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Published on: April 21, 2022
Age-dependent effect of hearing loss on cortical inhibitory synapse function
Anne E Takesian1, Vibhakar C Kotak, Dan H Sanes
1Center for Neural Science, New York University, New York, New York, USA. anne.takesian@childrens.harvard.edu
Journal of Neurophysiology
|November 18, 2011
Summary
Juvenile hearing loss permanently weakens inhibitory synapses in the brain, impacting auditory processing into adulthood. Adult hearing loss does not cause these lasting changes, highlighting a critical developmental window.
Area of Science:
- Neuroscience
- Developmental Biology
- Auditory Neuroscience
Background:
- Synaptic plasticity, particularly in excitatory synapses, is well-documented and age-dependent.
- The principles of developmental plasticity may also apply to inhibitory synapses, suggesting juvenile manipulations could have lasting effects.
Purpose of the Study:
- To characterize the maturation of cortical inhibitory synapse function during development.
- To investigate the long-term consequences of developmental conductive hearing loss (CHL) on inhibitory synapses.
- To determine if adult-onset CHL affects inhibitory synapse function.
Main Methods:
- Whole-cell recordings from gerbil thalamocortical brain slices.
- Characterization of inhibitory current decay time and synaptic strength.
- Assessment of inhibitory interneuron discharge rates.
- Comparison of developmental versus adult-onset CHL effects.
Main Results:
- Inhibitory current decay time significantly decreased during normal development (first 3 months).
- Developmental CHL resulted in enduringly decreased inhibitory synaptic strength and delayed decay time maturation in adults.
- Early CHL reduced the maximum discharge rate of fast-spiking interneurons but not low-threshold-spiking interneurons.
- Adult-onset CHL did not alter inhibitory current amplitude or decay time.
Conclusions:
- Inhibitory synapse function undergoes protracted development, with a critical window during juvenile stages.
- Juvenile, but not adult, hearing loss can induce long-lasting deficits in inhibitory synapse function.
- These enduring changes in inhibitory function may underlie auditory processing deficits linked to early hearing loss.
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