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The Biology of Mind and ConsciousnessBiology and behavior
Neural communication
The nervous system
The endocrine system
The brain
Brain states and consciousness
Biology and Behavior
Everything psychological—every idea, every mood, every urge—is biological
Biological psychologists study the links between biology and behavior
2-1 Why are psychologists concerned with human biology?
Neural Communication
A neuron’s structure
How neurons communicate
How neurotransmitters influence us
NeuronNerve cell; the basic building block of the nervous system
DendritesNeuron extensions that receive messages and conduct them toward the cell body
Axon
Neuron extension that ends messages to other neurons or cells
Action potential Nerve impulse
Glial cells (glia)Cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory
Neuron’s Structure
2-2 What are the parts of a neuron?
SynapseJunction between the axon tip of a sending neuron and the dendrite or cell body of a receiving neuron
Threshold Level of stimulation required to trigger a neural impulse
All-or-none responseNeuron’s reaction of either firing (with a full-strength response) or not firing
NeurotransmittersNeuron-produced chemicals that cross synapses to carry messages to other neurons or cells
Neuron’s Structure
A Typical Neuron
What is the branch of psychology that studies the links between behavior and biology?
When a neuron fires an action potential, the information travels through the axon, the dendrites, and the axon’s terminal branches, but not in that order. Place these three structures in the correct order.
How Neurons Communicate
IF excitatory signals MINUS Inhibitory
signals
EXCEED threshold
THEN Combined
signals trigger action potential
2-3 How do neurons communicate?
Let’s look more closely at this process
on the next slide.
How Neurons Communicate
How does our nervous system allow us to
experience the difference between a slap and a tap on the back?
What happens in the synaptic gap?
How Neurotransmitters Influence Us
Neurotransmitters have their own pathways which deliver specific messages that influence behavior and emotions
Some Neurotransmitters and Their Functions
The endorphins, serotonin, and dopamine are all chemical messengers called ________.
The Nervous System
The peripheral nervous system
The central nervous system
The Nervous System
Nervous systemBody’s speedy, electrochemical communication network, consisting of all the nerve cells of the central and peripheral nervous systems
Central nervous system (CNS) Brain and spinal cord
Peripheral nervous system (PNS)Sensory and motor neurons connecting the central nervous system (CNS) to the rest of the body
Types of Neurons
Sensory neuronsCarry messages from the body’s tissues and sensory receptors inward to your spinal cord and brain for processing
Motor neuronsCarry instructions from your central nervous system out to the body’s muscles
Interneurons within brain and spinal cordCommunicate with one another and process information between the sensory input and motor output
The Functional Divisions of the Human Nervous System
The Peripheral Nervous System
Two parts with subdivisionsSomatic nervous system
Autonomic nervous systemSympathetic nervous system
Parasympathetic nervous system
Autonomic Nervous System Subdivisions
The autonomic The autonomic nervous system nervous system
arouses and arouses and calmscalms
• Sympathetic subdivision arouses and expends energy
• Parasympathetic subdivision calms and conserves energy, allowing routine maintenance activity
The Central Nervous System
Adult brain has about 86 billion neurons (Azevedo et al., 2009)
Brain accounts for about 2 percent of body weight and uses 20 percent of energy
Neural networks and pathways govern reflexes through highly efficient electrochemical information system
The Endocrine System
Glands secrete chemical messengers through the bloodstream to target tissueAdrenal glands influence fight-or-flight responsePituitary gland, controlled by hypothalamus, releases hormones and sends messages to other endocrine glands to release their hormones
Growth and sex hormonesOxytocin
The Endocrine System
FEEDBACK SYSTEM •Brain → pituitary→ other glands → hormones→body and brain
•This reveals the interplay between the nervous and endocrine systems
Why is the pituitary gland called the “master
gland”?
How are the nervous and endocrine systems alike, and how do they differ?
The Brain
Older brain structures
The cerebral cortex
Our divided brain
Older Brain Structures
Less complex brain in primitive vertebrates handles basic survival functions
More complex brain in advanced mammals (including humans) contains new brain systems built on the old
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The Brainstem
THE BODY’S CROSS-WIRINGNerves from one side of the brain are mostly linked to the body’s opposite side.
• Brainstem• Oldest and innermost
brain region• Medulla • Located at base of the
brainstem; controls heartbeat and breathing
• Pons• Sits above medulla and
helps coordinate movementA
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The Brainstem and Thalamus
The brainstem, including the The brainstem, including the medulla and pons, is an medulla and pons, is an
extension of your spinal cord. extension of your spinal cord. The thalamus is attached to its The thalamus is attached to its
top. The reticular formation top. The reticular formation passes through both structures.passes through both structures.
Nerves from the left side of the brain are mostly linked to the ________ side of the body, and vice versa.
The Brain
Thalamus Area at the top of the brainstem; directs sensory messages to the cortex and transmits replies to the cerebellum and medulla
Reticular formationNerve network running through the brainstem and thalamus; plays an important role in controlling arousal
The Cerebellum
Aids in judgment of time, sound and texture discrimination, and emotional control
Coordinates voluntary movement and life-sustaining functions
Helps process and store information outside of awareness
THE BRAIN’S THE BRAIN’S ORGAN OF ORGAN OF
AGILITY Hanging AGILITY Hanging at the back of the at the back of the
brain, the brain, the cerebellum cerebellum
coordinates our coordinates our voluntary voluntary
movements, as movements, as when soccer star when soccer star Cristiano Ronaldo Cristiano Ronaldo controls the ball.controls the ball.
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In what brain region would damage bemost likely to (1)disrupt your ability to skip rope?
(2)disrupt your ability to hear and taste?
(3)perhaps leave you in a coma?
(4)cut off the very breath and heartbeat of life?
The Limbic SystemLimbic systemNeural system that sits between the brain’s older parts and its cerebral hemispheresIncludes hippocampus, amygdala, and hypothalamus
Hypothalamus controls the nearby pituitary gland
Associated with emotions and drivesElectrical stimulation of a cat’s amygdala provokes reactions such as the one shown here, suggesting its role in emotions such as rage
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The Limbic SystemAmygdala
Consists of two lima-bean-sized neural clusters in the limbic system; linked to emotion
Hypothalamus Neural structure lying below the thalamus
Directs several maintenance activities
Helps govern endocrine system via the pituitary gland, and is linked to emotion and reward
PAIN FOR PAIN FOR PLEASURE This PLEASURE This
ratrathas an electrode has an electrode
implanted in a implanted in a reward center of reward center of
its hypothalamus. its hypothalamus. It will cross an It will cross an electric grid, electric grid,
accepting painful accepting painful shocks, in order shocks, in order to press a lever to press a lever
that sends that sends impulses to its impulses to its reward center.reward center.
Brain Structures and Their Functions
• What are the three key structures of the limbic system, and what functions do they serve?
The Cerebral Cortex
Functions of the Cortex
Motor cortexFritsch and Hitzig: Discovered motor cortex
Forester and Penfield: Mapped motor cortex and discovered body areas requiring precise control and the mouth occupied the most cortical space
Motor functionsElectrically stimulating the motor cortex can cause body part movement
Mind over Matter
A series of strokes left Cathy A series of strokes left Cathy paralyzed for 15 years, unable to paralyzed for 15 years, unable to
make even simple arm movements. make even simple arm movements. Now, thanks to a tiny, 96-electrode Now, thanks to a tiny, 96-electrode implant in her brain’s motor cortex, implant in her brain’s motor cortex, she is learning to direct a robotic she is learning to direct a robotic
arm with her thoughts (Hochberg et arm with her thoughts (Hochberg et al., 2012).al., 2012).
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Functions of the Motor Cortex
Left hemisphere tissue devoted to each body part in the motor cortex and the somatosensory cortex
Try moving your right hand in a circular motion, as if polishing a car. Then start your right foot doing the same motion as your hand. Now reverse the right foot’s motion, but not the hand’s. Finally, try moving the left foot opposite to the right hand.
1. Why is reversing the right foot’s motion so hard?2. Why is it easier to move the left foot opposite to the right hand?
Functions of the Cortex
Sensory functionsSomatosensory cortex processes information from skin senses and body part movement
WATCHING THE BRAIN INACTION As this person looks at a photo, the fMRI (functional MRI) scan shows increased activity (color represents more blood flow) in the visual cortex in the occipital lobes. When the person stops looking, the region instantly calms down.
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Functions of the Cortex
Sensory functionsThe visual cortex of the occipital lobes at the rear of your brain receives input from your eyes
The auditory cortex, in your temporal lobes—above your ears—receives information from your ears
THE VISUAL CORTEX AND AUDITORY CORTEX
Our brain’s________ cortex registers and
processes body touch and movement sensations.
The ________ cortex controls our voluntary movements.
AREAS OF THE CORTEX IN FOUR MAMMALS
• More intelligent animals have increased “uncommitted” or association areas of the cortex
• These vast brain areas interpret, integrate, and act on sensory information and link it with stored memories
Functions of the Cortex
Association areas of the cortexAre found in all four lobes
Found in the frontal lobes; enables judgment, planning, and processing of new memories
Damage to association areas Result in different losses
Let’s take a closer look a one case.
Why are association areas important?
The Brain’s Plasticity
Brain damage effectsSevered neurons, unlike cut skin, usually do not repair themselves
Some brain functions seem forever linked to specific areas
Brain damage effectsSome brain tissue can reorganize in response to damage
Plasticity sometimes occurs after serious damage, especially in young children
BRAIN PLASTICITY
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PlasticityBrain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience
NeurogenesisFormation of new neurons
Corpus callosum Large band of neural fibers connecting the two brain hemispheres and carrying messages between them
Our Divided BrainSplit brain hemisphere
Isolated by cutting the fibers (mainly those of the corpus callosum) connecting them
Intact brainData received by either hemisphere are quickly transmitted to the other side, across the corpus callosum
Severed corpus callosum brainThis information sharing does not take place
THE INFORMATION HIGHWAYFROM EYE TO BRAIN
THE CORPUS CALLOSUM
This large band of neural fibers connects the two brain hemispheres. To photograph the half brain shown at left, a surgeon separated the hemispheres by cutting through the corpus callosum and lower brain regions. In the view above, brain tissue has been cut back to expose the corpus callosum and bundles of fibers coming out from it.
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Testing the Divided Brain
(1) If we flash a red light to the right hemisphere of a person with a split brain, and flash a green light to the left hemisphere, will each observe its own color?
(2) Will the person be aware that the colors differ?
(3) What will the person verbally report seeing?
Right-Left Differences in Intact Brains
Each hemisphere performs distinct functions. Humans have unified brains with specialized parts.
Left hemisphere is good at making quick, exact interpretations of language.
Right hemisphere excels in high-level language processing.
Brain States and Consciousness
Selective attention
Sleep and dreams
Brain States and Consciousness
ConsciousnessAwareness of self and environment
Selective attentionFocusing conscious awareness on a particular stimulus
Inattentional blindness Failure to see visible objects when our attention is directed elsewhere
ALTERED STATES OF CONSCIOUSNESS
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Clowning Around
HARD TO MISS? Would you notice a clown unicyclingpast you on campus? In this study, most students on cell phones did notnotice the clown; students who were off the phone generally did notice.
Hym
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2009
CHANGE BLINDNESSWhile a man (white hair) provides directions to a construction worker, two experimenters rudely pass between them carrying a door.
During this interruption, the original worker switches places with another person wearing different colored clothing. Most people, focused on their direction giving, do not notice the switch.
Explain three attentional principles that magicians may use to fool us.
Sleep and Dreams
Biological rhythms 24-hour biological clock
90 minute sleep cycle
Circadian rhythmInternal biological clock of 24-hour cycle of day and night
Altered by age and experience
REM (rapid eye movement)Recurring sleep stage during which vivid dreams commonly occur
REM reboundTendency for REM sleep to increase following REM sleep deprivation
SleepBrain waves and sleep stages
The beta waves of an alert, waking state and the regular alpha waves of an awake, relaxed state differ from the slower, larger delta waves of deep NREM-3 sleepAlthough the rapid REM sleep waves resemble the near-waking NREM-1 sleep waves, the body is more aroused during REM sleep than during NREM sleep
MEASURING SLEEP ACTIVITY
As this man sleeps, attached electrodes are picking upweak electrical signals from his brain, eyes, and facial muscles. (From Dement, 1978.)
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SleepPeriodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation (Adapted from Dement, 1999.)
Delta waves Large, slow brain waves associated with deep sleep
REM Sleep
About an hour after
first sleeping,
REM sleep
begins
For about 10
minutes, your brain
waves become
rapid and saw-
toothed, more like those of
the nearly awake
NREM-1 sleep.
But unlike NREM-1,
during REM sleep
your heart rate rises and your breathing becomes rapid and irregular.
Every half-
minute or so, your
eyes dart around in
a brief burst of activity behind closed
lids. Eye movemen
ts announce
the beginning
of a dream.
Your brain’s motor
cortex is active during REM
sleep, but your
brainstem blocks its message
s. Muscles relax and genitals become aroused.
Sleep cycle
repeats itself
every 90 minutes.
Stages in a Typical Night’s Sleep
What are the four sleep stages, and in what order do we normally travel through those stages?
Can you match the cognitive experience with the sleep stage?
1. NREM-1 a. story-like dreams
2. NREM-3 b. fleeing images
3. REM c. minimal awareness
Sleep Theories
Possible reasons why sleep evolvedSleep protects
Sleep helps us recover
Sleep helps us remember
Sleep feeds creative thinking
Sleep supports growth
What five theories explain our need for sleep?
Sleep Deprivation and Sleep Disorders
Effects of sleep lossSlows reactions Increases errors on visual attention tasksReduced concentration that may lead to “cyber-loafing”Immune system depressionRisk of depression
SLEEPLESS AND SUFFERING These fatigued, sleep-deprived earthquake rescue workers in Chinamay experience a depressed immune system, impaired concentration, and greater vulnerability to accidents.
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HOW SLEEP DEPRIVATION AFFECTS US
CANADIAN TRAFFIC ACCIDENTSOn the Monday after the spring time change, when people lose one hour of sleep, accidents increased, as compared with the Monday before. In the fall, traffic accidents normally increase because of greater snow, ice, and darkness, but they diminished after the time change. (Adapted from Coren, 1996.)
Sleep: Major Disorders
InsomniaRecurring problems in falling or staying asleep
NarcolepsySleep disorder in which a person has uncontrollable sleep attacks, sometimes lapsing directly into REM sleep
Sleep apneaSleep disorder in which a sleeping person repeatedly stops breathing until blood oxygen is so low it awakens the person just long enough to draw a breath
Looking for a Better Night’s Sleep?
Dreams
DreamSequence of images, emotions, and thoughts passing through a sleeping person’s mind
Manifest contentAccording to Freud, the remembered story line of a dream
Latent contentAccording to Freud, the underlying meaning of a dream
DreamsWhy we dream
To satisfy our own wishes
To file away
memories
To develop and
preserve neural
pathways
To make sense of neural static
To reflect cognitive
development
2-18 What do we dream about, and what are five theories of why we dream?
Dream Theories
What five theories explain why we dream?
