Flashcards in L1 - Intro to Sensory Motor Systems and Methods Deck (54):
What is needed to copy another person's motor actions?
Activation of the motor system, which is involved in action observation as well as action production.
Why do animals have nervous systems?
For learning and adaptable behaviour (and movement)
What does the sea squirt do that provides evidence for the nervous system being responsible for action and movement?
It attaches to a sedimentary rock at the bottom of the sea and digests it's own nervous system.
Which part of a neuron is responsible for the input of information?
Which part of the neuron is responsible for the output of information?
Which part of a neuron is the main cell body?
What is a multipolar neuron?
One that has a single axon and multiple dendrites
What is a unipolar neuron?
One that only has one protoplasmic process extending from the cell body.
What is a bipolar neuron?
One that has two extensions from the cell body - typically one axon and one dendrite.
How many neurons is the human brain estimated to have?
100 billion neurons
How many synapses is the human brain estimated to have?
100 trillion synapses
The adult brain will tend to lose how many neurons every day?
10,000-20,000 per day
What do neurons need electricity for?
To transmit signals
What are nerve signals not good for? What does it do instead?
Transmitting information long distances. Taking lots of signals and integrating them together.
What happens if multiple pulses/signals reach a terminal in quick session?
They will be summated into a larger signal/action potential (temporal integration)
If multiple cells signal to the same cell in quick session, what occurs?
They will be summated into a larger signal/action potential (spatial integration)
The speed of change in Na+ permeability is what?
The speed of change in K+ permeability is what?
What is the typical resting potential of an axon?
Briefly describe the stages that occur in an action potential.
Resting potential, depolarisation, repolarisation, hyperpolarisation, resting potential.
Influxes of sodium into the axon causes what?
An increased positive charge, meaning points in the axon slightly further down the cell will be more (in relative terms) negatively charged. This then causes a cascade of changes in charge, in and out of the axon, resulting in an increased positive charge inside the axon. This leads to K+ ions diffusing out of the cell. Continuous process that leads to a propagation of the action potential along the axon.
Why is the axon hillock important?
Has a high concentration of ion channels, which allow it to be sensitive and initiate the firing of action potentials.
Firing rates is the mechanism of communicating information over what?
What ensures the fast travel of action potentials in myelinated axons?
Many layers of myelin between the axon and the schwann cell.
What does white matter consist of?
What does gray matter consist of?
Cell bodies, synapses and non-myelinated axons
Gaps between myelin sheath in myelinated axons are called what?
Nodes of ranvier
The process of transmitting action potentials along myelinated axons is called what?
Why aren't all axons myelinated, if information can travel so quickly along them?
Because it takes up alot of space, and there just isn't enough space in the brain for all axons to be myelinated.
Does communication between neurons involve electricity?
No. Chemicals aid communication at synapses, between different neurons.
What does NMJ stand for?
What is the NMJ?
A complex synapse between a nerve (alpha motor neuron) and a muscle
What are alpha motor neurons?
Special neurons that connect specifically to muscle fibers.
How can we record and measure muscle neuron activity?
Single neuron recordings
What is the problem with using single neuron recordings to measure muscle neuron activity?
They are typically invasive methods, and are rare in humans as a result. Recording from the CNS is invasive, but peripheral nerves can be recorded more easily.
What does EMG stand for?
What is EMG?
A method of recording electrical activity produced by single skeletal muscles, using an electromyograph.
What does EEG and MEG stand for?
Electroencephalography and magnetoencephalography.
What are EEGs and MEGs used for?
Measuring the electrical actiivty of large populations of neurons, through the scalp.
What does PET stand for?
Positron Emission Tomography
What is PET used for?
The measuring of neuron activity using tracking of chemicals/neurotransmitters.
What are EEG signals largely driven by?
Post synaptic potentials, rather than action potentials themselves.
Why do EEG signals need to be averaged over many trials?
Because the signals tend to be tiny
When correlating electrical activity with behaviour using EEG, what is being measured/checked?
Synchronous activity across thousands of neurons
What blurs spatial resolution when using EEG?
What does an MRI scanner measure?
Local changes in blood oxygen levels
What does BOLD stand for?
Blood Oxygen Level Dependent (signal)
What does BOLD reflect?
Local processing, not the output of that region.
What is energy consumption in the brain mainly spent on?
Changes in synapse underlies what?
Learning and memory
The axon hillock can be referred to as what, and why?
The axon initiation segment - it has a high density of ion channels, which allows it to be sensitive to and initiate action potentials
What does a raster plot show?
Behaviour and rate coding for single cells
Describe the haemodynamic response and fMRI BOLD signals.
A stimulus would lead to excitatory or inhibitory activity in the specific brain region which it is related to.
The volume and flow of oxygenated blood sent to this area increases - vasodilation occurs. More blood is sent than is required, however, so there is an excess in that region. This oxygenated blood can be detected by the MRI scanner as it has a different magnetic field to de-oxygenated blood.