Methods of studying the brain: A brief history

First…. a few basic facts about your brain Approximately 3 lbs.; slightly larger than size of an adult fist Approximately 3 lbs.; slightly larger than size of an adult fist 2% of total body weight; burns 70% of your body’s glucose 2% of total body weight; burns 70% of your body’s glucose 100 billion+ neurons; trillions of synapses 100 billion+ neurons; trillions of synapses Biochemical signals travel at 220 mph Biochemical signals travel at 220 mph Half of the 30,000 genes are dedicated to the nervous system Half of the 30,000 genes are dedicated to the nervous system The brain itself feels no pain, but registers it from everywhere else The brain itself feels no pain, but registers it from everywhere else

Early 1800s Phrenology: measuring the bumps on peoples’ heads Phrenology: measuring the bumps on peoples’ heads They were wrong about bumps; right about the brain having localized functions! They were wrong about bumps; right about the brain having localized functions! /avp/cas/fnart/phrenology/ phrenology_frames.html /avp/cas/fnart/phrenology/ phrenology_frames.html /avp/cas/fnart/phrenology/ phrenology_frames.html /avp/cas/fnart/phrenology/ phrenology_frames.html

1848: Phineas Gage (open up last night’s homework so we can discuss; a video clip will also be shown:

1930s: Prefrontal lobotomies Dr. Walter Freeman: surgical disconnection of the frontal lobes from the thalamus with an icepick Dr. Walter Freeman: surgical disconnection of the frontal lobes from the thalamus with an icepick Eliminated severe behavioral problems; also took away emotions, problem solving, thinking Eliminated severe behavioral problems; also took away emotions, problem solving, thinking By 1949, 5,000 done annually By 1949, 5,000 done annually ms/lobotomist/ ms/lobotomist/

1950s: Electrical Stimulation of the Brain 1954: James Olds and Peter Milner placed an electrode in the hypothalamus of the brains of rats by mistake and discovered the pleasure center of the brain 1954: James Olds and Peter Milner placed an electrode in the hypothalamus of the brains of rats by mistake and discovered the pleasure center of the brain When the rats learned that they could control the electrical stimulation by pressing a lever, they pressed it 7,000 times an hour (endorphins). When the rats learned that they could control the electrical stimulation by pressing a lever, they pressed it 7,000 times an hour (endorphins). ml ml 1969: Jose Delgado’s “matador” experiment: stimoceiver 1969: Jose Delgado’s “matador” experiment: stimoceiver

Selective lesioning Selectively damaging parts of the brain using electrical instrument Selectively damaging parts of the brain using electrical instrument Only used in animals… obviously. Only used in animals… obviously. Rat hypothalamus study Rat hypothalamus study Accidents and brain damage are often studied in human beings. Accidents and brain damage are often studied in human beings.

For modern technology! And now…

Electroencephalogram (EEG)

Computerized Axial Tomography (CAT) X–rays taken along an axis to reveal brain structures X–rays taken along an axis to reveal brain structures

Positron Emission Tomography (PET) Can view brain activity while the subject is engaged in mental activity. Can view brain activity while the subject is engaged in mental activity. Injection of radioactive glucose is given. Injection of radioactive glucose is given.

Magnetic Resonance Imaging (MRI) The machine aligns the spinning atoms of brain molecules; radio pulses temporarily disorient the spin The machine aligns the spinning atoms of brain molecules; radio pulses temporarily disorient the spin

fMRI Scans Used to determine which parts of the brain “light up” during different types of mental activity; blood rushes to more active parts Used to determine which parts of the brain “light up” during different types of mental activity; blood rushes to more active parts

What love looks like in an fMRI Scan!