AP Psychology

UNIT 3: BIOLOGICAL BASES OF

BEHAVIOR

MODULE #5: THE BRAIN

Clinical Observation (Case Study) – Observing specific brain diseases and injuries.

Over 150 years ago people were studying patients with brain damage and linked loss of structure with loss of function.

Essentially, losing brain tissue caused brain damage.

TECHNIQUES TO LEARN ABOUT STRUCTURE & FUNCTION

WHO IS PHINEAS GAGE?

Phineas Gage was a level-headed, calm foreman of a railroad crew in 1848.

An explosion shot an iron rod through his head, severing the connections between his limbic system and his frontal cortex.

Gage became hostile, impulsive, and unable to control his emotions or his obscene language.

Autopsy revealed that the relationship between frontal lobes and control of emotional behavior.

PHINEAS GAGE

PHINEAS GAGE CLIP

Precise destruction of brain tissue.

Enabled more systematic study of the loss of function resulting from surgical removal, cutting of neural connections, or destruction by chemical applications.

LESIONS

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.

MEASURING BRAIN FUNCTION

The amplified tracings are called evoked potentials. Scientists introduce a stimulus and study the brain waves to learn about brain activity.

MEASURING BRAIN FUNCTION

Positron Emission Tomography (PET) scan: a visual display of brain activity that detects where a radioactive form of glucose (sugar) goes while the brain performs a given task.

MEASURING BRAIN FUNCTION

Active neurons hog the glucose (the brain’s chemical fuel), and the PET scan tracks where in the brain the radioactive glucose goes.

MEASURING BRAIN FUNCTION

Researchers can have participants think about certain topics or do activities to see where the glucose goes (thereby showing what part of the brain is active during that activity).

MEASURING BRAIN FUNCTION

Magnetic Resonance Imaging (MRI): a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.

BRAIN IMAGING

A head is put into a strong magnetic field to produce the image.

BRAIN IMAGING

Healthy Individual Schizophrenic

Functional Magnetic Resonance Imaging (fMRI): a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans show brain functions.

MEASURING BRAIN FUNCTION

Researchers compare images taken less than a second apart, they can see which parts of the brain “light up” with increased blood flow.

MEASURING BRAIN FUNCTION

Computerized Axial Tomography (CAT or CT): two-dimensional x-ray slices that are passed through various angles of the brain, arranged to show the extent of a lesion.

BRAIN IMAGING

Brainstem – oldest part of the brain. Connects the brain with the spinal cord.

Responsible for automatic survival function.

THE BRAIN

WATERBOY CLIP

Medulla: where most fibers cross above the brain stem, resulting in contralateral (opposite side) control.

regulates heart rate, blood flow, breathing, digestion, vomiting.

STRUCTURE OF BRAIN: BRAINSTEM

Reticular Formation: a nerve network in the brainstem (pons) that plays an important role in controlling arousal (awakening).

STRUCTURE OF BRAIN: BRAINSTEM

Pons: right above the medulla, helps coordinate movement, and is the bridge between cerebral hemispheres and both medulla and cerebellum.

STRUCTURE OF BRAIN: BRAINSTEM

Thalamus: relay “station” for the brain. It receives information from all of the senses (except smell) and routes it to the brain regions that deal with those senses.

Located at the top of the brain stem.

STRUCTURE OF BRAIN

Cerebellum: “little brain”-coordinates motor function integrating motion and positional information from the inner ear and muscles.

helps maintain balance.

STRUCTURE OF BRAIN

Responsible for emotions like fear and anger, and basic need for food and sex.

THE LIMBIC SYSTEM

Hippocampus: Enables formation of new long-term memories.

THE LIMBIC SYSTEM

Amygdala: influences anger and fear. Coordinates fight-or-flight response.

Removal will result in loss of anger.

Stimulation will cause aggression.

THE LIMBIC SYSTEM

Hypothalamus: controls autonomic functions such as body temperature and heart rate via control of sympathetic and parasympathetic centers in the medulla.

Sets appetite drives (e.g. thirst, hunger, sexual desire) and behavior.

THE LIMBIC SYSTEM

Hypothalamus: Integrates with endocrine system by secretion of hormones that regulate hormones from the pituitary.

It’s the reward center because it’s responsible for pleasure.

THE LIMBIC SYSTEM

An electrode is connected to the hypothalamus, which causes the rat to cross the painful electric grid to press the pedal to send electrical impulses to its pleasure center (reward).

Basal Ganglia: links the thalamus with the motor cortex and other motor areas.

regulates initiation of movements, balance, eye movements, and posture.

Involved in reward/punishment learning and focus.

STRUCTURE OF BRAIN

Cerebral Cortex: receives and processes sensory information and directs movement.

Center for higher order process such as thinking, planning, judgment.

STRUCTURE OF BRAIN

CEREBRAL CORTEX

Frontal lobe: The part of the cerebral cortex right behind the forehead.

Involved in speaking and muscle movements.

STRUCTURE OF BRAIN

Frontal lobe:Includes Broca’s area: in left frontal lobe controls production of speech.

Interpret and control emotional behaviors, make decisions, carry out plan.

STRUCTURE OF BRAIN

Temporal lobe: center for hearing.

STRUCTURE OF BRAIN

Temporal Lobe:Includes Wernicke’s area: in left temporal lobe, plays role in understanding language and making meaningful sentences.

STRUCTURE OF BRAIN

Temporal Lobe:Right temporal lobe important for understanding music/tonality.

Sound from both ears is processed mostly contralaterally.

STRUCTURE OF BRAIN

Parietal Lobe: Responsible for cognition (thinking), information processing, pain and touch sensation, speech, and visual perception.

STRUCTURE OF BRAIN

Occipital Lobe: Receives information from the eyes and processes it.

Responsible for visual perception and color recognition.

STRUCTURE OF BRAIN

STRUCTURE OF BRAIN

Occipital lobes

Parietal lobes

Frontal lobes

Temporallobes

Frontal LobeParietal Lobe

Corpus Callosum

Occipital Lobe

Cerebellum

Spinal Cord

Medulla

Pons

Temporal Lobe

Pituitary

It was concluded that damage to this so-called Broca’s area caused a loss of ability to speak, known as expressive aphasia.

BROCA’S AREA

Carl Wernicke found another brain area involved with understanding language in the left temporal lobe.

Destruction of Wernicke’s area results in loss of ability to comprehend written and spoken language, known as receptive aphasia.

WERNICKE’S AREA

Paul Broca (1861) did an autopsy on a patient named Tan, who couldn’t speak even though there was no physical damage and he could understand language.

Tan’s brain showed loss of tissue in part of the frontal lobe of the left central cerebral hemisphere (as did several other similar cases).

BROCA’S AREA

EEG – Wave cap; studies brain waves

PET – Inject glucose, track where it goes. Shows brain activity.

MRI – Uses magnetic fields to produce an image of soft tissue.

fMRI – Track blood flow through brain.

CAT – 2D x-ray of slice of brain.

REVIEW!!!

Medulla – Heart rate, breathing, blood flow

Reticular Formation – Arousal (awakening), located inside of pons

Pons – movementThalamus – Relay station; receives info from body (except smell) and sends to different parts of the brain.

REVIEW!!!

Cerebellum – Motor function, balanceHippocampus – MemoriesAmygdala – Emotions (anger & fear)Hypothalamus – autonomic functions (heart rate, body temp). Regulates hormones. Reward center.

Cerebral Cortex – Receives & processes sensory info & movement.

Basal Ganglia – motor functions, movement, balance, eye movement.

REVIEW!!!

Frontal – Speaking & muscle movement; Broca’s area (speech)

Temporal – hearing, music, & sound; Wernicke’s area (understanding language & making sentences)

Parietal – thinking, cognition, info processing, sensation, pain, & touch

Occipital – Visual perception & color recognition

REVIEW!!!

READING ALOUD

READING ALOUDDepending on the damaged area different forms of aphasia occurs.

Aphasia: impairment of languageDamage to:

A. Angular gyrus – can speak and understand but not read.

B. Wernicke’s area – can’t understand words

C. Broca’s area – disrupts speaking

Rotate your right hand in a circle. Now rotate your right foot in the same direction.

Now rotate your right foot in the opposite direction, without changing the direction of your hand.

Difficulties arise because you are asking your left hemisphere to do two things.

HEMISPHERES DEMONSTRATION

Rotate your right hand in a circle. Now rotate your LEFT foot in the same direction.

Now rotate your LEFT foot in the opposite direction, without changing the direction of your hand.

Easier because your left hemisphere controls your right hand and your right hemisphere controls your left foot.

HEMISPHERES DEMONSTRATION

The last evolutionary development of the brain is localization of functions on different sides of your brain.

THE BRAIN

The brain is contralateral.Contralateral: right/left hemisphere controls other side of body.

The right side of the brain controls the left side of the body and vice-versa.

LOCALIZATION AND LATERALIZATION OF THE BRAIN’S FUNCTION

nonverbalspatial, musical, and holistic functions

identifying facesrecognizing emotional facial expressions

controls the left side of the body

RIGHT HEMISPHERE:

verbal functionsmathematical functionsanalytical functionslanguagecontrols the right side of the body

LEFT HEMISPHERE:

Association areas: regions of the cerebral cortex that do not have specific sensory or motor functions, but are involved in higher mental functions, such as thinking, planning, remembering, and communicating.

LOCALIZATION AND LATERALIZATION OF THE BRAIN’S FUNCTION

Plasticity: when one region of the brain is damaged, the brain can reorganize to take over its function.

STRUCTURE OF BRAIN

Corpus Callosum: the wide band of axon fibers connecting the two hemispheres of the brain.

OUR DIVIDED BRAIN

Split Brain – cutting the corpus callosum, resulting in two separate hemispheres.

What we see:

OUR DIVIDED BRAIN

Cutting the corpus callosum alleviates the symptoms of epilepsy.

Split Brain results in both hemispheres operating independently of each other and can follow two separate orders simultaneously.

Eg. Drawing two pictures with both hands at the same time.

OUR DIVIDED BRAIN

SPLIT BRAIN CLIP

RIGHT BRAIN VS. LEFT BRAIN???