UNIT II: THE HUMAN BRAIN

Goal

• Understand that different parts of the brain control different aspects of our behavior.

• Identify those major parts.

The Freshmen Brain

Inquiring minds wanted to know…

Franz Joseph Gall – 1st phrenologist

Early 1800s…

• The idea of “self” was in the brain and not in the soul or the heart.

• 1st to suggest that different parts of the brain relate to specific functions

“Gall” was not lost…

• “The Curious Case of Phineas Gage”– Or –

• “Why you shouldn’t play with tamping rods”– Or –

• “How we came to love and understand the brain.”

And now, a story:

Phineas Gage

Phineas Gage

• While destroying a part of the brain may not kill you, it can affect you in a myriad of ways, not least of which your personality.– (hidden danger of concussions)

• Different areas of the brain really do affect different functions.

What can we learn from Phineas?

• If you watch reality TV it may seem like it, but no. - Sorry, “Lucy”, you wrong. You too, “Limitless”.

• Nearly every region of the brain lights up even during simple tasks like walking and talking.

So, do we really only use 10% of our brain?

• Evolutionary Psychologists:• Our brain uses 20% of our body’s energy– No sense in throwing that much energy into

something that is only minimally active.

More evidence?

• The proof is in your head!• We can trace our ancestors through our brain

structures.

“Evolution is for Real!”

• The following slides contain the “reptilian brain”, or the basic parts that function to keep any animal alive.

• Basically this is where the brain stops for most reptiles and lower intelligence creatures:

The Reptilian Brain

Medulla

• At the top of the spinal cord• controls vital reflexes, such as respiration,

heart rate, and blood pressure.

Pons

• Helps coordinate movement• Connects messages from spinal cord to brain• Makes the chemicals involved in sleep

Midbrain

• The reward or pleasure center• Stimulated by food, sex, money, music,

attractive faces, and some drugs. • Controls visual and auditory reflexes– like automatically turning your head towards a

noise.

Cerebellum

• coordinates movement• recognizes passage of time• helps perform timed motor responses – like playing sports or games

• Also easily affected by alcohol, hence the term “tipsy”

Forebrain

• Most of this is made up of the “cerebrum”; largest part of the brain– has left and right hemisphere

• Each hemisphere controls many functions like:– learning, memory, speaking, emotions, thinking,

planning, and feeling sensations.

• The following slides contain lobes that distinguish more intelligent creatures from lesser animals.

• The following lobes are the outer most layer of cells of the brain, the part you see in TV and movie brain surgery. In humans, these areas are only 2-4mm thick!

The Cerebral Cortex

Frontal Lobe

• Command center• Performs voluntary movements, interprets

and performs emotional behaviors, how to behave in social situations, your personality, making decisions, and planning.

• These are considered executive functions.

Parietal Lobe

• Processes sensory information from the body parts– including touching, locating positions of limbs,

and feeling temperature and pain– also carries out cognitive functions like

manipulating objects.

Occipital Lobe

• Processes visual information, including colors, perceiving and recognizing objects, animals, and people.

Temporal Lobe

• Involved in hearing, speaking coherently, understanding verbal and written material.

• (later we will discuss two very important speech disorders, Broca’s and Wernicke’s aphasia, which originates here)