Reproduced below was my comment on a scientific study entitled
Intracranial Mapping of a Cortical Tinnitus System using Residual Inhibition (
http://www.cell.com/current-biology/fulltext/S0960-9822(15)00278-X) which I read in Current Biology on the cell.com website. However, before I received a definite answer as to whether the comment would be appropriate for publication online by Cell Press Editors, I decided to go ahead and publish it immediately as a post on LinkedIn with a brief additional reflection included at the end of the comment.
'Tinnitus and the prefrontal cortex
I propose that residual inhibition (RI) in this study transiently brings about general aural alertness which would involve some of the impulses giving rise to tinnitus—such impulses being putatively associated with a proportion of sensory impulses from hair cells in the organ of Corti ascending via the non-specific projection nuclei of the thalamus (
http://what-when-how.com/neuroscience/the-thalamus-and-cerebral-cortex-integrative-systems-part-2/) and diverted to control sensory input over the suprageniculate/limitans complex via the S1/M1. The result is desynchronization of delta/theta and alpha waves during tinnitus suppression observed as delta/theta and alpha oscillatory power decreases.
The hyperactivity noted in the division of the ascending fibres implicated in tinnitus I would interpret not to originate in the suprageniculate/limitans complex itself but actually to be as a result of afferent impulses from the damaged or faulty part of the peripheral auditory system being employed in the control of auditory sensory input and memory after being amplified by associated prefrontal cortex interneurones and reflected back as a constant din or echo emanating from the organ of Corti and ear-drum in conjunction with Wernicke's area (Wernicke's area, along with the A1, forming part of the superior temporal gyrus, STG).
Concerning such an elusive topic, substantially the same thing can, with benefit, be viewed from a slightly different angle:-
The 'underlying' heightened activity 'in the ascending auditory pathway' which is said to be the basis of tinnitus perception stems, in my view, from part of the damaged or faulty peripheral auditory system of the subject in the study which would have an adverse effect on a proportion of sensory impulses from hair cells in the organ of Corti putatively ascending via the non-specific projection nuclei of the thalamus and involved in the control of auditory memory and cognition. The hyperactivity stemming from the peripheral aural damage or fault is thus proposed to leak, as superfluous auditory input, into the non-specific projection nuclei of the thalamus and echo, in the form of beta2 and gamma power increases, in the organ of Corti and ear-drum in conjunction with Wernicke's area (which forms part of the superior temporal gyrus). The wide propagation within the auditory cortex of these beta2 and gamma oscillatory power increases, during tinnitus suppression, is proposed to be greatly aided and abetted by excitatory interneurones in the prefrontal cortex and paralleled by pathological delta oscillatory power decreases which, in the same manner, would also leak into the cerebral cortex via the non-specific projection nuclei of the thalamus and as a result of being employed to control input over the suprageniculate/limitans complex via the S1/M1.
Crucially, as is clear from my book (
http://www.amazon.com/Human-Nervous-System-Programming-Behavioural/dp/1494917831/) overactive prefrontal cortex interneurones are well established to be a source of chronic physical and psychological disorders and tinnitus, in my view, is no exception in this regard. My recommendation as a mental health expert would be to desensitize those overactive parts of the prefrontal cortex which putatively amplify the tinnitus arising from the damaged or faulty part of the peripheral auditory system. The desensitization—possibly in the form of hypnosis, meditation or neurobiofeedback—may result in a beneficial disinhibition of the pathological delta frequency waves observed in this study in addition to a reduction in the level of tinnitus perceived by the individual affected.
For those who happen to have a copy of my aforementioned book, 'conflictive "interpretations" ' on pages 27, 31 and 32 give rise to emotional tension which in turn impels sustained cortical activities as an incentive in the individual to find semantically appropriate vocabulary to assuage such tension. 'Conflictive "interpretations" ' would directly correspond to 'prediction errors' in the present study that would give rise to high-end gamma oscillatory activity as an impetus in the subject concerned to assuage emotional tension (positive covariance)—apparently magnified by limbic structures—between various memory regions, for example auditory and visual memory centres involving association cortices and association fibres.
There is one apparently final puzzle to solve which is: What transiently causes the tinnitus suppression following the tonal stimulus (5 kHz) in the study? In my view, prefrontal cortex interneurones associated with sensory impulses arising from the non-specific projection nuclei of the thalamus and the S1/M1 and involved in controlling auditory input to A1
transiently inhibit reciprocal prefrontal cortex interneurones associated with impulses controlling auditory input to the non-A1 cortex, which latter impulses, as I have already emphasized, receive leaked superfluous ones from the damaged or faulty part of the peripheral auditory system—thereby producing tinnitus as an echo reverberating from the organ of Corti and ear-drum.
Readers of my book should be able to recognize, in the series of hypothetical diagrams of cortical activities, the prefrontal cortex interneurones associated with sensory impulses arising from the non-specific projection nuclei of the thalamus.