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Synaptic Inhibition in Avian Interaural Level Difference Sound Localizing Neurons.
1Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, Ohio 44272; School of Biomedical Sciences, Kent State University, Kent, Ohio 44240.
Eneuro
|December 30, 2016
Summary
This study reveals reciprocal inhibitory connections between avian auditory brain regions, crucial for sound localization. Hyperpolarizing inhibition, mediated by GABAA and glycine receptors, effectively regulates neural excitability.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Synaptic Physiology
Background:
- Synaptic inhibition is vital for neural processing of interaural level difference (ILD), essential for high-frequency sound localization.
- The posterior portion of the dorsal nucleus of the lateral lemniscus (LLDp) is the initial binaural level difference encoder in the avian auditory pathway.
Purpose of the Study:
- To investigate inhibitory synaptic currents in the chicken LLDp.
- To confirm the reciprocal inhibitory connection between the two LLDps.
- To elucidate the mechanisms and functional role of inhibition in LLDp neurons.
Main Methods:
- Whole-cell recordings in brain slices.
- Electrical and chemical stimulation of the contralateral LLDp.
- Gramicidin-perforated patch recordings to measure reversal potential.
- Pharmacological manipulation of KCC2 transporter activity.
Main Results:
- First evidence of monosynaptic inhibition between contralateral LLDp neurons, confirming reciprocal connections.
- Inhibition primarily mediated by GABAA receptors, with functional glycine receptors also identified.
- Hyperpolarizing reversal potential (-88 mV) indicates low intracellular chloride concentration (5.2 mm).
- LLDp neurons maintain low intracellular chloride under high load via KCC2 transporter activity.
- Hyperpolarizing inhibition is more effective than depolarizing inhibition in regulating LLDp neuron excitability.
Conclusions:
- Reciprocal inhibitory connections exist between LLDp neurons, crucial for binaural processing.
- Low intracellular chloride concentration enables effective hyperpolarizing inhibition in LLDp.
- Hyperpolarizing inhibition plays a key role in regulating auditory pathway excitability and sound localization.
Keywords:
GABAA receptordorsal nucleus of the lateral lemniscusinteraural level differencereversal potentialsynaptic inhibitionMore Related Videos
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