Robustness ?

[Edelman Shimon]

Robert A. Santiago wrote:

          The problem of robustness from a neurobiological perspective
          seems to originate from work done by Karl Lashley.  He
          sought to find how memory was partitioned in the brain.  He
          thought that memories were kept on certain neuronal circuit
          paths (engrams) and experimented under this hypothesis by
          cutting out parts of brains and seeing if it affected
          memory.  It didn't. 

This description of Lashley's results is incorrect. Lashley did find
an effect of the lesions he induced in the rat's brain, but the effect
seemed to depend more on the extent of the lesion rather than on its
location. By the way, some people who work in the rat (e.g., Yadin
Dudai, here at Weizmann) now believe that Lashley's results may have
to do with his method: the lesions may have been frequently induced
disregarding proximity to blood vessels. Damage to these vessels could
have secondary effects over wider areas not related directly to the
site of the original lesion... So, care should be taken not to jump to
conclusions based on 60 year old anecdotes - better data are available
now on the effects of lesions, including in humans. Some of these data
indicate that certain brain functions are surprisingly well-localized.
See, for example, McCarthy and Warrington, Nature 334:428-430 (1988).

-Shimon

Shimon Edelman             Internet: edelman at wisdom.weizmann.ac.il
Dept. of Applied Mathematics and Computer Science
The Weizmann Institute of Science
Rehovot 76100, ISRAEL