As part of a research project for a biological psychology class, you are assigned to work with experienced researchers who have access to equipment that allows you to study the human brain. Describe two electrical in vivo techniques and how they would allow you to learn about the human brain

Question

What will be an ideal response?

Answer 1

Electroencephalograms (EEGs) are recordings of the electrical frequencies and intensities of the living brain, typically recorded over relatively long periods. Through EEGs, it is possible to study brainwave activity indicative of changing mental states such as deep sleep or dreaming. To obtain EEG recordings, electrodes are placed at various points along the surface of the scalp. The electrical activity of underlying brain areas is then recorded. The information, therefore, is not localized to specific cells. The EEG is sensitive to changes over time. For example, EEG recordings taken during sleep reveal changing patterns of electrical activity involving the whole brain. Different patterns emerge during dreaming versus deep sleep. EEGs are also used to diagnose epilepsy because they can indicate whether seizures appear in both sides of the brain at the same time, or whether they originate in one part of the brain and then spread.

To relate electrical activity to a particular event or task (e.g., seeing a flash of light or listening to sentences), EEG waves can be measured when participants are exposed to a particular stimulus. An event-related potential (ERP) is the record of a small change in the brain's electrical activity in response to a stimulating event. The fluctuation typically lasts a mere fraction of a second. ERPs provide good information about the time- course of task-related brain activity. In any one EEG recording, there is a great deal of "noise"—that is, irrelevant electrical activity going on in the brain. ERPs cancel out the effects of noise by averaging out activity that is not task-related. Therefore, the EEG waves are averaged over a large number (e.g., 100) of trials to reveal the ERPs. The resulting wave forms show characteristic spikes related to the timing of electrical activity, but they reveal only general information about the location of that activity (because of low spatial resolution as a result of the placement of scalp electrodes).