Labs 1/2 Flashcards
What is latency?
Latency is the time between the delivery of a stimulus and the delivery of a response (the time delay).
What is an unpaired group?
Two different populations of people.
What is a paired group?
The same population before and after intervention
Describe the difference between a nerve, an axon and a neuron
A neuron is a singular nervous system cell comprising of a cell body, dentrites and an axon.
The axon is the long projection of the neuron that takes electrical impulses away from the cell body. Axons can be referred to as the nerve fibre.
A nerve is a bundle of axons. Measuring the Whole Nerve Potential is the summation of all the neuron’s in the one nerve.
Explain the basis of and the difference between intracellular and extracellular recording from the nerves and axon
Intracellular recordings are recordings taken from the INSIDE of an axon or neuron.
Extracellular recordings are recordings taken from electrodes placed at two different points on the OUTSIDE of an axon or neuron.
There are differences in results between the two: for example because of myelination more voltage is required to have an effect on the axon.
Explain the difference between the threshold for an axon and for a nerve
Threshold for an axon is an all or nothing event, whereas for a nerve it is graded. This is because every axon is different and therefore not all axons within the nerve have the same threshold.
Explain the mechanism of action of a local anaesthetic
Local anaesthetic work by blocking the Na+ channels on the nerves therefore pain signals cannot get to the brain.
The effects of anaesthetic are reversible / only provide temporary relief. Once the effect wears off the sodium channels reopen and nerves will send signals again.
What is a whole nerve potential (WNP)?
It is an action potential representative of the combined electrical activity of all the different axons within a nerves. The electrical events in all active axons within a nerve summate electrically to produce the WNP.
What colour is myelination?
White
Why is sampling rate important and what is the difference between a high and low sampling rate?
An optimal sampling rate is essential to recoding good quality data.
The signal is sampled at discrete and seperate intervals determined by the sampling rate - each point of data is then connected by a series of lines to complete the waveform.
A high sampling rate means the points are close together and there is very little data loss (ie it is unlikely that anything significant could have happened in the time period between the samples).
At a low sampling rate important events may have occurred between samples whilst the data was not being sampled and such event may not be recorded meaning data can be lost.
A higher sampling rate gives more accurate recording.
What effect does holding your breath have on the pulse waveform?
Stready increase/increased amplitude
What is the amplitude the measure of?
Measure of the strength of the ‘pulse’
How do you measure the electrical signals of the brain?
On an EEG (electronecephalogram)
What is prominent on a EEG when relaxed and what is prominent on EEG when active?
The state of consciousness effects the electrical waveform of a EEG.
When relaxed the alpha rhythm is prominent.
When more active it is the beta rhythm that is more prominent.
What is a cortical evoked potential (CEP)?
The recording of a specific activation of a particular population of cortical neurons in response to a defined stimulus.
What is a Visual Evoked Potential (VEP)?
The particular type of CEP that is evoked by a visual stimulus.
What does it mean when something is statistically significant?
That there is a significant difference between the means of two groups of data. It is the result of there being a less than 5% probability that the data in the two groups are the same.
