Human Auditory Attention: The Olivocochlear Bundle May Function as a Peripheral Filter

Abstract

Two experiments examined whether focused attention toward a visual display would alter the sensory transmission properties of the human auditory nerve and brainstem centers to irrelevant auditory tone pips. In the first experiment, 16 subjects either listened to 1000 Hz, 50dB SL tone pips presented binaurally at 10/sec (“Listen”), or mentally counted letters flashed rapidly on a screen (“Look”). The auditory brainstem potentials recorded from the vertex were averaged on‐line in groups of 500 with a 10‐msec sweep and a bandpass of 150–1500 Hz. Results indicated that during the “Look” trials, Wave 5 generated from the inferior colliculus (7.322 msec latency) was significantly reduced in amplitude by 16.4% and increased in latency by 27 μsec. A second experiment with 8 subjects demonstrated that the effects of attention are limited to the auditory nerve component when using 8000 Hz stimuli but are significant for both the auditory nerve and collicular components when a mid‐frequency (2000 Hz) tone pip is used. These results suggest that during concentrated attention toward visual stimuli, irrelevant auditory stimuli may be attenuated at a peripheral level possibly through the action of the efferent olivocochlear bundle.

Selective Attention to Visual Stimuli Reduces Cochlear Sensitivity in Chinchillas

“…In later experiments, Oatman (1971) found an amplitude reduction of the auditory-nerve compound action potential (CAP) during periods of visual attention in cats. Similarly, in humans, the auditory-nerve component of tone-pip-evoked brainstem potentials and the amplitude of click-evoked otoacoustic emissions were significantly reduced in subjects when instructed to count letters flashed on a screen (Lukas, 1980;Puel et al, 1988). However, other research groups failed to replicate these findings and attributed the observed decrease in cochlear responses to head or body movements (Dunlop et al, 1965;Wickelgren, 1968).…”

“…In humans, paying attention to clicks during an auditory discrimination task, as opposed to reading a book and ignoring the clicks, produced no changes in click-evoked auditory nerve responses recorded from the external ear canal, despite a significant enhancement in click-evoked cortical potentials (Picton et al, 1971;Picton and Hillyard, 1974). Also, in another study, no significant changes were observed in evoked otoacoustic emissions recorded in subjects performing the same visual selective attention task used previously by Lukas (1980) and Puel et al (1988) (Avan and Bonfils, 1992). Because of these contradictory results, the proposition that cochlear sensitivity is reduced during cross-modal attention has remained controversial.…”

Auditory Selective Attention Modulates Activation of Human Inferior Colliculus

“…There has been a long-lasting debate on whether attention modulates processing of sounds as early as in the subcortical structures of the auditory pathway (Hernández-Peón et al 1956;Jane et al 1965;Lukas 1980;Maison et al 2001;Michie et al 1996;Näätänen 1992;Oatman and Anderson 1977;Ryan and Miller 1977). Although functional MRI (fMRI) studies in humans have ascertained that attention has a strong effect on cortical activity elicited by sounds (Grady et al 1997;Jäncke et al 1999;Johnson and Zatorre 2006;Petkov et al 2004;Rinne et al 2005Rinne et al , 2007, there is no unambiguous evidence that attention modulates subcortical auditory activity.…”

Changes in otoacoustic emissions during selective auditory and visual attention

“…On the other half of the trials, the female voice was in the left ear-called the contralateral condition. Given the neural circuitry of the OC efferent system (Brown, 2011), and various facts and speculations about the functioning of that system (Cooper and Guinan, 2006;Giard et al, 1994;Guinan, , 2010Harkrider and Bowers, 2009;Jennings et al, 2011;Kawase et al, 1993;Kumar and Vanaja, 2004;Lukas, 1980;Walsh et al, 2010b), we expected that there could be differences in nSFOAE magnitude on ipsilateral and contralateral trials, and accordingly, the data were saved separately for the two situations. However, for the majority of our subjects, the nSFOAE responses for the ipsilateral and contralateral conditions were essentially the same (see below), and this was true for both triplets.…”