Neuropsychology Flashcards
Psychophysical laws
Three psychophysical laws have been proposed to explain the relationship between the magnitude of physical stimuli and psychological sensations:
(1) Weber’s Law
(2) Fechner’s law
(3) Stevens’s power law
Weber’s law
The “just noticeable difference” for any stimulus increases in size in direct proportion to the magnitude of the stimulus. i.e. if you sense a change in weight of .5 lbs on a 5 pound dumbbell, you ought to feel the extra pound added to a ten pound dumbbell.
“Near miss” of Weber’s law:
Auditory: Weber’s law does not quite hold for loudness. It is a fair approximation for higher intensities, but not for lower amplitudes
Visual: Perception of Glass patterns and mirror symmetries in the presence of noise follows Weber’s law in the middle range of regularity-to-noise ratios (S), but in both outer ranges, sensitivity to variations is disproportionally lower.
Numerical: Psychological studies show that it becomes increasingly difficult to discriminate among two numbers as the difference between them decreases. This is called the distance effect. This is important in areas of magnitude estimation, such as dealing with large scales and estimating distances. It may also play a role in explaining why consumers neglect to shop around to save a small percentage on a large purchase, but will shop around to save a large percentage on a small purchase which represents a much smaller absolute dollar amount
Psychostimulant drugs
Psychostimulants include prescription drugs such as methylphenidate and pemoline and drugs-of-abuse such as cocaine and methamphetamine.
Homonymous hemianopsia
It is the loss of half of the field of view on the same side in both eyes. It is also referred to as a homonymous hemianopia. It occurs frequently in stroke and traumatic brain injuries due to the way part of the optic nerve fibers from each eye crossover as they pass to the back of the brain.
Apraxia
Apraxia is a motor disorder caused by damage to the brain (specifically the posterior parietal cortex), in which someone has difficulty with the motor planning to perform tasks or movements when asked, provided that the request or command is understood and he/she is willing to perform the task.
Apraxia is an acquired disorder of motor planning, but is not caused by incoordination, sensory loss, or failure to comprehend simple commands (which can be tested by asking the person to recognize the correct movement from a series). It is caused by damage to specific areas of the cerebrum.
Apraxia should not be confused with:
Aataxia: a lack of coordination of movements
Aphasia: an inability to produce and/or comprehend language
Abulia: the lack of desire to carry out an action
Allochiria: patients perceive stimuli to one side of the body as occurring on the other.
Developmental coordination disorder: It is a developmental disorder of motor planning.
Stevens’s power law
There is an exponential relationship between psychological sensation and the magnitude of a physical stimulus, with the exponent varying for different kinds of stimuli
Psyhostimulants are used to treat
ADHD and narcolepsy
Fechner’s law/scaling
Predicts that psychological sensation is logarithmically related to the magnitude of the physical stimulus. Fechner scaling has been mathematically formalized. In fact, human perceptions of sight and sound work as follows: Perceived loudness/brightness is proportional to log of actual intensity measured with an accurate nonhuman instrument.
Common side-effects of Narcolepsy
Common side effects are insomnia, decreased appetite, weight loss, stomachaches, and dysphoric mood.
General adaptation system (by Selye)
Three stages. Mediated by adrenal and pituitary glands.
Alarm- In the initial phase of stress, humans exhibit a “fight or flight” response, which prepares the body for physical activity. However, this initial response can also decrease the effectiveness of the immune system, making persons more susceptible to illness during this phase.
Hypothalamus activates adrenal to increase the production of epinephrine (adrenaline).
Resistance- if the stress continues, the body adapts to the stressors it is exposed to. A person’s physiological self also undergoes some important modifications at this time.
During the resistance phase: (1)Glucocorticoids, which are steroid hormones, as well as other biochemicals, begin to play an important role. They cause things like the breakdown of fat so that this fat can be used as a source of energy during long periods of stress. (2) These biochemicals also elevate and stabilize the levels of blood sugar, particularly in order to power the nervous system.
Exhaustion- The body’s resistance to the stress may gradually be reduced, or may collapse quickly. Generally, this means the immune system, and the body’s ability to resist disease, may be almost totally eliminated. Patients who experience long-term stress may succumb to heart attacks or severe infection due to their reduced immunity.
Kluver-Bucy Syndrome
produced by bilateral lesions in the amygdala and temporal lobes of primates
Characterized by reduced fear and aggression, increased docility and compulsive oral exploratory behaviors, altered dietary habits, hypersexuality, and “psychic blindness” (an inability to recognize the significance or meaning of events or objects).
Anticholinergic effects
They include dry mouth, blurred vision, tachycardia (rapid heart rate), urinary retention, constipation, memory impairment, and confusion.
Caused by several drugs including the antipsychotics and tricyclic antidepressants.
Atypical antipsychotics (Clozapine)
effective for both positive and negative symptoms of Schizophrenia and are less likely to produce tardive dyskinesia than the traditional antipsychotics. However, they can produce agranulocytosis (deficiency of granulocytes in the blood, causing increased vulnerability to infection) and other blood dyscrasias (problems) as well as neuroleptic malignant syndrome (muscle rigidity, fever, autonomic instability,and cognitive changes such as delirium).
Clozapine and other atypical (newer) antipsychotic drugs affect receptors for several neurotransmitters including dopamine, serotonin, and glutamate.
Tardive dyskinesia
Tardive dyskinesia is characterized by repetitive, involuntary, purposeless movements. Some examples of these types of involuntary movements include: Grimacing Tongue movements Lip smacking Lip puckering Pursing of the lips Excessive eye blinking
difficult-to-treat and often incurable form of dyskinesia, a disorder resulting in involuntary, repetitive body movements. In this form of dyskinesia, the involuntary movements are tardive, meaning they have a slow or belated onset.
This neurological disorder most frequently occurs as the result of long-term or high-dose use of antipsychotic drugs, or in children and infants as a side effect from usage of drugs for gastrointestinal disorders
Effect of aginig on crystalized and fluid intelligence
Increasing age is associated with a decline in speed of information processing and fluid (vs. crystallized) intelligence but, for some adults, declines may be reversed with relatively simply training and practice.
