AP PSYCH 2.7 Tools for Examining Brain Structure and Function

Case studies were one of the earliest methods to study brain damage, injury, and illness
It would be unethical to artificially recreate these situations, however
We can gather important information from the changes in an individual’s behavior and mental processes * This knowledge can possibly be applies or compared to other case studies/groups

Molaison had severe epilepsy
In 1953, a surgeon removed the hippocampus, the origin of the seizures
At 27 years old, he lost the ability to form new memories * He did still have memories from before the surgery
Molaison was referred to neuroscientists Wilder Penfield and Brenda Milner * They studied Molaison extensively throughout the rest of his life * They determined that the function of the hippocampus was forming and storing new long-term memories
Molaison never regained the ability to form new memories

In 1861, at the age of 30, he suffered a stroke
When he entered the hospital, all he could say was “tan” * He could still use the term with inflection and gestures to communicate * The right side of his body became impaired
His physician, Pierre Paul Broca, studied his behaviors extensively as well as his brain * Leborgne agreed to have it donated when he died, which happened when he was 51
Broca’s research gave us our understanding of Broca’s Area * The region of the brain responsible for producing speech and choosing words * We now know that Leborgne suffered from Broca’s aphasia * The inability to produce speech and select words
Tan’s brain is now on display at the Dupuytren Museum of Paris

Gage was a railroad worker in Vermont * While tamping down gunpower, an explosion occurred * The tamping iron, a large metal rod, was shot through his head at extraordinary speeds and temperatures * It is thought that the rod was so hot it cauterized the wound on contact, saving Gage from bleeding out
Gage remained conscious and is said to have walked part of the way to the doctor
He suffered damage to his prefrontal cortex * This impaired his judgement * Emotion regulation * And planning
He was “no longer Gage” according to accounts from family and friends

A split-brain has to do with a damaged corpus callosum, which connects the two heispheres
Split brains cannot communicate from side to side, meaning many functions of the brain are limited
We continue to study this decades after the initial experiments

We process what we see on the opposite side that the eye is on
The right visual field is processed the in left visual cortex * With a split brain, individuals can still say what they saw, because the language areas are in the left hemisphere
In the left visual field, which is processed by the right visual cortex, they can draw what they saw, but not say it
This is how we came to the basic conclusion that the left side of the brain handles logic, and the right side handles vision/abstract/material features
This is a general assumption, because we are not “left-brained” or “right-brained” * We use our whole brain, all the time, for all functions * Even split brain patients are always using all of their brain, the two hemispheres just can’t communicate

The individual is injected with trace amounts of radioactive glucose
PET scans detect “hot spots” of cellular activity * Meaning spots with high neural firing * As neurons fire, they consume glucose
This enables us to map activity with a visual depiction
It shows us the brain in action, and where activity travels

The individual is placed in the large MRI machine
A low-level magnetic field is created
A pulse distorts the magnetic field and atoms in the body
As atoms return to normal, the MRI machine is able to produce very detailed images of brain slices
This can give a great amount of information on brain anatomy
It is also used to compare healthy and unhealthy brains

The process is very similar to an MRI
Rather than measuring the activity of atoms, this measures oxygen from blood flow
This reveals a lot about both brain anatomy and activity
Shows both detailed slices of the brain alongside “hot-spots” like in the PET scan