In article <36DD520A.EAF3227F at unf.edu>,
jander at unf.edu wrote:
> Thanks to everyone who responded to my query about activity-dependent
> plasticity in the adult brain. I have read a number of abstracts as a
> result of your responses, and have ordered several papers through
> interlibrary loan.
>> The abstracts indicate that there is little doubt that
> activity-dependent plasticity does occur in adult brains. However, what
> I am really after is whether the general feeling (as well as any
> relevant publications, of course, if they exist) is that plasticity
> ALWAYS increases in the vicinity of active neurons, or just under
> certain circumstances. Opinions? If only under certain circumstances,
> what are they?
>> Thanks again
> John E Anderson
> Department of Natural Sciences
> University of North Florida
> Jacksonville FL
I think plasticity, as a neuron growth change is a slower process than neural
adaptability which modifies synaptic efficacy. This means that any neural
activity would have to be greatly above the background neural noise level to
be noticed. If that high degree of neural activity occurs then I suspect the
neuron will show plasticity in all cases.
A very interesting form of plasticity is exhibited by long term potentiation
in the hippocampus. This seems to change the shape of the spines on the
neurons and some of these changes are mediated by actin filaments such that
they occur within seconds (Fischer, et al - 1998). So the hippocampus may be
a brain area very sensitive to activity levels so it can rewire connections
to provide the spatial and temporal context for memory.
Fischer, M., Kalch, S., Knulti, D., and Matus, A., (1998) "Rapid actin-based
plasticity in dendritic spines" Neuron 20:1-20
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