MOSCOW, December 13. /TASS/ Researchers from the Higher School of Economics (HSE) and Ludwig-Maximilian University of Munich (LMU) have discovered why people suffering from aphasia find it is easier to use instrumental verbs, such as "to fish", than non-instrumental ones, such as "to swim", said the HSE’s press service. The study’s results have been published in the Journal of Neurolinguistics.
Instrumental case verbs designate an action which is accomplished using an instrument, for example, "to fish" (with a fishing rod), "to cut" (with a knife), "to chop" (with an ax). Previous studies have shown that patients with aphasia (speech disturbances due to a stroke or head trauma) have fewer difficulties with verbs of this particular group. For instance, they complete tasks with instrumental verbs better than with non-instrumental verbs meaning actions which can be done without using an additional tool (or object) as "to swim".
"We were wondering which brain mechanisms were responsible for differences in processing speech for instrumental and non-instrumental verbs. We decided to study the impact of instrumental verb cases on the brain’s activity in the healthy group of people without speech impediments," the Chief of Laboratory of Neurolinguistics at HSE Olga Dragoi said.
The corresponding experiment was carried out in collaboration with LMU using a German-speaking group. The subjects had to select appropriate noun substantives for various verbs, both instrumental and non-instrumental cases. For instance, they were asked to choose which noun "bread" or "blood" goes better with the verb "to cut", while the MRI was being recorded.
The study’s results demonstrate that processing non-instrumental verbs requires an additional activation of the brain’s divisions related to the speech, for example, of the frontal or temporal regions of the left brain. As a rule, during aphasia, the main areas of damage are located in these particular regions. This explains why subjects with aphasia experience difficulties when pronouncing non-instrumental verbs as "to swim» and vice versa can achieve better results when using instrumental verbs such as "to fish". That means that the damaged brain of aphasia sufferers is not capable of supplying additional activation needed for generating and understanding non-instrumental verbs.