How To Study Brain Functions ?

Methods Employed in Studying Brain functions.

Study of Brain is known as Anencephaly. 

Brain-psychotalks

The Anatomical method:-  It is used by anatomists and those who pursuing medical education.

In this method, in the post death phase of the organisms, its tissues are treated in such a way that nerve tracks can be viewed with the help of a microscope. Anatomists learn as to what sense organs sends fibers where and what parts of brain sends of motor fibers to the spinal cord.

 

The Method of extirpation or ablation (remove):-  Extirpation means cutting out or destroyed, it take help of neurosurgeons and get removed some portions of brain tissue or destructive electric current applied through electrodes and resultant behavioural changes are observed. This kind of injuries whether experimental or accidental are termed as “lesions”.

 

Action potential method:- Researchers have some sensitive electrical recording devices. The neurons while conducting, produce electrical currents and the potential underlying them can be recorded. Some of these are tiny changes in electrical waves some other monitors of brain can detect differences in the amount of work going on in different sections of the brain, moment by moment.

 

The method of stimulation:- The area of brain Associated with sensation, can be mapped by stimulating patients brain, during surgical operation and obtained introspective report, and also observe as to which muscular part of the body make movement during stimulating of the brain.

 

In recent times, technique of stimulation has been developed with the help of electrodes fixed in the area of desired stimulation, a stiff wire positioned by a rack and pinion device is clamped to the head.

 

Chemical method:- some measured amount of drug or hormones are injected into test animals and resultant reactions are observed.(drug or hormones are independent variables while the resultant physical or behavioural changes are dependent variables)

 

Selective breeding:-  Experimenter raises a number of generations of plants and animals and systematically sort out each generation member and observe the changes occurred.

 

Theories of brain function:- 

 

Localisation theory of functions:-  Each part of the cerebrum perform definite functions which it can perform alone.

 

Localisation of function is the idea that certain functions (like,- language memory etc)have certain locations or areas within the brain. It could perform a definite function such as sensory, motor and Association function.

 

· Sensory function:- Johannes miller brought forth the doctrine of specific nerve energies. According to this, a sensory nerve produces certain type of experience even though it is stimulated. Example:- if back portion (occipital) of head of individual is struck , person “sees stars” because occipital lobe is related to vision.

 

· Motor function:- This area is narrower than sensory area. The structure of neurons of motor area is pyramidal tract. Three areas in the brain have been found to perform motor functions.

 

1) Primary area:- It concentrated in front of the fissure of Rolando which extends both- forward and backward. Long axons lead down from this area through spinal cord to the motor neurons, supplying motor nerve impulses. On stimulation of this area, some voluntary muscle-group have been found to respond. Conversely, when areas in this region are destroyed, impairment of movements occur.

 

2) Secondary area :- located near the fissure of Sylvius. But little is known about the functions of this area.

 

3) Supplementary motor area:- located in the longitudinal fissure near the middle line of the brain, involved in control of movement and with postural control and muscle tone.

 

Secondary and supplementary motor areas sends small axons to the nuclei in the interior of the cerebral hemisphere. Another small axon go to the nuclei in the brain stem and then make a chain of such neurons lead to spinal cord.

 

The short neuron system play a major role in the control of movement. If uncontrolled, disorderly movements happened such as trembling, jerks etc are caused as some part of it are damaged and can be cured.

 

· Association function:- Many large areas of the cerebral cortex which are unconnected with sensory motor processes are called association area. These areas perform integrative functions of the input coming from more than one sensory channel and perform higher order functions such as learning, memory and thinking, reasoning, emotionally charged activities, motivational behaviour etc.

 

Damage or injuries cause loss of connected functions. Disorders in association areas related to language are called “aphasias”. Some people fails to organise elementary sensory elements into Normal perception called “ agnosias” (inability to know).

 

The agnosias and aphasias on the basis of nature of the functions are of three types:- 

 

 Astereognosis:- loss of ability to recognise solid objects through the sense of touch.

 

Alexia:- “ word blindness” inability to recognise printed words.

 

Sensory aphasia:- “ word deafness” inability to recognise spoken words. 

 

Mass action theory or “ Equipotential theory” :-  it is the theory that the brain has the capacity ( in the case of injury) to transfer functional memory from the damaged portion of the brain to other undamaged portion of the brain. This hypothesis put forward by ‘karl Spence lashley’.

 

Memory can’t be localised to a single cortical area but is instead distributed throughout the cortex.

 

Different areas or part of the brain are more or less interchangeable functionally. The propounders of this view are franz, lashley, goltz, monakow etc.

 

It has been observed that impairment on injury in a particular area, though causes disturbance or almost complete loss of function connected with the area, but this is not a permanent loss of function. Gradually, owing to practice, the lost functions reoccur. It so happens because the adjoining area of the injured part takes over to discharge the function of the injured part such evidences go to prove that each area in the brain is equally potential to perform similar functions.

Hence, it is also called Equipotential theory.