Chapter 6

Section 2 Studying the Brain

The Hindbrain• Includes the cerebellum, pons and the medulla

• Cerebellum – part of the lower brain that coordinates and organizes bodily movements for balance and accuracy; sense of equilibrium; helps with posture

• Pons – bridge of fibers that connects the brain to the spinal cord; involved in producing chemicals the body needs for sleep

• Medulla – controls unconscious but vital functions like breathing, heart rate, blood flow, muscle tone, and reflexes

Where are the medulla and pons?

The Midbrain• The Reticular Activating System

• the alertness control center of the brain - Regulates how alert or how sleepy we are

• Nerve impulses from brain to body and vice versa pass through the RAS

• A major blow to the head causes such and overload of the RAS circuits that they shut off completely for a time causing unconsciousness

• It is quite sensitive to steady sounds – thus a slow and dull speech may put you to sleep

The Forebrain - Thalamus

• functions primarily as a central relay station for incoming and outgoing messages from the body to the brain and the brain to the body

• where all sensory information (Except Smell) must pass to get to the Cerebral Cortex

• Integrates sensory input

The Forebrain - Hypothalamus

• Why did I underline hypo?

• regulates basic needs (hunger, thirst) and emotions such as pleasure, fear, rage, and sexuality

• controls Autonomic Nervous System and Endocrine System

• regulates Survival - Fighting, Fleeing, Feeding, Mating

The Forebrain – Cerebral Cortex

• wrinkled outer layer of Cerebrum

• divided into lobes

The Forebrain – Cerebrum

• largest and most complex part of Brain

• inner layer of forebrain

• responsible for most complex mental activities

• controls learning, remembering, thinking, and consciousness itself

The Forebrain – Limbic System

• found in core of forebrain

• amygdala

• “the seat of emotion”

• primarily responsible for violent emotional responses - aggression, rage, and fear – and other emotions, pleasure

• helps with memory

The Forebrain – Limbic System

• Hippocampus

• enables us to form memories

• Memories are not stored here but it is critical to assembling information from elsewhere in the brain

• Damage makes forming new memories impossible

The Brain is divided into…

• Two hemispheres connected by the…

• corpus callosum

• a large bundle of nerve fibers that transfer information from one half of the cerebral cortex to the other

• Do you know what the “line” down the center is called?

• What are lobes?

• They refer to the four major sections of the cerebral cortex

The Frontal Lobe• contains the motor strip, prefrontal area,

and frontal association areas

• responsible for a number of very complex and fascinating functions –organization, planning, creative thinking, and personality

• Ability to “see” or to be aware of ourselves when we remember things we have done

The Frontal Lobe• motor strip

• band running down the side of the frontal lobe that controls all bodily movements (called motor functions)

• Motor means relating to movement

The Frontal Lobe• prefrontal lobe – enables us to re-experience

personal past events; lies just behind your forehead

• Used to come up with strategies or plans of action

• frontal association area – part of the frontal lobe that engages in elaborate associations or mental connections

• plays an important part in integrating personality and in forming complex thoughts

• forms the core of our personality

The Parietal Lobe• behind the frontal lobe

• contains the sense of touch – location for touch perception

• sensory strip – band running down the side of the parietal lobe that registers and provides all sensation

The Occipital Lobe• very back of the brain

• interprets visual information

• makes sense out of what you see

The Temporal Lobe• responsible for hearing, memory, emotion

and some speech functions

• contains major centers for hearing

• some of the centers related to speech are also here

Splitting the Brain

A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between the

Corpus Callosum

Martin

M. R

oth

er

Courtesy of T

erence William

s, University of Iow

a

How Psychologists Study the Brain

• Through recordings

• Electroencephalograph (EEG)

• Device that monitors the electrical activity of the brain over time by attaching electrodes to the scalp

Electroencephalogram (EEG)

An amplified recording of the electrical waves sweeping across the brain’s surface, measured by

electrodes placed on the scalp.

AJ P

hoto/ Photo R

esearchers, Inc.

Lesions

• Brain lesions can be caused by injury, infection, exposure to certain chemicals, problems with the immune system

• May also occur after deliberately destroying pieces of the brain and observing the effects - Mostly done on Animals

Brain Imaging• CAT or CT

• Computerized axial tomography

• scans are a series of x-rays of the skull taken from many different directions

• CAT scans generate cross-sections of the brain that show its structure in detail

• Computers measure the amount of radiation absorbed and transform this information into a 3-dimensional view of the brain

CAT/CT Scans

PET• Positron emission tomography

• first technique to capture brain activity

• can capture a picture of the brain as different parts are being used

• radiation, injected into the bloodstream, is absorbed in different amounts depending on the density of the brain tissue

• Scans measure emissions from radiation, producing 2- or 3-D images that reflect the amount of activity in various brain regions.

PET Scan

PET (positron emission tomography)

Scan is a visual display of brain

activity that detects a radioactive form of glucose while the

brain performs a given task.

Courtesy of N

ational Brookhaven N

ational Laboratories

MRI• Magnetic resonance imaging uses magnetic

fields and radio waves to produce highly detailed 2- or 3-D images of internal organs

• Combines features of both CT and PET scans

• Involves passing nonharmful radio frequencies through the brain

• A computer measures how these signals interact with brain cells and translates these signals into a detailed image of the brain

MRI Scan

• Uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue• Top images show ventricular enlargement in a schizophrenic patient• Bottom image shows brain regions when a participants lies

Both photos from Daniel Weinberger, M.D., CBDB, NIMH

James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations

fMRI• Functional magnetic resonance imaging

• special type of MRI that images changes in blood flow to specific areas of the brain as the subject performs a specific task

• FMRI scans provide both an anatomical and a functional view of the brain

• Used to directly observe both the functions and different structures of the brain and which structures participate in specific functions

• Provides high-resolution reports of neural activity based on signals that are determined by blood oxygen level

Accidents• Psychologists try to draw a connection between

the damaged parts of the brain and a person’s behavior

• Who was Phineas Gage?

• In 1848 Phineas P. Gage, a railroad foreman was injured when dynamite sent a 4 foot tamping iron, weighing over 13 pounds, into Gage’s head right about the left eye and it exited through the top of the skull