It’s estimated that, on average, a person’s memory stores several tens of thousands of words, but despite this, in ordinary life, we need only a few hundred milliseconds to find the desired word in our mental “dictionary”.
For a long time, it was believed that the speech system is isolated from other functions of the psyche. However, according to experts, the principle of the so-called “embodied cognition” has recently gained popularity.
According to this principle, the brain zones responsible for the corresponding actions work with the meaning of words: the meaning of the verb “to run” is stored in the area that controls the movement of the legs, while the meaning of the word “yellow” is in the area due to which we distinguish colours.
To test this hypothesis, the MSUPE scientists used magnetoencephalography (MEG), which measures the weak magnetic fields generated by the electrical activity of the brain. The MEG can measure the activity of a certain part of the cerebral cortex with millisecond accuracy, allowing us to determine whether the excitation corresponds to the extraction of meaning from the memory, or just to imagining the named action.
“We asked the study participants to come up with verbs for nouns. In half the cases it was easy, as, for example, the “sun- to shine” pair; sometimes it was more difficult. For example, what does a windowsill do? We detected some activation of the motor cortex in a period of time corresponding to the extraction of the verb meaning from the memory. When it was difficult to come up with a verb, motor activation was stronger, which confirms our hypothesis,” Anna Pavlova, a laboratory assistant at the MSUPE MEG Centre said.
According to the authors of the study, knowing how a healthy brain copes with such difficulties is the key to understanding and treating a number of pathological conditions, including, for example, Broca’s aphasia.
With Broca’s aphasia, the difficulty in extracting words from memory is a leading symptom. There is an effective treatment for this disease, but it’s not effective for all patients. The MSUPE researchers want to establish whether the effectiveness of such therapy can be predicted from the results of MEG recordings of the brain when generating verbs.