Age-Related Decrease in the Schaffer Collateral-Evoked EPSP in Awake, Freely, Behaving Rats
Synaptic response size in the CA1 region of the hippocampus in aged rats is reduced for a given stimulus intensity, compared with that elicited in young rats. Consistent with the in vitro findings of reduced Schaffer collateral-evoked CA1 EPSPs in old rats, the population currents evoked to iontopho...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2000-01-01
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| Series: | Neural Plasticity |
| Online Access: | http://dx.doi.org/10.1155/NP.2000.167 |
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| Summary: | Synaptic response size in the CA1 region of
the hippocampus in aged rats is reduced for a
given stimulus intensity, compared with that
elicited in young rats. Consistent with the in vitro
findings of reduced Schaffer collateral-evoked
CA1 EPSPs in old rats, the population currents
evoked to iontophoretically applied AMPA are
also smaller relative to the presynaptic fiber
potential amplitude. On the other hand, the size of
the presynaptic fiber potential and amplitude of
unitary intra-cellularly recorded EPSP responses
do not change across age in the CA1 region. These
electrophysiological findings are consistent with
the hypothesis that old rats have fewer functional
synaptic contacts per Schaffer collateral axon
than do young rats. The possibility that this age
change arises as a result of a differential tissue
recovery response to in vitro preparation was
examined in the present study. CA1 presynaptic
fiber potential and EPSP amplitudes evoked by
the stimulation of Schaffer collateral afferents
were studied in intact, freely behaving young
and old rats. We confirmed in vivo the pattern of electrophysiophysiological results previously
reported in vitro and found significant
correlations between the synaptic response
amplitudes and the accuracy of spatial behavior
in the Morris swim task. The data suggest that
changes in functional connectivity of old rats
may be a significant contributor to cognitive
changes during aging. |
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| ISSN: | 2090-5904 1687-5443 |