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Intercollicular commissural projections modulate neuronal responses in the inferior colliculus
Manuel S Malmierca1, Olga Hernández, Adrian Rees
1Auditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca and Institute for Neuroscience of Castilla y León, 37007 Salamanca, Spain. msm@usal.es
The European Journal of Neuroscience
|June 2, 2005
Summary
The inferior colliculi (ICs) commissure modulates auditory processing by influencing neural responses. Blocking this pathway affects sound processing, suggesting a role in response gain modulation.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Computational Neuroscience
Background:
- The inferior colliculi (ICs) are key auditory processing centers in the midbrain.
- The commissure of the IC connects the left and right ICs, with projections mainly from excitatory neurons.
- The precise functional role of the IC commissure in auditory processing remains largely unknown.
Purpose of the Study:
- To investigate the functional significance of the commissure of the IC in auditory processing in rats.
- To determine the influence of inter-aural connections via the IC commissure on neural responses.
Main Methods:
- Single-neuron recordings were performed in one IC of rats.
- Kynurenic acid was injected into the contralateral IC to reversibly block excitatory commissural projections.
- Sound-evoked responses were analyzed under conditions of intact and blocked inter-aural input.
Main Results:
- Blocking commissural input altered sound-evoked responses, indicating both excitatory and inhibitory influences.
- Inhibitory effects could be mediated by monosynaptic or disynaptic pathways.
- Effects were observed for both monaural and binaural stimulation, with greater impact at near-threshold sound levels.
Conclusions:
- The commissure of the IC plays a significant role in auditory processing.
- Commissural projections contribute to modulating the response gain of IC neurons.
- These findings shed light on the neural mechanisms underlying binaural hearing and sound localization.