Post-natal development of physiology across the auditory pathway at cellular and population levels

Yamini Venkataraman, Purdue University

Abstract

Background: During development, the sense of hearing changes gradually with age. Developmental changes occur at multiple levels of brain organization - from behavioral responses to cellular responses, and at every auditory processing center. Problem: Neuronal properties and sound processing change dramatically in auditory cortex (AC) neurons after the onset of hearing. However, development of its primary source, the auditory thalamus or medial geniculate body (MGB) has not been well studied over this critical time window. Significance: Development of auditory temporal processing is important for processing complex sounds as well as for acquiring reading and language skills. Developmental brain plasticity is directly related to the consequences and treatment of hearing loss. Aims: Cellular response properties of rat MGB neurons were recorded using the patch-clamp technique, at ages postnatal day (P) 7-9; P15-17 and P22-32. Additionally, non-invasive population responses were recorded in response to amplitude modulation, to determine if mid-brain inputs to the MGB are also changing. Findings: MGB membrane properties matured substantially and action potentials became about 5 times faster across the ages studied. Inhibitory synaptic responses were present at all ages. Inhibition became faster to single shocks, showed less depression to repetitive shocks at 5 Hz and 10 Hz, and was overall more efficacious in controlling excitability, with age. Population responses showed larger responses to amplitude modulation with age, indicating inputs to the MGB are concurrently maturing. Conclusion: Overall, MGB cellular responses and mid-brain population responses become faster and more precise during a time period of rapid changes across the auditory system.

Degree

Ph.D.

Advisors

Bartlett, Purdue University.

Subject Area

Neurosciences|Biomedical engineering

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