THE BRAIN

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THE BRAIN

• Suppose we took your brain out of your body right before you died. We keep your brain alive by floating it in a tank of cerebral fluid while feeding it enriched blood and then transplanted the living brain into the body of a person with severe brain damage….

• Who’s personality, traits, habits, talents, would that “new” person have?

• Would that be “YOU” in a new body or “Someone Else” in control of your brain?

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Tools of Discovery: How do we study the brain?

Early Methods• Observation: Clinical

Observations of patients revealed some brain-mind connections.

• For example: Damage To– one side of brain caused

paralysis on opposite side of body.

– back of brain disrupts vision.

– left front of brain causes speech difficulties.

Modern Methods

• Modern methods record the brains electrical, metabolic, and magnetic signals using various techniques. – Brain Lesion– EEG– CT Scan– PET Scan– MRI– fMRI

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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)

Microelectrode Techniques

• Very small electrodes inserted into individual neurons

• Used to study activity of a single neuron

• – studying the brain ted ed video by Moran Cerf

Macroelectrode Techniques• Used to get a picture of overall activity in the brain• An example is an EEG (Electroencephalogram),

which uses electrodes placed on a person’s scalp to measure an amplified recording of the electrical waves sweeping across the brain’s surface.

Functional ImagingShows the brain working (functioning in real time)

• EEG imaging– 21 Sensors on the scalp record changes in

electrical activity and feed them into a computer. The computer translates them into color and motion on a map of the brain displayed on a television monitor

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Structural Imaging• Computerized Axial Tomography (CAT-scan)

– Uses X-rays to create a 3-dimensional image of the brain

– CT scans can often show the size and locations of brain abnormalities caused by tumors, blood vessel defects, blood clots, strokes and other problems.

Structural Imaging cont’d• Magnetic Resonance Imaging (MRI)

– Uses a magnetic field and radio waves to produce computer-generated images

– They distinguish among different types of brain tissue.

– Image shows ventricular enlargement in a schizophrenic patient.

CT Scan vs. MRI

• CT may be less expensive than MRI. In addition, it is less sensitive to patient movement.

• CT can be performed if you have an implanted medical device of any kind, unlike MRI.

• MRI contrast materials used for image enhancement have very low incidence of side effects

Functional ImagingShows the brain functioning in real time (movies

or series of images)

• Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT)– Use radioactive glucose to determine location of

greatest brain activity

PET Scan of Alzheimer's

Disease Brain

PET Scan of

Normal Brain

Functional Imaging• Functional Magnetic Resonance

Imaging (fMRI)– Shows function and structure by measuring

movement of blood molecules within the brain.

Neuroimaging Techniques• 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.

Electrical TechniquesElectroencephalogram (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.

Uses for Scans

• Diagnosing psychological disorders

• Determining how drugs affect the brain and body

• Assessing the usefulness of hypnosis

• Examining whether unconscious processes affect behavior

• Exploring the interaction of sensation and perception.

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What do we have in common with these animals?

OUR “OLD BRAIN”

Medula Oblungata

OLD BRAIN STRUCTURES

• BRAINSTEM – Medula, Pons, Reticular Formation

• THALLAMUS

• CEREBELLUM

• LIMBIC SYSTEM – Hypothalamus, Pituitary Gland, Amygdala, Hippocampus

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Older Brain Structures

The Brainstem is the oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival

functions.

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Brain Stem

The Medulla [muh-DUL-uh] is the base

of the brainstem that controls heartbeat

and breathing.

Pons: is involved in motor control and sensory analysis... for example, information from the ear first enters the brain in the pons. It has parts that are important for the

level of consciousness and for sleep.

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Brain Stem

Pons and inside that the (Reticular Formation) is a nerve network in the brainstem that plays an important role in controlling arousal.•It is involved in motor control and sensory analysis... for example, information from the ear first enters the brain in the pons. It has parts that are important for the level of consciousness and for sleep.

The Reticular Formation controls:•Attention •Cardiac Reflexes •Motor Functions •Regulates Awareness •Relays Nerve Signals to the Cerebral Cortex •Sleep

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Thalamus

The Thalamus [THAL-uh-muss] is the brain’s sensory switchboard, located on top of the brainstem. It directs

messages to the sensory areas in the cortex and transmits

replies to the cerebellum and

medulla.

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The “little brain” attached to the rear of the brainstem. It

helps coordinate voluntary movements

and balance.

Cerebellum

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The Limbic System is a doughnut-shaped system of neural

structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and

drives for food and sex. It includes the hippocampus, amygdala, and hypothalamus.

The Limbic System

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The hippocampus: controls memory.

“You will never forget a Hippo running

through campus”

The Limbic System

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Amygdala

The Amygdala [ah-MIG-dah-la] consists of two almond-shaped neural clusters linked to the emotions of fear and

anger.

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HypothalamusThe Hypothalamus lies

below (hypo) the thalamus. Also called the

“reward center”. It directs several

maintenance activities like eating, drinking,

body temperature, and control of emotions. It

helps govern the endocrine system via the pituitary gland. (which controls the endocrine

system)

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Rats cross an electrified grid for self-

stimulation when electrodes are placed

in the reward (hypothalamus) center (top picture). When the

limbic system is manipulated, a rat will navigate fields or climb

up a tree (bottom picture).

Reward CenterS

anjiv Talw

ar, SU

NY

Dow

nstate

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The Cerebral Cortex

The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the body’s ultimate control and information processing center.

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Structure of the Cortex

Each brain hemisphere is divided into four

lobes that are separated by

prominent fissures. These lobes are the

frontal lobe (forehead), parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of

head).

The Cerebral Cortex

Frontal Lobes involved in speaking and muscle movements and in

making plans and judgments

Parietal Lobes include the sensory cortex

Occipital Lobes include the visual areas, which receive visual

information from the opposite visual field

Temporal Lobes include the auditory areas

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Functions of the Cortex

The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements. The Sensory Cortex (parietal cortex) receives

information from skin surface and sense organs.

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F M S

O

P

T

Functions of the Cortex

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Visual Function

The functional MRI scan shows the visual cortex is active as the subject looks at faces.

Courtesy of V

.P. Clark, K

. Keill, J. M

a. M

aisog, S. Courtney, L

.G.

Ungerleider, and J.V

. Haxby,

National Institute of M

ental Health

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Auditory Function

The functional MRI scan shows the

auditory cortex is active in patients who

hallucinate.

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More intelligent animals have increased “uncommitted” or association areas of the

cortex.

Association Areas

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.

Language

• Aphasia–Broca’s area

–Wernicke’s area

Language

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 an area of the left frontal lobe that directs the muscle

movements involved in speech

Wernicke’s Area an area of the left temporal lobe involved in language

comprehension and expression zombie brains

Language

Plasticity

= the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

Split Brain

• Corpus Callosum• the large band of neural fibers

connecting the two brain hemispheres and carrying messages between them.

• ..\..\Myers Pwr Points 2013 edition\Myers AP - Unit 03B.ppt

• 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.

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Right-Left Differences in the Intact Brain

LEFT & RIGHT BRAIN

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Dual Processing

=the principle that information is often simultaneously processed on separate conscious and unconscious tracks.

Interactive Websites

• 3D Brain • Split Brain Game

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