How Psychologists Study the Brain

Chapter 6, Section 2

Recording

• Electrodes can be inserted into the brain to record activity.– Can detect changes that occur when neurons fire.

• EEG: Attached to the scalp so many neurons can be monitored at once.

• Electrical activity of the brain rises and falls rhythmically.– Depends on wakefulness or sleepiness. – They are called brain raves.

Stimulation

• Electrodes can also set off the firing of neurons.

• Wilder Penfield– Stimulated the brains of patients during surgery to

determine functions various parts of the brain perform.

Lesions

• Cutting/destroying parts of the brain.– Sometimes scientists create these in animal

testing.

Accidents

• Learning from tragedy.• Phineas Gage, 1848– Respected railroad foreman, who executed good

judgment, and worked well with others.– Tamped a narrow hole with dynamite, and it

exploded. – Tamping iron weighed 13 lbs and 3 feet long.

Entered Gage’s head below the left eye, and exited through the top of the skull.

– Gage survived, but his personality changed greatly. Caused damaged to the frontal cortex.

• CT Scans– Moving ring passes X-ray

beams around and through a subject’s head. Radiation is absorbed, depending on brain tissue density.

– This produces a 3-D view of the brain.

• PET Scans– Injecting a radioactive

solution into the blood and measuring amount of radiation absorbed.• Active neurons absorb more

solution.

Images

• MRI– Combines features of CT

and PET scans.– Radio frequencies– Detailed images of the

brain– Structure /Tumors

• fMRI– Observe the functions of

different structures and specific functions.

– Determined by blood oxygen level

Images, (cont’d)