PSYC122 weeks 1-3 Flashcards
How can we study the brain, behaviour and the mind?
- Ask questions
- Observe what you are doing
- Measure your performance on a specific task
- See how damage to the brain can impact performance
- Measure activity of healthy brains
Wellington Zoo’s Meerkats, complex social hierarchy, Example: Investigating food preference in meerkats (Brox et al., 2021).
controlled how much food they had before, time of day, zookeeper’s outfit
* IV: Food type
* DV: number of meerkats present at each site.
* Tells us about which foods animals prefer when they are given a range of foods to choose from.
The value of observing behaviour, we all observe the world around us, helps us understand processes, teaches us about the world around us
Stroop test
a grid filled with names of colours. Your job is to say the names of the colours that the words are printed in from left to right as fast as possible- the colours don’t have to match the word
Automaticity Theory
The word interferes with the colour naming when the word and colour do not match because reading is an automatic process and recognising colours is a more controlled process.
Selective Attention process
Reading requires less attention compared to identifying a colour, that’s why it takes us longer to identify the colour of words in incongruent trials.
Aphasia
- Language disorder that affects a person’s ability to communicate.
- The result of a stroke or brain injury.
- People with aphasia may find the following tasks difficult:
Talking
Comprehending spoken, or written language
Writing
Using numbers, for example calculating answers to problems.
Broca’s area Aphasia
- Involved in speech production.
- Difficulty in producing language
- Comprehension abilities relatively conserved
Wernike’s area Aphasia
- Involved in language comprehension
- May speak fluently
- Spoken language often lacks meaning
- Difficulty with language comprehension
- Can produce word salad- say a number of words that have no connection to each other
Example: fMRI
- Safe and non-invasive
- Detects changes in the flow of blood
- Increases in blood flow are correlated with neuronal activation
Central Nervous System (CNS)
made up of the brain and the nerves that go along your spinal cord down your vertebrate
Example 1: Transcranial Magnetic Stimulation (TMS)
- Non-invasive technique that disrupt specific brain activity for a fraction of a second.
- Allows us to investigate the role of these areas in human functioning.
Electric currents flow into different parts of the brain as you process different information
Peripheral Nervous System (PNS)
made up of all nerves that come out from your spinal cord and goes to fingers, arms, legs, other organs
Neurons
Cells that send/receive information
The main structures of a Neuron
classic structures to almost every neuron, dendrites= branches that form from round/fat bit, they reach out and expect to receive information from other cells, detect signals, send the information to centre of the cell (round bit) called the cell body or soma, similar to other cells, it contains a lot of organelles which are things that keep the cell alive, creating protein to grow/move, life support system, longer looking tube is called axon, carries information away from the cell body, moves it down towards terminal region/axon terminal they have bulbs at the end, reaching out to send a signal to another cell’s dendrites
How information travels through a Neuron
signals always go from the dendrites to the cell body, and then from the cell body down the axon to the axon terminals
When a neuron “fires”
the signal may stop or not be allowed to be sent down the rest of the cell, just because the dendrites brings in information from another cell does not mean it is automatically going down the axon, something special happens in the neuron at the very beginning of the axon, called the axon hillock, counting the different signals and keeping a score and there is a threshold where if the signal coming in does not reach this threshold then it does nothing at all, not enough signal to go down the axon- “fires” sends a signal, the axon hillock generates the signal and sends it down- all or nothing principle, either no information or fires
The myelin sheath
how signals can move faster down the axon!
Unmyelinated Speed: ~1 metre per second
Myelinated Speed: up to 100 metres per second!
Myelin: a fatty (lipid-rich) substance that insulates the axon, allowing signals to travel faster!- may be myelinated because it is really important for what that information carries for it to get really quickly to your brain
In myelinated neurons, the signal “jumps” from one Node of Ranvier to the next as it moves down that axon. Nodes of ranvier- gaps between the myelin sheath
Other cells in the Nervous system that support Neurons: Glia cells
3 kinds- Oligodendrocytes (cell body with arms), Astrocytes (cell body with arms and feet), Schwann Cells
Oligodendrocytes
- Form the myelin sheath around axons in the central nervous system.- form crescent shape from the centre, find an axon that is not myelinated and wrap itself around and around and around and tighten up, can do this on different axons because of multiple arms/form multiple different sections on one axon
- Help increase speed of information travelling through the axon
Schwann Cells
- Form the myelin sheath around axons in the peripheral nervous system (PNS).- find an axon and wrap their entire cell body around the axon, only forms one part of the myelin sheath
- Help increase speed of information travelling through the axon
Astrocytes
. Helps repair neurons
. Helps bring nutrients from the bloodstream to the neurons using the blood-brain barrier
. Provides structural support for neurons.
Two kinds of signals can travel into the cell body
- Excitatory signals make the cell more likely to fire
- Inhibitory signals make the cell less likely to fire
Summation
A process occurs in the Axon Hillock where the sum of all incoming signals (excitatory and inhibitory) determines whether the neuron fires.
Threshold value at which the neuron fires:
-55 mV (millivolts)
Value the neuron starts at (before any signals arrive):
-70 mV (millivolts)
You need 15 more excitatory mV than inhibitory
Resting Membrane Potential
below membrane is inside the cell (intracellular), above is outside the cell (extracellular), Inside of the cell is more negatively charged (70 mV more negative) compared to outside the cell, resting membrane potential is achieved when both forces are equally strong and then cell fires
What are these charged particles that reside inside and/or outside the cell?
Ions: Molecular clusters with an electrical charge
K+ Na+
Potassium Sodium
These two ions are crucial to sending signal down an axon
How do these charged particles get into the cell (or out of the cell) to make it more positive or more negative?
Ion Channels: Doors in the Membrane- openings in the cell that can happen, leaky potassium channel- never closes, potassium can sneak out of the cell
Why don’t these charged particles just stay put where they are?
Concentration gradients- Ions move from area of high concentration and toward lower concentration until equilibrium occurs
Electrical gradients- Charged particles will move across membrane until equilibrium occurs (same charge on both sides)
What actually is an Action
Potential?
An Action Potential is a change in the voltage (inside is more positive and outside is more negative) inside a cell (relative to outside of the cell) taking place at one section of the cell at a time (not the whole cell at once)- moving change in voltage down the axon
How does an action potential travel down the axon?
Action potential propagation- voltage gated sodium channel, only open when it detects certain voltage, -55 mV or greater, opens gates, sodium floods into the cell (less sodium and more negative)
What about potassium- gates open to let potassium in- First not much will happen: Concentration Force (CF) wants to move K+ out; Electrical Force (EF) wants to push K+ in, However, as Na+ flows in, the inside become less negative, leading to a reduction in EF, Now CF is winning and K+ flows out
Action Potentials (change in voltage across time)
Depolarization- inside of cell becomes crazy positive, +30 mV threshold closes gates
Repolarization- more negative- goes down lower than it was at beginning -80
Refractory- trying to get back to resting potential -70, can’t fire in the meantime- Voltage gated channels have closed so there’s no way for Sodium to travel down its electrical gradient to leave the cell, This is where the Na+/K+ Pump comes in!- need to get extra sodium out, always need extra potassium since it leaks out the gates
