The human brain has about 40-60 billion neurons. Each neuron can be
connected to up to 10,000 other neurons – most complex system
You Will Be Expected to Understand:
Basic mechanisms of the brain (neuron)
How we study the mind/brain relationship
Information about laterality in the brain (left vs right)
The functional roles of various brain regions
You Will NOT Be Expected To:
Memorize brain anatomy or the anatomy of the nervous or endocrine
Things to Think About:
Your reality is created by your brain. It is subjective
We know something about
o The basic biological and chemical units of the brain
o How physical energy in the world is transformed into
psychological phenomena (ie how a light wave is translated
into your perception of the color red)
o The behavioral consequences of damage to a particular part of
We know (next to) nothing about
Brain Basics: The Neuron
The body’s information system is built from billions of
interconnected cells called neurons.
The neuron is a building block.
All of conscious/subconscious experiences arise from patterns in
Interconnected neurons form networks in the brain. These networks
are complex and modify with growth and experience.
Action potential – a brief electrical charge that travels down an
axon and is generated by the movement of positively charged atoms in
and out of channels in the axon’s membrane.
You can detect these electrical events!
Excitatory Threshold Each neuron receives excitatory and inhibitory signals from many
When the excitatory signals minus the inhibitory signals exceed a
minimum intensity (threshold) the neuron fires an action potential
Refractory period – creates limit on how the neuron can fire
4/1000ths of a second
Action Potential Properties
All-or-none response: a strong stimulus can trigger more neurons to
fire, and to fire more often, but it does not affect the action
potential’s strength or speed.
Intensity of an action potential remains the same throughout the
length of the axon.
It either fires or doesn’t fire, it cannot fire a little bit!! *
Neurons have more (or less) action potential.
Neurons can fire more quickly – there are difference pathways for
Neurons don’t actually touch each other. Gaps between neurons
(called the synapse)
Neurotransmitters (chemicals) released from the sending neuron
travel across the synapse and bind to the receptor sites on the
Different neurotransmitters work on different pathways in the brain.
Lock & Key Mechanism
Neurotransmitters bind to the receptors of the receiving neuron in a
A drug can either be agonist or antagonist
same as excitatory transmitter. Open the gate
Binds as well. Won’t cause cell to open. By binding to site,
nothing else can come in. cannot open the gate.
Neurotransmitters in the synapse are reabsorbed into the sending
neurons through the process of reuptake. This process applies the
brakes on neurotransmitter action. By blocking this reuptake, it is
harder to excite these pathways?
Brain Basic Anatomy
Old brain: basic life functions: breathing, arousal, heart beat, etc Limbic system: emotion, motivation, learning/memory
Cerebral cortex: sensation, perception, languag