Transcript
AP Psych Prep. 3
Biological Psychology Part I: Neurons and Signals, General Nervous System, and Brain Research Methods
Biological Psychology
Can also be called biopsychology,
physiological psychology, or neuroscience
Structures and functions of the components
of the brain, and other ways our physical bodies influence our behaviour
Is a strong and growing field in psychology
Part I Overview:
Neurons – The Cellular basis of behaviour Neuron Signal Transmission General Nervous System
Methods of Researching the Brain
Nervous System Overview:
(Pink) (Green)
Neurons – cellular basis of behaviour
Neuron – individual nerve cell; the cells that
send and receive the fast messages that make up our thoughts, feelings, behaviours, etc.
Neurons are found in your brains, and also in
the rest of your body
Neurons are very specialized cells with
important parts.
Neurons / Nerve Cells
Neurons – Components / Parts
Dendrites – tree-like parts that stretch out
from the cell body. These connect to other neurons, and receive signals from them
Cell Body / Soma – round part of the cell that
holds the cell organelles and keeps the cell alive and operating properly
Axon – wire that extends out of the cell body
towards other cells.
Neurons – Components / Parts
Myelin Sheath – oval shaped coverings on the
axon; like the plastic covering on wires. Act to make the signal transmission faster
Terminal button / synaptic knob – the
ending(s) of the axon, where it meets with another nerve cell. Contains neurotransmitters
Neurons – Components / Parts
Neurotransmitters – chemicals used by
neurons to communicate with each other. They match with receptor sites on the opposite neuron.
Synapse – the space between the terminal
button of one neuron and the dendrites of the next neuron.
Neurons – Components / Parts
Neurons – Signal Transmission
Nerve signals travel along the axon of the
neuron by an electrical signal called a nerve impulse, or action potential.
It starts from the cell body end of the cell. If
the cell is stimulated enough by other neurons, (threshold level is reached) it will fire a signal down the axon to communicate to other cells.
Neurons – Signal Transmission
First Action Potential Video http://www.youtube.com/watch?v=U0NpTdge
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Second Action Potential Video
(file only)
Neurons – Signal Transmission
Nerve impulse animation
http://www.youtube.com/watch?v=dSkxlpN
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Neurons – Signal Transmission
Signals travel 120 meters per second – very
fast
Threshold of -55 millivolts is required before
the neuron will fire (+ All-or-none principle, can only fire, or not fire, no half signals)
When the signal reaches the end of the
neuron, it causes CHEMICAL signal to start. Chemicals are how one cell talks to another. Electric signal is just WITHIN one neuron
Neurons – Signal Transmission
Nodes of Ranvier are the gaps between the
myelin sheath blobs. These little gaps allow the signal to “jump” from one gap to the next, making the signal much much faster.
(loss of myelin sheath causes problems in
humans; for example, the disease multiple sclerosis)
Neurons – Signal Transmission
After a neuron sends a signal, it will wait for a
small period of time before sending another one. This is called the refractory period.
If cells fire signals too quickly and too often,
they can die. This can happen if your brain is injured, and excitatory neurotransmitters are released in great numbers.
Neurons – Signal Transmission
Neurons – Neurotransmitters
Between cells, chemical signal happens by
movement of neurotransmitters. They travel from one nerve cell to the next one across the gap (synapse).
Some neurotransmitters excite the cell they
attach to (make more positive more likely to fire), and some will inhibit (make more negative, less likely to fire).
Neurons – Neurotransmitters
Amount and type of neurotransmitters that
attach to the cell will determine if it fires or not.
Neural Synapse Signal Communication
http://www.youtube.com/watch?v=HXx9qlJ
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A Few Important Neurotransmitters:
Different types of neurotransmitters tend to
do different jobs in our brains. Here are a few examples. There are many more…
SSRI Medications
General Nervous System
Nervous system is our mind’s connection to
the outside world. Our nerve cells can only fire in ONE direction, so we need two sets of cells; one for signals to the brain, one for signals from the brain.
Sensory Neurons (Afferent) – signals from the
senses to the brain Motor Neurons (Efferent) – signals from the brain out to the rest of the body
General Nervous System
Interneurons – transmits signals between
sensory and motor, or between areas of the brain.
Nervous system can be divided into different
parts. Central and Peripheral was mentioned before. There are further divisions possible.
General Nervous System
Nervous System – Central (CNS)
Brain and Spinal Cord – nerves housed within
bone. Spinal cord – large number of nerves that run out of the brain and send information to and from the brain and the body.
Peripheral Nervous System (PNS)
The periphery (edges) Somatic NS – controls our voluntary
movements; the movements we choose to make.
Autonomic NS (think of “automatic”) –
controls functions of our body that we don’t consciously control (breathing, heart beat, digestion, etc)
Autonomic Nervous System:
Has two pieces: 1. Sympathetic Nervous
System – gets us ready to react to a sudden stressful situation.
Makes your heart and breathing faster, etc. to
make you ready to fight or run. Also slows other functions that aren’t needed right then (like digestion) to save resources for the emergency situation.
Autonomic Nervous System:
2. Parasympathetic Nervous System – changes
our bodies actions in the opposite direction. Moves us away from the stressful position to a normal relaxed state.
Slows heartbeat, breathing, lowers blood
pressure, etc. Speeds up digestion again, etc.
Peripheral Nervous System Operation
Both sensory and motor neurons are required
for normal everyday behaviour.
What parts of your nervous system might be
involved when you see some candy, and reach out to get it? ______________________________________ ______________________________________ ______________________________________ __________________________________
Reflexes
Automatic reactions to certain stimuli. Some of our reflexes happen WITHOUT any
action by our brains. Spinal cord can initiate action by itself sometimes.
When doctor hits just below your knee and
your leg jerks up. Touching very hot or cold things – pull away
Spinal Reflexes
Signal is ALSO sent to your brain, but decision to act has already happened
The Brain – (part of CNS)
Hard to study the brain. It’s hidden beneath
skin and bone, and even if we can see it it’s hard to tell what it’s doing.
We use many different technologies to study
the brain.
Brain Research Methods:
Accidents – Sometimes a rare accident to
someone’s brain will give us some clues. (Case Study) E.g. Phineas Gage – railway worker hurt on the job behaviour and personality changed
Brain Research Methods:
Lesions – removal or destruction of part of the
brian. NEVER done just out of curiosity. Sometimes medically necessary
E.g. H.M. a patient who had brain seizures.
Had part of his lateral hippocampus removed to stop the seizures. The surgery probably saved his life. Hippocampus is very important in memory formation, and so…
Brain Research Methods:
H.M. could not make NEW memories at all
after the surgery happened.
He could remember old memories. He could also learn new motor
skills, just couldn’t form new declarative memories.
This idea explored in this
movie, though it’s inaccurate
Brain Research Methods:
Electroencephalogram (EEG) – measures brain
electrical energy from outside the head; Common in sleep research, but can be used in other areas as well.
Brain Research Methods:
Computerized Axial Tomography (CAT) –
multiple angle xray creates a very detailed image of an internal body area; can not show functioning
Brain Research Methods: CAT
Brain Research Methods: CAT
Brain Research Methods:
Magnetic Resonance Imaging (MRI) – Similar
to CAT scan, but uses a large magnet and radio waves to capture a very detailed internal image. High resolution, and avoids the radiation of CAT. See animation.
Brain Research Methods:
Positron Emission Tomography (PET) – Uses a
slightly radioactive tracer element in a chemical used by the body to make a picture of ACTIVITY of the body.
E.g. we can watch which parts of the brain are
using more glucose (a sugar burned as fuel by the body), and therefore which parts of the brain are most active.
Very useful to see where the brain is active,
not just what it looks like. However, very expensive to make tracers, etc. And not quite as high resolution as other techniques.
Brain Research Methods:
Functional MRI – a new method that combines
aspects of PET and MRI to create very detailed images of BOTH structure and activity.
Uses the difference
in how much blood is in different areas of the brain to measure activity.