Monday 27th September 2016
PSY100 - Lecture 5 - The Brain
“The question of how the ebb and flow of a highly developed mind can be catered to by a
physical brain, and the related question of how the one impacts the other, are the hardest-ever
challenges to human ingenuity and imagination.”
- Susan Greenfield (from the Private Life of the Brain, 2000)
These tools help cover what you may have forgotten during an experiment:
Confounds: What are you manipulating?
Third variable: Correlations
Operationalization: Measuring things
Consciousness - A Multi-Level Process
1. Neurochemical/ cellular: Neurotransmitters and neurons
2. Neuroanatomical: Major brain structures and their organization
3. Physiological: major contributions of physiological systems e.g. autonomic nervous system,
There is also a social level: while it isn't really neurochemistry, it effects a person’s
There is also the physical environment, which effects you.
Example: Learning in Convocation Hall vs a room of 20 people leads to different learning
experiences, and how much information you absorb.
Structure of a Neuron
* You must be able to understand the
functions of and label the neuron. Read
the textbook for the full process.
- Receives information from other
neurons and transmits it toward the
Lined with protein receptor sites,
which acts like a harbour for boats
to dock. These “boats” are
packages of info meant to reach the
- Makes decisions to fire/not fire
information depending on signals
called neurotransmitters. Monday 27th September 2016
- Relays information between neurons in order to pass on
• Excitatory chemicals:
• Stimulates the brain and allows information to be
• Inhibitory chemicals:
Calms the brain
The neuron’s cell body is the official decision maker.
• There is an electrical decision making process.
• The electrical potential that lies across the cell membrane
changes as the “mind makes up its mind”
- electrically make decision making process write up process about the electrical
- Inhibitory signals are taken to the receptor parts of the dendrites and start a chain of
processes, the outcome of which increases the polarity across the membrane (increases
net negative charge).
- Excitatory signals decrease the net negative charge.
The cell has to depolarize (less negative charge) to the threshold point (-40 to -55 millivolts).
Once the threshold point is crossed, ion gates open.
Axon Hillock: Place where ionic concentration starts to accumulate, which effectively
depolarizes the next segment in the axon. More ions flood in and depolarize the next micro
segment and so on with the flow of the action potential (refer to diagram).
Long fibre that conducts impulses away from the cell body
- This happens through successive opening and closing of ion channels
- Ions rush in, in an electrically regulated process (since the channels are voltage gated)
- Once the ions flood in, in a short amount of time, the next gate leading to the next micro
segment opens, and the one “behind” them closes.
- The ions have only one direction to go.
The professor put up a slide with this paragraph from Wikipedia for clarification.
Action potentials are generated by special types of voltage-gated ion channels embedded in a
cell's plasma membrane.These channels are shut when the membrane potential is near the
resting potential of the cell, but they rapidly begin to open if the membrane potential increases to
a precisely defined threshold value. When the channels open (in response to depolarization in
transmembrane voltage), they allow an inward flow of sodium ions, which changes the
electrochemical gradient, which in turn produces a further rise in the membrane potential