TAs office hours cancelled this week

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TAs office hours cancelled this week
Mass Testing Session 830 950 pm
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Evolution and Genetics
The Human Species
What (if anything) sets humans apart from other
species of animals?
- language?
- tool use?
- self-awareness?
- abstract thought?
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Evolution and Genetics
The Human Species
Most, if not all, human abilities and
characteristics can be found in other animal
species
Alex
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Evolution and Genetics
The Human Species
Are humans (at least for now) the dominant
species on the planet?
- depends strongly on perspective
- e.g., strong case can be made that corn is the
dominant species
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Biopsychology
a.k.a. behavioral neuroscience behavior
genetics neuropsychology physiological psychology
How does biology relate to behavior?
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Neural Communication
The Neuron
A nerve cell
Basic building block of the nervous system
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Neural Communication
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Neural Communication
The dendrites receive signals from other neurons
Excitatory Post-Synaptic Potentials (EPSPs)
increase the charge in the cell body
Inhibitory Post-Synaptic Potentials (IPSPs)
decrease the charge in the cell body
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The Action Potential
At rest, there is an electrical potential (a
difference in charge) between the inside of the
neuron and the surrounding fluid
-70 mV
inside cell is negative (-70 mV) relative to
outside of cell
cell is polarized
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IPSPs from presynaptic cells act to increase this
negative charge
cell is now hyperpolarized, and even less likely
to fire
-75 mV
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EPSPs from presynaptic cells act to decrease this
negative charge
-65 mV
cell is now depolarized, and more likely to fire
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The Action Potential
If this difference in charge decreases to -65 mV,
the neuron will generate an action potential (it
will fire)
-65 mV
The action potential is a small area of positive
charge (about 50 mV)
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The Action Potential
When the action potential reaches the terminal
buttons, neurotransmitters are released
-65 mV
These neurotransmitters activate receptors on
postsynaptic neurons and produce IPSPs and/or
EPSPs in those neurons
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Neural Communication
The Action Potential
If the right combination of inputs are received
in the soma, the cell fires
Action potentials are all or nothing
The action potential travels down the axon and
causes the release of neurotransmitters at the
terminal boutons
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Neural Communication
The Action Potential
The resting potential of a neuron is 70 mV
(slightly more negative charge inside the cell
than outside)
During an action potential channels open in the
cell membrane allowing positively charged sodium
(Na) ions to enter the cell
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Generating the Action Potential
- when the cell is sufficiently depolarized,
voltage-gated ion channels embedded in the
membrane of the axon hillock open, allowing Na
(sodium) ions to enter the cell
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The Action Potential
Axon
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Neural Communication
The Action Potential
Influx of Na results in area of positive charge
Positive charge spreads down the axon, opening
more Na channels
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The Action Potential
- the increase in charge causes more downstream
ion channels to open
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Neural Communication
The Action Potential
Influx of Na results in area of positive charge
Positive charge spreads down the axon, opening
more Na channels
When this charge reaches the end of the axon,
neurotransmitters are released
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The Action Potential
- other ion channels then begin to open, allowing
K (potassium) ions out of the cell
- this acts to reduce the positive charge in the
cell, and close the ion channels
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The Action Potential
The Na/K Pump
Other channels in the cell membrane act as
pumps. After an action potential has occurred,
these pumps move Na ions back out of the cell
and K ions back into the cell.
- 3 Na out for every 2 K in
- works to repolarize cell by reducing positive
charge
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Neural Communication
The Action Potential
Myelinated vs Unmyelinated Axons
Myelin is a fatty substance that wraps around the
axons of some neurons (particularly in the CNS),
increasing speed of action potential travel down
the axon
Nodes of Ranvier small gaps between myelin
segments
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Neural Communication
The Synapse
Neurons do not actually touch each other. The
space between the terminal button of the
pre-synaptic (sending) neuron and the dendrite or
cell body of the post-synaptic (receiving) neuron
is the synapse.
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Neural Communication
The Synapse
Neurotransmitters are released from the the
pre-synaptic neuron into the synapse, where they
may (or may not) end up binding to special
receptor molecules on the membrane of the
post-synaptic neuron.
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Neural Communication
Neurotransmitters (NTs)
There are many different NTs in the brain
e.g., Dopamine (DA)
- experience of pleasure/reward
- control of motor movements
- Parkinsons Disease loss of DA-producing
neurons
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