If you want to tell somebody what you have seen, first you have to seize the point and then describe it with words. If one is unable to do it, then a specific part of his brain is damaged – this is the traditional view of this problem. But M.A. Grytsyshina, research fellow of RAS Sechenov Institute of Evolution Physiology and Biochemistry, suspects that different stages of phrase formation depend on different brain sections and hemispheres. To prove this hypothesis, she asked healthy people and patients with focal lesions of right and left cerebral hemispheres to write a story based on the “Guest” strip of Herluf Bidstrup.
Ms. Grytsyshina has analyzed 73 stories, 20 of which were written by healthy testees, 40 – by patients with left cerebral hemisphere lesions (half of patients had anterior lobe lesions, another half had posterior temporal lobe lesions) and 13 – by patients with right cerebral hemisphere lesions (6 cases of anterior and 7 – of posterior temporal lobe lesions). Analysis results proved the scientist’s hypothesis and showed some interesting patterns.
To understand a painter’s conception your right cerebral hemisphere should be healthy. Testees with damaged right cerebral hemisphere had difficulties with illustration plot interpretation. These difficulties were different depending on what part of the hemisphere is damaged. Patients with damaged anterior lobes were able to describe particular episodes, but couldn’t unite them. Patients with posterior lobe lesions didn’t have such a problem, but they didn’t get the meaning of the illustration. They made a wordy, connected speech, which had little to deal with the illustration, rather with associations, brought by the picture.
Left cerebral hemisphere is responsible for words, describing the concept seized by right cerebral hemisphere. Anterior lobes of left hemisphere play primary role in word selection. Patients with lesions in these areas spoke in monosyllables. They caught the plot well and their every word applied to the point of this simple story, but they were not able to tell a connected and detailed story. The situation is vice versa when right hemisphere is damaged: the words are flowing but not appropriate words.
Ms. Grytsyshina’s studies allowed colligating roles of anterior and posterior brain lobes. When posterior lobes are damaged, it’s almost impossible to express an idea clearly because it’s either hard to catch the meaning (right cerebral hemisphere), or difficult to find appropriate words (left hemisphere). Anterior lobes are responsible for uniting separate episodes, where right hemisphere rules ideas and details, and left makes sentences out of words and speech out of phrases.