CLASS NOTES
HISTORY
First there were theologians, philosophers, poets, and novelists
and then came psychologists. Questions about human behavior, thoughts, and feelings were being asked and answered long before
the beginning of the psychology. The ancient Greek philosophers, Plato and Aristotle, were interested in understanding the
human mind. They differed about the source of knowledge. Plato claimed that we are born with complete knowledge and only need
to access this knowledge. Aristotle argued that we acquire knowledge through experience. These two positions continue to this
day in a somewhat different guise as nature versus nurture as determinants of human behavior.
The ancient Greek philosophers explained the personality
characteristic, temperament, in terms of the amounts of four humours; blood (enthusiasm), black bile (depression), yellow bile (anger), and phlegm (apathy). This question is still being examined today, but
now the neurotransmitters and hormones have replaced humours as the basis of temperament. We now rely on the scientific method
to find answers to questions that were explored long ago in a very different way.
SENSATION & PERCEPTION
Negative Afterimages
Each of the two color inputs to a specialized thalamus color
cell suppresses the activity of the other color component. When a color input stops, the suppressed component becomes overexcited
and yields the experience of that color. For example, for a red-green cell, a green input suppresses the red output. When
the green input stops, the cell generates a red output. The same applies to blue-yellow and black-white cells.
BRAIN AND BEHAVIOR, THOUGHTS, AND FEELINGS
Sexual organization of the brain
Research beginning in the 1950’s demonstrated that, in rats, testosterone
levels during a specific “critical period " during fetal development can determine the size of a nucleus in the
hypothalamus. This sexually dimorphic nucleus (SDN) is typically larger in genetic males than females. Exposing genetic females
to testosterone results in a SDN that is the size of the SDN seen in genetic males. Blocking the action of testosterone during
the critical period in genetic males leads to a SDN that is the size seen in genetic females. These brain alterations are
associated, in rats, with masculinization of behavior in females and feminization of behavior in males.
Human males have a larger SDN ( INAH3) than females. The size
difference in the INAH3, in humans, does not appear until about age four, the same time when gender identity emerges.
There have been recent reports of size and activity differences of some brain stuctures in heterosexual
and homosexual men and women. Much more research will be needed to determine the
functional relationship among gender identity, sexual orientation and differences in size and other characteristics
of various brain structures( Swaab, D. F, Hofman, M. A., Trends in Neuroscience18, 264-270, 1995), D.F. Swaab, Proceedings
of the National Academy of Sciences, 105, 10273-10274, 2008) , Savic, I Linstrom, P(2008) Proc Natl Acad Sci USA 105:9403-9408.
It does appear that prenatal events play a role in sexual orientation,
at least in males. Recent findings support the view that prenatal events of some kind contribute to the determination of sexual
orientation in adult human males. Later born male siblings have a higher probability of exhibiting homosexuality than earlier
born siblings. This correlation was not found in families with adopted male siblings . This indicates that the social family
environment was not a factor in the birth order findings regarding homosexuality (Bogaert, A. F. Proc. National Academy of
Sciences, 103, 10771-10774, 2006). Human females that were exposed to unusually high levels of testosterone during fetal development
show evidence of masculinization of behavior, but not necessarily homosexuality (Hart, K, Child Development, 2002). Recent
findings indicate that the level of testosterone in amniotic fluid predicts the level of male-typical play behavior in
both male and female children(Auyeung et. al. Psychological Science, 2009.
Intracranial Reward
In 1950, James
Olds accidentally discovered brain areas involved in reward processes. The most important area involves cells in the lateral
hypothalamus and fiber systems extending from the midbrain to areas in the anterior areas of the brain. Subsequent research
has indicated that the neurotransmitter dopamine is an important neurotransmitter involved in these systems. More recently,
it has been discovered that there are different systems involved in “wanting” and “liking”. This finding
has important implications for understanding substance abuse. In long term drug addicts there is a strong wanting but diminished
liking of the drug, (The Journal of Neuroscience, 2007, 27, 7, 1594-1605).
Food Intake Regulation
The ventromedial hypothalamic nucleus
(VMH) plays an important role in food intake and body weight regulation by controlling meal duration. When this structure
is damaged, meal duration becomes longer and the resulting increase in caloric intake results in increased body weight.
Recent findings have identified two
hormones, Leptin and Ghrelin, and one neuropeptide, NPY, that act on hypothalamic nuclei to influence food intake. Leptin
inhibits food intake and NPY and Ghrelin stimulate food intake.
The Hypothlamus and Stress-induced
Suppression of the Immune System
The hypothalamus can produce a suppression
of the immune system in three different ways. 1. The hypothalamus can stimulate the anterior pituitary gland to stimulate
the adrenal cortex to release cortisol. High levels of cortisol can suppress the immune system. 2. The hypothalmus, via the
sympathetic nervous system, can stimulate the adrenal medulla to release adrenalin and noradrenalin. High levels of adrenalin
and noradrenalin can suppress the immune system. 3. The hypothalamus, via the sympathetic nervous system, can
directly suppress lymphocyte activity in the lymph nodes which results in a diminished immune response.
For more details on the effects of
stress on health see the section Stress and Health below.
The Hippocampus and Amygdala
The hippocampus
is involved in the consolidation of memories or engrams as permanent traces. Damage to the hippocampus interferes with converting
short-term temporary memories into permanent memories. H.M. is a well known example
of the consequences of damage to the hippocampus. The hippocampus is also involved in response inhibition processes. Finally,
recent findings suggest that the cell count in the hippocampus can vary from time to time and low cell counts are correlated
with clinical depression , It may be that stress-related elevations in cortisol
from the adrenal cortex may induce cell loss in the hippocampus that may actually be a cause of some clinical depression.
J. Neuroscience 27, 2734-2743, 2007.
The amygdala plays
an important role in fear and anxiety. This structure appears essential for the establishment and recall of memories
for negative experiences. Also, the amygdala appears important for recognition of emotional signs of fear in facial expressions.
Psychopaths have an impaired ability
to experience fear that may be related to abnormal functioning of the amygdala.
See below for more details about the
amygdala and memories involving fear related experiences.
Pruning
There
is an ongoing process of cell loss in the brain that is most evident from about age 12 to 20 years. This is a normal and adaptive
process that eliminates unnecessary connections. Pruning, when too little, can result in brain nuclei that are unusually large.
This may account for the larger amygdala seen in autistic children around age 6. Excessive pruning is seen in the excessive cortical cell
loss of adolescents who begin showing signs of schizophrenia.
Mirror Neurons
Mirror neurons
are activated during the observation of a behavior or display of a behavior. For example, monkeys observing another monkey
performing a movement, display activity in a subset of cortical neurons that are also active when the observer monkey
engages in the same behavior. These neurons may play an important role in observational learning.
The ability to understand
the feelings of others may also depend upon mirror neurons that are excited when an individual experiences an emotion or observes
another individual displaying the same emotion as evident in facial expressions etc. Recent research indicates that autistic
individuals may have impaired mirror neuron function. For more information see Marco Iacobini, "Mental Mirrors" Natural History,
2008 and Sandra Blakeslee, "Cells that read minds" New York Times, 1/10,2006.
MEMORY
State Dependent Memory
Sensory feedback from various physiological systems can serve as contextual dues for retrieval in the same way as do
external environmental cues. When internal cues generated by drug and hormonal influences are present during learning, the
absence of these cues can compromise recall at a later time. For example, recall while drugged or not drugged is better when
the individual is in the same biochemical state as during learning.
The Amygdala and Fear-related Memory
The amygdala appears
to be essential for memory of fear-related events as well as recognition of fear in the facial expressions of others and the
facial expression of fear.
Drugs that block the
action of noradrenaline in the amygdala impair the recall of negative emotional events, but not neutral of positive emotional
events. With stories that contain negative, positive and emotionally neutral material, the drug propranolol, that blocks noradrenaline,
selectively impairs recall of the negative content.
False Memories
A technology
is emerging that allows detection of false and real memories. Recent studies reported different brain wave patterns
for real and false memories. Subjects were given a list of words and asked later to recognize, which words had been previously
seen. When subjects incorrectly identified a word as part of a previously learned list, the brain wave pattern
was different than for previously learned words from the list( Sederberg et. al. Gamma oscillations distinguish true
from false memories, Psychological Science, 18, 2007, 927-932.
Automatic memory
Encoding
some types of information requires no effort. For example, information related to location, frequency, or duration of events
or objects is remembered equally well with or without instructions to do so.
LANGUAGE
There are various
types of evidence that suggest that there is a “hardwired” system for acquiring early language skills. Language
stages occur in the same sequence in all children in all cultures at the same points in time. Babbling occurs in both hearing
(vocal) and non-hearing children (manual gestures). Deaf children develop their own signing in the absence of signing caretakers.
Six-month old infants ignore minor variations in the different sounds in their own language, but notice similar variations
in the sounds that are unique to another language.
There has been
interest in the language capacities of animals. Other than parrots, other species cannot make language sounds. This was painfully
evident in the studies of the home-reared chimpanzee, Gua. Washoe learned ASL signing. Kanzi learned ASL from observing
her mother. Both Kanzi and Koko have displayed simple creative uses of ASL signing. The evidence seems quite clear that chimpanzees
and gorillas are capable of simple language. The jury is out regarding Alex the parrot who has a remarkable vocabulary, but
may not have language as it is commonly defined.
DEVELOPMENTAL
Low correlations
between early childhood experience and behavior and adult measures of personality have encouraged psychologists to accept
the possibility that other periods in development are more influential than childhood in determining adult personality characteristics.
All developmental psychologists agree that genetics play an important role in adult personality. Judith Harris believes that
socialization influences of adolescent peer groups are the other major personality influence ( The Nurture Assumption, Free
Press, 2000) . Michael Lewis believes that adult personality characteristics are strongly influenced by the current social
context of the adult. Both Harris and Lewis minimize the influence of childhood experiences as an influence on adult personality
characteristics. It may well be that while genetics are a strong influence,
childhood, adolescent group socialization, and adult social contexts will also influence personality but to a different degree
for different individuals.
While
some findings suggest that the typical range and variety of childhood experiences may not be as influential in shaping adult
personality as previously thought, it is also clear that severely limited social and intellectual stimulation,
during early development, can have measurable negative effects on intellectual abilities and social skills. Studies of Romanian
orphanages indictate that impoverished intellectual and social stimulation can result in cognitive impairments and
difficulties in establishing close, intimate social relationships These negative effects were observed in some but not
all of these orphans, after adoption (Rutter, M. L. et. al., British Journal of Psychiatry, 2001, 179, 97-103; Rutter,
M.L. et. al., Developmental Psychology, 2004, 40, 1, 81-94).
Recent research
indicates that organizational changes in the brain continue after birth until a least the close of adolescence. "Pruning of
cortical neurons progresses from the rear of the brain to the frontal cortex from about age 12 to age 18. These changes may
account for the impulsivity and risk taking that is characteristic of the adolescent. (
Neuroscience 14,3, 2007, 961-968, Current Directions in Psychological Science, 2007, 16, 2, 55-59). Risk taking in adolescents
does not appear to be due to underestimation of risk, as compared to adults, but to an inability to inhibit behavior and overestimation
of benefits of particular behaviors, Scientific American Mind, December 06/January 07, pages 59-65., Steinberg, L. Current
Directions in Psychological Science, 2007, 16, 2, 55-59, and also see research writings by Abigail Baird .
STRESS & HEALTH
Stressors are stimuli
that induce a state called stress that is defined in terms of physiological changes including increased inflammatory activity,
heightened activity of the sympathetic nervous system, elevation of cortisol from the adrenal cortex ,and adrenalin and noradrenaline
from the adrenal medulla. Elevation of the adrenal hormones can suppress lymphocyte activity related to the immune response
and sympathetic nervous system output directly to the lymph nodes can also suppress lymphocyte activity. Some individuals have unusually strong sympathetic nervous system response to stressors which can make
them particularly vulnerable to stress-related suppression of the immune system.
Stressors of brief
duration induce physiological changes that facilitate coping with infection and other consequences of injuries. However. long
duration stressors induce changes in lymphocyte activity in that can compromise the immune system's ability to cope
with disease. In addition, long term stressors can result in inflammatory conditions that can also compromise health.
The ability of
a stimulus to induce stress depends upon an individual’s appraisal of a stimulus.
Research has shown that parents of terminally ill children will have episodes of denial of the severity of the illness
and these episodes are accompanied by a reduction in physiological activity associated with stressors. Similarly, Vietnam
War medivac pilots had different perceptions of the risk of medivac flights as compared to crew members and had below normal
levels of adrenal hormones usually associated with stressors. Crew members had elevated levels of adrenal hormones and viewed
the missions as much more dangerous as compared to the medivac pilots.
Frankenhauser has
reported that physiological adrenal hormone responses to cognitive stress, while initially higher in males as compared to
females, were matched, decades later by females in the same task. She interpreted her findings as reflection of a change in
the attitudes regarding task performance and failure in females.
MOTIVATION
Research
has identified different neuronal populations related to detection of physiological need for food, search behavior for food,
recognition of food, and finally ingestion of food. The neurons for each function were located in the hypothalamus except
for neurons related to ingestion which were located in the brain stem. This type or organization will probably be found for
other types of drive states.
With regard
to sexual motivation, research has found that there is not a strong correlation between sex hormone level and sexual
motivation. Males are less dependent upon sex hormones for sexual motivation than females and more complex-brain species are
less dependent upon sex hormones for sexual motivation as compared to more simple-brain species.
SLEEP
Recent research has found that processing
of the engram occurs during sleep and that such processing improves retrieval.
(R. Stickgold & J. Ellenbogen,
Scientific American, August 7, 2008)
Sleep deprivation, particularly REM
sleep, interferes with retrieval of learned material. Sleep deprivation also increases the probabability of work-related
driving accidents.
There is no scientific evidence that
indicates that learning can take place during sleep.
REM sleep dreams are typically more
emotional and vivid that dreams occuring during NREM sleep. Dream content typically reflects events of the day
of the dream or events that occurred a week earlier. Much of dream content involves negative emotions, usually anxiety.
Even as little as 24 hours of sleep
deprivation can result in lapses in cognitive function, perception, and arousal (Chee, Michael W. et al. The Journal of Neuroscience,
May 2008, 28, 5519-5528).
ABNORMAL BEHAVIOR
Schizophrenics
are sometimes troubled by an attentional gating disorder that impairs their ability to filter out irrelevant stimuli.
Early-onset schizophrenia,
around age 14, is associated with progressive loss of cortical gray matter. This may reflect excessive “pruning”
which is the natural loss of cells that occurs as a part of organizational brain changes that continue until adulthood.
Recent studies
have indicated that schizophrenia is associated with elevated dopamine activity and diminished glutamate activity. In laboratory
studies, normal subjects given a drug, methamphetamine, that elevates dopamine activity results in brief displays of
symptoms of schizophrenia and a drug that lowers glutamate activity, ketamine, also results in symptoms of schizophrenia.
" From the elusiveness of schizophrenia,
new clues to treatment " Benedict Carey, New York Times, June, 13, 2008.
Schizophrenia: More dopamine, more
D2 receptors, Seeman, P. and Kapur, S., Proceedings of the National Academy of Sciences, July 5, 2000, 97, 7673-7675.
MOOD DISORDERS
Some cases
of clinical depression may be associated with a decrease in cell number in the hippocampus induced by stress-related elevations
in cortisol. In laboratory animals, antidepressants are associated with elevations in hippocampus cells
The bipolar
disorder appears to be associated with elevated levels of glutamate during mania and depressed levels of glutamate during
depressive episodes. Recent research suggest the possibility of involvement of dopamine and serotonin in this disorder, in
addition to glutamate.
Treatment
for depression involves one or more of the approaches below.
Selective serotonin
reuptake inhibitors (SSRI) increase serotonin activity by slowing reuptake
Monoamine oxidase inhibitors increase
noradrenaline, and serotonin activity by slowing metabolic breakdown in the synapse
Tricyclics and
SSNRIs elevate levels of serotonin and noradrenaline activity by slowing
reuptake
Buproprion(Wellbutrin)
increases dopamine and noradrenalin activity by slowing reuptake.
Electroconvulsive shock therapy
Cognitive therapy
Recent findings from the Star-D research
project indicate that for depressed individuals who do not show a positive response to an initial antidepressant,
trying other classes of antidepressants and cognitive therapy can result in almost 70 % of depressed individuals eventually showing
a positive response to a treatment or a combination of treatments, Current Psychiatry Reports, 2007, 9, 6,
449-459.
PSYCHOPATH/ANTISOCIAL PERSONALITY/
SOCIOPATH
The terms psychopath, antisocial personality,
and sociopath are by used by some mental health professionals to refer to the same disorder that involves antisocial
behavior. Other mental health professionals such as psychologist Robert Hare reserve the term psychopath for individuals who
display antisocial behavior and, in addition, are manipulative, charming, and experience little or no fear or guilt.
Some psychopaths may also display aggressiveness and or impulsivity. ( Snakes in Suits, Paul Babiak & Robert
Hare, Harper Collins, 2007). There is some evidence that the psychopath's impaired ability to experience fear may be related
to abnormal amygdala functioning. According to Hare the term sociopath refers to an individual who abides by the rules and
moral codes of a subgroup that does not conform to the moral codes and rules of the larger community. Antisocial personality
disorder refers to indivuals who break societal rules due to lack of control and feel guilt after breaking rules that they
accept and try, unsuccessfully, to obey.
AUTISM
Autism is characterized
by motor control problems, repetitive behaviors, impaired expression and comprehension of emotional states, and impaired communication.
The prefrontal cortex, cerebellum, and amygdala are unusual in size and or function in individuals with this disorder.
Autistic individuals
appear to have impaired "mirror neuron" function that may interfere with observational learning of behaviors and understanding
of emotional states in others (Oberman, L.M. & Ramachandran, V. S., Psychological Bulletin 2007, 133, 2, 310-327).
The
promise of "facilitated communication" therapy did not materialize and current therapies emphasize behavior modification techniques
that may compensate, to some degree, for the lack of learning behaviors via observational learning.
Recent findings indicate that a commonly used intelligence test, the Wechsler,
underestimates the intelligence of autistic children. The Raven test, that requires less social interaction during testing,
yields higher IQ scores than the Wechsler. Dawson, M.; Soulieres, I; Gernsbacher, M; and M, Laurent: Psychological
Science, 18, 8, 2007, 657-662.
Psychosurgery
The frontal
lobotomy was developed by Egas Moniz in 1936. The procedure involved disconnection of fibers connecting the frontal lobes
to the rest of the brain. The procedure was introduced in the United States by Walter Freeman. Over 50,000 patients received the procedure from 1936 until the mid
1950”s. The typical outcome was diminished motivation, inability to plan, occasional impulsivity and a more manageable
patient.
