Karl S. Lashley (1890-1958)

Karl Spencer Lashley (see here)

Karl Spencer Lashley (1890-1958) was one of the founders of modern experimental psychology (see the obituaries by his contemporaries Walshe, 1958, and Carmichael, 1959, but compare Dewsbury 2002 and Weidman 2002 for a recent criticism of his racial and genetic determinist positions). He was the first to argue that since his migraine aura symptoms propagate, a neural disturbance that causes them must propagate as well. Although that was not the first attempt to connect migraine with cerebral functions, Lashley (1941) for the first time made detailed suggestions about how brain functions may cause characteristic visual aura symptoms.

Four subsequent migraine scotomata drawn by Lashley 1941. The crosses indicate the center of gaze, and the numbers state the time in minutes that passed for each fortification pattern since its first appearance close to the center of gaze. © 1941 American Medical Association

Lashley's scotomas can be mapped from the visual field (left) onto the cortical surface (right). The kidney shape is transformed to a wave front with constant width. © 2005 Markus Dahlem

On a coarse scale, the migraine aura seemed to reflect a fundamental organizing principle of the cerebral cortex, that is, its ability to map sensory input in an orderly topographic fashion. Thus, if the aura travels, so does the underlying neural process. By disturbing the functioning of the normal brain, the aura discloses this fundamental organizing principle of the cerebral cortex.

Even more intriguingly, on a finer scale further so-called cortical feature maps are disclosed. Jung (1979), for example, pointed out that Lashley anticipated cortical iso-orientation domains 18 years before their discovery by Hubel and Wiesel (1959). Lashley clearly thought that "Patterns of cerebral integration [are] indicated by scotomas of migraine" (as his paper was titled). Nowadays, it is generally accepted that the typical fortification pattern can be interpreted as a direct view on the layout of orientation columns in humans. Interestingly, therefore, the visual aura provides the only functional evidence so far of orientation tuning cells in human cortex.

References

Carmichael L. Karl Spencer Lashley, experimental psychologist. Science 1959; 22; 129 (3360): 1410-1412.
Dewsbury DA. Constructing representations of Karl Spencer Lashley. J Hist Behav Sci 2002; 38: 225-245.
Hubel DH, Wiesel TN. Receptive fields of single neurones in the cat's striate cortex. J Physiol 1959; 148: 574-591.
Jung R. Translokation corticaler Migrainephosphene bei Augenbewegung und vestibularen Reizen. Neuropsychologia 1979; 17: 173-85.
Lashley K. Patterns of cerebral integration indicated by scotomas of migraine. Arch. Neurol. Psychiatry 1941; 46: 331-339.
Walshe FM. Karl S. Lashley. Neurology 1958; 8: 870.
Weidman N. The depoliticization of Karl Lashley: A response to Dewsbury. J Hist Behav Sci 2002; 38: 247-253; discussion 255-257.

top