Rat Habit

Habit Formation and Localization

An outstanding example of an attempt to relate brain function to rats behavior was that of K. S Lashley (1890-1958). The animal he principally used were laboratory rats, but he also work on monkey. The behavior studied was the learning of discriminations and simple manipulation , and how to find the way through a maze of branching passages. His method was usually to destroy portion of isocortex, or to make cuts in it, with an electro cattery, and study the effect on behavior.

Lashley himself publish a late review of his work in 1950, other valuable discussion are those Osgood and Zangwill, but Lashley’s own earlier work should be consulted for its historical importance and the elegance and interest of the writing.

Lashley’s most remarkable experiments are those which suggest, that learning any task, regardless of its nature and the senses involved, is a function of the hole cortex; that the ability both to develop new habits and to retain old skills is proportional to the amount, regardless of region, of cortical tissue present (mass action); and that one part of the cortex can take over the functions of other that have been destroy (equipotentiality).

One of the concepts strongly critical by lashley was that of the reflex arc, with of overtones of telephone system, as applied to the brain. He made incisions between the visual and motors area of the cortex of adult rats. He then trained them to make a difficult discrimination; this involved their avoiding cross (X) and approaching triangle when these were presented on a black background, but approaching cross (X) and avoiding triangle on a stripe background . This same to dispose of any simple sensory –motor connections as the basis of learning; but since this worked was done, the extend of connections of the cortex with the thalamus and reticular formation have come to be more fully understood ; and these connections were lefts intact in the experiments.