Biological Psychology - Semester 1 Flashcards
What is biological psychology?
‘The relationship between brain and though/behaviour’
What does brain function underlie?
Thought and behaviour
What is the brain the crucial centre for?
Skilled movement, sensory, communication, language, emotion and thought itself
What did Descartes believe?
He believed that there was a role for the physical body bit he thought that the soul was in charge of flexibility and thought. However, nowadays we believe the brain to be in charge of this not the soul.
How is information sent?
Information is sent via electrical signals (movement of charged particles) and chemical signals.
What do changes in wiring or brain chemicals lead to?
Changes in how we think and behave
What does our thinking and behaviour rely on?
Our brain, brain chemicals and how they work
What is Parkinson’s caused by?
Lack of dopamine
How does drug abuse affect dopamine levels?
Too much dopamine
Do all brain areas carry out the same function?
No. If they were all the same, then damage to one part of the brain would have the same effect as damage to any other part of the brain but this is not true. Each part of the brain is good at one function.
What is Brodmann’s areas?
He made maps of brain function and found that the function of each bit of the cortex have different functions and different connections with other brain areas. At the time he did not know the role of these areas of the brain however nowadays we are understanding the functions of these areas.
What happened to Patient HM?
Patient HM, had brain surgery to remove part of his brain to stop his epilepsy. However, this caused his memory to be reduced, and he did not have ability to make new memories.
How do parallel systems within the drain function?
Most of them function without consciousness
What are double dissociations?
Double dissociations – different parts of the brain are used when looking at an item than interacting with an item. It doesn’t feel like this, but it does use different areas.
What does common sense tell us about the world?
Common sense tells us that: we perceive the world exactly as it is and we act according to our ‘will’.
What does biological psychology tell us about the world?
However, biological psychology shows us that: we perceive what is useful to us, there are multiple parallel brain processes governing our cognition and action, most of these processes are unconscious.
What is psychology?
Psychology is the study of how our minds actually work. Studying the brain is crucial to a full understanding of psychology.
What is grey matter?
Grey matter is smooth and soft and contains cell bodies
What is white matter?
White matter is bundles of fibres that come off the cell bodies. Signals from cell bodies are taken to talk to other cell bodies potentially in the brain or elsewhere.
What is the role of grey matter?
What is the role of white matter?
Grey matter does the processing of information. Transmitting is the role of the white matter.
What is Structural magnetic resonance imaging (MRI)?
A way of getting a picture of someone’s brain/ other parts of the body when people are still alive without need of dissection. Uses water, it can be detected from the outside. MRI can tell which part of the brain has more or less water.
What is histology?
Using an electron microscope you can get a clearer picture of the structure of the cortex
Tracing neuronal pathways?
If part of the brain is in charge of hand movements, then there need to be a connection from the brain to the spine. Certain chemicals are taken up by cells and transported forwards or backwards, even between cells – this reveals the pathways between brain area. Only possible to do in animals
What did Brodmann do?
Looked at different parts of the brain under a microscope and drew sketches. He discovered that different structures had different roles within the brain. The structure is different when the connections are different.
How do we trace neuronal pathways using diffusion tensor imaging (DTI)?
Uses the differential diffusion of water molecules in different types of tissue to show routes of axons.
What is a Positron Emission Tomography (PET)?
Uses radioactivity (via water, glucose, neurotransmitter) injected into blood & detected by a PET scanner. There tends to be more blood in areas of high activity. Detects healthy cells through blood flow, glucose levels and neurotransmitters. If you are making a difficult decision the blood will rush to the decision-making part of the brain. You can detect these things from a distance without having to physically go into their brain.
We can see in a PET scan if someone has Alzheimer due to glucose levels.
What is a functional magnetic resonance imaging (fMRI)?
Looks at brain function and brain activity, to a large extent it does the same as PET. Avoids use of radioactivity making it safer. Detects increased blood flow (via magnetic haemoglobin) in active brain tissue. Active brain tissue has more oxygen filled blood flowing to it.
What are the pros and cons of fMRI?
Precise spatial information, imprecise temporal information (same is true for PET). It is not very time accurate as it takes a couple of seconds for the blood to flow. You cannot get the timings of brain activities with a fMRI due to the fact that it is just based on blood flow.
What is an electroencephalography (EEG)?
Records electrical signals at scalp, signals produced by electrical brain activity.
What are the pros and cons of an EEG?
Price temporal information, imprecise spatial information. The timings are very accurate, but it is difficult to know what part of the brain does each activity.
What is a magnetoencephalography (MEG)?
Records magnetic field at scalp. Note: these fields are produced by electrical brain activity
What are the pros and cons of Magnetoencephalography (MEG)?
Precise spatial and temporal information). They give precise timings and specific locations of brain activity. (very expensive).
What are the pros and cons of single-cell (single unit) recording?
Very precise spatial and temporal information
Only one cell at a time
Impractical in humans
Not a standard technique
What does prosopagnosia due to brain lesion cause?
These people may have struggles recognising faces due to damage to inferior temporal cortex damage.
What is meant by lesion?
damage, due to e.g. stroke, surgery, tumour
What does amnesia due to Alzheimer’s cause?
poor new learning following damage to medial temporal lobe.
What does dysfunction due to Parkinsons cause?
Lack of dopamine impairs function of frontal lobes, including, ‘executive functions’
What is Transcranial magnetic stimulation (TMS)?
Focused magnetic field disables briefly (for a few milliseconds) a small area of cortex; a “reversible lesion”; precise temporal and spatial information. Let’s us see what parts of the brain need to be disrupted in order to prevent a task being done. Let’s us see what types of the brain are involved in which activities.
What is a neuron?
- The body is composed of cells
- Cells are specialised to perform specific functions (e.g. red blood cells, muscle cells)
- Neurons (nerve cells) are specialised for communication
What are the two main roles of a neuron?
Information transmission
Information processing
What does the neuron do in terms of information transmission?
- E.g. from eye to brain, or brain to muscle
- Action potential
- The part of the neuron that is important for this is the Axon
- Maintains a clear signal
What does the neuron do in terms of information processing?
- E.g. to interpret a pattern of visual information as being a human face
- Integration of signals
- The parts of neurons that are involved are the synapse/dendrites and cell body
- Modify signals according to context
What is the axon hillock?
The very beginning of the axon, this is where the signal begins.
What is the action potential?
- The action potential is the ‘output’ signal of a cell, triggered by a particular combination of ‘inputs’
Where does the action potential begin?
Axon hillock
What are the three steps for the action potential?
Begins at the axon hillock
Travels along the axon to the terminal
Triggers activity at the synapse
What are the steps of neuronal ‘firing’?
- First, an electrical potential is set up: the resting potential
- This is allowed to suddenly discharge: the action potential
- This triggers further action potentials further along the axon
What does the row of matches/dominos show in terms of neuronal firing?
IF you set up a row of matches close enough together and then light the first one it will light the second one and so on so close. Same with dominos. You put a lot of work into setting up these things but not much energy to set it off.
What are cells enclosed by?
Lipid (fatty) membranes. Semi-permeable membrane
Where do different ions live?
- Different ions (electrically charged molecules) are concentrated in the fluid inside and outside the cell.
What needs to take place in order for the action potential to be reached?
- In order for the action potential to be reached certain ions need to be inside a cell and some need to stay outside.
What is the role of proteins?
- Protein pumps actively transport ions across the membrane. - requires energy
What allows ions to cross the membrane?
- Protein ion channels allow ions to cross the membrane
What do ‘voltage-gated’ ions do?
- ‘Voltage-gated’ ion channels open at a particular membrane voltage.
- What makes the gates open or closed? The voltage across the cell - the voltage of the fluid inside and the voltage of the fluid outside – affects whether the gate is open or closed.
What is the resting potential?
- At rest, the membrane is polarised
- -70mV (inside of cell more negative than outside)
- This acts like a store of energy, work had to be done to make it like that.
- The energy is used to create the action potential
How is the resting potential set up and maintained?
- The sodium-potassium pump exchanges three sodium ions for two potassium ions
- Sodium and potassium are both positive but as the push out 3 sodium this means that the outside is more positively charged that the inside.
- This makes the inside of the cell relatively negative.
- This uses energy
Where is there more negative charges when resting potential occurs?
More negative charges inside than outside
What is depolarization?
When the membrane becomes more depolarized it goes more towards 0
What causes the membrane to become partially depolarized?
- An ‘excitatory’ input is received from another neuron (next lecture)
- Neighbouring membrane is depolarised (passive conduction – this lecture)
What happens when the depolarization reaches the excitation threshold?
If depolarisation reaches the excitation threshold (around -60 mV), an action potential is triggered.
When do voltage-gated sodium channels open?
- Voltage-gated sodium channels open when depolarisation reaches a threshold level
What happens when voltage-gated sodium channels open?
- Sodium ions (positively charged) flood in.
- The membrane potential changes from -70mV to +40mV
What is the refractory period?
- Sodium ion channels close and briefly lock – they become ‘refractory’
What are the functions of the refractory period?
- Signal never goes backwards
- Keeps signals separate
- E.g. candle example, can’t unburn candles
What is repolarization?
- Voltage-gated potassium channels open, letting positive charge out of the cell, to re-establish the negative resting potential
- The sodium-potassium pump continues to work, maintaining the resting potential
What are some key features of the action potential?
- The action potential is ‘all or none’
- It is always the same size
Why is the action potential important?
- Important for preserving the message – signal is regenerated every time
What happens with a ‘bigger’ message?
A ‘bigger’ message is sent by more rapid firing, or by involving more neurons; the size of each action potential is identical.
What is diffusion?
- Within any fluid, the particles are constantly moving in random directions
- They will eventually become evenly distributed within the fluid, e.g. drop of ink in the water.
What is the conduction of the action potential?
- Passive conduction (diffusion of ions within the intracellular fluid) will ensure that adjacent membrane depolarizes; sufficient deporlization triggers a new action potential
What does setting up the membrane for an action potential use?
Valuable energy
What does myelination provide?
- Myelination provides saltatory conduction for some types of axons
What does the myelin do?
Provides insulation
In the brain what is the myelin sheath provided by?
Oligodenfrocytes
What are the pros of insulated axons?
- Ions cannot leak out of an insulated axon
- So, it takes less energy to maintain the resting potential
Where does the action potential only occur?
occurs in the unmyelinated regions (it ‘jumps’ from one to the next)
What do unmyelinated regions need to do?
The unmyelinated regions need to maintain the resting potential, saving energy
What is multiple sclerosis?
Immune system mistakenly breaks down myelin scarring
What is the synapse?
Many axon terminals synapsing with a single post-synaptic cell
What is synaptic transmisson?
- Information transmission between neurons
- Allows integration and processing of information
- The synapse allows information to be changed according to other information
- (roundabout analogy)
Synpatic transmission?
- Chemical neurotransmitters cross the synapse
- From the presynaptic to postsynaptic cell
- The synapse is very narrow, so transmission is fast
What are the fourstages of synaptic transmisson?
- Release
- Diffusion
- Binding
- Termination
What is release (synaptic transmission)?
- An action potential causes neurotransmitter release from the presynaptic membrane
- The action potential causes voltage-gated calcium channels to open; calcium ions flood in.
- Calcium ions affect synaptic vesicles containing neurotransmitter
- Calcium ions cause vesicle membrane to fuse with presynaptic membrane and empty contents