Lecture 3: Neuropsychology
P x E in order to interact with your environment effectively, two things must occur:
1. You must be able to detect the world outside of yourself (sensation and perceptual
process) and then be able to interpret the detections.
2. And in turn, you must be able to respond/behave to your world.
i.e.: Baseball coming at your face.
**Incoming processes is known as an afferent process, and outgoing processes are known as efferent
Virtually all of our thoughts, feelings, and actions can be brought down to a neuron’s
• Neurons vary widely in shape and size. They all contain:
1. Cell body (soma); nerve centre of the cell, contains the nucleus.
2. Dendrites; extensions of the cell body, branchlike in appearance.
3. Axon; a stem that comes out of the nucleus, varies dramatically in length.
4. Terminal endings; essential part of the neuron.
There are different types of neurons, categorized by their job.
1. Sensory neurons; devoted to the afferent process (getting information to the
a. Afferent direction
b. Comes from the sensory organs via the dendrites
c. Goes to the CNS via the axons
d. Approx. 2-3 million
2. Motor neurons; devoted to the efferent process (taking information out of the
brain and transmit it to the muscles/glands of the body to trigger a reaction).
a. Efferent direction
b. Comes from the CNS via the dendrites
c. Goes to the Muscles and Glands via the axons
d. Approx. 2-3 million
3. Interneurons; exist directly inside the CNS; complete all the
a. Communicates only with other neurons
b. Approx. 10-100 billion
c. Using their terminal endings, they communicate with the motor and
• There was a debate about whether the brain was run on electrical
currents or chemical reactions. The first discovery on the matter (base work on the electric theory) was founded by Galvani
(1737-98); an Italian physicist.
o He took a frog and killed it, then hooked electric wires to
the legs of the frog. The frog would jump. Galvani
deduced that this was because the frog’s muscles reacted to
electricity and thereby proving in his opinion that the brain
ran on electricity.
o **It is rumoured that Mary Shelly got her idea for
Frankenstein from this experiment.**
o People disputed his idea, but there was no experiment to go
against it. Auto Loewi wished to prove that the neurotal
messaging was run by chemicals. He failed several times,
not finding anything to prove the chemical theory. His
experiment eventually came to be:
Gets a heart from an animal, places it into a beaker,
and fills the beaker with sterile water. He repeats
the Galvani experiment by shocking the heart, and it
has the same reaction. He has a second heart in
another beaker, filling this beaker with the liquid
from the first. Once bathed in that liquid, the heart
reacts the same. He deduces that there was
something released in the last water. (He actually
• In 1952, the debate was settled by deciding that the brain functioned both from
electricity and chemicals. The process inside the neuron is entirely electrical, but
for them to communicate, the process is chemical:
o The chemicals from one neuron attaches to specific dendrites of another.
In the soma, there will be a specific code for each molecule. Once a
specific number of molecules are attached, it sends out a message
(electrical impulse) that runs down the axon to the terminal endings.
Messages will fire off endlessly until the molecules detach from the
dendrites. This process takes ~.00005/sec.
o In order to speed up the process, sections of the axons are covered by the