Tinnitus and the Triple Network Model: A Perspective

Abstract

Tinnitus is defined as the conscious awareness of a sound without an identifiable external sound source, and tinnitus disorder as tinnitus with associated suffering. Chronic tinnitus has been anatomically and phenomenologically separated into three pathways: a lateral "sound" pathway, a medial "suffering" pathway, and a descending noise-canceling pathway. Here, the triple network model is proposed as a unifying framework common to neuropsychiatric disorders. It proposes that abnormal interactions among three cardinal networks-the self-representational default mode network, the behavioral relevance-encoding salience network and the goal-oriented central executive network-underlie brain disorders. Tinnitus commonly leads to negative cognitive, emotional, and autonomic responses, phenomenologically expressed as tinnitus-related suffering, processed by the medial pathway. This anatomically overlaps with the salience network, encoding the behavioral relevance of the sound stimulus. Chronic tinnitus can also become associated with the self-representing default mode network and becomes an intrinsic part of the self-percept. This is likely an energy-saving evolutionary adaptation, by detaching tinnitus from sympathetic energy-consuming activity. Eventually, this can lead to functional disability by interfering with the central executive network. In conclusion, these three pathways can be extended to a triple network model explaining all tinnitus-associated comorbidities. This model paves the way for the development of individualized treatment modalities.

Keywords: Default Mode Network; Executive Network; Salience Network; Tinnitus.

Fig. 1.

The anatomical pathways associated with three different aspects of tinnitus (loudness, suffering, and presence). A sound stimulus leads to a cognitive, emotional, and autonomic response, which is phenomenologically expressed as catastrophizing, attention paid to the tinnitus, unpleasantness, fear, anger or frustration with tinnitus, and arousal/distress. These cognitive, emotional, and autonomic symptoms are all phenomenological expressions of altered activity in the medial pathway.

Fig. 2.

In subjects with acute tinnitus, the default mode network and the central executive network are anti-correlated. When tinnitus becomes chronic, the anticorrelation between the two networks disappear and the triple network including the salience network causes suffering, embodiment, and functional impairment because of tinnitus.