VI. Give the summary of the text. Unit 2 How the Brain is Studied

Цель – формирование представлений студентов об изучении человеческого мозга, использование знания иностранного языка в профессиональной деятельности и профессиональной коммуникации.

Key words

brain concussion	сотрясение мозга
stroke	удар, инсульт
injury	травма
surgical ablation	удаление
tumors	опухоль
tissue	ткань
sensations	ощущения
appropriate	соответствующий
assess	оценивать
damage	повреждать, повреждение
determine	определять
device	прибор, устройство
hemisphere	полушарие
ingenuity	изобретательность, мастерство
removal	удаление
require	требовать
surgery	хирургия, операция

Text

The brain is a very complex structure and great ingenuity is required to discover how it operates. How can we tell whether a particular part of the brain is associated with a particular behavior? Historically, the question of localization of brain function — whether certain brain areas control specific acts or functions — has been a topic of debate. Technological advances in recent years have made it possible to study the brain more precisely than ever before. It is now well established that some functions are localized in fairly circumscribed brain areas: speech, recognition of spoken words, and the production of motor responses are examples. All areas of the human brain are not equipotential. On the other hand, many different brain regions are involved in such higher mental processes as reasoning and problem solving. In addition many functions are duplicated in more than one brain area. Thus, if one part of the brain is damaged by concussion or stroke, other areas can often take over its functions.

The following methods are the ones used most often by physiological psychologists and neurophysiologists in studying the brain.

1. Injury or surgical ablation. Noting the kind of symptoms produced when tumors or injuries damage certain parts of the brain may give clues about functions controlled by the area. Early observations that injury to the left side of the brain usually resulted in speech defects, whereas damage to the right side did not, led to localization of a speech center in the left cerebral hemisphere. Improved methods of locating the area of injury and assessing the kind of language functions disturbed have specified more exactly the areas involved in different linguistic abilities.

In experiments with animals it is possible to remove systematically parts of the brain (or destroy the tissue electrically) and observe the kinds of defects that result. Sometimes ablation operations are performed on human patients when the removal of abnormal brain tissue is essential to their well-being (for example, to remove tumors or control epilepsy). Such patients are carefully studied to assess the effects of the operation on their abilities.

2. Electrical or chemical stimulation. Stimulating parts of the brain with mild electrical currents produces effects on behavior. Brain surgery on human patients is often done under local anesthesia, so the surgeon can tell (by the patient's responses when different parts are stimulated electrically) which area to remove.

From patient reports of sensations during stimulation, fairly accurate maps of the cortex have been obtained.

Studies with permanently implanted electrodes in animals help determine where sensory effects occur and where various types of muscular activity are controlled. Chemical stimulation has also been widely used to affect behavior.

3. Electrical effects of neural activity. When neural action occurs, slight electrical currents are produced. By inserting at appropriate places electrodes connected to measuring devices, the experimenter can detect whether impulses starting at, say, the ear reach the part of the brain where the electrodes are inserted.

The brain as a whole also produces rhythmical electrical discharges. The record of these total brain discharges, known as an electroencephalogram (EEG), plays its part in the study of central nervous system activity.

Results obtained by these methods further our psychological understanding.

EXERCISES