Technology in brain research

Brain-imaging technologies

Invasive techniques

• Instead of invasive techniques such as ablation (removing) and lesioning (scarring), which raise serious ethical concerns due to:

• damage cannot be reversed• Causing pain• Potential harm unknown

• One can use…

Invasive techniques

• Remember Broca, Wernicke and Sperry and their patients and how they could have been studied differently today using modern technology

Cerebral hemispheres

Photographs taken during Penfeld's brainmappingexperiments using an electrode to stimulate

different areas of the brain. The numbered tags were usedto identify specific brain areas.

Brain Scanning Techniques

• EEG (electroencephalogram)

• PET (positron emission topography)

• FMRI (functional magnetic resonance imaging)

• MRI (magnetic resonance imaging)

EEG (electroencephalogram)• The EEG registers patterns of voltage change

(electrical activity) in the brain• Help the researchers in the Study of sleep,

emotions and epilepsy• Weaknesses are: 1. provide only limited information 2. cannot reveal what is happening in the deeper

brain regions3. Cannot show the actual functioning of the brain(the electrodes are outside of the skull)

What is Happening in the Brain of a Person with ADD ?

Here is a sample Q-EEGs of two Attention Deficit Disorder children compared to two non- ADD ADHD children. The Attention Deficit Disorder children show excessive slow brainwave activity (theta and alpha ranges) compared to non- ADD ADHD activity. The slow brainwave activity indicates a lack of control in the cortex of the brain.

PET (positron emission topography)

• Monitors glucose metabolism in the brain (using up energy)

• The patient is injected with a dose of radioactive glucose• The scans produce coloured maps of brain activity• Used to: diagnose abnormalities like tumours,

Alzheimer’s, schizophrenia• Greatest advantage is: can record ongoing activity in the

brain, such as thinking• Weakness: less precise than fMRI• Study: could meditation change brain activity? On p. 47

in your book

PET Scans Show Cigarette Smoke Affects Organs • with support from the National

Institute for Biomedical Imaging and Bioengineering and the National Institute on Drug Abuse, National Institutes of Health, and the Department of Energy, shows that cigarette smoke also decreases levels of a critical enzyme called monoamine oxidase B (MAO B) in the kidneys, heart, lungs, and spleen.

• Too much or too little of this crucial enzyme can have an effect on a person's mental or physical health.

MRI (Magnetic Resonance Imaging)• This scan expose the body to strong magnetic field,

and the protons in the water inside our bodies will then change their position. Together with radio waves the changes will be detected by a scanner

• +: scan for tumours, no harmful radiation• - : might be dangerous for those with metal, any

movement can affect the pictures, no cause and effect

• Study: Ashtari et al. 2009 who investigated whether substance abuse (marijuana) can damage the developing brain in adolescents and young adults

• Bremner et al. 2003 studied stress, PTSD and memory problems related to reduction of hippocampal volume

http://www.youtube.com/watch?v=H0adTNhzGxU

FMRI (functional magnetic resonance imaging)

• A modification of the MRI scan. • Provides three-dimensional pictures of the

brain structures, using magnetic fields and radio waves

• Shows actual brain activity (map metabolic changes)

• Higher resolution than PET scans and easier to carry out and more flexible than MRI scans

• The most frequently used today

fMRI (functional magnetic resonance imaging)

• Provides a picture that shows increasing precision which parts of the brain are active while certain activities are being performed or when certain thoughts or emotions occur.

• http://www.youtube.com/watch?v=nvB9hAarzw4

• Studies: Harris and Fiske 2006 who used fMRI scans to study

students brains processes regarding out-groups. Karl Kim and Joy Hirsch 1997 on p. 43 in your book

Brain scan 'can read your mind'

• An fMRI scan of the brain

The researchers used scans of the brain to predict decisions

Brain scans have been developed which it is claimed can predict what a person is about to do.

German, British and Japanese scientists were able to "read minds" using sophisticated functional magnetic imaging (fMRI) and computer programs.

Current Biology reported people were asked to think about adding or subtracting - scientists were able to read intentions in 70% of cases. http://www.youtube.com/watch?v=Cwda7YWK0WQ

Evaluation of brain scansWeakness: 1. not a natural environment, low ecological validity2. The use of colours may exaggerate the different activities

of the brain3. Brain activates for various reasons – parts can be

“lighted” but not necessarily used in the response

• …“we know that it is not possible to definitively determine whether a person is anxious or feeling connected simply by looking at activity in a particular brain region.”

• …“a one-to-one mapping between a brain region and a mental state is not possible.” Michael Shermer © 2008 SCIENTIFIC AMERICAN

Ethics

• Read TOK: ethics on p. 45 and discuss with the person sitting next to you

Task

• You have several studies to choose between when supporting your answer:

• Pick one study per scan and summarize them (we will cover several through out the course)

• For example:• McGuire (Taxi drivers’ study) MRI• Ashtari et al. MRI• Harris & Fiske fMRI