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Responses to Predictable versus Random Temporally Complex Stimuli from Single Units in Auditory Thalamus: Impact of Aging and Anesthesia.

Authors :
Rui Cai
Richardson, Ben D.
Caspary, Donald M.
Source :
Journal of Neuroscience; 10/12/2016, Vol. 36 Issue 41, p10696-10706, 11p
Publication Year :
2016

Abstract

Human aging studies suggest that an increased use of top-down knowledge-based resources would compensate for degraded upstream acoustic information to accurately identify important temporally rich signals. Sinusoidal amplitude-modulated (SAM) stimuli have been used to mimic the fast-changing temporal features in speech and species-specific vocalizations. Single units were recorded from auditory thalamus [medial geniculate body (MGB)] of young awake, aged awake, young anesthetized, and aged anesthetized rats. SAM stimuli were modulated between 2 and 1024 Hz with the modulation frequency ( fm) changed randomly (RAN) across trials or sequentially (SEQ) after several repeated trials. Units were found to be RAN-preferring, SEQ-preferring, or nonselective based on total firing rate. Significant anesthesia and age effects were found. The majority (86%) of young anesthetized units preferred RAN SAM stimuli; significantly fewer young awake units (51%, p<0.0001) preferred RANSAM signals with16%preferringSEQSAM.Compared with young awake units, there was a significant increase of aged awake units preferring SEQSAM(30%, p<0.05).We examined RAN versus SEQ differences across fms by measuring selective fm areas under the rate modulation transfer function curve. The largest age-related differences from awake animals were found for mid-to-high fms in MGB units, with young units preferring RAN SAM while aged units showed a greater preference for SEQ-presented SAM. Together, these findings suggest that aged MGB units/animals employ increased top-down mediated stimulus context to enhance processing of "expected" temporally rich stimuli, especially at more challenging higher fms. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
02706474
Volume :
36
Issue :
41
Database :
Complementary Index
Journal :
Journal of Neuroscience
Publication Type :
Academic Journal
Accession number :
118856301
Full Text :
https://doi.org/10.1523/JNEUROSCI.1454-16.2016