Cortical Tonotopic Map Changes in Humans Are Larger in Hearing Loss Than in Additional Tinnitus

Elouise Koops, the benefactor of the Danny Boy Memorial Fund, released a new paper last month. Unfortunately I can't access the full paper. I'm also not sure if the money of the fund was used for this particular paper.

ABSTRACT
Neural plasticity due to hearing loss results in tonotopic map changes. Several studies have suggested a relation between hearing loss-induced tonotopic reorganization and tinnitus. This large fMRI study on humans was intended to clarify the relations between hearing loss, tinnitus, and tonotopic reorganization. To determine the differential effect of hearing loss and tinnitus, both male and female participants with bilateral high-frequency hearing loss, with and without tinnitus, and a control group were included. In a total of 90 participants, bilateral cortical responses to sound stimulation were measured with loudness-matched pure-tone stimuli (0.25-8 kHz). In the bilateral auditory cortices, the high-frequency sound-evoked activation level was higher in both hearing-impaired participant groups, compared with the control group. This was most prominent in the hearing loss group without tinnitus. Similarly, the tonotopic maps for the hearing loss without tinnitus group were significantly different from the controls, whereas the maps of those with tinnitus were not. These results show that higher response amplitudes and map reorganization are a characteristic of hearing loss, not of tinnitus. Both tonotopic maps and response amplitudes of tinnitus participants appear intermediate to the controls and hearing loss without tinnitus group. This observation suggests a connection between tinnitus and an incomplete form of central compensation to hearing loss, rather than excessive adaptation. One implication of this may be that treatments for tinnitus shift their focus toward enhancing the cortical plasticity, instead of reversing it.

SIGNIFICANCE STATEMENT
Tinnitus, a common and potentially devastating condition, is the presence of a “phantom” sound that often accompanies hearing loss. Hearing loss is known to induce plastic changes in cortical and subcortical areas. Although plasticity is a valuable trait that allows the human brain to rewire and recover from injury and sensory deprivation, it can lead to tinnitus as an unwanted side effect. In this large fMRI study, we provide evidence that tinnitus is related to a more conservative form of reorganization than in hearing loss without tinnitus. This result contrasts with the previous notion that tinnitus is related to excessive reorganization. As a consequence, treatments for tinnitus may need to enhance the cortical plasticity, rather than reverse it.

https://www.jneurosci.org/content/40/16/3178

Edit: No mention of Tinnitus Talk or the Danny Boy Fund, but the research was being conducted before the Fund was granted.

 

Full paper in all its glory uploaded to my post.

 

Thanks @Nobody19 @annV... just what is tinnitus? I am tired of asking myself this question and seeking an answer which seems to be so complex? Sorry for ranting.

 

We all feel the same way... Step by step we're solving the mystery!

 

What does this mean in practice? Does it mean that treatments where you work on your tinnitus frequencies will actually increase your tinnitus? For example in https://plasticity.szynalski.com/ use frequencies that are far away from your tinnitus if you want accelerate cortical plasticity? Any drugs that enhance cortical plasticity?

 

I find this sentence confusing: "enhancing" and "reversing" aren't antonyms.

en·hance| inˈhans, enˈhans | verb [with object] intensify, increase, or further improve the quality, value, or extent of: his refusal does nothing to enhance his reputation | computer techniques that enhance images.

re·verse| rəˈvərs | verb [with object] make (something) the opposite of what it was: the damage done to the ozone layer may be reversed.

Neuroplasticity refers to the brain's ability to change and adapt as a result of experience. You can't reverse an ability.

Enhancing plasticity simply means increasing the ability to change, or increasing its malleability. It doesn't define which direction it's going to go. Reversing plasticity doesn't make sense: what most therapies were trying to do was to reverse the (maladaptive) changes that occurred due to the existing plasticity characteristics of the brain.

That said, I'm glad we're spending time learning more about Tinnitus.