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Questions and Answers
What type of signal does Magnetoencephalography (MEG) primarily record?
What is a significant drawback of using Electroencephalogram (EEG) technology?
Which method allows for the measurement of single neuron activity?
Which invention is associated with Hans Berger's work in 1924?
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What is a notable disadvantage of Magnetoencephalography compared to EEG?
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What does Deep Brain Stimulation primarily involve?
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Which technique uses light to change the function of neurons?
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What was the primary focus of Wilder Penfield's research?
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Who was instrumental in the development of the first high-resolution image of the living brain using CT technology?
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What is one key difference between Computerized Tomography (CT) and Positron Emission Tomography (PET)?
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Which imaging technology relies on the magnetic properties of hydrogen atoms?
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What does the term 'BOLD' in functional MRI stand for?
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Which technology is closely related to PET and is more affordable but offers lower resolution images?
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What is a significant drawback of CT technology?
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In diffusion tensor imaging, what is primarily tracked?
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What substance is commonly used in conjunction with a radiotracer in PET scanning to indicate active areas in the brain?
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Study Notes
Computerized Tomography (CT)
- Combines the terms “tomos” (slice) and “grapha” (write/describing).
- Utilizes X-ray technology for imaging.
- First high-resolution living brain image created by Godfrey Hounsfield in 1971.
- Builds on previous work by William Oldendorf and Allan Cormack.
- Modern CT scans generate 3D structural images in minutes, significantly faster than earlier methods.
- Drawbacks include exposure to radiation and inability to capture brain activity (thoughts, feelings, behaviors).
Positron Emission Tomography (PET)
- Developed in the mid-1970s by Phelps and Hoffman for brain function research.
- Employs a gamma camera to detect radiation emitted by radioactive atoms.
- Involves a radiotracer that decays and releases positrons, interacting with body electrons to emit photons.
- Radiotracers coupled with substances (like glucose) target active brain areas, allowing imaging of brain activity through differential decay rates.
- Capable of producing multiple slices for 3D imaging.
- Can provide insight into specific neurochemicals and receptor binding.
Single Photon Emission Computed Tomography (SPECT)
- Similar to PET, but offers lower resolution and is more affordable.
- Drawbacks include radiation exposure and lack of structural detail.
Magnetic Resonance Imaging (MRI)
- Utilizes strong magnetic fields and radio waves to generate detailed body images.
- Notable for being very loud and cold during scans.
- First whole-body MRI image produced in 1977 by Damadian, Minkoff, and Goldsmith.
- Leverages hydrogen atom magnetic properties and relaxation processes for imaging.
- Provides high structural resolution due to varying hydrogen concentrations in different tissue types (e.g., gray matter protein, white matter fat, CSF salt water).
- Functional MRI relies on blood oxygenation levels for brain activity representation.
- Diffusion tensor imaging tracks water movement in white matter fiber pathways.
- Drawbacks include claustrophobia, specific contraindications (e.g., tattoos, metal implants), and longer scan duration.
Electroencephalogram (EEG)
- Measures electrical brain activity through scalp electrodes.
- Excellent temporal resolution; developed by Hans Berger in 1924.
- Useful for monitoring wakefulness, sleep, anesthesia, and epilepsy.
- Event-related potentials (ERPs) provide insights into responses to specific events.
- Drawbacks include gel application in hair and poor spatial resolution.
Magnetoencephalography (MEG)
- Captures the brain’s magnetic activity from active neurons producing tiny magnetic fields.
- Developed by Cohen in 1972, measurements occur in a magnetically shielded room using SQUID technology.
- Magnetism is unaffected by skull/bone tissue, leading to better spatial resolution compared to EEG.
- Advantages include a quieter environment than MRI and wearable technology.
- Main drawback is the lack of structural imaging.
Single Cell Recording
- Measures activity from individual neurons using microelectrodes.
- Capable of monitoring freely moving animals or human subjects, particularly in epilepsy research.
Brain Stimulation Techniques
- Direct electrical stimulation under local anesthesia helps localize brain function during surgeries.
- Wilder Penfield contributed to understanding cortical function through the cortical homunculus.
- Deep brain stimulation is a long-lasting implant treatment for conditions like Parkinson's and treatment-resistant depression.
- Repeated Transcranial Magnetic Stimulation (rTMS) applies magnetic pulses to alter brain activity momentarily.
Optogenetics
- Involves genetic (viral) modification of neurons for precise functional control through light stimulation.
Lesion Studies
- Investigate the impact of tissue damage (lesions) on brain function.
- Lesions may be natural or artificially induced; methods include surgical ablation, neurotoxins, and cooling.
- Provides insights into the localization of functions within the brain.
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Description
Explore the fundamentals of Computerized Tomography (CT), a pivotal advancement in medical imaging technology. Learn about its historical development, key figures like Godfrey Hounsfield, and the benefits and drawbacks of this X-ray-based technique, including safety concerns regarding radiation exposure.
