The Basic BrainThe Basic BrainChapter 2, Lecture 4Chapter 2, Lecture 4

“Our brain processes most informationoutside of our awareness.”

- David Myers

The Brain: 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.

Brainstem

The Medulla [muh-DUL-uh] is the base of the brainstem that

controls heartbeat and breathing.

Brainstem

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.

Brainstem

Reticular Formation is a

nerve network in the brainstem that plays an important role in controlling arousal.

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

helps coordinate voluntary movements

and balance.

Cerebellum

Listen to some interesting research on

tickling…

Research also indicates that part of the cerebellum’s function is to tell the brain what to expect from the body’s own movements. In this way, the brain can ignore expected pressure on the soles of the feet while walking and attend to more important sensations such as stubbing a toe.

Cerebellum

Sarah-Jayne Blakemore and her colleagues at University College, London, have addressed the interesting question, “Why can’t we tickle ourselves?” For their study, the researchers had six volunteers lie in a brain-scanning machine with their eyes closed. A plastic rod with a piece of soft foam attached to it moved up and down, tickling the participants’ left palms. The experimenter and the volunteers took turns moving the rod, so the volunteers were either tickling themselves or were being tickled. In a third condition, the foam was secretly removed, so the volunteers moved the rod by felt nothing.

Cerebellum

Throughout this process, the researchers used functional MRI (fMRI) scans to compare activity in different parts of the brain. On the basis of the results, they concluded that during self-tickling one part of the brain tells another: “It’s just you. Don’t get excited.” The cerebellum is involved in predicting the specific sensory consequences of movement. It provides the signal that is used to cancel the sensory response to self-generated stimulation. In short, it tells the somatosensory cortex what sensation to expect and this dampens the tickling sensation.

Cerebellum

Blakemore, S., Wolpert, D., & Frith, D. (1998). Central cancellation of self-produced tickle sensations. Nature Neuroscience, 1, 635-640.

The Brain

Techniques to Study the Brain

A brain lesion experimentally

destroys brain tissue to study animal behaviors after such destruction.

Hubel (1990)

Clinical ObservationClinical observations have shed light on a

number of brain disorders. Alterations in brain morphology due to neurological and

psychiatric diseases are now being catalogued.

Tom

Landers/ B

oston Globe

Electroencephalogram (EEG)An amplified recording of the electrical waves

sweeping across the brain’s surface, measured by electrodes placed on the scalp.

AJ Photo/ Photo R

esearchers, Inc.

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 ScanMRI (magnetic

resonance imaging) 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/ SalzanoPhoto

Lucy Reading/ LucyIllustrations

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

Amygdala

The Amygdala [ah-MIG-dah-la] consists of two lima bean-sized neural clusters linked

to the emotions of fear and anger.

Hypothalamus

The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating,

drinking, body temperature, and

control of emotions. It helps govern the

endocrine system via the pituitary gland.

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 CenterSanjiv T

alwar, SU

NY

Dow

nstate

Page 67

HomeworkRead p.68-75

“To be learning about the neurosciences now islike studying world geography while Magellanwas exploring the seas. This truly is the goldenage of brain science.”

- David Myers