- Understand what neuropsychology is and what a neuropsychologist does.
- Gain knowledge of the basic structures and functions of the brain.
- Understand the tools a neuropsychologist uses, and what each can help diagnose and why.
- Understand the different areas that a neuropsychologist tests, and examples of tests that are used.
Psychological testing in health is mostly done by neuropsychologists in a field called neuropsychology. Neuropsychology is the study of the brain and how it relates to behavior. The neuropsychologist uses neuropsychological tests in order to test for dysfunction in the brain that affects behavior. Through these tests, neuropsychologists can identify disorders of the brain and spinal cord for further treatment or for the sake of gaining knowledge. It is also a diverse field which overlaps with the studies of psychological testing, neurology, and psychiatry.
Neuropsychologists study the brain in many different disorders. Some of these include how alcohol affects the functioning of the brain, how the AIDs virus changes brain functioning, problems in memory, the effects of Alzheimer's disease, deficiencies in language, motor and movement problems, malingering, injury or disease of the brain, epilepsy, and learning disabilities such as attention deficit hyperactive disorder.
Lateralization in the BrainEdit
In order to understand neuropsychological tests a basic understanding of the nervous system and brain. The nervous system is made of two parts, the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord, while the peripheral nervous system is made up of cranial nerves.
The central nervous system is the part of the nervous system that is more important to neuropsychologists, especially the function of the brain. The brain is made up of both neurons and glial cells. One of the characteristics of a normal adult brain is that it is lateralized into the right and left hemispheres. Lateralization is the separation of the function of both side of the brain.
In order to study the functions of each hemisphere, neuropsychologists study split-brain patients. Split brained patients have had the corpus callosum severed. This area of the brain is the major commisure, or major pathway for communication between the two hemispheres, in the brain. When it is severed, it's as if both sides of the brain operate independently of one another, thus it's like having two separate brains that are specialized for different tasks that can't communicate with one another; however, this lack of communication is short-lived since the brains other commisures (posterior, anterior, and hippocampal) start to take on additional functioning in order to allow for the hemispheres to communicate.
For example: "[a] patient with a split brain, when shown an image in their left visual field (the left half of what each eye sees), will be unable to say what they have seen. This is because the speech control center is in the left side of the brain in most people and the image from the left visual field is sent only to the right side of the brain. Since the two sides of the brain cannot communicate, the patient can't say what they are seeing. The person can, however, pick up a corresponding object with their left hand, since that hand is controlled by the right side of their brain." (en.wikipedia.org)
This example of a neuropsychological test in split-brained patients shows how neuropsychologists know that left hemisphere of the brain is dominant for speech. Other generalities is that the left hemisphere works in a sequential manner, it is also dominant for understanding language while the right hemisphere is better at understanding emotional tone of speech. The right hemisphere also works in simultaneous way and is better at spatial tasks.
Although these generalities in most people, it should be noted that not all people share this same type of lateralization. For example, many left-handers and a few right-handers have language dominance in the right hemisphere instead of in the left.
Wernicke and Broca's Areas
Two are of the brain that are specialized for language are Wernicke and Broca's Areas. Wernicke's Area is specialized in the ability to understand spoken language while Broca's Area is specialized in the ability to speak and use expressive language.
The Three AreasEdit
The brain is organized into three areas. The hindbrain, the midbrain, and the forebrain. The hindbrain is believed to be the most ancient part of the brain because it controls the most basic functions of life. In addition, it is also the closest area of the brain to the spinal cord or it is the lowest part of the brain. The hindbrain controls breathing, swallowing, vomiting, and blood pressure. It also is used for basic things such as general arousal, consciousness, muscle tone, posture, and hand eye movements.
The next higher level of the brain is the midbrain. The midbrain controls head and eye movements, and it is used to localize and follow visual stimuli as well as auditory stimuli. The diagnosis of dysfunction in the midbrain is done by neurologists, those who study the biological function of the brain, because this part of the brain deals with more with cranial nerves.
The last and most advanced area is the forebrain. The forebrain is composed of six major areas: the pineal body, thalamus, hypothalamus, hippocampus, basal ganglia, and the corpus callosum. The pineal body's major function is in the secretion of hormones. The second structure, the thalamus, is the area in which all sensory information is sent initially before it is projected to other areas. Next, the hypothalamus is the area in feeding, sexual behavior, sleeping, temperature regulation, emotional behaviors and movement. While the major role of the hippocampus is in memory. As for the basal ganglia, it is responsible for motor functions, in fact, damage to this area results in Parkinson's disease. Last, the corpus callosum, as mentioned above, allows both hemispheres to communicate with each other.
The brain is separated into four lobes: frontal, temporal, occipital, and parietal. The frontal lobe is responsible for executive functions and motor performance. For example, executive functions are the ability to plan, carry out the plan, organize, and to engage in goal directed behavior.
The temporal lobe is responsible for auditory information, sensations, long-term memory storage and control of biological drives such as aggression and sexuality. The occipital lobe is responsible for vision and the parietal lobe is responsible for sensory skills.
Neuropsychologists use a series of brain imaging techniques to localize the areas of dysfunction. First, the electroencephalograph (EEG). In this electrodes are placed on the skull and the EEG record the electrical activity of the brain. This tool is useful in diagnosing epilepsy because part of epilepsy is abnormal electrical activity which an EEG can measure.
The next imaging technique is computerized tomography (CT scan). In this, x-rays are passed through the brain measuring the density it. Because a CT scan can detect density differences it is helpful in identifying any abnormality in density, such as in the presence of cancer or blood clots.
Another technique is positron emission tomography (PET scan). In order to perform a PET scan, glucose is injected with a radioactive tracer and then the positrons are measured with the instrument. This works because glucose is permeable to the blood-brain barrier and the radioactive tracer can get into the brain. A PET scan helps to diagnose Alzheimer's disease and schizophrenia. This is because it can detect differences in glucose metabolism thus differences in brain functioning and structure which are affect by Alzheimer's disease and schizophrenia.
The last technique is the use of magnetic resonance imaging (MRI). In an MRI, atoms and radio waves scan the brain to determine the structure of the brain. Since this also can detect abnormalities it is useful in finding brain tumors. It also can determine neurological diseases if damage to brain areas can be detected in the MRI.
Neuropsychologists use many techniques in order to diagnose psychological disorders. The tests measure sensory input, attention and concentration, learning and memory, language, spatial skills, executive functions, and motor output. These different areas allow the neuropsychologist to determine the area in which the dysfunction exists.
Sensory input is important because humans need to hear, feel, smell and perceive incoming stimuli accurately to learn and function well. Neuropsychologists measure the senses to see if their is a deficiency or dysfunction. One example of a test is asking a blindfolded subject, after touching one hand, to determine what hand has been touched. This test determines if the sense of touch is operating correctly. In addition, a faint sound could be presented to one ear to test if hearing is working correctly.
Attention and concentration is the ability to attend to stimuli, sustain attention, shift attention, the ability to ignore irrelevant stimuli and the ability to divide attention to different tasks at the same time. Most attention tasks measure one component of attention. An example of an attention test is the continuous performance tests. This test measures sustained attention. In it, a person is asked to press a key when a certain letter or shape appears on the computer monitor. This test is used often to diagnose children with ADHD although it is not very reliable.
Another important area is learning and memory. Learning and memory are connected to each other and it is not meaningful to separate them in tests. Tests measure the various aspects of learning and memory such as short term memory, long term memory, auditory and visual memory, and verbal memory. Examples of tests for learning and memory is the Wechsler Memory Scale-3 (WMS-3).
The use and understanding of language is the ability to speak, write and read language. Expressive language is the ability to speak whereas receptive language is the ability to understand language. A deficiency in language skills due to brain damage is known as aphasia. There are two major forms of aphasia, Wernicke's aphasia and Broca's aphasia. Wernicke's aphasia is deficiencies understanding language and Broca's aphasia is difficulty producing language. Aphasia's can be determined using an MRI because the MRI will reveal structural damage to the brain.
To test executive functioning (conceptual reasoning, planning, organization, flexibility in thinking) the Wisconsin Card Sorting test can be used. In this test, a number of cards which have varying numbers, colors, and shapes are used. The subject is then asked to sort the cards according to different aspects of the cards. This tests for frontal lobe damage.
The last area in which neuropsychologists measure is motor output. The tests measure both motor speed and accuracy. One test is the finger tapping test. In this test, subjects are asked to tap their index fingers of both hands as fast as they can in one minute, the number of taps are counter as an indication of motor speed. As for the grooved pegboard tests, subjects are asked to put pegs in holes in a certain time with their left and right hand. The number of pegs put in the pegboard are counted also as an indication of motor speed.
- Neuropsychology: The study of the brain and it's function in a psychological context.
- Neuropsychologist: A qualified person who studied neuropsychology
- Central Nervous System (CNS): The part of the nervous system that consists of the brain and the spinal cord.
- Peripheral Nervous System (PNS): The part of the nervous system that consists of the cranial nerves in the extremities of the body.
- Brain Hemispheres: The fact that the there are two separate sides of the brain divided into the right and left hemisphere, which are joined together by one or more commisures.
- Right Hemisphere: The hemisphere of the brain that, in most humans, is specialized for emotional recognition, spatial reasoning, and simultaneous information processing.
- Left Hemisphere: The hemisphere of the brain, that in most humans, is specialized for speech production and comprehension, and sequential processing.
- Lateralization: the separation of function of both brain hemispheres.
- Split Brained Patients: People, who have had their corpus callosum severed.
- Corpus Callosum: the main commisure in the human brain.
- Commisure: an area the brain where the hemispheres exchange information.
- Wernicke's Area: This area of the brain is specialized in the ability to understand spoken language
- Broca's Area: This area of the brain is specialized in the ability to speak and use expressive language.
- Hindbrain: This is the most ancient part of the brain and provides the most basic functions including: breathing, swallowing, vomiting, blood pressure, general arousal, consciousness, muscle tone, posture, and hand-eye movements.
- Midbrain: This part of the brain controls head and eye movements, it allows for localization and following of visual and auditory stimuli.
- Forebrain: this is composed of six major areas: pineal body, thalamus, hypothalamus, hippocampus, basal ganglia, and corpus callosum. It provides a variety of functions.
- Pineal Body: The area of the brain that is used for the secretion of hormones.
- Hypothalamus: This area is used for feeding, sexual behavior, sleeping, temperature regulation, emotional behaviors, and movement.
- Hippocampus: This area provides functioning for memory.
- Basal Ganglia: This area is responsible for motor functions.
- Frontal Lobe: The lobe in the brain that is responsible for executive functions and motor performance.
- Temporal Lobe: The lobe in the brain that is responsible for auditory information, sensations, long-tern memory storage, and control of biological drives such as aggression and sexuality.
- Occipital Lobe: This lobe in the brain is responsible for vision.
- Parietal Lobe: This lobe in the brain is responsible for sensory skills.
- Electroencephalograph (EEG): Testing technique in which electrodes measure eletrical activity in the brain.
- Computerizzed Tomography (CT Scan): Brain imaging technique where x-rays are passed through the brain to measure its density.
- Positron Emission Tomography (PET Scan): Radioactive tracers are measured through a scanning machine, which allows for imaging of the structure of the brain.
- Magnetic Resonance Imaging (MRI): Imaging technique in which radio waves scan the brain to determine its structure.