Effects of cross-modal selective attention on the sensory periphery: Cochlear sensitivity is altered by selective attention

Abstract

There is increasing evidence that alterations in the focus of attention results in changes in neural responding at the most peripheral levels of the auditory system. To date, however, those studies have not ruled out differences in task demands or overall arousal in explaining differences in responding across intermodal attentional conditions. The present study sought to compare changes in the response of cochlear outer hair cells, employing distortion product otoacoustic emissions (DPOAEs), under different, balanced conditions of intermodal attention. DPOAEs were measured while the participants counted infrequent, brief exemplars of the DPOAE primary tones (auditory attending), and while counting visual targets, which were instances of Gabor gradient phase shifts (visual attending). Corroborating an earlier study from our laboratory, the results show that DPOAEs recorded in the auditory ignoring condition were significantly higher in overall amplitude, compared with DPOAEs recorded while participants attended to the eliciting primaries; a finding in apparent contradiction with more central measures of intermodal attention. Also consistent with our previous findings, DPOAE rapid adaptation, believed to be mediated by the medial olivocochlear efferents (MOC), was unaffected by changes in intermodal attention. The present findings indicate that manipulations in the conditions of attention, through the corticofugal pathway, and its last relay to cochlear OHCs, the MOC, alter cochlear sensitivity to sound. These data also suggest that the MOC influence on OHC sensitivity is composed of two independent processes, one of which is under attentional control.

The eardrums move when the eyes move: A multisensory effect on the mechanics of hearing

“…More generally, we have demonstrated that multisensory interactions occur at the most peripheral possible point in the auditory system and that this interaction is both systematic and substantial. This observation builds on studies showing that attention-either auditory-guided or visually-guided-can also modulate the auditory periphery (21)(22)(23)(24)(25)(26)(27). Our findings also raise the intriguing possibility that efferent pathways in other sensory systems-for instance, those leading to the retina (67-77)-also carry multisensory information to help refine peripheral processing.…”

“…In short, the actions of the MEMs and OHCs affect not only the response to incoming sound but also transmit vibrations backwards to the eardrum. Both the MEMs and OHCs are subject to descending control by signals from the central nervous system (see refs: 18, 19, 20) for reviews), allowing the brain to adjust the cochlear encoding of sound in response to previous or ongoing sounds in either ear and based on global factors, such as attention (21)(22)(23)(24)(25)(26)(27). The collective action of these systems can be measured in real time with a microphone placed in the ear canal (28).…”

Why Do Forward Maskers Affect Auditory Intensity Discrimination? Evidence from "Molecular Psychophysics"

“…Does this imply that object-based attention cannot be a valid explanation of the observed effects? In our view, this is not the case because the corticofugal (descending) auditory system [66] modulates response properties in the thalamus [67], [68], the midbrain [69] and even in the cochlea [70], [71]. Thus, corticofugal projections may contribute to selective attention because they can enhance neuronal responses to relevant stimuli and suppress responses to irrelevant stimuli [72], [73].…”

The Neural Consequences of Age-Related Hearing Loss

“…Although we have focused largely on the ascending (afferent) auditory pathway, efferent connections occur at every level of the auditory system [84] and allow higher-level cortical regions to modify auditory peripheral processing [85-88]. At the cortical level, ongoing oscillations in auditory cortex track the acoustic speech signal [89,90], a process which can be modulated by directed attention (for example, to focus on a target talker instead of a competing talker) [91-94].…”