Transcript File

Objective 2.1:
Explain one study related to
localization of function in the
brain.
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Things to consider….
• Localization of function - The principle that specific
functions have relatively circumscribed locations in some
particular part of the brain.
• Multiple studies (Broca’s study, Wernicke’s study, The
case study of HM, The case study of Phineas Gage) can
be used to explain localization of function in the brain.
• Contemporary studies (Hull & Vaid, 2006) vastly
differentiate from older studies (Sperry, 1968) in aim and
participants.
• The study that is chosen MUST be explained in detail.
Example: aim, method, results, implications/relevance to L.O.F.
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Localization in the Brain
 The first quarter of the nineteenth
century witnessed a growth of
interest in the localization of
functions in the brain.
 Most neuroscientists would agree
that the foundations of modern
neuropsychology and cognitive
neuroscience were laid by the
French surgeon, anatomist and
anthropologist, Paul Broca, in the
1860s.
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Localization in the Brain
 At that time, Broca and his
colleagues in Paris were
discussing a lingering claim
that language functions
were located in the frontal
lobes of the brain (Gall and
Spurtzheim, 1809; Clarke and
O’Malley, 1968; Schiller, 1992;
Monod-Broca, 2005).
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Localization in the Brain
 Amidst these discussions, Broca was consulted about a
51-year-old patient who was nicknamed “Tan” with
multiple neurological problems, who had been without
any productive speech for many years.
 Every time “Tan” attempted to utter a phrase or
respond to a question, he could only produce a single
repetitive syllable, ‘tan’.
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Localization in the Brain
 He could vary the intonation of the sound but was not
able to produce any recognizable words or phrases.
 Broca saw Tan's lack of speech as a test case for the
question of language localization in the frontal lobes,
since the patient clearly had no productive language.
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Localization in the Brain
 Tan died of his ailments several days later and, using
post-mortem methods, a lesion was found on the
surface of the left temporal lobe as Broca had
suspected.
 He presented his finding to the Anthropological Society
(Broca, 1861) where some of the earlier discussions had
taken place, and to the more established Anatomical
Society of Paris (Broca, 1861) several months later.
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Localization in the Brain
 The finding was met with enthusiasm and taken as
support for the premise that cognitive functions could
be localized to specific parts of the brain.
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Lelong
• Broca encountered a second patient named
Lelong(age 84) who also exhibited reduced
productive speech as the result of a stroke 1 year
before
• Could say only five words:
o ‘oui’ (‘yes’)
o ‘non’ (‘no’)
o ‘tois’(a mispronunciation of ‘trois’ (‘three’) which he used to represent any
number)
o ‘toujours’ (‘always’)
o ‘Lelo’(a mispronunciation of his own name).
• His autopsy showed a lesion in approximately the
same region of the lateral temporal lobe as the Tan
o Broca reported it to the Anatomical Society as an important case,
confirming the localization of speech to this area.
The Facts
• Modern lesion studies have found that Broca’s
aphasia is caused by large lesions encompassing
not necessarily Broca’s area, but surrounding frontal
cortex, underlying white matter, the insula, basal
ganglia and parts of the anterior superior-temporal
gyrus.
(e.g. Mohr, 1976; Mohr et al., 1978; Naeser and Hayward, 1978; Kertesz et al., 1979; Schiff et al.,
1983; Basso et al., 1985; Murdoch et al., 1986; Alexander et al., 1990)
Example Lesions
The Evidence Doesn’t Lie
• 3D MRI images of Tan’s
brain have been made
over the years.
o The extent of the damage is
obvious when comparing the
sizes of the two hemispheres on
the MRI images. The left
hemisphere, as measured from
the midline to the lateral
surface, is up to 50% smaller
than the right hemisphere.
*MRI images allow us to see an
anatomical view of the brain ->
Localization in the Brain
 Although one single case would not be enough to
conclude that specific parts of the brain are
responsible for specific behaviors, Broca’s research laid
the foundation for many research hypotheses that
investigated specific parts of the brain correlating to
specific behaviors.
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Objective 2.2:
Using one or more examples,
explain effects of
neurotransmission on human
behavior.
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Things to consider….
Multiple studies have suggested that
neurotransmission plays a significant role
in behavior.
Research should be used to support your
explanation of the effects of
neurotransmission on behavior.
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Review
What do we already know about
the role of neurotransmission and
behavior?
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Looking back…
• Our chemical balances/imbalances
correlate to specific human behaviors
• Higher or lower levels of certain
hormones and/or neurotransmitters can
lead to changes in behavior.
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Neurotransmission and behavior
 Neurotransmitters are produced and
stored in the brain cells (neurons),
and are released into action when
neurons are electrically activated.
 Neurotransmitters play a large role in
every thought, mood, pain and
pleasure sensation that we feel. They
control our energy level, appetite
and what foods we crave.
 Neurotransmitters regulate how well
we sleep and even our cognition.
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Neurotransmission and behavior
 The brain is composed of
billions of branching treelike nerve cells called
neurons. They stretch out
but never actually touch
each other.
How do the cells
communicate with each
other?
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Neurotransmission
 Neurotransmission also called synaptic
transmission, is the process by which
neurotransmitters are released by a neuron
(the presynaptic neuron), and bind to and
activate the receptors of another neuron
(the postsynaptic neuron).
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Synaptic Communication
 Through a highly
regulated electrochemical chain of events,
the brain uses
neurotransmitters to
communicate with both
itself and other organs
and tissues in the body.
 Thus, Information is
transmitted, neuron to
neuron, from one area of
the brain or body to
another.
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Synaptic Communication
 When this information eventually reaches its
final destination, the message is translated
into the contraction of a muscle, a emotion, a
memory, etc. Of course, this is a highly simplistic
version of the actual process.
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How important is
neurotransmission?
•
•
Proper amounts of neurotransmitters are
necessary for maintaining optimal mental and
physical health.
Some of the most significant clinical issues linked
to neurotransmitter imbalances
are: anxiousness, appetite control, attention
issues, developmental delays, behavioral
problems, low mood, fatigue, mood disorders,
sleep disorders, weight issues, and many more.
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Examples of Neurotransmitters
responsible for behavior
Dopamine: Thinking & Decision-making
Higher levels: Assist with problem-solving, Able to generalize
situations, Lowers impulsive behavior.
Lower levels: Impulsive behavior, Irrational thinking.
Norepinephrine: Alertness, Ability to focus attention
Higher levels: Anxious, Hyper-alert, Paranoid
Lower levels: Lethargy, Low energy, Depression
Epinephrine: provide immediate strength and single-focused
concentration for “Flight or Fight” reflex.
Higher levels: Overstimulation of all mental and physical
functions, Manic behavior
Lower levels : Lethargy, Low energy, Depression
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Important note
• Please note that these associations are
merely correlations, and do not necessarily
demonstrate any cause and effect
relationship.
• We don’t know what other variables may be
affecting both the neurotransmitter and the
mental illness, and we don’t know if the
change in the neurotransmitter causes the
illness, or the illness causes the change in the
neurotransmitter.
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Acetylcholine
• Acetylcholine is important for memory and
learning and is a neurotransmitter used
throughout the body. It controls muscle
contraction for example.
• Acetylcholine may be extremely important
for short term memory. It determines your
brain speed. If you have too little, your brain
is going to slow down. This will play a role in
reaction time, cognitive retention, and
alertness.
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Review of Acetylcholine
• Psychologists Martinez and Kesner (1991)
aimed to investigate the role acetylcholine in
memory function.
• Procedure: Experimental study using rats.
They were trained to run a maze. They were
divided into 3 groups.
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Review of Acetylcholine
• The study shows that acetylcholine is
important in memory since the rats showed
different memory capacity as a result of the
level of the neurotransmitter acetylcholine.
• Since the work was a controlled lab
experiment, it can be concluded that levels
of acetylcholine play a role in memory (but
the neurobiology of memory is very
complex).
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Acetylcholine
• You can think of acetylcholine as a lubricant
for your brain and body.
• Acetylcholine along with dopamine are the
neurotransmitters that allow it to work hard
and fast.
• A lack of either one can lead to memory and
attention problems.
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Acetylcholine
• Acetylcholine deficiency can display as
Alzheimer’s, Multiple Sclerosis, dementia, dry
mouth, dry skin, reading/writing disorders,
speech problems, slow movement, mood
swings, learning disorders, verbal memory
problems, memory lapses, attention
problems, difficulty concentrating,
carelessness, and decreased creativity.
• Many medications that fight the onset of
these disorder provides the body with the
amino acid that increase acetylcholine levels
in brain.
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Natural ways of
increasing acetylcholine
• Egg yolk
• Cod, salmon, or
tilapia
• Shrimp
• Soy protein
• Peanut butter
• Oat bran
• Almonds
• Hazelnuts
• Macadamia nuts
• Broccoli
• Brussels sprouts
• Cucumber, zucchini,
lettuce
• Skim milk
• Trimmed ham
• Low-fat cheese
• Low-fat yogurt
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Review of Acetylcholine
• Although neurotransmission is only correlated
with behaviors (as previously stated),
Psychologist do not deny the significant role
that neurotransmitters play in behavior.
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Objective 2.3:
Using one or more examples,
explain functions of two
hormones in human behavior.
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Things to consider….
 Multiple studies have suggested that hormones are not
necessarily the only factor explaining human behavior.
More research must be done to understand the extent
to which hormones can truly effect behavior in
humans without the contribution of multidirectional
models. This is important to note before you assume
that hormone A causes behavior B.
 Research should be used to support your explanation
of the effects of neurotransmission on behavior.
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Hormones and behavior
connections
 Our bodies are designed in such a manner that they will
function to their fullest with the right proportions and mix
of hormones.
 Hormones are chemicals secreted from specialized cells
into the bloodstream, from where they are transported to
various parts of the body to act on target tissues, thereby
producing physical and mental effects in an individual.
 They are secreted by various glands in the body such as
thyroid gland, pituitary gland, pineal gland, pancreas,
adrenal gland, parathyroid glands and gonads. Each
hormone secreted by these glands have a specific set of
functions.
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“The Stress Hormone”
•
Cortisol (hydrocortisone) is a steroid hormone, or
glucocorticoid, produced by the adrenal gland. It is
released in response to stress and a low level of blood
glucocorticoids.
•
Although stress isn’t the only reason that cortisol is
secreted into the bloodstream, it has been termed “the
stress hormone” because it’s also secreted in higher
levels during the body’s ‘fight or flight’ response to
stress, and is responsible for several stress-related
changes in the body.
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“The Stress Hormone”
Small increases of cortisol have some positive effects:
•A quick burst of energy for survival reasons
•Heightened memory functions
•A burst of increased immunity
•Lower sensitivity to pain
•Helps maintain homeostasis in the body
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“The Stress Hormone”
•
Cortisol secretion varies among individuals. People are
biologically ‘wired’ to react differently to stress. One
person may secrete higher levels of cortisol than another
in the same situation. This is why some people perceive
things as being stressful when others do not.
•
Studies have also shown that people who secrete higher
levels of cortisol in response to stress also tend to eat
more food, and food that is higher in carbohydrates
than people who secrete less cortisol.
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“The Stress Hormone”
•
Excessive cortisol frequently causes increased
fatigue/decreased energy, irritability, impaired memory,
depressed mood, decreased libido, insomnia, anxiety,
impaired concentration, crying, restlessness, social
withdrawal and feelings of hopelessness.
For more info:
http://www.physorg.com/news/2011-02-behavioralproblems-linked-cortisol.html
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Oxytocin and behavior
 Oxytocin regulates social affiliation and
social recognition in many species and
modulates anxiety, mood and aggression.
 The hormone is released during labor and
remains abundant throughout the weening
period.
 It is believed to stimulate the bonding
receptors between the mother and child.
Oxytocin is also released when physical
contact is made and sends a soothing
message throughout our body triggering an
instinctual trust.
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“The
love
hormone”
 The neuropeptide oxytocin (OXT) is currently attracting
considerable attention as a result of the discovery of the amazing
behavioral functions it regulates, especially in the context of social
interactions. A broad variety of behaviors, including maternal care
and aggression, pair bonding, sexual behavior, and social
memory and support, as well as anxiety-related behavior and
stress coping, are modulated by brain OXT (Neuman, 2008).
 This hypothesis is substantiated by the finding that intranasal OXT
makes humans more trusting (Neuman, 2008) . Moreover, reduced
levels of anxiety to psychosocial stress were described in subjects
treated with intranasal OXT and receiving social support.
For more info:
http://www.ahealthymind.org/library/brain%20oxytocin.pdf
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