Neural hyperactivity and altered envelope encoding in the central auditory system: Changes with advanced age and...

Area of Science:

• Auditory Neuroscience
• Neurophysiology
• Speech Perception

Background:

• Temporal modulations are crucial for auditory perception.
• Aging and hearing loss impair temporal processing, affecting speech recognition.
• Paradoxically, some evidence suggests enhanced neural encoding of temporal envelopes in these conditions.

Purpose of the Study:

• To review physiological changes in neural encoding of temporal envelopes with age and hearing loss.
• To discuss the role of disinhibition and neural hyperactivity.
• To explore the implications for auditory perception deficits.

Main Methods:

• Review of neurophysiological literature in human and animal models.
• Analysis of studies on neural encoding of periodic and naturalistic speech envelopes.
• Examination of frequency-dependent effects on envelope encoding.

Main Results:

• Aging and hearing loss are associated with stronger neural representations of temporal envelopes, especially for low modulation frequencies (<80 Hz).
• Exaggerated envelope encoding may occur at cortical and subcortical levels.
• Evidence suggests altered inhibitory neurotransmission and neuronal hyperactivity contribute to these changes.

Conclusions:

• Understanding altered temporal envelope encoding is key to addressing age- and hearing-loss-related auditory deficits.
• This knowledge may inform the development of interventions and assistive devices.
• Targeting disinhibition and hyperactivity could be a therapeutic strategy.