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Published on: May 24, 2018
Age-related changes in neural gap detection thresholds in the rat auditory cortex
Yin Zhao1, Xiaoxiao Xu, Juan He
1Key Laboratory of Brain Functional Genomics, Ministry of Education, NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai, School of Life Science, East China Normal University, Shanghai, 200062, China.
Insights
Juvenile rats show poorer auditory temporal resolution than adults, indicated by higher gap detection thresholds in the auditory cortex. Temporal acuity improves with age but not significantly between young and older adults.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Developmental Neuroscience
Background:
- Auditory temporal resolution is vital for communication.
- Gap detection threshold measures auditory temporal resolution.
- Infants have higher thresholds than adults, but neural mechanisms are unclear.
Purpose of the Study:
- To compare neural gap detection thresholds in the auditory cortex across different age groups of rats.
- To investigate age-related changes in auditory temporal acuity.
- To examine the effect of sound level on neural gap detection.
Main Methods:
- Neural gap detection thresholds were measured in the primary auditory cortex of juvenile (postnatal day 20-30) and adult rats (8-10 weeks and 28-30 weeks).
- Electrophysiological recordings were used to assess the auditory cortex's response to silent gaps in sound.
- Data were analyzed to compare thresholds across age groups and sound levels.
Main Results:
- Juvenile rats had significantly higher neural gap detection thresholds than adult rats.
- No significant difference in thresholds was observed between the two adult groups.
- Auditory cortex units showed better gap detection at higher sound levels, indicating level-dependent temporal acuity.
Conclusions:
- Neural auditory temporal acuity develops with age during the postnatal period.
- The auditory cortex exhibits age-related changes in processing temporal information.
- Sound level influences temporal processing in the auditory cortex, with enhanced acuity at higher levels.
Abstract:
The ability of the auditory system to resolve sound temporal information is crucial for the understanding of human speech and other species-specific communications. Gap detection threshold, i.e. the ability to detect the shortest duration of a silent interval in a sound, is commonly used to study the auditory temporal resolution. Behavioral studies in humans and rats have shown that normal developing infants have higher gap detection thresholds than adults; however, the underlying neural mechanism is not fully understood. In the present study, we determined and compared the neural gap detection thresholds in the primary auditory cortex of three age groups of rats: the juvenile group (postnatal day 20-30), adult group I (8-10 weeks), and adult group II (28-30 weeks). We found age-related changes in auditory temporal acuity in the auditory cortex, i.e. the proportion of cortical units with short neural gap detection thresholds (< 5 ms) was much lower in juvenile groups compared with that in both adult groups at a constant sound level, and no significant differences in neural gap detection thresholds were found between the two adult groups. In addition, units in the auditory cortex of each group generally showed better gap detection thresholds at higher sound levels than at lower sound levels, exhibiting a level-dependent temporal acuity. These results provided evidence for neural correlates of age-related changes in behavioral gap detection ability during postnatal hearing development.
