The time factor may be even more critical after
brain damage given the dynamic changes in the neural
environment that are occurring independent of any
rehabilitation. As previously mentioned, there are major
cascades of neuronal reactions to brain damage
that occur over periods of months or longer (Badan, Platt,
et al., 2003; Kelley & Steward, 1997). A consideration
in the timing of behavioral treatments may be whether
treatment is primarily neuroprotective in nature—that
is, sparing of neuron death and loss of neural connections
or whether the treatment works primarily by
driving reorganization of remaining connections, as typically
proposed for rehabilitative training. These are
not independent processes because neurons that are
driven to form new synaptic connections are likely to
receive more signals promoting of survival (e.g., Purves,
Snider, & Voyvodic, 1988), but they are likely to vary,
temporally, in their sensitivity to behavioral experience
effects