L2 - Methods Flashcards
Overview of experimental methods. Strengths and weaknesses for each technique, different techniques suitable for different questions
Describe the 5 classifications of the senses for vision.
Sense, Stimulus, Receptor, Sensory Structure, Cortex
Sense: Vision
Stimulus : Electromagnetic Energy
Receptor: Photoreceptors
Sensory Structure: Eye
Cortex: Primary Visual Cortex
Describe the 5 classifications of the senses for hearing.
Sense, Stimulus, Receptor, Sensory Structure, Cortex
Sense: Hearing
Stimulus: Air pressure waves
Receptor: Mechanoreceptors
Sensory Structure: Ear
Cortex: Auditory Cortex
Describe the 5 classifications of the senses for Touch.
Sense, Stimulus, Receptor, Sensory Structure, Cortex
Sense: Touch
Stimulus: Tissue distortion
Receptor: Mechanoreceptors, Thermoreceptors
Sensory Structure: Skin, Muscle etc.
Cortex: Somatosensory Cortex
Describe the 5 classifications of the senses for Balance.
Sense, Stimulus, Receptor, Sensory Structure, Cortex
Sense: Balance
Stimulus: Gravity, Acceleration
Receptor: Mechanoreceptors
Sensory Structure: Vestibular Organs
Cortex: Temporal Cortex
Describe the 5 classifications of the senses for Taste/Smell.
Sense, Stimulus, Receptor, Sensory Structure, Cortex
Sense: Taste/Smell
Stimulus: Chemical Composition
Receptor: Chemoreceptors
Sensory Structure: Nose, Mouth
Cortex: Primary Taste Cortex, Olfactory Cortex
What is ‘Steves’ Power Law’?
Equal ratios of intensity correspond to equal ratios of sensory magnitude
Looks at the stimulus magnitude, then the magnitude estimate.
If a line is longer, we can say it’s longer, if a spot is brighter, we can say its brighter etc.
Does Stevens’ Power Law suggest that sensory systems are reporting changes in intensity or raw intensity?
Changes in intensity
e.g. for shock, if the intensity doubles the estimate increases 10 fold
What are Lesion Experiments?
An animal’s brain is lesioned (through surgery or ablation).
Behaviour in the lesioned animal is then compared to that in the normal animal.
What are the positives and negatives of Lesion Experiments?
Discrete Loss of Brain Matter (albeit crude).
Data helped establish the idea of localisation and function.
Have to be careful interpreting data.
How can Clinical Studies help us understand perception?
Look at a patient with a brain injury.
Assess the functional and anatomical extent of the damage (neuropsychological test, experiments)
Insight into brain function by comparing patient behaviour with normal behaviour.
- What was patient DF’s experimental test?
- What were the results?
- What does this imply for the brain?
- . She was asked to match the orientation of a held object perceptually then she had to “post” it by bringing it to to the line.
- She could not match it perceptually but had little problem posting it (carrying out the action).
- There is a dissociation between perception and action in the brain.
(There is conflicting evidence of this)
What are the Pluses and Minuses for using clinical studies?
Positive: Very Interesting Cases
Complexities: No two patients are the same - hard to control groups
Age, Extent of injury, experience prior to insult
What are Psychophysics experimental techniques?
Experimental techniques for measuring the percept associated with a stimulus of a given intensity.
What are the pluses and minuses of Psychophysics?
Non-invasive technique - but no direct measure of brain function
Behaviour is often what matters - useful information for applied areas (e.g. human factors, assessment of disease)
Relatively inexpensive.
What is the Single Unit Recordings technique for measuring perception?
Recording the change in the action potential of a single cell (neuron).
Records from awake, behaving or anaesthetized animals.
What is the process of how information is transmitted from different parts of the brain?
The Stimulus goes to the Receptor
A Nerve Impulse goes across the Axon to the Synaptic Vesicles
These Synaptic vesicles release Neurotransmitter Molecules
These cross the junction and go into the Receptor Sites
What is this diagram?
What do the lines and the images represent?
What is this an example of?
- A diagram of an experimental setup for a single cell recording.
- The lines indicate an increase in response to the angle of the stimulus.
- This is an example of Tuning?
What are tuning tests?
We use tuning tests to determine where the neural activity is happening when the stimulus is presented in a certain way.
There are certain responses that certain stimuli fire for and this suggests they are coding that dimension of information in the environment.
What are the pluses and minuses to single unit recordings?
Pros: Excellent spatial and temporal resolution
Cons: Only small window into brain activity
Long, expensive experiments
What does Functional Magnetic Resonance Imaging (fMRI) do?
What is it used for?
Measures change in blood flow.
Detects changes in haemoglobin levels caused by changes in blood oxygenation levels
Has been used extensively to infer localisation of function.
What is this chart showing us?
Which techniques should be used depending on what you are trying to measure in the brain.
What are the pluses and minuses of using an fMRI?
Pros: Whole brain activity in real time (i.e. as an experiment is performed),
Excellent spatial resolution,
Can bring together structure and function
Cons: Poor temporal resolution
Very expensive, time-consuming experiments
With fMRI’s, what are ‘Slices’?
How big of a part of the brain you wish to look at using the fMRI.
What is the difference between a Sagittal Slice and an In-Plane Slice?
Sagittal = Slice Thickness (6mm means 6mm deep)
In-Plane = Looking down from above from that part of the brain
