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Lecture 3

PSYC 1010 Lecture Notes - Lecture 3: Transcranial Magnetic Stimulation, Magnetic Resonance Imaging, Positron Emission Tomography


Department
Psychology
Course Code
PSYC 1010
Professor
Agnieszka Kopinska
Lecture
3

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3 | HH/PSYCH 1010 The Biological Bases of Behaviour
THE BIOLOGICAL BASES OF BEHAVIOUR
Chapter 3: “The Biological Bases of Behaviour”
The Basic Hardware: The Brains Communicators
Neurons are individual conducting cells in the nervous system that receive, integrate, and transmit
information.
Some (Cell Body) contains the cell nucleolus and much of the chemical machinery common to
most cells (soma is Greek for body).
oCentral region of the neuron.
oMaterials needed by the neuron are made here.
oContains genetic information determining cell function and what that neuron is going to
do.
Dendrites are the parts of the neuron that are specialized to receive information, known as
receivers – Spread out and listen in on information from neighboring neurons and pass it on to the
cell body.
Axon is a long, thin fiber that transmits signals away from the soma to other neurons or to muscles
or glands.
oConducts electrical impulses.
oPortion of the neuron that receives signals and information – Takes the information from
the dendrites and moves it along, almost like an information hideaway.
Myelin Sheath is insulating material, derived from glial cells, that encases some axons.
oThe myelin sheath speeds up the transmission of signals that move along axons.
Terminal Buttons that are small knobs that secrete chemicals called Neurotransmitters, which
are chemicals that transmit information from one neuron to another.
oThese chemicals serve as messengers that activate neighboring neurons.
Synapse is a space between two connecting neurons where information is transmitted from one
neuron to another.
oSynaptic Cleft a microscope gap between the terminal button of one neuron and the cell
membrane of another neuron.
Signals have to cross this gap to permit neurons to communicate. The neuron
that sends a signal across the gap is called the presynaptic neuron and the neuron
that receives the signal is called the postsynaptic neuron.
oPostsynaptic Potential (PSP) a voltage change at a receptor site on a postsynaptic cell
membrane.
Excitatory Postsynaptic Potential (EPSP) is a positive voltage shift that
increases the likelihood that the postsynaptic neuron will fire action potentials.
Inhibitory Postsynaptic Potential (IPSP) is a negative voltage shift that
decreases the likelihood that the postsynaptic neuron will fire action potentials.
oReuptake processes in which neurotransmitters are sponged up from the synaptic cleft
by presynaptic membrane – Recycling of neurotransmitters.
oLong-Term Potentiation refers to a long-lasting increase in neural excitability un
synapses along a specific neural pathway.
Glia are cells found throughout the nervous system that provide various types of support for
neurons.
oSupport, nourish, and protect the neurons.
Manufacture nutrition chemicals neurons need.
Absorb toxins and waste materials.
Provide insulation around other neurons.
The Neural Impulse: Using Energy to Send Information
Inside and outside the neuron are fluids containing electrically charged atoms and molecules
called ions.
The Resting Potential of a neuron is its stable charge when the cell is inactive.
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3 | HH/PSYCH 1010 The Biological Bases of Behaviour
oWhen a neuron is at rest there are no NTs acting on a neuron and there are positive and
negative ions on both sides of the membranes.
The Action Potential occurs when there is enough of a charge inside the neuron (threshold).
oPositive particles rapidly flow into the axon.
oDescribed as “firing”, neurons obey the “All-Or-None Law”: they either fire or they
don’t.
The Absolute Refractory Period is the minimum length of time after an action potential during
which another action potential cannot begin, also known as “Downtime”.
Neurotransmitters and Behaviour: How Neurons Communicate
Communication inside neurons is electrical (via the Action Potential), but communication between
neurons is chemical (via signals at the synapse).
Lock and key.
Agonist is a chemical that mimics the action of a neurotransmitter.
Antagonist is a chemical that opposes the action of a neurotransmitter.
Neurotransmitter Functions and Characteristics
Acetylcholine (ACh) Cortical arousal (CNS) and muscle contraction (PNS).
Involved in muscle movements and learning and memory.
Nicotine stimulates Ach receptors.
Alzheimer Disease – Decrease number of ACh neurons.
Endorphin Internally produced.
Controls pain and pleasure.
Runners High – Feeling of pleasure after a long run is due to
heavy endorphin release.
Narcotic drugs – Codeine, Morphine, and Heroin – Reduces pain
and produces euphoria.
Amino
Acids
GABA Main inhibitory neurotransmitter in the nervous system (brain
activity).
Alcohol and anti-anxiety drugs increase GABA activity.
Huntington’s disease involves loss of neurons in striatum that
utilize GABA.
oJerky involuntary movements.
oMental deterioration.
Glutamate Main exhibitory neurotransmitter in the nervous system.
Sensory information, memory.
Monoamin
e
Dopamine (DA) Motor function, attention, and learning.
Pleasurable and rewarding sensations.
Dopamine imbalance involved in Schizoprenia.
Schizophrenia – Decrease of Dopamine.
Increase of Dopamine is used to treat Parkinson’s disease.
Norepinephrine
(NE)
Arousal, mood, hunger, learning, and memory.
“Fight or Flight” response.
Imbalances lead to depression and bipolar disorder.
Serotonin Mood and temperature regulation, sleep, depression, eating
disorders, addictions and disorders.
Prozac works by keeping serotonin in the synapse longer, giving
it more time to exert an effect.
Looking Inside the Brain: Research Methods
Electroencephalograh (EEG) is a recording of the brains electrical activity at the surface of the
skull.
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