Transcript
Standards
• Techniques used to study the brain in relation to behavior
– The choice of techniques used to correlate the brain with behaviour is based on a variety of factors including opportunity, available technology and costs. An awareness of these limitations as well as the strengths of these different techniques is important when evaluating the contribution they have made to understanding behaviour.
• Localization
– Students should understand the concept of localization and how the function of different parts of the brain is determined as well as the limitations of this model.
• Neuroplasticity
– The development of neural networks through repetition and neural pruning is both genetic and subject to environmental influences. Neural networks can change developmentally, over time or after injury. This is termed neuroplasticity.
• Neurotransmitters & their effect on behavior– The effect of neurotransmitters on human behaviour can be explained
using an appropriate example. Neurotransmitters allow the impulse to cross a synapse (excitatory) or stop the impulse and prevent it from crossing a synapse (inhibitory).
– Neurotransmitters are themselves affected by agonists which amplify their effect and antagonists which reduce their effect.
– As a result, neurons working together can produce a large variety of effects resulting in a complex repertoire of behaviours. As a result any claim of cause and effect should be treated with caution.
• Hormones and behavior
– The effect of a hormone on human behaviour can be examined using one or more examples.
• Pheromones & behavior
– There is increasing evidence that pheromones may play a role in human behaviour, however, none are conclusive.
– A discussion on the effect of pheromones on behavior is a useful exercise in critical thinking.
• Genes & behavior– The evidence for links between genes and certain types of
behaviour requires critical evaluation in the light of environmental factors.
• Genetic Similarity– Genetic similarity is referred to as relatedness. The greater
the genetic similarities between two individuals or a group of individuals the higher the degree of relatedness.
– An awareness of the degree of relatedness between MZ and DZ twins, siblings, parents and children, and parents and adopted children provides a critical perspective in evaluating twin or kinship studies.
• Evolutionary explanations for behavior
– If genes code for behavior as well as physical traits, then behaviour is subject to evolutionary pressures in the same way that physical traits are subject to evolutionary pressures.
• The role of animal research in understanding human behavior (HL)
• For all three topics in the biological approach, and with reference to research studies, HL students should study the following.
• The value of animal models in psychology research.
• Whether animal research can provide insight into human behaviour.
• Ethical considerations in animal research.
Key Concept
• Everything we study in bio psych should come back to this:
“Humans evolved to live in cultures; cultures that required the evolution of complex biologically based language and cognitive abilities for development” – Jamison, 2010
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History of Mind
Plato correctly placed mind in the brain. However, his student Aristotle believed that
mind was in the heart.
Ancient Conceptions About Mind
Today we believe mind and brain are faces of the same coin. Everything that is psychological
is simultaneously biological.
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The Nervous System
Nervous System: Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system.
Central Nervous System (CNS): the brain and spinal cord.
Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
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Peripheral Nervous System
Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles.
Autonomic Nervous System: Part of the PNS that controls the glands and other muscles.
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Autonomic Nervous System (ANS)
Sympathetic Nervous System: Division of the ANS that arouses the body, mobilizing its energy in stressful situations.
Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy.
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Autonomic Nervous System (ANS)
Sympathetic NS “Arouses”
(fight-or-flight)
Parasympathetic NS “Calms”
(rest and digest)
The Amazing Phineas Gage & Localization of Brain Function
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Phineas Gage – Article – Tech Sheds Light
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The brain is sculpted by our genes but also by our experiences.
Plasticity, or neuroplasticity, refers to the brain’s ability to modify itself. Often after some type of injury or illness.
Does this anytime neurological connections are rearranged due to learning or experience
The Brain’s Plasticity
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Localization & LanguageAphasia is an impairment of language, usually
caused by left hemisphere damage either to Broca’s area (impaired speaking) or to Wernicke’s area
(impaired understanding).
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Splitting the Brain
A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the
corpus callosum) between them. *Sperry & Gazzaniga*
Corpus Callosum
Martin
M. R
oth
er
Courtesy
of T
erence W
illiams, U
niv
ersity o
f Iow
a
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Split Brain Patients
With the corpus callosum severed, objects (apple) presented in the right visual field can be named.
Objects (pencil) in the left visual field cannot.
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Try This!
Try drawing one shape with your left hand and one with your right hand, simultaneously.
BB
C
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Non-Split Brains
People with intact brains also show left-right hemispheric differences in mental abilities.
A number of brain scan studies show normal individuals engage their right brain when
completing a perceptual task and their left brain when carrying out a linguistic task.
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The Nerves
Nerves consist of neural “cables” containing many axons. They are part of the peripheral nervous system and connect muscles, glands, and sense
organs to the central nervous system.
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Neural Communication
The body’s information system is built from billions of interconnected cells called neurons.
Estimated that there are b/w 10-100 billion that can make 13 trillion connections
Neurotransmission & Action Potentials
• Neurotransmission is the process by which messages are sent between neurons
• When an individual neuron “fires” it is called an action potential – it’s an all or nothing response – it either fires or doesn’t
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Refractory Period
Refractory Period: After a neuron fires an action potential it pauses for a short period to recharge
itself to fire again.
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Synapse
A junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the
synaptic gap or cleft.
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Neurotransmitters
Neurotransmitters (chemicals) released
from the sending neuron travel across the
synapse and bind to receptor sites on the
receiving neuron, thereby influencing it to
generate an action potential.
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Lock & Key Mechanism
Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.
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Reuptake
Neurotransmitters in the synapse are
reabsorbed into the sending neurons
through the process of reuptake. This process applies the brakes on
neurotransmitter action.
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Neurotransmitters
Neurotransmitter Function(s)
Acetylcholine
Enables muscle action, learning
& some memory (muscle
memory - more specifically,
habits)
Dopamine
Influences voluntary movement,
learning, feelings of pleasure
Endorphins
Painkillers, lead to feelings of
euphoria
Norepinephrine
Alertness & arousal – stimulates
sympathetic nervous system
Serotonin
Affects mood, hunger, sleep, and
arousal (primary drives) – limbic
system
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How Neurotransmitters Influence Us?
Serotonin pathways are involved with mood
regulation.
From Mapping the Mind, Rita Carter, © 1989
University of California Press
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Dopamine Pathways
Dopamine pathways are involved with diseases such as
schizophrenia and Parkinson’s disease.
From Mapping the Mind, Rita Carter, © 1989
University of California Press
Kasamatsu & Hirai, 1999
• Sensory deprivation of Buddhist monks
• After 48 hours – hallucinations
• Blood samples show increase of Serotonin
• Activates hypothalamus & frontal cortex
• Serotonin altered perception
Martinez & Kesner, 1991
• Acetylcholine and Memory
• Rats learned to navigate a maze
• Block ACh in group of rats, prevent its reuptake in others, and control group
• Group 1 slowest at going through maze
• Group 2 faster than both other groups and fewer mistakes
Remember
• It is reductionist to suggest that complex behavior is a product of the right mix of chemicals in our brains
• Neurotransmission plays a role but cannot explain behavior alone
• Read Purple Book 46-48 Effects of Nt on Behavior
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- James Olds (1950’s) Rats cross an electrified grid for self-stimulation when electrodes are placed in the “reward center” called the Nucleus Accumbens
- Robert Heath (1950’s) – similar research on humans (no shock grid) , patients push button themselves –B-19 did it 1500 times in 3 hours to the point of euphoria. Disconnected despite his protests.Pg. 44 Companion
Localization of Brain Function & the Reward Center
San
jiv T
alwar, S
UN
Y D
ow
nstate
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The Brain
Techniques to Study the Brain
A brain lesion experimentally
destroys brain tissue to study animal behaviors after such destruction.
Hubel (1990)
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Clinical Observation
Clinical observations have shed light on a number of brain disorders. Alterations in brain
morphology due to neurological and psychiatric diseases are now being catalogued.
Tom
Lan
ders/ B
osto
n G
lobe
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Electroencephalogram (EEG)
An amplified recording of the electrical waves sweeping across the brain’s surface, measured
by electrodes placed on the scalp.
AJ P
hoto
/ Photo
Research
ers, Inc.
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PET Scan
PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of
glucose while the brain performs a given task.
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MRI Scan & fMRIMRI (magnetic resonance imaging) uses magnetic
fields and radio waves to produce computer-
generated images that distinguish among
different types of brain tissue. Top images show
ventricular enlargement in a schizophrenic patient.
Bottom image shows brain regions when a
participants lies. fMRI shows actual brain activity
in video while subjects engage in behaviors. Most
frequently used.
Both photos from Daniel Weinberger, M.D., CBDB, NIMH
James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations
Near-Infrared Spectroscopy (NIRS)
• Non-invasive optical imaging that uses low levels of light to measure blood flow as a measure of a brain’s activity.
• Used for brain mapping and brain function n motor and visual studies
Discussion
• Do you think doctors should scan patients to let them know if they have a predisposition for mental illness? What effect(s) do you think this could have on the individual?
• Could brain scanning tech be misused? Does the potential misuse of technology & knowledge mean that it should not be pursued?
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The Endocrine System
The Endocrine System is the body’s
“slow” chemical communication
system. Communication is
carried out by hormones
synthesized by a set of glands.
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Hormones
Hormones are chemicals synthesized by the endocrine glands that are secreted in the
bloodstream. Hormones affect the brain and many other tissues of the body.
For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar and
feelings of excitement during emergency situations.
Crane, 2009
Hormone Glands Function
Adrenaline Adrenals Arousal, Fight or Flight, Tend
& Befriend
Cortisol Adrenals Arousal, Stress, Pain Control,
Memory, Inhibits Insulin from
breaking down Glucose
Melatonin Pineal Regulation of sleep
Oxytocin Pituitary & Hypothalamus Attachment: Parents to
offspring, mates etc.
Testosterone &
Estrogen
Gonads Sexual Development, Mood,
Aggression
Tissue Repair
Mirror Neurons
• TED Talk http://www.ted.com/talks/vs_ramachandran_the_neurons_that_shaped_civilization?language=en (7:43)
• Nova https://www.youtube.com/watch?v=Xmx1qPyo8Ks(13:50)
• Example https://www.youtube.com/watch?v=N6XC9nHIsWQ&index=2&list=PL8W7oxRplXBxnYW-9i9Wz38q7rk7cbxiy
• Rubber Hand
https://www.youtube.com/watch?v=XEayC_fXGYY
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