The Perception-Update (PU) Model

Sound Change Integration Error: An Explanatory Model of Tinnitus

A growing body of research is focused on identifying and understanding the neurophysiological mechanisms that underlie tinnitus. Unfortunately, however, most current models cannot adequately explain the majority of tinnitus features. For instance, although tinnitus generally appears within minutes after entering a silent environment, most models postulate that tinnitus emerges over a much larger timescale (days). Similarly, there is a limited understanding of how the severity of tinnitus can differ in patients with a similar degree of hearing loss. To address this critical knowledge gap, we have formulated a novel explanatory model of tinnitus, the perception-update (PU) model, which rests on a theory of information processing and can explain several key characteristics of tinnitus onset. The PU model posits that the brain continuously updates the information received from the inner ear by comparing it to the received information immediately before. That is, the auditory system processes the relative change in sensory input, as opposed to the absolute value of the auditory input. This is analogous to the functioning of data compression technology used for music and images called differential pulse code modulation (differential PCM). The PU model proposes that the inner ear transmits sound change to the auditory cortex via an auditory N1 response, an event-related potential component that constitutes is a prime signaler of auditory input change. In cases of hearing impairment, the PU model posits that the auditory system finds itself in a state of uncertainty where perception has to be predicted based on previous stimulation parameters, which can lead to the emergence of tinnitus.

Source: https://www.frontiersin.org/articles/10.3389/fnins.2018.00831/abstract

 

So, then, find a way to 'reset' the brains learned parameters in regards to hearing input. Put it in a sort of 'relearn' mode. But HOW??!?!?!?!?!?!

 

Does anyone have access to the full articles?

Prediction and perception: Insights for (and from) tinnitus
Jeffrey Hullfish, William Sedley, Sven Vanneste

Highlights

• Perception is an inference about the causes of activity in sensory pathways.
• Hallucinations can occur when this activity is not caused by environmental stimuli.
• Tinnitus is well explained under a predictive coding framework.
• Predictive coding offers a bridge between several different brain (dys)functions.

Abstract

Spoiler

More than 150 years have passed since Helmholtz first described perception as a process of unconscious inference about the causes of sensations. His ideas have since inspired a wealth of literature investigating the mechanisms underlying these inferences. In recent years, much of this work has converged on the notion that the brain is a hierarchical generative model of its environment that predicts sensations and updates itself based on prediction errors. Here, we build a case for modeling tinnitus from this perspective, i.e. predictive coding. We emphasize two key claims: (1) acute tinnitus reflects an increase in sensory precision in related frequency channels and (2) chronic tinnitus reflects a change in the brain’s default prediction. We further discuss specific neural biomarkers that would constitute evidence for or against these claims. Finally, we explore the implications of our model for clinical intervention strategies. We conclude that predictive coding offers the basis for a unifying theory of cognitive neuroscience, which we demonstrate with several examples linking tinnitus to other lines of brain research.

Tinnitus: Does Gain Explain?
William Sedley

Highlights

• Gain changes comprise changes in synaptic properties, neuronal excitability and neural synchrony.
• Dramatic gain changes, at all levels of the central auditory pathway, follow damage to the peripheral auditory system.
• Lack of hearing-matched control groups has been the main factor preventing attribution of gain changes to tinnitus.
• For gain to be a sufficient explanation of tinnitus, it must provide accurate classification at the individual subject level.
• Alternative/additional processes are summarized to explain tinnitus if gain changes are non-contributory or insufficient.

Abstract

Spoiler

Many or most tinnitus models rely on increased central gain in the auditory pathway as all or part of the explanation, in that central auditory neurones deprived of their usual sensory input maintain homeostasis by increasing the rate at which they fire in response to any given strength of input, including amplifying spontaneous firing which forms the basis of tinnitus. However, dramatic gain changes occur in response to damage to the auditory periphery, irrespective of whether tinnitus occurs. This article considers gain in its broadest sense, summarizes its contributory processes, neural manifestations, behavioral effects, techniques for its measurement, pitfalls in attributing gain changes to tinnitus, a discussion of the minimum evidential requirements to implicate gain as a necessary and/or sufficient basis to explain tinnitus, and the extent of existing evidence in this regard.

Overall there is compelling evidence that peripheral auditory insults induce changes in neuronal firing rates, synchrony and neurochemistry and thus increase gain, but specific attribution of these changes to tinnitus is generally hampered by the absence of hearing-matched human control groups or insult-exposed non-tinnitus animals. A few studies show changes specifically attributable to tinnitus at group level, but the limited attempts so far to classify individual subjects based on gain metrics have not proven successful. If gain turns out to be unnecessary or insufficient to cause tinnitus, candidate additional mechanisms include focused attention, resetting of sensory predictions, failure of sensory gating, altered sensory predictions, formation of pervasive memory traces and/or entry into global perceptual networks.

 

When I click on the headline for the second one, I seem to get the full article. Not for the first one. Does it show the same way to you?

 

I got them for you.

 

Tinnitus Does Not Interfere with Auditory and Speech Perception

• After controlling for age, hearing loss and stimulus variables, we discovered that contradictory to the widely-held assumption, tinnitus does not interfere with perception of external sounds in 32 out 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 co-morbid conditions when addressing tinnitus sufferers’ complaints about hearing difficulty.