Synaptic Adaptation to Environmental Alteration

From Quartz & Sejnowski: Neural Basis of Cognitive Development (1997)

Quartz and Sejnowski. The neural basis of cognitive development: a constructivist manifesto. Behav Brain Sci (1997) vol. 20 (4) pp. 537-56; discussion 556-96

Above you see an excellent summary table found in a seminal work by Quartz and Sejnowski. I’m reading this paper now, and aside from the die-hard representationalist instincts of the authors, it is an excellent overview of the development of neuroplasticity research and the relation of various forms of plasticity to learning and cognition. I find the above table fascinating simply because it demonstrates in one tidy arena the scope and temporal shape of brain development. You see for example, infamous studies in which the eyes of rats are sutured shut at birth alongside equally high-impact studies in which alterations in environmental complexity alter synaptic densities.

Overall, this is a list of studies in which the alteration of sensory motor input alters synaptic density and complexity in a dynamical fashion. I find it particularity interesting that the overall direction appears to be on in which increased complexity equals increased density. One stand out result is Valverde (1971) where an 20 day period of darkness is synaptically overcome when the mice are returned to a normal environment. Overall this table is a historically stunning account of the resilience of neural systems.

One big question though- why has it taken so long for plasticity to make its way into neurological acceptance?? Clearly the data was there… guess we needed fancy magnets to believe in it!