Discuss the methods that scientists developed to map brain functions.
Mapping of brain was an important step to understand the specific function of each part of the brain. An instigator of this method was Marshall Hall. He decapitated animals, and examined their movements.
He observed that even after decapitation, animals would move for some time when the required nerve endings were stimulated. By this, he suggested that voluntary movements are dependent upon cerebrum, reflex action on the spinal cord and the medulla was responsible for respiratory movement
Another scientist Pierre Flourens destroyed parts of the brain to study the consequences. He stated that higher mental processes were carried out by the cerebrum, auditory and visions were in control of the mid brain, and cerebellum looked after the coordination. The medulla was responsible for the heart beat, respiratory functions, and other vital processes.
Another method to study brain functions was to perform autopsy, and study the brain. Broca a surgeon studied the brain of a dead man, who had problem speaking intelligibly. In the left hemisphere of cerebral cortex, lesions were found in the third frontal convolution. He named it ‘Speech centre’ but now it is known as broca’s area. This method was the clinical method because it was difficult to convince humans for extirpation.
Apart from the clinical method, electrical stimulation was another method. The method employed the use of electrodes having weak currents. This was done to study the cerebral cortex. It was found out that when certain parts were stimulated, it led to certain motor movements like the movement of back and front legs in dogs.