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Published on: April 27, 2015
Dentate granule cell modulation in freely moving rats: vigilance state effects
J D Bronzino1, J H Blaise, D J Mokler
1Department of Engineering, Trinity College, Hartford, CT 06106, USA. joseph.bronzino@mail.trincoll.edu
Brain Research. Developmental Brain Research
|April 21, 1999
Summary
Dentate granule cell excitability changes with age, showing less early inhibition in young rats and more late inhibition in adults across different vigilance states (quiet waking, sleep). This highlights developmental maturation of hippocampal activity modulation.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Sleep Research
Background:
- Dentate granule cell excitability is crucial for hippocampal function.
- Modulation of neuronal activity changes with age and vigilance states.
- Paired-pulse stimulation is a key method to assess neuronal inhibition.
Purpose of the Study:
- To investigate age-related changes in dentate granule cell excitability.
- To examine the influence of vigilance states (quiet waking, SWS, REM sleep) on this excitability.
- To determine how paired-pulse inhibition matures during postnatal development.
Main Methods:
- Paired-pulse stimulation of the perforant pathway in freely moving rats.
- Recording of evoked field potentials in dentate granule cells.
- Calculation of the paired-pulse index (PPI) across various interpulse intervals (IPIs) and ages (15, 30, 90 days).
- Analysis during quiet waking, slow-wave sleep, and REM sleep.
Main Results:
- Younger animals (15 days) exhibited significantly lower early inhibition (20-40 ms IPIs), indicated by higher PPI values, across all vigilance states compared to older rats.
- Adult animals (90 days) displayed significantly greater late inhibition (300-1000 ms IPIs), indicated by lower PPI values, than younger animals during quiet waking and SWS.
- Age-dependent alterations in the modulation of dentate granule cell activity were observed.
Conclusions:
- Dentate granule cell population responses mature significantly between 15 and 90 days of age.
- Developmental changes in neuronal inhibition and excitability are evident in the dentate gyrus.
- Vigilance states modulate dentate granule cell activity, with age-dependent patterns emerging.
