Representation of tone in fluctuating maskers in the ascending auditory system

被引:73
作者
Las, L
Stern, EA
Nelken, I
机构
[1] Hebrew Univ Jerusalem, Dept Neurobiol, IL-91904 Jerusalem, Israel
[2] Hebrew Univ Jerusalem, Interdisciplinary Ctr Neural Computat, IL-91904 Jerusalem, Israel
[3] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Dept Neurol, Charlestown, MA 02129 USA
关键词
auditory cortex; auditory thalamus; inferior colliculus; physiology; cat; comodulation masking release;
D O I
10.1523/JNEUROSCI.4007-04.2005
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
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 MGB and all A1 neurons displayed striking suppressive effects. These neurons were hypersensitive, showing suppression already with tone levels lower than the threshold of the neurons in silence. The hypersensitive locking suppression in A1 and MGB had a special timing structure, starting >75 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.
引用
收藏
页码:1503 / 1513
页数:11
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