Transcranial Magnetic Stimulation & Rat Experiments
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Questions and Answers

What is the main purpose of subtracting the baseline in experimental tasks?

  • To isolate the activity of interest (correct)
  • To enhance the quality of fMRI imaging
  • To compare different tasks without any controls
  • To increase the overall brain activity measured

    • Which of the following is considered a limitation of functional MRI (fMRI)?

  • It shows the specific function of brain regions clearly.
  • It has limited temporal resolution compared to EEG. (correct)
  • It can accurately measure individual differences without averaging.
  • It provides a direct measure of causation in brain activity.

    • What is the function of the Default Mode Network (DMN)?

  • Associated with external sensory processing only
  • Involved in resting states and mind-wandering activities (correct)
  • Active primarily during specific tasks requiring concentration
  • Active only during sleep or unconscious states

    • Why is spatial averaging a problem in interpreting fMRI results?

    <p>It can mask the underlying neural functions by averaging results.</p> Signup and view all the answers

    What does resting-state functional connectivity MRI (rsfcMRI) specifically measure?

    <p>Functional connections between brain regions at rest</p> Signup and view all the answers

    What is a key limitation associated with analyzing fMRI data on a voxel-by-voxel basis?

    <p>Every voxel is analyzed independently, causing statistical challenges.</p> Signup and view all the answers

    What does functional connectivity in the brain indicate?

    <p>Regions show synchronized activity with each other.</p> Signup and view all the answers

    Which of the following statements about the limitations of fMRI is TRUE?

    <p>It may not clarify the specific functions indicated by observed brain activity.</p> Signup and view all the answers

    Which brain regions are part of the Default Mode Network?

    <p>Medial prefrontal cortex, posterior parietal cortex, lateral temporal cortex</p> Signup and view all the answers

    What issue was raised in the case study comparing heavy metal lovers and classical music lovers?

    <p>No behavioral measurements were taken alongside the fMRI data.</p> Signup and view all the answers

    What is the primary purpose of rTMS?

    <p>To induce electrical changes in the brain.</p> Signup and view all the answers

    What is assessed using the Forced-Swim Test?

    <p>Depression-like symptoms.</p> Signup and view all the answers

    Which behavioral test is utilized to study spatial learning in rats?

    <p>Morris Water Maze.</p> Signup and view all the answers

    What is a major benefit of using a within-subjects design in animal studies?

    <p>No separate control group needed.</p> Signup and view all the answers

    What type of lesion method allows for temporary inactivation of brain regions?

    <p>Reversible Lesions.</p> Signup and view all the answers

    Which injection method provides rapid entry of drugs into the bloodstream?

    <p>Intramuscular (IM).</p> Signup and view all the answers

    What is a major challenge of conducting intracellular unit recording?

    <p>Movement may dislodge the electrode from the cell.</p> Signup and view all the answers

    What is the primary benefit of optogenetics in neural research?

    <p>It allows precise control of neural activity using light.</p> Signup and view all the answers

    Which type of stain is best for visualizing individual neurons?

    <p>Golgi Stain.</p> Signup and view all the answers

    What type of brain imaging captures structural differences over time?

    <p>Static (Structural) Imaging.</p> Signup and view all the answers

    What is a significant limitation of chemical lesions?

    <p>Excess excitatory chemicals can damage neurons.</p> Signup and view all the answers

    Which of the following accurately describes a characteristic of the hippocampal disruption in rats?

    <p>Hippocampal damage leads to difficulty in finding platforms.</p> Signup and view all the answers

    What is used to bypass the blood-brain barrier in drug administration?

    <p>Intraventricular injection.</p> Signup and view all the answers

    What is the main advantage of using Computerized Axial Tomography (CAT/CT) over traditional X-rays?

    <p>Lower radiation risk</p> Signup and view all the answers

    Which imaging technique relies on the alignment and relaxation of hydrogen atoms?

    <p>Magnetic Resonance Imaging (MRI)</p> Signup and view all the answers

    What does Diffusion Tensor Imaging (DTI) primarily track in the brain?

    <p>Movement of water molecules</p> Signup and view all the answers

    Which technique measures brain activity by detecting changes in blood oxygen levels?

    <p>Functional MRI (fMRI)</p> Signup and view all the answers

    What is a significant limitation of Positron Emission Tomography (PET)?

    <p>Requires fresh radioactive tracers</p> Signup and view all the answers

    What does the BOLD response refer to in the context of Functional MRI?

    <p>Blood Oxygen Level Dependent response</p> Signup and view all the answers

    What is a common use of the technique known as resting-state functional connectivity MRI?

    <p>Identifying default brain network activity</p> Signup and view all the answers

    Which imaging technique has the highest risk associated with radiation exposure?

    <p>X-Ray</p> Signup and view all the answers

    In what way can Functional MRI (fMRI) be said to have a limitation compared to EEG methods?

    <p>Temporally slower than EEG methods</p> Signup and view all the answers

    Which of the following techniques is specifically designed to provide clear images of white matter bundles?

    <p>Diffusion Tensor Imaging (DTI)</p> Signup and view all the answers

    What method improves the image quality of CT scans?

    <p>Advanced image processing software</p> Signup and view all the answers

    What is one main reason why Positron Emission Tomography (PET) is considered expensive?

    <p>It uses a radioactive tracer</p> Signup and view all the answers

    Which imaging method has the lowest radiation risk?

    <p>Magnetic Resonance Imaging (MRI)</p> Signup and view all the answers

    What does the mechanism of X-ray imaging primarily rely on?

    <p>Tissue absorption of X-rays</p> Signup and view all the answers

    Study Notes

    Transcranial Magnetic Stimulation (TMS)

    • TMS is repeated transcranial magnetic stimulation
    • Uses magnetic fields to induce electrical changes in brain activity
    • Targets the cortex to briefly turn off a brain region
    • Used for therapeutic applications, like treating depression resistance

    Deep Thoughts by the Rat

    • Morris Water Maze:
      • Rats are placed in a pool of opaque water with a hidden platform
      • Rats swim randomly to locate the platform
      • Repeated trials decrease the time to find the platform
      • Swimming route becomes more direct
      • Visual markers (e.g., stars, trees) help spatial navigation
      • Hippocampal dependent
      • Rats with hippocampal damage have difficulty finding the platform
    • 5-Choice Serial Reaction Time Task:
      • Conducted in an operant chamber with 5 lighted holes
      • Rats must identify which hole lights up and poke their nose into the correct hole, for a sugar reward
      • Measures accuracy, implying attention
      • Avoid poking their heads into holes before the light fires (in order to avoid the 5 seconds timeout penalty)
      • Measures impulsivity, focusing on the lights
      • Success depends on focusing on lit holes.
      • Failure to wait for the light demonstrates impulsive behavior

    Drug Administration in Animal Models

    • Drugs can be administered acutely or chronically
    • Intramuscular (IM): Injection into shoulder muscle.
      • Advantages: Rapid entry to bloodstream
      • Disadvantages: Disrupts the muscle's pH causing soreness and pain
    • Intravenous (IV): Injection into a vein
      • Advantages: Used for self-administration studies
      • Disadvantages: Risk of the animal removing the catheter, or infection risk
    • Subcutaneous (SC): Injection just under the skin
      • Advantages: Minimal discomfort, good for injection
      • Disadvantages: Slower absorption rate
    • Intraperitoneal (IP): Injection into the abdominal cavity
      • Advantages: Quick absorption
      • Disadvantages: Slower absorption rate compared to IM
    • Intraventricular (IVT): Injection directly into the brain ventricles
      • Allows drugs to bypass blood-brain barrier

    Dose-Response Curve

    • Drugs typically exhibit a dose-response relationship
    • Example: Alcohol in small doses may stimulate, and in higher doses may be depressive

    Invasive Electrical Recording Methods

    • Intracellular Unit Recording: Records activity inside a single cell
      • Very difficult, especially in awake/behaving animals
      • Movement can dislodge the electrodes
    • Extracellular Unit Recording: Records activity outside a neuron
      • More common and reliable method
      • Electrodes are stable
    • Multiple-Unit Recording: Simultaneous recording from multiple neurons
      • Monitors activity from multiple neurons at once
    • Invasive EEG Recording: Places EEG electrodes near the brain
      • Used to study sleep in animal models
    • Stereotaxic Surgery: Used to access specific brain regions via lesions, optogenetics, or electrode implants.
      • Stereotaxic atlases pinpoint specific brain regions in millimeters
      • Bregma is used as a reference point on the skull

    Lesion Methods

    • Chemical Lesions: Using chemicals to target specific neuron types
      • Excitotoxic Lesions (e.g., quinolinic acid, ibotenic acid): Excess excitatory chemicals cause harmful neuron damage
      • Selective Chemical Lesions: Chemicals (e.g., 6-hydroxydopamine or 5,7-hydroxytryptamine) target specific neurotransmitters
    • Reversible Lesions: Temporary inactivation of brain regions
      • Injected drugs (e.g., baclofen + muscimol)
      • Allows for within-subjects design without permanent damage
    • Electrical Lesions: Using electric currents to affect neurons. Imprecise nature leads to unintended widespread damage, a drawback

    Optogenetics

    • Uses light-gated ion channels to precisely control or target neurons
    • Light exposure affects the protein shape for ion flow
    • Genetic model needed to introduce light-gated protein gene

    Stains

    • Nissl Stain/Cresyl Violet Stain: Visualizes neuron cell bodies
    • Fibre Stains (e.g., Luxol-fast blue, Toluidine blue): Visualizes white matter
    • Green Fluorescent Protein (GFP): Fluorescent protein from jellyfish allowing visualization inside neurons/cells
    • Brainbow Mouse: Modified GFP to visualize neurons in multiple colors

    Neuroimaging

    • Static (Structural Imaging): Captures a single point in time
      • Computerized Axial Tomography (CAT/CT): Multiple X-ray images create 3D image.
      • Strengths: Good for identifying tissue, low radiation risk
      • Limitations: Lower resolution compared to MRI, high radiation risk
    • Magnetic Resonance Imaging (MRI): Aligns hydrogen atoms in the brain using a magnetic field, then measures energy release as atoms return to alignment
    • Strengths: High quality 3D images, no radiation risk
    • Limitations: Requires extremely low temperatures to maintain the strong magnetic field
    • Diffusion Tensor Imaging (DTI): Tracks water movement within axons, focusing on white matter tracts, and helping differentiate across individuals
    • Strengths: Provides clear white matter images, helps identify white matter issues
    • Limitations: High radiation exposure and low detail compared to other modalities

    Dynamic (Functional Imaging)

    • Positron Emission Tomography (PET): Radioactive tracer is injected into the patient; brain activity measured by distribution and concentration.

    Paired Image Subtraction

    • Two sessions to isolate specific activity that happened during the second session.
    • Baseline activity is subtracted to isolate the activity of interest.
    • Averaging many trials to reveal consistent activity patterns

    fMRI

    • Functional Magnetic Resonance Imaging (fMRI): Measures brain activity by detecting changes in blood oxygen levels (BOLD signal). - Strengths: High spatial resolution, non-invasive.
    • Limitations: Slower time resolution than other methods.

    Functional Connectivity (rsfcMRI)

    • Used to measure functional connections between brain regions during rest
    • Starts with a Seed Region (e.g., medial prefrontal cortex) and compares its activity to other regions
    • Synchronized activity signifies functional connectivity

    Default Mode Network (DMN)

    • Active during rest and mind-wandering
    • Includes medial prefrontal cortex, posterior cingulate cortex, and lateral temporal cortex

    Case Study: Heavy Metal Brain

    • Compared functional connectivity in heavy metal lovers and classical music lovers
    • Found differences in brain activity but no direct link to behavior was established
    • The study had limitations, and the interpretation of results could have been biased

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    PSYC 304 Final Part 1 PDF

    Description

    Explore the fascinating world of Transcranial Magnetic Stimulation (TMS) and its therapeutic applications. Additionally, dive into the cognitive experiments involving rats, including the Morris Water Maze and the 5-Choice Serial Reaction Time Task, to understand their learning and navigation abilities.

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