Sydelene Igno
BRAIN RESEARCH METHODS
Case Studies
Description: is an intensive, in-depth investigation of some behavior or event of interest in an individual, small group or situation. It is to develop a detailed profile of a client & may involve a combination of data-collection techniques
Key Feature: The method is used when large number of participants is not available for study
How the technique is used: The client may be interviewed at length. Information may also be collected through interviews of family members, friends, & teachers or co-workers. The client’s medical records & school reports may also be considered. It can also include extensive psychological testing & observations of the person’s behavior
Research Example: The earliest & best-known case studies of brain damage are that Phineas Gage, which was reported by his Doctor John Harlow in 1848. Gage was a railway construction supervisor who accidentally exploded gunpowder that sent an iron rod through his skull, causing massive damage to his frontal lobes. He survived his temperament (mood), social behavior & personality changed very noticeably after the accident. The last sentence of his doctor’s report reads, ‘His mind was radically changed, so decidedly that his friends & acquaintances said that he was “no longer Gage.” The case provided an early insight in the roles of the upper front area (frontal lobes) in mental processes & behavior
Advantages:
- Provide useful way of obtaining detailed & valuable information on mental processes & behavior, particularly in relation to rare/unusual disorders
- No manipulation/control of variables
-Can avoid artificially & provide a ‘snapshot’ of the actual or real-life experience of one or more individuals at a particular time in a particular situation
- Provide insights into how others may think, feel or behave under similar circumstances
Limitations:
- The process of analyzing, summarizing & reporting these data can be a time-consuming process
- Generalising/applying the results to others in the population, particularly those without rare disorder or ability, cannot be done with certainty
- More susceptible to biased information from the patient or researcher
Direct Electrode Stimulation
Description: Involves using a device that emits a weak electric current to activate or disrupt the normal activity of neurons in a specific brain area. It can be done by using electrode or with transcranial magnetic stimulation.
Key Feature: The electrode can be used to deliver a precisely regulated electric current to the brain, thereby directly stimulating a specific brain area
How the technique is used: An electrode is a small, electrified fine wire/ disc that is inserted into or placed onto a specific area of the brain. It can be used to deliver a precisely regulated electric current to the brain, thereby directly stimulating a specific brain area
Research Example: In a recent study of six patients who had failed to respond to ‘treatment resistant remission of depression’ following stimulation through electrodes planted deep in their brain. The stimulation served to reduce activity in area believed by the researchers to be overactive in depression. After the treatment, it was reported of mental experiences such as a ‘disappearance of the void’ & a sense of ‘connectedness.’
Advantages:
- Very effective technique for brain research
- Use of electrodes has been useful & reliable
- Using this technique has advanced our understanding of the role of the brain in mental processes & behavior
- Provided means for researchers to identify the locations & functions of numerous brain structures & areas, as well as hemispheric specialization for different functions
Limitations:
- Extremely invasive research procedure, that imposes risks which may be considered unacceptable
- Involves difficulties in generalizing the results – it is very difficult to generalize the results to people with normal healthy brains
Single-Pulse TMS (Transcranial Magnetic Stimulation)
Description: It is a general term for a direct brain stimulation technique that delivers a magnetic field pulse through the skull and temporarily activates or disrupts the normal activity of neurons in a specific area of the cerebral cortex
Key Feature: The magnetic field induces a harmless electrical current in time-varying charges (‘pulses’)
How the technique is used: While receiving stimulation, the person is fully alert & awake. It is a non-invasive procedure & there is no need for substances to be taken or for anaesthetic to be controlled. The magnetic field pulse is transmitted from a small copper electromagnetic coil that is enclosed in plastic and placed next to the scalp. An electric current is sent through the coil, which induces a magnetic field around the coil & creates the pulse. Single pulse is then directed through skin & scalp to underlying clusters of neurons.
Research Example: TMS was used in volunteers to induce isolated thumb movements in a particular direction by stimulating the area of the cortex responsible for thumb movement. The participants were then required to practice moving their thumb in a different direction for 15 – 30 minutes. When TMS was used again on the same area of the cortex, it was found that to induce thumb movement in the new direction for several minutes before the response goes back to the original direction
Advantages:
- Can be used in clinical settings for diagnostic purposes to help pinpoint specific areas of cortical brain damage & to track patient recovery
- Completely safe & harmless
Limitations:
- If the researcher stimulates at the wrong time, TMS will not disrupt the cognitive process of research interest
rTMS (Repetitive Transcranial Magnetic Stimulation)
Description: It is used in procedures involving repeated, but not necessarily rapid, delivery of a pulse.
Key Feature: It can be used with patients who have suffered a stroke, head or spinal injury & show signs of brain damage. Can also be sued for pre-surgical assessment of patients with brain tumours and suffering from neuronal diseases; E.g. affecting motor skills – Parkinsons, motor neuron disease & multiple sclerosis
How the technique is used: When rTMS is used, the consecutive pulses cause the neurons to lose their ability to fire. This results in suppression to their activity & consequently brain activity in the stimulated area. This is ‘turning off’ a small area of the brain without causing any damage or unwanted side effects
Research Example: In mid 1990’s, it was studied as a therapy for depression. In an independent-groups experiment using double-blind procedure, 67 Israelis with major depression were randomly allocated to two groups. One group received rTMS to the cortex of the left frontal lobe daily for 30 minutes over a two-week period, while the other group received a placebo treatment without TMS.AT the end of the two weeks, half of the stimulated patients showed at least 50% improvement in their scores on a scale (test) used to measure depression, as in comparison with a 25% improvement in the placebo group (Myers, 2007)
Advantages:
- Can be used to study how the brain organizes different functions such as language, memory, vision or attention
- Researchers can now temporarily create brain ‘malfunction’ &stimulate brain damage, permitting them to perform experiments with human participants that would otherwise not be possible
Limitations:
- Most common side effect is scalp pain or discomfort during treatment session. A mild headache at site of stimulation following rTMS
The magnetic field affects only that part of the brain that lies immediately below the skull
EEG (Electroencephalograph)
Description: Can be used to detect, amplify & record general patterns of electrical activity of the brain
How the technique is used: The electrical activity constantly produced by the billions of neurons in the brain, particularly neurons in the cerebral cortex just below the scalp, can be detected by small electrodes that are attached (taped/pasted) to the surface of the scalp at the top & sides of the head. A patient maybe required to wear a device that looks like a swimming cap, with electrodes attached. It amplifies & translates the relatively weak electrical activity in areas of the brain beneath the electrodes in a visual pattern of brain waves. They are then recorded & displayed as a graph on a computer monitor or as a moving sheet of graph paper
Key Feature: Brainwaves are used in conjunction with other physiological & psychological measures to help identify & describe an individual’s state of consciousness
Research Example: When alert & active during normal waking consciousness – the beta wave EEG pattern occurs with high-frequency (fast) & low amplitude (small) brain waves. When an individual is extremely relaxed or in a meditative state, the alpha brain wave pattern is evident
Advantages:
- Can help your healthcare provider identify any other abnormalities existing in the brain, such as a coma or the presence of a tumor or a stroke.
CT (Computerised Tomography)
Description: It is more specifically more specifically referred to as a neuroimaging technique that produces a computer enhanced image of a cross-section (‘slice’) of the brain X-rays taken from different angles.
Key Feature: It involves moving an X-ray in an arc around the head while a computer complies different ‘snapshots’ of the brain area being investigated
How the technique is used: The participant must first receive an injection of a substance (contrast, based on iodine) into the arm/ hand. It is used to highlight the brain’s blood vessels & greatly assists the radiologist & researcher in interpreting CT images. During the procedure, the participant is required to live very still on the CT scanner bed with their head inserted into the scanner opening. An x-ray detector opposite the x-ray source & detectors are then moved to a new position, & then the procedure is repeated many times. A computer then combines the many cross-sectional images taken from all different angles around the head into a composite cross-sectional, two-dimensional/three-dimensional image.
Research Example: CT scan help identify the location & size of tumors & the location & extent of damage caused by a stroke, injury or other brain disorder.
Advantages:
- Useful for spotting & identifying the precise location & extent of damage to or abnormalities in various brain structures/areas
- Provides a new way of looking at a live intact human brain without using invasive, dangerous procedures
Limitations:
- It shows only brain structure/anatomy. It does not provide information about the activity of the brain; that is brain function
MRI (Magnetic Resonance Imaging)
Description: A neuroimaging technique that uses harmless magnetic fields & radio waves to vibrate atoms in the brain’s neurons to produce an image of the brain
Key Feature: three-dimensional imaging
How the technique is used: The vibrations are detected by a huge magnet in the chamber surrounding the motionless person, & are channeled into a computer. It then processes the vibrations & assembles them into a coloured image that indicates areas of high & low brain activity. It can also analyze the signals for subtle differences that identify the type of brain tissue that generated them, such as blood, nerve fibres or membranes. It provides an image of the brain & structures that is clearer & more detailed. It is used for diagnosing structural abnormalities of the brain & can be used to detect & display extremely small changes in the brain.
Research Example: MRI’s can more clearly distinguish between brain tissue that is cancerous & non-cancerous. The image can reveal tissue degeneration & blood clots & leaks that may indicate a stroke
Advantages:
- Enabled more precision in the study of the structure of the live human brain in a non-invasive & harmless way
- Invaluable for determining damage or abnormalities to particular brain areas or structures in photographic quality
- It does not use X-rays or radioactive substances
Limitations:
-Like other neuroimaging devices it cannot be used with people who have internal metallic devices such as heart pacemakers or steel pins in bones
- For brain study, it can show only brain structure/anatomy & not function
PET (Positron Emisson Tomography)
Description: Is a neuroimaging technique that uses a radioactive tracer to enable production of a computer-generated image that provides information about brain structure, activity & function during tasks
Key Feature: Used to record levels of activity in different areas of the brain, while the participant is involved with cognitive activity or behavioral activity such as thinking, imagining, remembering, talking or moving a body part
How the technique is used: In PET simple tasks are set. It provides images of the working brain by tracking blood flow around the brain. Blood flow is tracked by measuring the use of glucose by neurons in the brain area that is active. A harmless radioactive substance is injected into the blood vessels of the patient. It travels to the brain. As a particular area of the brain is activated during some mental process or behavioral response, the radioactive substance in the blood, which serves as a tracer that can be followed, send out radioactive signals. The signals are detected by a sensitive electronic device & recorded in the PET computer. The computer then compiles the signals into images called PET scans. The use of colour code is used to indicate different levels of brain activity
Research Example: PET scans can compare different areas of brain activity in individuals with schizophrenia & depression. In studies of people with schizophrenia, it has been found that when individuals indicate that they are hearing voices, activation of the auditory cortex in the temporal lobe is evident in the PET scan
Advantages:
- Useful technique for brain study & has enabled researchers to obtain valuable information about the role of the brain in behavior & mental processes
- Advanced our understanding of how the brain functions
- Enables detailed images of the functioning brain as it performs tasks
- People without brain damage can be sued in research studies – overcomes the criticism that patients with brain damage sometimes compensate & complete tasks differently from those who have no brain damage
- The use of colour coding makes it simple to identify areas of the brain that are active or inactive
Limitations:
- Researchers cannot determine whether an active brain area is actually involved in the mental process or behavior under investigation
- PET scanning is that because the radioactivity decays rapidly, it is limited to studying short tasks
- Needs a 40 second interval between each scan & each individual scan takes 30 seconds to complete – meaning it doesn’t necessarily pick up the very rapid progression/ changes, in brain activity associated with different brain functions