Neurophysiology Overview - Exam #1 Flashcards
What is the relationship in the Psychophysical level?
An attended stimulus and a person’s perception
Give an example of an experiment at the Psychophysical level
Someone looking at a light, turning up the brightness/intensity, and ask them how they perceive it
What is the relationship at the Neurophysiological level?
An environment and a neuron’s firing rate
Give an example of an experiment at the Neurophysiological level
A cat looking at a bar of light and looking at the neuron’s firing rate
Why is it “the environment” instead of the stimulus at the Neurophysiological level?
Because if it’s the cat, how can you tell that the cat is really attending the
What is the relationship between in the Perceptual Neuroscience level?
Brain activity and a person’s perception
What is the “Physiology” part of an experiment? Give two examples
The physical part; the brain activating, the neuron firing, etc…
What is an example of an experiment at the Perceptual Neuroscience level?
Scanning a subject’s brain while asking them what they see; seeing a certain area of the brain light up as they say “I see a square”
What is a Macroscopic view of the brain?
Imagine a pretty normal brain picture–bumps and grooves, the little brain, brain stem, etc…
What is a Microscopic view of the brain?
Looking at all those little neurons! The little APs, the signals, etc…
How many neurons are there in a cubic millimeter in the brain?
About 10,000!!!!
Neurons are highly…
…interconnected with each other! Axons and Dendrites!
Why are neurons so interconnected?
They all have to talk to each other!
What do Dendrites do?
Collect signals from other neurons
What does the Axon do?
Signal transmission WITHIN a neuron
What do the Terminal Branches do?
Transmit a signal to the dendrites of another neuron
What’s up with the cell body of a neuron?
It holds things like the nucleus, mitochondria, etc…
Name the parts of a neuron from left to right
Dendrite -> cell body -> axon -> terminal branches
Do neurons look different? Why?
Yes! Converting different types of energy!
What do receptor neurons do?
They convert stimulus from the environment into an electrical signal/AP!
How does the AP get from the outside world to other neurons?
The receptor neuron processes it into an AP and that AP goes does it’s nerve fiber and over to the other neurons!
What is a mechano receptor?
A sensory receptor!
Are the neural connections/signal passings a chemical or electrical event?
Both!
What speed is an axon? Why?
Very fast! Electrical event!
What do the terminal branches do once they get an electrical signal from the Axon? How does the other neuron receive it? Is this chemical or electrical?
They release neurotransmitters to the dendrites of another neuron/ passing a signal onto the dendrites of another neuron–bind to the dendrite–chemical!
What is a Neural Network?
A lot of neurons strung together all talking to each other
What can happen in a Neural Network if one Neuron fires?
A chain reaction!
What’s a funky definition for a chain reaction?
When a bunch of neurons become activated by only stimulating a small amount of them
When a Neuron is resting, what is usually inside and outside of the cell in large amounts?
Lots of Potassium ions inside (K+) and lots of Sodium ions outside (Na+)
What’s in and around the resting Neuron?
Chloride is in and out, Sodium is out, and Potassium is in
What are our bodies made of, and why does it matter?
Salt water! NaCl! IT matters because it creates tension between the negative and positive wanting to get in/out of a Neuron
What charge is Potassium?
Positive! (K+)
What charge is Sodium?
Positive! (Na+)
What charge is Chloride?
Negative! (Cl-)
Who really wants to bind in the Neuron?? Why can’t they??
Sodium and Chloride! Salt! They can’t because of the semi-permeable cell membrane
When I talk about charges and all this jazz for the neuron, what part are we mainly talking about?
The Axon!!
What causes there to be a charge in the axon?
The tension between the positive and negative ions being pulled to each other (opposites attract!)
What would happen if there was no semi-permeable membrane in the axon?
The ions would balance out and there would be no charge!
What does the electrical differential allow to happen in the Axon?
The AP!
When the Neuron is resting, what is the electrical potential of the inside of the neuron relative to the outside?
-70mV
What causes the -70mV resting potential?
Lots of the potassium ions inside the cell and lots of sodium ions outside the cell
What happens to the sodium when a neuron fires?
It comes rushing into the Axon
What happens when the sodium rushes into the Axon?
It changes the charge of the inside of the Axon from -70mV to +40mV
When does a neuron fire?
When there’s an integration of information
What does it mean for a neuron to “integrate information”? When does the neuron fire?
The neuron summs up the negative and positive neurotransmitters; it fires when there’s enough positive neurotransmitters
What are the sodium ion channels?
Protein Molecules!
What does it mean for a Sodium Ion Channel to open and close?
It means what shape it’s in–whether that shape allows sodium to come into the axon or not
What happens once Sodium ions start flowing into the neuron? (After there’s a positive charge) Why?
The Potassium starts getting pushed out because the positives repel each other–which leads to an almost equal negative charge inside the neuron again
How does the neuron reset back to it’s resting potential?
It switches out Sodium ions for Potassium ions using the Sodium-Potassium pump
Why is it important to restore the gradient of Sodium outside and Potassium inside?
So that the neuron can fire again
What is an Action Potential?
The act of the sodium ions coming in and the Potassium going out and the like–this whole process creates an electric current that results in the chemical stuff of neuron’s communicating
How many action potentials can a neuron have a second? Is it fast?
It’s kind of fast; not as fast as a computer; but it’s 1000 APs a second!
Define a Synapse–where is it?
The gap between two neurons, typically between the terminal branches of one and the dendrites of another
What happens when the AP reaches the end of the Axon?
It triggers the release of Neurotransmitters from the terminal branches
What happens once the Neurotransmitters get released?
They diffuse over the synapse and eventually bind with receptors on the post-synaptic neuron
What are the Neurotransmitters contained in when being released?
Synaptic Vesicles
How do other neurons take in the Neurotransmitters from another neuron?
They take them in via Receptor Sites
What causes the AP signal in the first place?
The binding of Neurotransmitters into the Receptors of another Neuron
What are the two kinds of Neurotransmitters? Can a neuron put out both at once?
Inhibitory and Excitatory–A neuron can only put out one type at a time
What does an Inhibitory Neurotransmitter do?
It decreases the amount of APs in it’s target neuron
What does an Excitatory Neurotransmitter do?
It increases the amount of APs in it’s target neuron
What type of neurotransmitter is Serotonin?
Inhibitory
The Excitatory and Inhibitory signals from the _____neuron are ___ by the ____neuron
The Excitatory and Inhibitory signals from the pre-synaptic neuron are summed by the post-synaptic neuron
What happens if a Neuron is given an equal amount of Excitatory and Inhibitory Neurotransmitters?
They cancel out and it stays at it’s base-line firing rate!
When is a Neuron at it’s base-line firing rate?
If there’s no signal, or if there’s an equal amount of positive and negative signal
What is Single-cell Neurophysiology?
When an experimenter records the activity of a single neuron in response to a stimulus
How do experimenters measure the firing rate of a Neuron?
They insert a micro-electrode into it!
What are they testing for when they measure the firing rate of a Neuron?
They want to see which types of stimuli make the neuron fire the most/best
Neurons have a preferred ___ and only respond when these stimuli are in their _____
Neurons have a preferred stimuli and only respond when these stimuli are in their Receptive Field
What is Tuning and what type of study is it involved in?
It’s seeing what properties in the world a Neuron is tuned into; where their receptive field is, etc… It’s a part of Single-Cell Neurophysiology
Why do Neurons need to be so interconnected with each other?
So they can piece together a percept of the world–they’re all tuned to something specific
What is an important tool in understanding how the brain analyses patterns?
Single-cell Neurophysiology
A Neuron is Tuned or ___ for a specific pattern
Coded
What happens when a Neuron Coded for a horizontal line sees a vertical line in it’s Receptive Field?
It becomes inhibited; it’s firing rate decreases
What happens when a Neuron Coded for a horizontal line sees a horizontal line in it’s Receptive Field?
It becomes excited ; it’s firing rate increases
What happens when a Neuron Coded for a horizontal line sees a diagonal line in it’s Receptive Field?
It fires a little bit
What have researchers made using Single-Cell Neurophysiology?
They’ve created a detailed functional map of pattern analyzers in the brain (parts of the cortex)
How is the vast majority of pattern-specific brain maps created?
Using Single-Cell Neurophysiology
Who won the Nobel Prize in Physiology and Medicine for their discoveries in Information Processing in the Visual System?
Hubel and Wiesel
Explain why an AP can be graphed as an upside-down U?
First sodium comes rushing into the neuron causing it’s charge to increase and become positive, but then it starts going down in charge as the Potassium is thrown out, and then it reaches it’s normal equilibrium by switching out the potassium and the sodium through a Potassium-Sodium pump
