Making the brain plastic: early neuroanatomical bench
strategies to adapt behavioural changes to morphology
As Edward Jones has recently mentioned, the concept of neuronal plasticity is widely used but seldom defined in the neurosciences. It may signify a vast amount of different phenomena from behavioural adaptations to the alteration of synapse formation in dendrites. This historical paper will explore how the concept of neuronal plasticity and some of its precursors entered the field of neuroanatomy and became popular with recent work on the hippocampal formation.
Early morphological research on the de- and regeneration phenomena in the late 19th century is well documented and linked with the works of Albrecht Bethe (1909) and Augustus Waller (1850). Although already concentrated on the cell-level, these studies were almost exclusively based on peripheral nerve tissue. Probably Ioan Minca (in 1909) in Bucharest was the first neurologist to actually use the term plastic reactions already popular with material sciences and biology. Taken up by Santiago Ramón y Cajal (1913/14), it became associated with regenerative capacities, but not widely used. The term rested regeneration or Sprossbildung (Hermann Stieve, 1952). However, it was time form a conceptual change, when Cajal transferred the idea of regenerative capacities from PNS to CNS, posing hypotheses on scarce evidence that cortical and cerebellar tissue would also display sprouting phenomena.
Yet until the 1970s the leading opinion of neuroscience still regarded the CNS as more or less incapable of regeneration under in vivo conditions. "Wired" once, morphological alterations after lesions were regarded only as "clearing processes" of the brain to get rid of cell detritus. Now, this conventional view has undergone important theoretical changes which have been attributed to the basic works of Geoffrey Raisman and Carl W. Cotman since the latter part of the 1960s. Drawing on published anatomical literature, I would like to fill in some of the gaps in how morphological research has regained its interest in regenerative "plastic" phenomena in CNS.
Session II -- 19th/20th Century Approaches to the Nervous System
Sixth Annual Meeting of the International Society for the History of the Neurosciences (ISHN) and