loud sound and after 2 or 3 weeks of recovery, single-neuron recordings in inferior colliculus were made to confirm hyperactivity. Olivocochlear axons were electrically stimulated and effects on cochlear neural output and on highly spontaneous neurons in inferior colliculus were assessed. Olivocochlear stimulation suppressed spontaneous hyperactivity in the inferior colliculus. This result is in agreement with our earlier finding that hyperactivity can be modulated by altering cochlear neural output. Interestingly, the central suppression was generally much larger and longer lasting than reported previously for primary afferents. Blockade of the intracochlear effects of olivocochlear system activation eliminated some but not all of the effects observed on spontaneous activity, suggesting also a central component to the effects of stimulation. More research is needed to investigate whether these central effects of olivocochlear efferent stimulation are due to central intrinsic circuitry or to coactivation of central efferent collaterals to the cochlear nucleus.

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“…Rhode and Greenberg 1994;Joris et al 1994;Moller 1976) and the inferior colliculus (e.g., Nelson and Carney 2007;Krishna and Semple 2000;Langner and Schreiner 1988;Muller-Preuss et al 1994;Rees and Moller 1983). However, very few studies have directly tested the neuronal correlates of signal detection when the masker is temporally modulated (CN: Pressnitzer et al 2001;Neuert et al 2004). The studies in the cochlear nucleus found that very few neurons in the ventral CN showed neuronal correlates of enhanced thresholds such as those seen in behavior (Pressnitzer et al 2001).…”

Section: Bohlen Et Al: Detection Of Modulated Tones In Modulated Noisementioning

confidence: 99%

“…The studies in the cochlear nucleus found that very few neurons in the ventral CN showed neuronal correlates of enhanced thresholds such as those seen in behavior (Pressnitzer et al 2001). However, a majority of neurons in the dorsal CN showed such neuronal correlates (Neuert et al 2004), and these threshold enhancements were postulated to result due to wideband inhibition. However, magnitude of neuronal threshold changes in the dorsal CN could not account for behavioral threshold changes.…”

Section: Bohlen Et Al: Detection Of Modulated Tones In Modulated Noisementioning

confidence: 99%

Detection of Modulated Tones in Modulated Noise by Non-human Primates

Bohlen

Dylla

Timms

et al. 2014

JARO

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In natural environments, many sounds are amplitudemodulated. Amplitude modulation is thought to be a signal that aids auditory object formation. A previous study of the detection of signals in noise found that when tones or noise were amplitude-modulated, the noise was a less effective masker, and detection thresholds for tones in noise were lowered. These results suggest that the detection of modulated signals in modulated noise would be enhanced. This paper describes the results of experiments investigating how detection is modified when both signal and noise were amplitude-modulated. Two monkeys (Macaca mulatta) were trained to detect amplitude-modulated tones in continuous, amplitude-modulated broadband noise. When the phase difference of otherwise similarly amplitude-modulated tones and noise were varied, detection thresholds were highest when the modulations were in phase and lowest when the modulations were anti-phase. When the depth of the modulation of tones or noise was varied, detection thresholds decreased if the modulations were antiphase. When the modulations were in phase, increasing the depth of tone modulation caused an increase in tone detection thresholds, but increasing depth of noise modulations did not affect tone detection thresholds. Changing the modulation frequency of tone or noise caused changes in threshold that saturated at modulation frequencies higher than 20 Hz; thresholds decreased when the tone and noise modulations were in phase and decreased when they were anti-phase. The relationship between reaction times and tone level were not modified by manipulations to the nature of temporal variations in the signal or noise. The changes in behavioral threshold were consistent with a model where the brain subtracted noise from signal. These results suggest that the parameters of the modulation of signals and maskers heavily influence detection in very predictable ways. These results are consistent with some results in humans and avians and form the baseline for neurophysiological studies of mechanisms of detection in noise.

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Responses of Dorsal Cochlear Nucleus Neurons to Signals in the Presence of Modulated Maskers

Cited by 40 publications

References 40 publications

Representation of Tone in Fluctuating Maskers in the Ascending Auditory System

Representation of Tone in Fluctuating Maskers in the Ascending Auditory System

Efferent Pathways Modulate Hyperactivity in Inferior Colliculus

Detection of Modulated Tones in Modulated Noise by Non-human Primates

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