THE BRAINSeptember 18, 2013

WAYS WE STUDY THE BRAIN 52-54

CAT Scan PET Scan MRI Functional MRI

LESIONS

Removal or destruction of some part of the brain.

Frontal Lobotomy

WHAT IS IT? Jellylike mass of fat and protein Weighs about 3 pounds (1/45th of the

body’s weight) 100 billion neurons make up the "gray

matter” Millions of dendrites and axons are the

"white matter"

BRAIN STRUCTURES 54-62

• Hindbrain• Midbrain• Forebrain• Cerebral Cortex (part of

forebrain)

“OLDER” BRAIN STRUCTURES-HINDBRAIN Brainstem

Oldest and innermost partWhere spinal cord enters brain (medulla)Controls heartbeat, breathing, & blood

pressureCrossover point for nerves

Injury results in death

OLDER BRAIN STRUCTURES, CONT’D.-HINDBRAIN Cerebellum

Extends from back of brainstem (bottom rear of brain)

Means “little brain” Involves coordination of

voluntary movementCoordinates fine muscle

movements.Habitual motor skills

OLDER BRAIN STRUCTURES, CONT’D.-HINDBRAIN

PONS Located just

above the medulla.

Connects hindbrain with midbrain and forebrain.

Involved in facial expressions.

MIDBRAIN Coordinates simple

movements with sensory information.

Most important structure in Midbrain is the Reticular Formation: controls arousal and ability to focus our attention.

If Destroyed

If stimulated

MIDBRAIN CONT’D

ThalamusLocated at top of

brainstemSensory “switchboard”

of brainReceives sensory signals

from the spinal cord and sends them to other parts of the forebrain.

Every sense except smell.

MIDBRAIN CONT’D Limbic System

Border between older brain and two halves

Amygdala – aggression and fear

Hypothalamus – hunger, thirst, body temperature, sex

Hippocampus - memory

AMYGDALA

Involved in how we process memory with emotions.

Emotions connected to survival: anger, fear, disgust

The emotion of anger has not changed much throughout evolution.

HYPOTHALAMUS

Maybe most important structure in the brain.

Controls and regulates Body temperature Sexual Arousal Hunger Thirst Endocrine System

The most powerful structure in the brain.

Rat with an Implanted Electrode in pleasure

center of Hypothalamus

HIPPOCAMPUS

Involved in the processing and storage of new memories.

IN WHAT BRAIN REGION WOULD BRAIN DAMAGE BE MOST LIKELY TO …

… disrupt your ability to jump rope?

… disrupt your ability to hear sounds?

… leave you unable to move faster in a threatening situation?

… leave you unable to breathe?

FOREBRAIN 58-62 What makes us

human. Largest part of the

brain. Made up of the

Cerebral Cortex.

CEREBRAL CORTEX

Layer of densely packed neurons “gray matter” and “glial cells”(glue), that support brain cells & cover the cerebral hemispheres.Wrinkles are called fissures.

80% of brain’s weight Divided into four regions

Frontal lobesParietal lobesOccipital lobesTemporal lobes

FRONTAL LOBES Abstract thought and

emotional control. Contains Motor Cortex:

sends signals to our body controlling muscle movements.

Contains Broca’s Area: responsible for controlling muscles that produce speech.

Damage to Broca’s Area is called Broca’s Aphasia: unable to make movements to talk.

PARIETAL LOBES Contain Sensory

Cortex: receives incoming touch sensations from rest of the body.

Most of the Parietal Lobes are made up of Association Areas.

Where would this girl feel the most pain from her sunburn?

OCCIPITAL LOBES Deals with vision. Contains Visual

Cortex: interprets messages from our eyes into images we can understand.

TEMPORAL LOBES Process sound sensed

by our ears.

NOT LATERALIZED.

Contains Wernike's Area: interprets written and spoken speech.

Wernike's Aphasia: unable to understand language: the syntax and grammar jumbled.

CEREBRAL CORTEX, CONT’D.

ASSOCIATION AREAS Any area not associated with receiving

sensory information or coordinating muscle movements.

CEREBRAL CORTEX, CONT’D. MOTOR FUNCTIONS

Sends messages out to bodyHow do scientists know what it does?

electrical stimulation of different parts neural prosthetics

CEREBRAL CORTEX, CONT’D. SENSORY FUNCTIONS

Receives information from skin’s sensesMore sensitive body regions have greater

area of sensory cortex devoted to them

Motor and Sensory Cortexes

LOCALIZATION OF BRAIN FUNCTION How do scientists

know the functions of different parts of the brain?“Old” methods

phrenologyBrain damage case

studies Example: Case of

Phineas GageModern technology

EEG, CT, MRI, PET

ACCIDENTS

Phineas Gage Story Personality changed

after the accident.What does this tell

us? That different part

of the brain control different aspects of who we are.

Specialization and Integration in Language

HEMISPHERES

Divided into two hemispheres.

Contralateral control: right controls left and vice versa.

In general,Left Hemisphere: logic

and sequential tasks.

Right Hemisphere: spatial and creative tasks.

Brain Activity when Hearing, Seeing, and Speaking Words

BRAIN PLASTICITY The idea that the

brain, when damaged, will attempt to find news ways to reroute messages.

Children’s brains are more plastic than adults.

THE CORPUS CALLOSUM

Divides the 2 hemispheres.

SPLIT BRAIN PATIENTS

Those who suffer from epilepsy, have their corpus callosum severed partially.

Testing the Divided Brain

http://www.youtube.com/watch?v=ZMLzP1VCANo