Abstract
The structure of neurons in the central auditory system is vulnerable to various kinds of acoustic exposures during the critical postnatal developmental period. Here we explored long-term effects of exposure to an acoustically enriched environment (AEE) during the third and fourth weeks of the postnatal period in rat pups. AEE consisted of a spectrally and temporally modulated sound of moderate intensity, reinforced by a behavioral paradigm. At the age of 3–6 months, a Golgi–Cox staining was used to evaluate the morphology of neurons in the inferior colliculus (IC), the medial geniculate body (MGB), and the auditory cortex (AC). Compared to controls, rats exposed to AEE showed an increased mean dendritic length and volume and the soma surface in the external cortex and the central nucleus of the IC. The spine density increased in both the ventral and dorsal divisions of the MGB. In the AC, the total length and volume of the basal dendritic segments of pyramidal neurons and the number and density of spines on these dendrites increased significantly. No differences were found on apical dendrites. We also found an elevated number of spines and spine density in non-pyramidal neurons. These results show that exposure to AEE during the critical developmental period can induce permanent changes in the structure of neurons in the central auditory system. These changes represent morphological correlates of the functional plasticity, such as an improvement in frequency tuning and synchronization with temporal parameters of acoustical stimuli.
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Acknowledgement
This study was supported by the Operational Programme Research, Development and Education in the framework of the project “Center of Reconstructive Neuroscience,” registration number CZ.02.1.01/0.0./0.0/15_003/0000419, and by the project INTER-ACTION LTAIN19201.
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Both authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Jana Svobodová Burianová. The first draft of the manuscript was written by Jana Svobodová Burianová, and both authors commented on previous versions of the manuscript. Both authors read and approved the final manuscript.
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All experimental procedures were approved by the Ethical Committee of the Institute of Experimental Medicine of the Czech Academy of Sciences and followed the guidelines of EU Directive 2010/63/EU for animal experiments.
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Svobodová Burianová, J., Syka, J. Postnatal exposure to an acoustically enriched environment alters the morphology of neurons in the adult rat auditory system. Brain Struct Funct 225, 1979–1995 (2020). https://doi.org/10.1007/s00429-020-02104-8
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DOI: https://doi.org/10.1007/s00429-020-02104-8