Another technique that is worth mentioning is transcranial magnetic stimulation (TMS). TMS is a noninvasive method that causes depolarization or hyperpolarization in neurons near the scalp. In TMS, a coil of wire is placed just above the participant’s scalp (as shown in Figure 2.5.12.5.1\PageIndex{1}). When electricity flows through the coil, it produces a magnetic field. This magnetic field travels through the skull and scalp and affects neurons near the surface of the brain. When the magnetic field is rapidly turned on and off, a current is induced in the neurons, leading to depolarization or hyperpolarization, depending on the number of magnetic field pulses. Single- or paired-pulse TMS depolarizes site-specific neurons in the cortex, causing them to fire. If this method is used over primary motor cortex, it can produce or block muscle activity, such as inducing a finger twitch or preventing someone from pressing a button.

TMS is able to explore neural plasticity, which is the ability of connections between neurons to change. This has implications for treating psychological disorders as well as understanding long-term changes in neuronal excitability.

Functional imaging techniques allow researchers to learn about the brain activity during various tasks by creating images based on the electrical activity or the absorption of various substances that occurs while a subject is engaging in a task.

Within functional imaging techniques, researchers are frequently focused on one of two questions. They may ask “When does this activity occur?” Or “Where does this activity occur?” Some techniques are better for answering one of these questions, whereas other techniques are better for answering the other question. We describe how well a technique can determine when the activity has occurred as temporal resolution. For example, was the brain region activity occurring sometime in the last hour, the last minute, the last second, or within milliseconds? While some techniques are excellent at determining precisely when the activity occurred and other techniques are quite terrible at it. Additionally, we can describe how well a technique can determine where the activity has occurred as spatial resolution. For example, did the activity occur in the temporal lobe somewhere or can we narrow that down to a specific gyrus (ridge) or sulcus (groove) of the cerebral cortex? If it occurred on a particular gyrus can we narrow it down to a particular portion of that gyrus? As with temporal resolution, some techniques are excellent at determining precisely where the activity occurred whereas other techniques are less accurate.

Many researchers are also interested in how the brain works. Some studies begin with the scientific question of “what does this part do?” Or more commonly, “Where in the brain does this happen?” Functional imaging techniques allow researchers to learn about the brain activity during various tasks by creating images based on the electrical activity or the absorption of various substances that occurs while a subject is engaging in a task. Such techniques can be used, for example, to visualize the parts of the brain that respond when we're exposed to stimuli that upset us or make us happy.

We have come a long way since Phineas Gage with how we study the brain. Many techniques now allow us to understand how the brain works without waiting for a horrific accident to occur or conducting some sort of surgery (although, as you will see, we still use surgical techniques to study the brain). Techniques have been developed that allow us to see what the brain looks like, as a still image (structurally) or in action (functionally).

This chapter will describe the various ways that biological psychologists study the brain. There are many ways to categorize the techniques that are used when studying the brain. We will start by covering the non-invasive techniques, where we are able to study the brain without getting direct physical access to the brain (think of fixing a broken pipe in a wall without having to open the wall up). Then we will move into the invasive techniques, where we study the brain by having direct access (an example would be fixing a broken pipe in a wall by tearing a hole in the wall). Then we will discuss various neuropsychological techniques, where we learn about the brain using people with some sort of brain “issue.” For example, people with epilepsy have been extensively studied and we can learn a lot about how the brain works from them. Finally, the last section will address ethical considerations of biological psychology research.

Positron emission tomography (PET) is a medical imaging technique that is used to measure processes in the body, including the brain (see Figure 2.4.32.4.3\PageIndex{3} for a PET scanner). This method relies on a positron-emitting tracer atom that is introduced into the blood stream in a biologically active molecule, such as glucose, water, or ammonia. A positron is a particle much like an electron but with a positive charge. One example of a biologically active molecule is fludeoxyglucose, which acts similarly to glucose in the body. Fludeoxyglucose will concentrate in areas where glucose is needed—commonly areas with higher metabolic (energy) needs. Over time, this tracer molecule emits positrons, which are detected by a sensor. The spatial location of the tracer molecule in the brain can be determined based on the emitted positrons. This allows researchers to construct a three-dimensional image of the areas of the brain that have the highest metabolic needs, typically those that are most active. Images resulting from PET usually represent neural activity that has occurred over tens of minutes, which is very poor temporal resolution for some purposes. PET images are often combined with computed tomography (CT) images to improve spatial resolution, as fine as several millimeters. Tracers can also be incorporated into molecules that bind to neurotransmitter receptors, which allow researchers to answer some unique questions about the action of neurotransmitters. Unfortunately, very few research centers have the equipment required to obtain the images or the special equipment needed to create the positron-emitting tracer molecules, which typically need to be produced on site.

Functional magnetic resonance imaging (fMRI) is a method that is used to assess changes in the activity of tissue, such as measuring changes in neural activity in different areas of the brain during thoughts or experiences. This technique builds on the principles of structural MRI techniques and also uses the property that, when neurons fire, they use energy, which must be replenished. Glucose and oxygen, two key components for energy production, are supplied to the brain from the blood stream as needed. Oxygen is transported through the blood using hemoglobin, which contains binding sites for oxygen. When these sites are saturated with oxygen, it is referred to as oxygenated hemoglobin. When the oxygen molecules have all been released from a hemoglobin molecule, it is known as deoxygenated hemoglobin. As a set of neurons begin firing, oxygen in the blood surrounding those neurons is consumed, leading to a reduction in oxygenated hemoglobin. The body then compensates and provides an abundance of oxygenated hemoglobin in the blood surrounding that activated neural tissue. When activity in that neural tissue declines, the level of oxygenated hemoglobin slowly returns to its original level, which typically takes several seconds. Figure 2.4.12.4.1\PageIndex{1} shows a subject about to go into a functional MRI machine.

Indirect brain imaging techniques rely on an assumption that activity in the brain correlates to something else that we are able to measure. In these cases, these techniques measure blood flow in the brain. The assumption is that blood flow in the brain is related to the activity level in that area of the brain. Of course, with any assumption, there is always the risk that it could be wrong. Thankfully there is extensive research examining this assumption and the scientific consensus currently is that blood flow is an appropriate indication of brain activity. The two main indirect brain imaging techniques that we will cover are functional MRI (fMRI) and positron emission tomography (PET).

EEG and MEG have been used to examine ASD. One of the findings included a delay in the brain wave associated with auditory stimuli. In short, there are differences in the time for processing auditory sounds in children with ASD compared to those without ASD. Furthermore, this delay appears more pronounced in children with ASD who have language developmental delays as opposed to children with ASD without linguistic delays (Roberts et al., 2019). This delay has even been proposed to help clinicians diagnose autism in young children.

Direct imaging techniques are those that allow for a direct measure of brain activity. EEG and MEG are both considered direct brain imaging techniques since EEG measures the electrical activity from groups of neurons and MEG measures the magnetic fields that the electrical activity gives off. Neither of these techniques relies on measuring something else with an assumption that they are linked. This is not true in the next set of techniques we will discuss.

Magnetoencephalography (MEG) is another technique for noninvasively measuring neural activity. The flow of electrical charge (the current) associated with neural activity produces very weak magnetic fields that can be detected by sensors placed near the participant’s scalp. Figure 2.3.32.3.3\PageIndex{3} depicts a subject in an MEG machine. The number of sensors used varies from a few to several hundred. Due to the fact that the magnetic fields of interest are so small, special rooms that are shielded from magnetic fields in the environment are needed in order to avoid contamination of the signal being measured. MEG has the same excellent temporal resolution as EEG. Additionally, MEG is not as susceptible to distortions from the skull and scalp. Magnetic fields are able to pass through the hard and soft tissue relatively unchanged, thus providing better spatial resolution than EEG. MEG analytic strategies are nearly identical to those used in EEG. However, the MEG recording apparatus is much more expensive than EEG, so MEG is much less widely available.

Given that this electrical activity must travel through the skull and scalp before reaching the electrodes, localization of activity is less precise when measuring from the scalp, but it can still be within several millimeters when localizing activity that is near the scalp. While EEG is lacking with respect to spatial resolution, one major advantage of EEG is its temporal resolution. Data can be recorded thousands of times per second, allowing researchers to document events that happen in less than a millisecond. EEG analyses typically investigate the change in amplitude (wave height) or frequency (number of waves per unit of time) components of the recorded EEG on an ongoing basis or averaged over dozens of trials (see Figure 2.3.22.3.2\PageIndex{2}). The EEG has been used extensively in the study of sleep. When you hear references to "brain waves", those are references to information obtained using EEG.

Electroencephalography (EEG) is one technique for studying brain activity. This technique uses at least two and up to 256 electrodes to measure the difference in electrical charge (the voltage) between pairs of points on the head. These electrodes are typically fastened to a flexible cap (similar to a swimming cap) that is placed on the participant’s head. Figure 2.3.12.3.1\PageIndex{1} shows a patient wearing such a cap. From the scalp, the electrodes measure the electrical activity that is naturally occurring within the brain. They do not introduce any new electrical activity.

One example that we will use throughout this chapter is that of how we use these research techniques to study Autism Spectrum Disorder (ASD). ASD is a developmental disorder frequently characterized by issues including various combinations of interaction issues, communication difficulties, and even repetitive behaviors. Throughout each section, we will discuss some of the ways the main tools of brain research have been used to examine this disorder. Structural imaging techniques with ASD have focused on which brain structures have physical differences. MRIs have found a thicker frontal cortex (Carper & Courchesne, 2005) and a thinner temporal cortex (Hardan et al., 2006) in patients with ASD. These areas are notable because the frontal cortex is linked to communication and language abilities and the temporal cortex is linked to auditory processing (ie. language input), both of which are issues that many with ASD struggle with.

Magnetic resonance imaging (MRI) is a noninvasive medical imaging technique based on a phenomenon of nuclear physics discovered in the 1930s, in which matter exposed to magnetic fields and radio waves was found to emit radio signals. In 1970, a physician and researcher named Raymond Damadian noticed that malignant (cancerous) tissue gave off different signals than normal body tissue. He applied for a patent for the first MRI scanning device, which was in use clinically by the early 1980s. The early MRI scanners were crude, but advances in digital computing and electronics led to their advancement over any other technique for precise imaging, especially to discover tumors. MRI also has the major advantage of not exposing patients to radiation. Drawbacks of MRI scans include their much higher cost, and patient discomfort with the procedure. The MRI scanner subjects the patient to such powerful electromagnets that the scan room must be shielded. The patient must be enclosed in a metal tube-like device for the duration of the scan, sometimes as long as thirty minutes, which can be uncomfortable and impractical for ill patients. The device is also so noisy that, even with earplugs, patients can become anxious or even fearful. These problems have been overcome somewhat with the development of “open” MRI scanning, which does not require the patient to be entirely enclosed in the metal tube. Figure 2.2.42.2.4\PageIndex{4} shows an MRI machine with a platform for the patient to lie on. Patients with iron-containing metallic implants (internal sutures, some prosthetic devices, and so on) cannot undergo MRI scanning because it can dislodge these implants.

Tomography refers to imaging by sections. Computed (or computerized) tomography (CT) is a noninvasive imaging technique that uses computers to analyze several cross-sectional X-rays in order to reveal small details about structures in the body. The technique was invented in the 1970s and is based on the principle that, as X-rays pass through the body, they are absorbed or reflected at different levels. In the technique, a patient lies on a motorized platform while a computerized axial tomography (CAT) scanner rotates 360 degrees around the patient, taking X-ray images. Figure 2.2.22.2.2\PageIndex{2} shows a CT scanner with a platform for the subject to lie on. A computer combines these images into a two-dimensional view of the scanned area, or “slice.” Figure 2.2.32.2.3\PageIndex{3} shows a series of slices of the brain for one subject. Figure 2.2.22.2.2\PageIndex{2}: A CT scanner at the University of Pittsburg Medical Center East. Figure 2.2.32.2.3\PageIndex{3}: A series of axial CT scans of the brain of one subject. Each image is a slice of the brain starting with a bottom slice and incrementally moving to higher and higher slices. Since 1970, the development of more powerful computers and more sophisticated software has made CT scanning routine for many types of diagnostic evaluations. It is especially useful for soft tissue scanning, such as of the brain and the thoracic and abdominal viscera. Its level of detail is so precise that it can allow physicians to measure the size of a mass down to a millimeter. The main disadvantage of CT scanning is that it exposes patients to a dose of radiation many times higher than that of X-rays. Whether this is particularly dangerous is still being debated (McCollough et al., 2015).

German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible “ray” would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an “X-ray” image (as it came to be called) of his wife’s hand. Scientists around the world quickly began their own experiments with X-rays, and by 1900, X-rays were widely used to detect a variety of injuries and diseases. In 1901, Röntgen was awarded the first Nobel Prize for physics for his work in this field. The X-ray is a form of high energy electromagnetic radiation with a short wavelength capable of penetrating solids and ionizing gases. As they are used in medicine, X-rays are emitted from an X-ray machine and directed toward a specially treated metallic plate placed behind the patient’s body. The beam of radiation results in darkening of the X-ray plate. X-rays are slightly impeded by soft tissues, which show up as gray on the X-ray plate, whereas hard tissues, such as bone, largely block the rays, producing a light-toned “shadow.” Thus, X-rays are best used to visualize hard body structures such as teeth and bones. Figure 2.2.12.2.1\PageIndex{1} depicts an X-ray of a knee. Like many forms of high energy radiation, however, X-rays are capable of damaging cells and initiating changes that can lead to cancer. This danger of excessive exposure to X-rays was not fully appreciated for many years after their widespread use.

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They use several credit cards so they don’t have to worry about finances until after graduation.

They have few friends, because social relationships distract one from academics.

They eat fast food so they have more time for studying.

They develop their writing skills.

They avoid talking with their instructors, so they can remain anonymous.

They know how to speed-read so they don’t have to underline or highlight in their textbooks.

They know better than to try to think on their own.

They don’t need to schedule study periods because they study at every available moment every day.

They know how to stay motivated.

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They use several credit cards so they don’t have to worry about finances until after graduation.

They have few friends, because social relationships distract one from academics.

They eat fast food so they have more time for studying.

They develop their writing skills.

They avoid talking with their instructors, so they can remain anonymous.

Are you a “traditional” or “returning” student? List an important advantage you have as a result of being in this classification:

They know how to speed-read so they don’t have to underline or highlight in their textbooks.

They know better than to try to think on their own.

They don’t need to schedule study periods because they study at every available moment every day.

They know how to stay motivated.

Most college graduates later look back on their college years as one of the best times in their lives.

To do well in college, you basically have to give up everything else in life for a while.

If you sit back, wait patiently, and stick it out long enough, success in college will inevitably come to you.

Attitude is one of the most important factors affecting college success.

Life in college usually differs in many ways from one’s previous life in high school or in the workforce. What are the biggest changes you are experiencing now or anticipate experiencing this term?

What do you value that will you likely have less time or money to spend on while in college?

What do you value that will be richer in your future life because you will have a college education?

Which of the following are benefits of a college education?

Participating in clubs, organized activities

Going to parties

Talking on the telephone, texting, e-mail

Going to religious services

Attending classes

Cleaning house

Volunteering your time for a good cause

Setting your own schedule

Engaging in your hobbies

Having a positive romantic relationship

Being your own boss

Exercising, being physically active

Eating nice meals out

Going to movies or entertainments

Meeting new people

Looking good, personal hygiene

Working your job

Getting out in nature

Enjoying time alone

Watching television

Having nice clothing

Studying and reading textbooks

Being liked by others

Shopping

Traveling to new places

Reading a good book

Sleeping

Online social networking

Cooking

Playing computer or video games

Hanging out with friends

Playing sports

taying current with the news

Having intelligent conversations

Having a nice car

Learning new things about your interests

Having good friends

Making a good income

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Most college graduates later look back on their college years as one of the best times in their lives.

To do well in college, you basically have to give up everything else in life for a while.

If you sit back, wait patiently, and stick it out long enough, success in college will inevitably come to you.

Attitude is one of the most important factors affecting college success.

Life in college usually differs in many ways from one’s previous life in high school or in the workforce. What are the biggest changes you are experiencing now or anticipate experiencing this term?

What do you value that will you likely have less time or money to spend on while in college?

What do you value that will be richer in your future life because you will have a college education?

Which of the following are benefits of a college education?

Make sure you budget time in your speech preparation to work on the speaking outline.

Despite the fact that first impressions aren’t formed with much conscious effort, they form the basis of inferences and judgments about a person’s personality

While this is an important contribution to society, Wikipedia is not considered a scholarly or credible source.

At most colleges and universities, you can find a reference librarian who has at least a master’s degree in library and information sciences, and at some larger or specialized schools, reference librarians have doctoral degrees.

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