Eyes and Ears: Cross-Modal Interference of Tinnitus on Visual Processing

Investigating sensitivity to multi-domain prediction errors in chronic auditory phantom perception

The perception of a continuous phantom in a sensory domain in the absence of an external stimulus is explained as a maladaptive compensation of aberrant predictive coding, a proposed unified theory of brain functioning. If this were true, these changes would occur not only in the domain of the phantom percept but in other sensory domains as well. We confirm this hypothesis by using tinnitus (continuous phantom sound) as a model and probe the predictive coding mechanism using the established local-global oddball paradigm in both the auditory and visual domains. We observe that tinnitus patients are sensitive to changes in predictive coding not only in the auditory but also in the visual domain. We report changes in well-established components of event-related EEG such as the mismatch negativity. Furthermore, deviations in stimulus characteristics were correlated with the subjective tinnitus distress. These results provide an empirical confirmation that aberrant perceptions are a symptom of a higher-order systemic disorder transcending the domain of the percept.

The Impact of Sleep Quality on Cognitive Function in Patients with Chronic Subjective Tinnitus

BACKGROUND

The aim of this study was to explore the impact of sleep quality on cognitive function in patients with chronic subjective tinnitus.

METHODS

The Pittsburgh Sleep Quality Index (PSQI) and the Montreal Cognitive Assessment Scale (MoCA) were used to assess sleep quality and cognitive function in patients with chronic subjective tinnitus, sleep disorder patients (SD), and normal controls (NC). The tinnitus evaluation questionnaire (TEQ) and tinnitus loudness were used to assess the severity in patients with chronic subjective tinnitus. Tinnitus patients were divided into two groups based on PSQI results: "tinnitus with sleep disorder (TwSD)" and "tinnitus without sleep disorder (TnSD)." The MoCA scores in TwSD and TnSD groups were compared with those in SD and NC groups, and the correlation between PSQI, TEQ, tinnitus loudness, and MoCA scores in subjective tinnitus patients were analyzed.

RESULTS

Whether TwSD group or TnSD group, the MoCA score was significantly lower than those in the NC group and SD group. Meanwhile, there was no significant difference between TwSD and TnSD groups in MoCA score, and PSQI, TEQ, and tinnitus loudness were not significantly correlated with MoCA.

CONCLUSION

Subjective tinnitus may be an independent risk factor for cognitive impairment. The underlying neural mechanisms between subjective tinnitus, sleep disorders, and cognitive impairment need to be further explored and clarified.

Tinnitus Does Not Interfere with Auditory and Speech Perception

Tinnitus is a sound heard by 15% of the general population in the absence of any external sound. Because external sounds can sometimes mask tinnitus, tinnitus is assumed to affect the perception of external sounds, leading to hypotheses such as "tinnitus filling in the temporal gap" in animal models and "tinnitus inducing hearing difficulty" in human subjects. Here we compared performance in temporal, spectral, intensive, masking and speech-in-noise perception tasks between 45 human listeners with chronic tinnitus (18 females and 27 males with a range of ages and degrees of hearing loss) and 27 young, normal-hearing listeners without tinnitus (11 females and 16 males). After controlling for age, hearing loss, and stimulus variables, we discovered that, contradictory to the widely held assumption, tinnitus does not interfere with the perception of external sounds in 32 of the 36 measures. We interpret the present result to reflect a bottom-up pathway for the external sound and a separate top-down pathway for tinnitus. We propose that these two perceptual pathways can be independently modulated by attention, which leads to the asymmetrical interaction between external and internal sounds, and several other puzzling tinnitus phenomena such as discrepancy in loudness between tinnitus rating and matching. The present results suggest not only a need for new theories involving attention and central noise in animal tinnitus models but also a shift in focus from treating tinnitus to managing its comorbid conditions when addressing complaints about hearing difficulty in individuals with tinnitus.SIGNIFICANCE STATEMENT Tinnitus, or ringing in the ears, is a neurologic disorder that affects 15% of the general population. Here we discovered an asymmetrical relationship between tinnitus and external sounds: although external sounds have been widely used to cover up tinnitus, tinnitus does not impair, and sometimes even improves, the perception of external sounds. This counterintuitive discovery contradicts the general belief held by scientists, clinicians, and even individuals with tinnitus themselves, who often report hearing difficulty, especially in noise. We attribute the counterintuitive discovery to two independent pathways: the bottom-up perception of external sounds and the top-down perception of tinnitus. Clinically, the present work suggests a shift in focus from treating tinnitus itself to treating its comorbid conditions and secondary effects.

Loss of Vision Dominance at the Preresponse Level in Tinnitus Patients: Preliminary Behavioral Evidence

At present, the mechanisms underlying changes in visual processing in individuals with tinnitus remain unclear. Therefore, we investigated whether the vision dominance of individuals with tinnitus disappears at the preresponse level through behavioral study. A total of 38 individuals with tinnitus and 31 healthy controls completed a task in which they were asked to attend to either visual or auditory stimuli while ignoring simultaneous stimulus inputs from the other modality. We manipulated three levels of congruency between the simultaneous visual and auditory inputs: congruent (C), incongruent at the preresponse level (PRIC), and incongruent at the response level (RIC). Thus, we differentiated the cross-modal conflict explicitly into the preresponse (PRIC > C) and response (RIC > PRIC) levels. The results revealed no significant difference in the size of the preresponse level conflict between the auditory attention and visual attention conditions in tinnitus group. In brief, the preresponse level of individuals with tinnitus showed a loss in vision dominance. This may be due to the reduced interference of visual information in auditory processing.