Biological Approach to Understanding

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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The Nervous System

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Central Nervous System

The Spinal Cord and Reflexes

Simple Reflex

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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

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Courtesy

of T

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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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Divided Consciousness

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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.

Localization and Language pt. 2

• Compare Hull & Vaid with Kim & Hirsch (Companion book, pg. 43)

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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

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Neuron

A nerve cell, or a neuron, consists of many different parts.

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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Agonists

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Antagonists

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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

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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

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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.

CT Scans

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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

Pheromones

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