Neuroscience Brain Lesion Techniques Quiz

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Questions and Answers

What is the primary outcome of experimental ablation?

Destruction of brain tissue without observation

Observation of enhanced behaviors

Integration of neural circuits

Evaluation of behavior post-brain damage (correct)

Which method involves using suction to draw off cortical tissue?

Radio frequency lesions

Knife cuts

Aspiration lesions (correct)

Excitotoxic lesions

What is a potential disadvantage of using excitotoxic lesions?

They are completely non-destructive.

They can affect axons that pass through the damaged region. (correct)

They do not allow for behavioral observation post-damage.

They exclusively destroy axons.

What distinguishes radio frequency lesions from aspiration lesions?

Radio frequency lesions involve passing electrical currents. Signup and view all the answers

Which statement accurately describes knife cuts in brain lesion techniques?

They require precise positioning for effective results. Signup and view all the answers

How do lesion studies infer the function of a brain area?

By observing behaviors lost after the area is damaged. Signup and view all the answers

What characteristic of excitotoxic lesions allows for behavioral determination of the damaged area?

They preserve intact neuron function. Signup and view all the answers

What is a potential source of behavioral deficits observed in studies involving RF and excitotoxic lesions?

Incidental damage caused by the insertion of the electrode/cannula Signup and view all the answers

What technique is used to insert an electrode or cannula into a specific brain location?

Stereotaxic surgery Signup and view all the answers

Which component of the stereotaxic apparatus ensures the animal's head remains in a standard position?

Head frame Signup and view all the answers

What does a stereotaxic atlas provide to researchers performing brain surgery?

Images of brain sections at various distances from the bregma Signup and view all the answers

How does saporin selectively affect neurons in targeted studies?

By killing neurons through antibody binding to specific proteins Signup and view all the answers

What is the primary function of muscimol in reversible brain lesion procedures?

To stimulate GABA receptors and inhibit neuronal activity Signup and view all the answers

What must be done to position the tip of a wire accurately in a brain structure during stereotaxic surgery?

Drill a hole above the targeted structure and lower the electrode to the correct depth Signup and view all the answers

What is a key limitation of the stereotaxic atlas used in brain surgery studies?

It may only give approximate locations that need verification due to variability Signup and view all the answers

Which procedure helps avoid complications associated with tissue damage in lesion studies?

Producing sham lesions during surgical procedures Signup and view all the answers

What primary aspect differentiates functional MRI (fMRI) from positron emission tomography (PET)?

fMRI indicates brain activity through blood oxygen levels. Signup and view all the answers

Which of the following is a limitation of using positron emission tomography (PET)?

PET requires the injection of radioactive materials. Signup and view all the answers

What does the BOLD signal in fMRI represent?

The blood oxygen level changes related to brain activity. Signup and view all the answers

Which of the following statements is true regarding the spatial and temporal resolutions of fMRI and PET?

fMRI has the highest spatial resolution compared to PET. Signup and view all the answers

What process occurs when the radioactive molecules of 2-DG decay in PET scanning?

They emit positrons that interact with electrons. Signup and view all the answers

What is a primary difference in how CT and MRI scan the head?

MRI uses a strong magnetic field while CT uses X-rays. Signup and view all the answers

How does blood appear in a CT scan compared to surrounding brain tissue?

Blood appears white because it absorbs more radiation. Signup and view all the answers

What phenomenon occurs when a person's head is placed in an MRI scanner's magnetic field?

Hydrogen atoms in the brain align with the magnetic field. Signup and view all the answers

What type of imaging technique allows visualization of small bundles of white matter fibers?

Diffusion tensor imaging (DTI) Signup and view all the answers

What is the role of the coil of wire in an MRI scanner?

To detect the energy released by hydrogen nuclei. Signup and view all the answers

What does MRI distinguish between in the brain's structure?

Gray matter and white matter. Signup and view all the answers

What is a primary limitation of structural MRI compared to DTI?

MRI cannot visualize small fiber bundles. Signup and view all the answers

What is the primary function of intracellular unit recording in neural activity analysis?

To measure changes in a neuron's membrane potential. Signup and view all the answers

What causes water molecules in white matter to move in a non-random direction in DTI?

The presence of nerve fibers aligned parallel to axons. Signup and view all the answers

Which imaging technique is primarily known for providing high-resolution images of the brain's structure?

MRI Signup and view all the answers

What happens to the metabolic rate of a brain region when its neural activity increases?

It increases due to higher energy demands. Signup and view all the answers

Which of the following statements about MEG is correct?

MEG has high temporal resolution but requires patients to remain still during recordings. Signup and view all the answers

What does the term 'signal averaging' refer to in EEG studies?

A technique to enhance the clarity of brain signals by reducing background noise. Signup and view all the answers

What is the function of radioactive 2-deoxyglucose (2-DG) when measuring brain activity?

It mimics glucose to indicate active brain regions without being metabolized. Signup and view all the answers

What is a significant disadvantage of MEG technology?

MEG machines are expensive and require large facilities. Signup and view all the answers

What primarily triggers the increase in metabolic activity in a brain region during neural activation?

The operation of ion channels requiring energy. Signup and view all the answers

What is the purpose of using SQUIDs in MEG recordings?

To enhance the spatial resolution of magnetic field detection. Signup and view all the answers

What is the primary reason that only the brain's surface magnetic signals can be recorded using scalp EEG?

Electrodes cannot penetrate through the skull effectively. Signup and view all the answers

What is the main outcome of autoradiography after injecting 2-DG into an animal's bloodstream?

Identification of the regions with the highest metabolic activity. Signup and view all the answers

What does the P300 wave signify in the context of brain response to stimuli?

A positive wave linked to meaningful stimuli processing. Signup and view all the answers

Study Notes

Experimental Ablation

Destroying part of the brain to assess subsequent behavior.
Lesion studies involve damaging a brain region and observing the resulting behavioral changes.
Inferring function from lost behaviors is possible.
Brain regions interact, so damage to one can impact others.

Producing Brain Lesions

Aspiration lesions: Suction through a glass pipette, removes cortical tissue without damaging underlying white matter.
Radiofrequency (RF) lesions: Insulated wire delivers high-frequency current, producing heat and killing cells in the surrounding area.
Knife cuts: Precisely cuts through the brain to eliminate conduction in nerve tracts.
Excitotoxic lesions: Injecting an excitatory amino acid, selectively killing neurons in a region, while leaving nearby axons intact.
Additional damage from electrode/cannula insertion is avoided by including a sham control group.
More selective methods target specific neuron types using saporin/antibodies.

Reversible Brain Lesions

Temporarily disrupting brain activity.
Methods include anesthetics, muscimol (GABA receptor agonist), and cooling.

Stereotaxic Surgery

Precisely placing electrodes or cannulas in the brain.
Stereotaxic apparatus holds animal's head still, allows controlled movement of devices.
Stereotaxic atlas provides coordinates for brain structures.
Accuracy is dependent on animal strain/age.

Visualizing the Structure of the Living Human Brain

X-Ray-based Techniques

Conventional x-rays: Pass x-rays through the body, visualize structures that absorb differently.
Contrast x-ray techniques: Using a contrasting substance to highlight specific structures.
Cerebral angiography: Injecting a radio-opaque dye in arteries for visualizing the circulatory system.
X-Ray techniques have limited use in the brain due to overlapping structures, however, contrast techniques can be used.

Computerized Tomography (CT)

Computer-assisted X-ray procedure.
Patient's head within a ring, producing X-ray images from multiple angles.
Computer reconstructs a 3D image, showing variations in tissue density (e.g., tumors, bleeding).

Magnetic Resonance Imaging (MRI)

More detailed brain images than CT, using a strong magnetic field.
Measures the signals emitted by hydrogen atoms in response to radio waves.
Distinguishes gray and white matter, showing major fiber bundles, but smaller ones not visible.

Diffusion Tensor Imaging (DTI)

Modification of MRI to visualize movement of water molecules in white matter fiber bundles.
Allows visualization of fiber tracts and the connectivity of brain regions.

Recording and Stimulating Neural Activity

Intracellular Unit Recording: Measures a neuron's membrane potential directly.
Single-unit (Extracellular) Recording: Records electrical activity from a neuron's surroundings. Uses microelectrodes.
Multiple-unit Recording: Recording activity from many neurons within a region. Uses macroelectrodes.
Electroencephalogram (EEG): Records electrical activity from many neurons on the scalp.
Event-related potentials (ERPs): EEG waves linked to specific events.
Invasive EEG: Recording via implanted electrodes.

Recording Brain's Activity

Positron Emission Tomography (PET): Detecting radioactive markers that accumulate in active brain regions, demonstrating metabolic activity.
Functional MRI (fMRI): Measuring brain activity based on blood oxygen levels, creating images of active regions in real-time.
Functional MRI, like PET, differentiates active and inactive brain regions, however, PET requires a radioactive substance to be injected.
Functional Ultrasound Imaging (fUS): Using ultrasound to measure changes in blood volume in brain regions.

Stimulating Neural Activity

Transcranial Magnetic Stimulation (TMS): Using magnetic pulses to stimulate specific brain regions non-invasively, allowing for insights on the link between brain activity and cognitive function.
Transcranial Electrical Stimulation (tES): Applying electrical current to stimulate brain activity.
Transcranial Ultrasound Stimulation (tUS): Using ultrasound waves to activate brain areas.
Optogenetics: A technique using light-sensitive proteins to control the activity of specific neurons in the brain or certain areas.

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Description

Test your knowledge on various brain lesion techniques, including experimental ablation, excitotoxic lesions, and stereotaxic methods. This quiz covers the methods and implications of these techniques in neuroscience research. Explore how these tools help in understanding brain function and behavior.