Neurológia pre prax 1/2015

Reaction time proper. Unilateral tumour of the frontal lobe-does it affect the reaction time?

In 51 patients with unilateral involvement of the anterior frontal cortex, the reaction time of hand movement to a somesthetic stimulus was assessed. The actual reaction time (the reaction time left after subtracting the time taken for a stimulus to reach the brain and the time of brain output to muscle) is independent of the site, size, and tissue composition of a frontal lobe tumour of the cerebrum. Extensive gliomas of the dorsolateral prefrontal cortex and those of the orbitofrontal cortex, large convexity meningiomas, and parasagittal meningiomas failed to cause a significant disturbance in the reaction time. The actual reaction time in unilateral frontal lobe tumours of the cerebrum is not laterally different. In 87% of those investigated, it ranged from 110 to 260 ms. The actual reaction time, corresponding to the time taken to process a decision to move and to produce a movement pattern, is provided by the neuronal system resistant to focal involvement of the anterior frontal cortex. This finding is an important clue for surgeries in the premotor area.

Keywords: reaction time, preparation of movement to an external stimulus, frontal lobe tumours.