Neuroscientific Techniques: EEG and TMS
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Questions and Answers

What is the frequency of an alpha wave?

  • 5 Hz
  • 50 Hz
  • 20 Hz
  • 10 Hz (correct)

    • What is the role of the ground electrode in EEG recording?

  • To act as a reference point for the other electrodes
  • To amplify the EEG signal
  • To account for environmental noise (correct)
  • To measure the electrical activity of the brain

    • Which of the following is NOT a factor that affects the EEG signal?

  • 5 Hz
  • 10 Hz
  • 20 Hz
  • 50 Hz (correct)

    • What is the primary purpose of Fourier analysis in EEG research?

    <p>To isolate and measure specific frequencies in the EEG signal (A)</p> Signup and view all the answers

    What is the significance of the 10-20 system in EEG recording?

    <p>It determines the placement of electrodes on the scalp (A)</p> Signup and view all the answers

    What type of electrical activity does EEG measure?

    <p>Postsynaptic potentials (C)</p> Signup and view all the answers

    What is the primary location where the electrical activity measured by EEG originates?

    <p>Dendrites and cell bodies (D)</p> Signup and view all the answers

    Why are postsynaptic potentials the main contributor to the EEG signal?

    <p>They have a longer duration compared to action potentials. (C)</p> Signup and view all the answers

    What is the role of electrode impedance in EEG data quality?

    <p>It can reduce the signal-to-noise ratio, affecting data quality. (A)</p> Signup and view all the answers

    What is the primary method for recording EEG signals from the scalp?

    <p>Using conductive gel and silver/silver chloride electrodes. (C)</p> Signup and view all the answers

    What is the relationship between a waveform and sine waves, according to the text?

    <p>A waveform is equivalent to the sum of multiple sine waves with varying frequencies, amplitudes, and phases. (A)</p> Signup and view all the answers

    Which of the following methods, when applied for 10-15 minutes, is likely to result in long-term depression (LTD) of neuronal excitability?

    <p>Low frequency (slow) rTMS (B)</p> Signup and view all the answers

    Which of the following is NOT a potential therapeutic benefit of TMS?

    <p>Assessing the functional role of a brain area (C)</p> Signup and view all the answers

    If TMS is applied to Broca's area, what is the likely outcome?

    <p>Speech arrest or difficulty speaking (A)</p> Signup and view all the answers

    What is the primary way in which high-frequency rTMS (fast rTMS) affects neuronal activity?

    <p>Long-term potentiation (D)</p> Signup and view all the answers

    Which of the following best describes the role of TMS in Parkinson's disease?

    <p>Treatment for Parkinson's disease symptoms (D)</p> Signup and view all the answers

    Which of the following neuroimaging techniques can directly stimulate brain activity?

    <p>TMS (D)</p> Signup and view all the answers

    Rösler et al (2014) investigated language mapping in healthy volunteers and brain tumor patients. What was the key finding of their study?

    <p>Patients with brain tumors showed a shift in language function from the left hemisphere to the right hemisphere. (B)</p> Signup and view all the answers

    What is a key advantage of using TMS as a neuroimaging technique?

    <p>TMS can provide causal information about the role of specific brain regions in cognitive processes. (A)</p> Signup and view all the answers

    Broca's area is a brain region that is crucial for...

    <p>Generating and understanding language. (B)</p> Signup and view all the answers

    What is a significant limitation of TMS?

    <p>TMS is only effective in stimulating the surface regions of the brain. (B)</p> Signup and view all the answers

    Which of the following neuroimaging techniques is most similar to TMS in terms of its ability to investigate causal relationships between brain activity and behavior?

    <p>fTCDS (A)</p> Signup and view all the answers

    What is the primary difference between EEG and ERPs?

    <p>EEG measures the electrical activity of the brain, while ERPs measure the brain's response to specific stimuli. (A)</p> Signup and view all the answers

    Which of the following neuroimaging techniques provides information about the structure of the brain?

    <p>DTI (D)</p> Signup and view all the answers

    What is the main advantage of using EEG over other neuroimaging techniques?

    <p>Directly measures neuronal activity (C)</p> Signup and view all the answers

    What does the term 'latency' refer to in the context of ERP components?

    <p>The time it takes for the ERP component to reach its peak (C)</p> Signup and view all the answers

    Why is averaging used when analyzing ERP data?

    <p>All of the above (D)</p> Signup and view all the answers

    What is the main difference between the raw EEG data and the averaged ERP data?

    <p>Averaged ERP data represents event-related brain activity (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic commonly used to name ERP components?

    <p>Amplitude (C)</p> Signup and view all the answers

    What is a potential limitation of using EEG to study brain activity?

    <p>It has poor spatial resolution compared to other imaging techniques (A)</p> Signup and view all the answers

    Which of the following is NOT a potential benefit of using ERP technology?

    <p>ERPs can be used to directly stimulate specific brain areas (C)</p> Signup and view all the answers

    What are the advantages of using EEG as a research tool?

    <p>All of the above (D)</p> Signup and view all the answers

    What is the main goal of averaging EEG data to create an ERP?

    <p>To reduce the impact of noise and isolate the event-related activity (D)</p> Signup and view all the answers

    What can ERP components be used for?

    <p>All of the above (D)</p> Signup and view all the answers

    Study Notes

    Neuroscientific Techniques & Cognition 2: Electrophysiology & Brain Stimulation

    • Ciara Egan is a lecturer in the School of Psychology at the University of Galway and director of the MSc Clinical Neuroscience program
    • The presentation covers electrophysiology and brain stimulation techniques, including EEG, ERPs, and TMS
    • Lecture 1 covered the background to neuroscientific techniques, including MRI, DTI, fMRI, and fTCDS
    • Lecture 2 focuses on EEG, ERPs, and TMS

    Electroencephalography (EEG)

    • EEG measures electrical fields generated in the brain and propagated to the scalp
    • The signal is a continuous, ongoing oscillatory activity independent of stimulus
    • Activity arises from postsynaptic potentials, lasting longer than action potentials, primarily in dendrites and cell bodies of the neocortex
    • EEG signals are measured using electrodes placed on the scalp, connected by conductive gel
    • Electrode impedance (resistance and inductance) can affect signal quality
    • At least three electrodes are needed for recording
    • A reference electrode and grounding electrode are used to account for environmental noise

    Basic Recording of EEG

    • EEG signals are small compared to electrical and environmental noise
    • EEG signal calculation: (Recording - Ground) – (Reference – Ground)
    • This calculation removes the signal from the ground and the noise common to the active and reference
    • The 10-20 system is a standard layout for electrode placement

    Frequency Domain (EEG Oscillations)

    • EEG frequencies are analysed using Fourier analysis to identify individual sine waves
    • Frequencies not equivalent to specific functions
    • The different frequency bands (gamma, beta, alpha, theta, delta) are associated with various brain states (e.g., high focus, active mind, resting state, drowsiness, sleep)

    Alpha Wave

    • An oscillation with a frequency of 10 Hz
    • Prominent over the back of the head
    • Associated with relaxation and sleepiness
    • A sub-segment of the ERP, representing a functionally distinct neuronal aggregate's activity in response to a stimulus
    • ERP components include latency (time between stimulus and response), amplitude (strength of response), polarity, and ordinal position
    • ERPs are measured by averaging EEG signals across multiple trials

    Averaging

    • The process of averaging EEG signals to eliminate noise to form an ERP
    • Consists of evoked activity (the signal) and noise
    • Signal: Associated neural activity, responding to stimulus of interest
    • Noise: Unrelated neural activity and electrical noise
    • The average across segments eliminates ongoing activity, leaving the ERP
    • The signal/noise ratio increases with the square root of the number of trials

    What is EEG good for?

    • Direct measure of ongoing neural activity
    • Identifying mechanisms of disorder (comparing patients and controls)
    • Used as a potential biomarker
    • Neurofeedback applications

    EEG – Pros and Cons

    • Advantages:*

    • Very good temporal resolution

    • Direct measure of neural activity

    • Non-invasive

    • Can be used on many populations

    • Relatively inexpensive

    • Implicit measure

    • Disadvantages:*

    • Very poor spatial resolution

    • Topography does not equal location of activity

    • Mostly activity from cortical regions

    • Requires participants to remain still

    Transcranial Magnetic Stimulation (TMS)

    • Works based on Faraday's law
    • A brief pulse of current induces a magnetic field perpendicular to the plane of the coil.
    • This induces an electric field predominantly parallel to the volume conductor surface.
    • The electric field generates secondary currents which lead to neuronal changes.
    • TMS can be used to facilitate or inhibit specific brain regions, leading to temporary impacts
    • Types of TMS include single pulse and repetitive TMS (rTMS)
    • Frequency types include low-frequency (slow) and high-frequency (fast), leading to LTD (inhibition) and LTP (increase excitability) respectively

    What is TMS good for?

    • Facilitation: Potential therapeutic benefits, may improve symptoms, promote neuroplasticity
    • Inhibition: Assessing functional roles of a brain area
    • Infer causation in brain function (e.g., speech deficits if Broca’s area is stimulated)
    • Investigating cognitive functions

    TMS – Pros and Cons

    • Advantages:*

    • Can give causal information about brain function

    • Informative about brain function in neuropsychological studies

    • Disadvantages:*

    • Not everyone can undergo TMS

    • Limited to cortical surface stimulation

    • Cannot stimulate near the brainstem

    Research Spotlights

    • The presentation includes studies on the effects of emotion on ERP responses (N170), expert object recognition, and language mapping in healthy and tumour patients. Specific studies include Tanaka and Curran (2000), Rösler et al (2014) and Hinojosa et al (2015), Blau et al (2007)

    Other

    • The presentation uses illustrations to explain EEG, ERPs and TMS principles and examples
    • Several figures visually represent different types of signals, frequencies power and examples of how recordings are made

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    Description

    Explore the fascinating world of electrophysiology and brain stimulation in this quiz on EEG and TMS techniques. Learn about how electrical fields in the brain are measured and the impact of these methods on understanding cognition. This quiz is ideal for students in Clinical Neuroscience and Psychology.

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