In 1965, Norman Geschwind, an American neurologist, wrote ‘Disconnexion syndromes in animals and man’ where he described a disconnectionist framework that revolutionized neurosciences and clinical neurology. Studies of the monkey brain led to his theory that disconnection syndromes were higher function deficits. Building on Wernicke and previously mentioned psychologists’ idea that disconnection syndromes involved white matter lesion to association tracts connecting two regions of the brain, Geschwind was more detailed in explaining some disconnection syndromes as lesions of the association cortex itself, specifically in the parietal lobe. He described the callosal syndrome, an example of a disconnection syndrome, which is a lesion in the corpus callosum that leads to tactile anomia in just the patient’s left hand.
