Extra hjärnavbildning + hjärnstimulering Flashcards
Vad är DBS och vad används det för?
Deep brain stimulation: Placing an electrode near a neuron and passing an electrical current through it produces an action potential in that neuron. Today, electrodes are surgically implanted for DBS stimulation beneath the surface of the cortex.
Forskningsanvändning: The region’s function can be inferred from any resulting behavior.
Klinisk användning: DBS is a routine procedure used in treating psychiatric, neurological and psychological conditions. Used to treat depression and OCD when other treatments have failed. Can also treat epilepsy by coopting the processes of neurons involved in abnormal activity, thereby preventing discharges. Parkinsons is characterized both by tremors and by akinesia. When DBS electrodes are implanted in the brain in a number of regions in the basal ganglia, including the globus pallidus or subthalamic nucleus, both tremors and akinesia are lessened by electrical stimulation. Reviews of DBS for parkinsons show that the treatment improves movement, cognition and mood as well.
Vad är TMS och vad används det till?
Transcranial magnetic stimulation: noninvasive method that allows brain stimulation through the skull. A small wire coil in a figure-8 shape is placed adjacent to the skull. High-voltage current is passed through the coil. Each electrical pulse produces a rapid increase and then decrease in the magnetic field around the coil. The magnetic field penetrates the skull and changes the electrical activity of adjacent neurons. Does not harm brain tissue.
Forskningsanvändning: To map the brain’s function areas, TMS researchers move the stimulation and note the results, identifying and mapping cortical functions.
Klinisk användning: For example to treat pain, stroke-induced impairments, movement disorders and depressions.
Vad är rTMS och vad används det till?
rTMS(repetitive transcranial magnetic stimulation): repetitive pulses can inactivate an area of brain tissue for a short time, allowing TMS researchers to make a temporary virtual lesion in the brain and study its consequences.
Vad är (ECoG)?
Electrocorticography: Procedure for intracranial EEG recordings during surgery. Electrodes are placed directly onto the brain surface. More direct way of identifying the source of the seizure because electrodes are closer to the generators of electrical activity and also because the meninges and skull reduce the amplitude of brain signals.
Single cell recording
records action potential. In single-cell recording, an electrode is inserted directly into the brain, adjacent to or into a single neuron, to record the neuron’s electrical activity on a computer
Experiments with various animal species can reveal remarkable insights into what single neurons are up to. Although peripheral nervous system cells are accessible for recording, only a few select situations, such as brain surgery, permit researchers such direct access to the central nervous system in a living human brain. Today, miniaturization, computerization, and arrays of hundreds of electrodes allow recording from as many as 2000 individual neurons simultaneously
Vad är MRS och vad kan det användas till?
Typ en “variant” av MRI typ där man kan använda MRI-utrustning med lite extra hårdvara och mjukvara.
MRI depicts differences in water density. The hydrogen nuclei in water molecules affected by MRI constitute 80% of the brains soft tissue. MRI does not image the remaining 20%, including all macromolecules(DNA, RNA, most proteins etc), cell membranes, organelles(like mitochondria), glial cells. Magnetic resonance spectroscopy: a method that varies the radiofrequency used for aligning hydrogen protons to allow imaging of the concentrations of the remaining brain material. For example, MRS can detect N-acetyl aspartate(NAA), a brain metabolite found in neurons and glia cells, and creatine, an acid that helps supply cells with energy and is present in much higher concentrations in neurons than glia. Thus MRS can distinguish brain cells from other substances and neurons from glia. MRS can detect brain-cell loss in degenerative disorders such as alzheimers, loss of myelin in demyelinating disorders(like MS), and persisting abnormalities in brain metabolism in disorders such as concussion. MS can also image molecules that participate in transmitting information between neurons.
Pneumoencephalography
method for enhancing conventional X-ray radiography by taking advantage of the fact that x-rays are not absorbed by air. A small amount of CSF is removed from the subarachnoid space in the spinal cord and replaced with air. X-rays are taken as the air moves up the spinal cord and enters the ventricular system. Because of the air the ventricles stand out clearly in the resulting image. Has diagnostic value because expanded ventricles han mean loss of brain tissue and constricted ventricles can indicate tumors - but it’s painful and invasive so it has been largely replaced by MRI.
Angiography
method for imaging blood vessels. Substance that absorbs X-rays is injected into the bloodstream. Produces image of the blood vessels, revealing any circulatory abnormalities that might affect blood flow, including dilation, constriction och abnormalities in blood vessels. Dangerous and painful so nowadays other methods are used instead.
