Transcript Slide 1
Unit 3B: Biological Bases of Behavior: The Brain
Unit Overview
• The Tools of Discovery: Having Our Head Examined
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Right-Left Differences in the Intact Brain
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The Tools of Discovery: Having Our Head Examined
Introduction
• Lesion - in the interests of science
or medicine, scientists can selectively destroy tiny clusters of brain cells/tissue.
• Today, we can also stimulate (electrically/chemically) various parts of the brain and note the effects.
Recording the Brain’s Electrical Activity We are now able to detect an electrical impulse from a single neuron = detect exactly where information goes from any stimulus.
Electroencephalogram (EEG) reads regular brain
waves of electrical activity that sweeps the surface of the brain = a computer can filter out unrelated brain activity http://www.youtube.com/watch?v=bO _ZtIxcr0&feature=related&safe=active
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Neuroimaging Techniques
– – (CAT Scan)- Takes X-ray photographs that can reveal brain damage http://www.youtube.com/watch?v=uHu9aa0QDiE&feature=related&safe=act ive
PET (Positron Emission Tomography) scan
– Shows the brain’s consumption of glucose (sugar) which creates a visual display of brain activity http://www.youtube.com/watch?v=d9iOxMFmPlA&feature=related&safe=active
Neuroimaging Techniques
• • • MRI (Magnetic Resonance Imaging)- brain scan where the head is put in a strong magnetic field which aligns, and then disorients the atoms = pictures of brain’s soft tissue http://www.youtube.com/watch?v=xi8HRkFTHgw&safe=active fMRI (Functional MRI)- reveals brain’s functioning and structure. Where the brain is active, the blood goes.
– – The brain “lights up” as you perform different mental functions http://www.youtube.com/watch?v=xi8HRkFTHgw&safe=active
Older Brain Structures
The Brainstem
–Pons
The Thalamus
–All the senses EXCEPT smell
The Cerebellum
–“Little brain”
The Limbic System
–Hippocampus
The Limbic System
The Amygdala
–Aggression and fear
The Limbic System
The Hypothalamus
–Influence on the pituitary gland –Reward Centers –Reward deficiency syndrome
The Cerebral Cortex
Introduction
• Cerebrum – Cerebral cortex • Fabric of interconnected neural cells covering the cerebral hemispheres • The body’s ultimate control and information-processing center • Gives certain areas of the body different attention -DEMO • Moving up the ladder of life means a larger cerebral cortex – Allows humans to adapt, learn, and think
Structure of the Cortex
(“glue cells”) – provide the myelin and nutrients that neurons need.
– The more complex the animal, the more glial cells • Lobes
– speaking, muscle movement, and making plans/judgments
– receives sensory information for touch and body position
– receives information from visual fields
– receive information from the opposite ear • Scenario DEMO
Functions of the Cortex -
Association Areas
areas of the cortex that are not involved in primary motor or sensory functions, but are involved in higher mental functioning learning, speaking, remembering, thinking – Phineas Gage Video
Functions of the Cortex
Motor Functions
(in the frontal lobe) output controls voluntary movements • Mapping the Motor Cortex – different areas of the cortex control different parts of your body – Being able to predict a monkey’s movement .10 seconds before it happens • Neural Prosthetics- research showing it is possible to control objects by tracking what neurons fire in the motor cortex
Functions of the Cortex • Sensory Cortex-
Sensory Functions
– Front of the parietal lobes that registers and processes body touch and movement sensations – The more sensitive the body region, larger the sensory cortex area devoted to it.
Functions of the Cortex
Language
– an impaired use of language can result from damage to one of the following areas-
(disrupts speaking) – controls language expression and directs the muscle movements involved in speech
(disrupts understanding) – controls language reception – a brain area involved in language comprehension and expression
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Language Continued
Is language only located in the left hemisphere?
– Left handed and divided brain woman • When a word is in her left visual field (processed in right half of brain) she can write it but not say it • When a word is in her right visual field (processed in left half of brain) she can say it, but not write it Clear scientific evidence that in some people the capacities for spoken and written language may be located in different hemispheres Learning a second language – At a young age- the brain shows activity in the same area as your native language – After childhood- brain activity is in an adjacent area while speaking
Language
Language
Language
Language
Language
Language
The Brain’s Plasticity
• Brain Damage
– the ability of the brain to modify itself after some types of damage (VIDEO) • The younger the child, the greater chance the remaining hemisphere can take over functions of the surgically removed one • Unused or damaged parts of the brain looks for signals to process (Deaf people have enhanced peripheral vision) – Constraint-induced therapy – restrain a fully functioning limb to force the “bad limb” to be reprogramed
– neural stem cells to rebuild or replace damaged brain cells
Our Divided Brain
• • • •
Right v Left Brained
The “right versus left brain” is a myth.
There is no evidence to support the idea that the two brains do not communicate with one another.
Neither “logic” or “musical ability” is kept in one brain or the other.
HOWEVER, there is NEW research that suggests lateralization (hemispheric specialization)- functions on the brain may be either on the left or right – The right hemisphere processes emotional expressions. Which face is happier?
Splitting the Brain
• Vogel and Bogen
– large band of neural fibers (axons) that connect the two brain hemispheres and carry messages
– a surgeon can cut through the corpus callosum (to eliminate seizures) (VIDEO) – It is as if you have two competing brains; and will follow their own instructions “two separate minds” • Left- deliberating (rationalize) • Right- simple requests • Shirt unbutton/Grocery store items • “Walk”
Demos -Two Brains -Hand/Leg -Hand tapping -Circle/Square
The Brain and Consciousness
Introduction
– our awareness of ourselves and our environment – Reproductive advantage?
– Acting on long term interests rather than short term pain/pleasure?
– Survival of being able to read other people?
Cognitive Neuroscience
– study of brain activity linked with cognition – Perception, thinking, memory, and language – How do the mind and the brain interact?
– Non-communicative woman after car accident with no signs of conscious awareness was asked to imagine people playing tennis • Resulted in fMRI scan with activity
The Two-Track Mind
• Two-Track Mind – Visual perception track • enables us to recognize things and to plan actions – Visual action track • Guides our moment-to-moment actions • Much of our everyday thinking, feeling, and acting operates outside our conscious awareness - - you may act before you are conscious of doing something (driving familiar route) – Seeing a bird flying • Cognitive- It’s a cardinal!
• Sub-processing- color, form, movement, distance
The End
Definition Slides
Lesion
= tissue destruction; a brain lesion is a naturally or experimentally caused destruction of brain tissue.
Electroencephalogram (EEG)
= an amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are measured by electrodes placed on the scalp.
CT (computed tomography) Scan
= a series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body.
• Also called CAT scan.
PET (positron emission tomography) Scan
= a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
MRI (magnetic resonance imaging)
= a technique that uses magnetic fields and radio waves to produce computer generated images of soft tissue. MRI scans show brain anatomy.
fMRI (functional MRI)
= a technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function.
Brainstem
= the oldest part of the central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.
Medulla
= the base of the brainstem; controls heartbeat and breathing.
Reticular Formation
= a nerve network in the brainstem that plays an important role in controlling arousal.
Thalamus
= the brain’s sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
Cerebellum
= the “little brain” at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance.
Limbic System
= doughnut-shaped neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives.
Amygdala
= two lima bean-sized neural clusters in the limbic system; linked to emotion.
Hypothalamus
= a neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.
Cerebral Cortex
= the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.
Glial Cells
= cells in the nervous system that support, nourish, and protect neurons.
Frontal Lobes
= portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments.
Parietal Lobes
= portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.
Occipital Lobes
= portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.
Temporal Lobes
= portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.
Motor Cortex
= an area at the rear of the frontal lobes that controls voluntary movements.
Sensory Cortex
= area at the front of the parietal lobes that registers and processes body touch and movement sensations.
Association Areas
= areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.
Aphasia
= impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding).
Broca’s Area
= controls language expression that directs the muscle movements involved in speech.
Wernicke’s Area
= controls language reception – a brain area involved in language comprehension and expression; usually in the left temporal lobe.
Plasticity
= the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.
Neurogenesis
= the formation of new neurons.
Corpus Callosum
= the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.
Split Brain
= a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.
Consciousness
= our awareness of ourselves and our environment.
Cognitive Neuroscience
= the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory and language).
Dual Processing
=the principle that information is often simultaneously processed on separate conscious and unconscious tracks.