Psychology 1000 Lecture Notes - Lecture 5: Myelin, Afferent Nerve Fiber, Reflex Arc

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2 Aug 2016
Department
Professor
Sept.23
Biological foundations
-More research design
-The Neuron
-Action potential
Next time: The synapse
Scan: page 69-74
What is the bias structure of a neuron?
What is the basic structure of a neuron?
How do neurons “work”?
Within groups design
-All subjects exposed to all conditions
-Problem: the first experiment may containment the second
-Potential order effect: need to counter balance
Measuring aggression
-Self report
-Verbal attack
-Physical attack
-“Safe” attack
Threats to validity
Internal Validity
-Degree to which experiment supports causal conclusion
Demand characteristics
-Cues in experiment convey hypothesis to participants
-They “help” experimenter
-Geen and Berkowitz 1967
Experimenter expectancy
-Experimenter “conveys” hypothesis to participants
-Intons-Peterson (1983)
External Validity
-Degree to which results can be generalized
FAQ’S of lab experiments
1. What do lab experiments tell us about everyday life?
-They don’t, everyday life is not studied in a lab setting
2. Doesn’t behavior depend on culture, gender or personality?
-Yes it does, random assignment has to be used to avoid corruption since it cannot be controlled
3. What do animal experiments tell is about human behavior?
-Sometimes they act similar to humans (ex. Cats have the same visual system as humans)
4. Is it ethical to do experiments on animals/ humans?
-Informed consent must be given in the experiment
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5.How do I determine whether my study worked?
-Look at the data (statics)
The nervous system
1. Descartes- reflex arc- stimuli transferred from periphery to brain and reflected back.
How? – “Animal spirits”- importance of pineal gland (Center of the brain)
2. Swammerdam’s
Frog experiment
3. Bell
-Performed autopsy’s
-Types of nerves
Sensory nerves= afferent fibers
Motor nerves = efferent fibers (got to effectors= muscle/gland)
4.Bell and Muller
-Specific nerve energy
-How does the brain distinguish stuff?
5. Speed of Impulse
Muller – 9000 ft/ Min to 57 Billion ft/ sec
Helmholtz- 50-100 meters /second (he’s right)
6. Reaction time
-Maskelyne and Kinnerbrook
The Neuron
Cell body –main structure
Dendrites- branches off cell body, takes information in (100’s)
Axon- (1) output
Axon terminals- transmitter (sends information out)
(Synaptic knobs)
Myelin sheath- fatty sheet that cover electron
-“Insulator on wire”
-Those that have it transmit faster than those that don’t
Nodes of Ranvier- break in myelin sheath
-Exposed to external surroundings
Classified by shape
Bipolar- two poles with cell body in the middle
Unipolar- cell body to the side
Multipolar- most common
-Cell body at top
-Looks like someone stepped on it
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Sept.29
Synaptic Communication
-How do Neurons work?
-Neural Connection
-The synapse
Next time: The brain
Scan: Page 76-87
Next Time: Statistics
Scan: Appendix
How do neurons produce an electoral signal?
How does a neuron code intensity?
How does one neuron communicate with another?
Classify by function
1. Sensory Neurons – afferent
2. Motor neuron – Efferent
3. Inter Neurons – Relay stations
How do neurons work?
How does a cell produce an electoral signal?
-charges of ions
****The action potential ****
-Resting potential = -70 millvolts (mV)
-When stimulated the charge goes up
-Holes in membrane get bigger
-Depolarization= Na+ inflow
-Sodium comes in at the threshold (-55)
-If a neuron depolarizes in threshold sodium rushes (holes expand) in and mV increases
and goes above 0 and can go up until +40 mV
-Depolarization (K+ outflow) –drops down to below resting potential and then returns to resting
potential
-Below resting potential = hyperpolarization
-+40 = refractory period
-Absolute refractory period, nothing can happen (neuron will not fire anything, incapable
of reaching action potential)
- Relative refractory period= Neuron will fire again but stimulus has to be stronger, below
resting potential
-Action potential sent down axon (only occurs in axons)
Graded potential
-Allow cell body and dendrites to accumulate information and pass it on
Coding Intensity
-Neuron fires on all – or –none fashion
-Height of “Spike” is fixed
How to code intensity?
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