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)