Lecture 1: Basic Concepts and Methods in Neuropsychology Flashcards
What is a Gyrus
A fold or convolution on the brain’s surface
What is a sulcus
A groove or furrow on the brain’s surface
What did Galen (130AD - 210AD) study?
The injuries of gladiators
What did Galen posit
That only head injuries lead to mental disorders
What is the Lesion method
When an area of brain damage correlates with the development of a deficit in behaviour or cognition
What are the limitation of lesion studies
- That they (scientists) do not assess the function of the damaged brain area, but rather they focus on how the rest of the brain functions without the area
- The function of a brain area can be masked by alternative ways of solving the task
What are the strengths of Animal studies
- More controlled than human studies
- Allow for systemic studies with lesions (deliberate brain damage)
What are some limitations of animal studies
- Might not be a good model of human cognition
- Ethical Issues
What is a systemic study
Carefully controlled experiments that isolate specific variables
What are the four main techniques for assessing brain anatomy
- Computerised Axiel Tomography
- Magnetic resonance Imaging
- Positron Emission Tomography
- Functional Magnetic resonance imaging
What does CAT/CT scan stand for?
Computerised Axiel Tomography
How does a CAT/CT scan work?
- Uses X rays to look into the area
- Blood and high density objects appear light
- Non-dense appears dark, like cerebrospinal fluid
What is a CT scan good for?
Detecting organs and body details
What does MRI stand for?
Magnetic Resonance Imaging
How does an MRI work
- They use magnets that distort the behaviour of protons
- Protons in different substances revert to the original state at a different speed (this is relaxation time)
- The analysis of the relaxation time reveals brain structure
What does PET stand for?
Positron Emission Tomography
How does a PET scan work?
- Radioactive molecules are introduced into blood flow
- The accumulation of radioactive material in specific brain regions reveals active brain areas during specific tasks
What does fMRI stand for
Functional Magnetic Resonance imaging
How does an fMRI work?
- Measures blood flow and oxygenation during specific tasks
- Oxygen risk blood has magnetic properties
- When oxygen is extracted, blood loses its magnetic properties
As neuronal activity requires oxygen from blood , fMRI provides indirect information about the bloods location and time-course
What is an EEG
It is an Electroencephalogram
What does an EEG measure
It measures brain consciousness and can even measure specific parts of the brain, depending on where the nodes are
What is an ERP
Event related potentials
What does an ERP do?
Measures localised potential in response to specific stimuli, events or tasks
What are the two main techniques for modulating brain activity
- TMS
- tDCS
What doe TMS stand for?
Transcranial Magnetic stimulation
How does the TMS work?
- An electrical field is induced on the scalp
- It penetrates the skull and induces a small electrical current in the neurons beneath it
It can either stimulate or disrupt the neurons (get them working or stop them working) depending on the frequency of the TMS
What does tDCS stand for
Transcranial Direct Current Stimulation
How doe tDCS work?
- Electrodes are placed on the scalp over a targeted brain region
- A constant current is passed from one electrode to the other over a period of time
- The stimulation leads to polarity specific modulations in cortical excitability
- Anodal tDCS, increases neuronal activity
- Cathodal tDCS: Decreases neuron activity
What are some differences between tDCS and other electrophysiological research techniques
- Unlike correlational methods such as functional magnetic resonance imaging (fMRI), tDCS can provide causal evidence that a brain region is involved in a behaviour of interest
- tDCS influences a larger region of the cortex than TMS
- tDCS acts as a neural modulator without causing action potentials
- tDCS can produce opposing effects through anodal and cathodal stimulation, but with similar peripheral sensations (scalp tingling)
- tDCS produces fewer physiological artefacts than TMS
- tDCS is cheaper, more portable and easier to apply than TMS
What does the effectiveness of tDCS rely on?
- Polarity
- Location of reference stimulus
- Single vs repeated tDCS sessions
- Intensity
- Duration
- Online-offline stimulation
- Participants
What are 3 other types of Transcranial Electrical Stimulation
- Oscillatory tDCS
- tACS
-tRNS
What is an Oscillatory tDCS
- An application of a current in which intensity fluctuates at a given frequency
- Each electrode remains polarity specific
What does tACS stand for?
Transcranial alternating current stimulation
What does tDCS do?
- Current intensity fluctuates at a given frequency as in oscillatory tDCS
- However, each electrode does not remain polarity specific
What does tRNS stand for?
Transcranial random noise stimulation
What does tRNS do?
- Random fluctuations in current intensity add neural ‘noise’ to the targeted region(s)
- A process called stochastic resonance can cause a weak signal to be boosted by increased background noise
