Computerized Tomography Overview

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Questions and Answers

What type of signal does Magnetoencephalography (MEG) primarily record?

Chemical signals in the brain

Optical signals from brain cells

Electrical activity of neurons

Magnetic activity related to brain function (correct)

What is a significant drawback of using Electroencephalogram (EEG) technology?

Inability to measure electrical activity in real-time

Poor spatial resolution of brain activity (correct)

Extensive training required for setup

High costs associated with the equipment

Which method allows for the measurement of single neuron activity?

Deep brain stimulation

EEG

Single cell recording (correct)

MEG

Which invention is associated with Hans Berger's work in 1924?

Electroencephalogram Signup and view all the answers

What is a notable disadvantage of Magnetoencephalography compared to EEG?

It cannot measure subcortical signals Signup and view all the answers

What does Deep Brain Stimulation primarily involve?

Permanent implant delivering electrical pulses Signup and view all the answers

Which technique uses light to change the function of neurons?

Optogenetics Signup and view all the answers

What was the primary focus of Wilder Penfield's research?

Localized brain function during surgery Signup and view all the answers

Who was instrumental in the development of the first high-resolution image of the living brain using CT technology?

Godfrey Hounsfield Signup and view all the answers

What is one key difference between Computerized Tomography (CT) and Positron Emission Tomography (PET)?

PET utilizes a gamma camera to detect radiation, while CT does not. Signup and view all the answers

Which imaging technology relies on the magnetic properties of hydrogen atoms?

MRI Signup and view all the answers

What does the term 'BOLD' in functional MRI stand for?

Blood Oxygenation Level Dependent Signup and view all the answers

Which technology is closely related to PET and is more affordable but offers lower resolution images?

SPECT Signup and view all the answers

What is a significant drawback of CT technology?

It cannot detect brain function or activity. Signup and view all the answers

In diffusion tensor imaging, what is primarily tracked?

Movement of water in fiber pathways Signup and view all the answers

What substance is commonly used in conjunction with a radiotracer in PET scanning to indicate active areas in the brain?

Glucose Signup and view all the answers

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.