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Comparison of plasticity in vivo and in vitro in the developing visual cortex of normal and protein kinase A RIbeta-deficient mice.

Authors :
Hensch TK
Gordon JA
Brandon EP
McKnight GS
Idzerda RL
Stryker MP
Source :
The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 1998 Mar 15; Vol. 18 (6), pp. 2108-17.
Publication Year :
1998

Abstract

Developing sensory systems are sculpted by an activity-dependent strengthening and weakening of connections. Long-term potentiation (LTP) and depression (LTD) in vitro have been proposed to model this experience-dependent circuit refinement. We directly compared LTP and LTD induction in vitro with plasticity in vivo in the developing visual cortex of a mouse mutant of protein kinase A (PKA), a key enzyme implicated in the plasticity of a diverse array of systems. In mice lacking the RIbeta regulatory subunit of PKA, we observed three abnormalities of synaptic plasticity in layer II/III of visual cortex in vitro. These included an absence of (1) extracellularly recorded LTP, (2) depotentiation or LTD, and (3) paired-pulse facilitation. Potentiation was induced, however, by pairing low-frequency stimulation with direct depolarization of individual mutant pyramidal cells. Together these findings suggest that the LTP defect in slices lacking PKA RIbeta lies in the transmission of sufficient net excitation through the cortical circuit. Nonetheless, functional development and plasticity of visual cortical responses in vivo after monocular deprivation did not differ from normal. Moreover, the loss of all responsiveness to stimulation of the originally deprived eye in most cortical cells could be restored by reverse suture of eyelids during the critical period in both wild-type and mutant mice. Such an activity-dependent increase in response would seem to require a mechanism like potentiation in vivo. Thus, the RIbeta isoform of PKA is not essential for ocular dominance plasticity, which can proceed despite defects in several common in vitro models of neural plasticity.

Details

Language :
English
ISSN :
0270-6474
Volume :
18
Issue :
6
Database :
MEDLINE
Journal :
The Journal of neuroscience : the official journal of the Society for Neuroscience
Publication Type :
Academic Journal
Accession number :
9482797