What is the role of the hippocampus and parahippocampal gyrus in the persistence of tinnitus?

Abstract

The hippocampus and parahippocampal gyrus have been implicated as part of a tinnitus network by a number of studies. These structures are usually considered in the context of a “limbic system,” a concept typically invoked to explain the emotional response to tinnitus. Despite this common framing, it is not apparent from current literature that this is necessarily the main functional role of these structures in persistent tinnitus. Here, we highlight a different role that encompasses their most commonly implicated functional position within the brain—that is, as a memory system. We consider tinnitus as an auditory object that is held in memory, which may be made persistent by associated activity from the hippocampus and parahippocampal gyrus. Evidence from animal and human studies implicating these structures in tinnitus is reviewed and used as an anchor for this hypothesis. We highlight the potential for the hippocampus/parahippocampal gyrus to facilitate maintenance of the memory of the tinnitus percept via communication with auditory cortex, rather than (or in addition to) mediating emotional responses to this percept.

Prediction of acoustic tinnitus suppression using resting state EEG: An explainable AI approach

“…Given structural vicinity and functional overlap of the anterior cingulate complex’ subregions (i.e., rostral anterior cingulate cortex, pregenual anterior cingulate cortex, and subgenual anterior cingulate cortex), it was proposed by [84] to extend the functional locus of the key node of the noise-canceling system to the entirety of the ventromedial prefrontal cortex. Predictive trait-like alpha power in the posterior cingulate cortex could be both reflective of an intact DMN including its inhibitory properties and/or normal modes of memory processing, which could imply that tinnitus is not filled-in from the hippocampus as proposed in recent models [85, 86]. In similar veins, predictive alpha in (superior) frontal regions could be indicative of functioning control (networks) within the tinnitus brain, allowing for better attentional (or auditory gating) control and possibly suppression of the phantom sound perception [87].…”