MEG ger objektivt mätbara signaler av ljud i audiocortex

[JM]

Utvecklingen av MEG har nu nått en milstolpe där den neurofysiologiska responsen på ljudstimuli kan mätas direkt i audiocortex utan subjektiva psykologiska dubbelblindstudier. Temporala upplösningen ( < 1 ms) är mycket bättre än fMRI men samtidigt är den spatiala upplösningen sämre.

Kan sannolikt leda till helt nya mer objektiva utvärderingar av hörbart audioljud och hörselhandikapp.
Personligen var jag för ett antal år sedan perifert inblandad i en tidig MEG installation på Karolinska som inte var någon vetenskaplig hit.
Nature mars 2016
http://www.nature.com/ncomms/2016/16032 ... 11070.html
https://en.wikipedia.org/wiki/Magnetoencephalography

JM

[Amit]

Spännande. Undrar om man kan mäta fram tinnitus då? Bara en tanke.

[JM]

Spännande. Undrar om man kan mäta fram tinnitus då? Bara en tanke.

Tinnitus o andra defekter genererade i innerörat borde enligt studien bli mätbara.
Detta är en jungfrulig relativt begränsad studie så efterkommande studier kommer bli ännu intressantare.

JM

[Objektivisten]

Äntligen!

[JM]

Spännande. Undrar om man kan mäta fram tinnitus då? Bara en tanke.

Tinnitus hör nog till de lättare sakerna att detektera.
Om jag mins rätt är du i psykoterapisvängen. Har en del erfarenhet av forskning i området med några äldre PET-publikationer.
I princip kan fMRI, PET och ffa MEG i realtid ge info om tex psykoterapi har effekt eller ej. Ffa MEG men även fMRI kan på relativt okomplicerat sätt ge info om tex KBT lyckas bryta destruktiva tanke banor eller ej. FMRI med traktografi-diffusion före o efter terapi borde ge tydliga skillnader i flödet mellan relevanta områden i hjärnan om terapin lyckades.
Spännande!

JM

[Svante]

Vad är MEG?

[petersteindl]

Vad är MEG?

Magnetencefalografi is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers.

[JM]

Vad är MEG?

Fördelen med MEG är ffa den korta temporala upplösningen, att den registrerar synapsaktivtet och relativt EEG har en bättre spatial upplösning. Analyserna är inte lätta o felkällorna är många. För jämförelse är temporala upplösning för fMRI är vanligen minuter.

magenetoencephalography (MEG): non-invasive investigation of human brain activity at high temporal resolution

Magnetoencephalography (MEG) allows us to measure the ongoing brain activity with millisecond time resolution. Since the neuronal activity is detected by ~300 sensors distributed over the head, it is possible to identify where in the brain the activity is produced with reasonable accuracy. This makes MEG suited for studying the human brain as a network of interacting brain areas during performance of various tasks. The main applications of MEG are clinical investigations and cognitive neuroscience research.

MEG basics: Synaptic input to a neuron results in a small post-synaptic current that is associated with a very small magnetic field. When a sufficiently large population of neurons receives synaptic inputs within a short time-window, the dendritic currents will sum up, producing a field which is large enough to be detected outside the head. The neuromagnetic fields of the brain are typically in the order of 50-500 fT (10-15 Tesla), which is about 100 million times weaker than the earth's magnetic field. Magnetoencephalography (MEG) is a technique, which allows us to measure the magnetic fields produced by the brain.

MEG is based on SQUID technology. The superconducting quantum interference device (SQUID), which was introduced in the late 1960s, is a sensitive detector of magnetic flux. Today's whole-head MEG systems contain a large number of SQUIDs (between 100 to 300) connected to sensor coils in a configuration roughly following the curvature of the head. The technique is completely non-invasive. Since the environmental magnetic noise level due to traffic, elevators etc is several orders of magnitude higher than the neuromagnetic signals, the MEG system needs to be placed in a magnetic shielded room.

Since the magnetic field measured by MEG is produced directly by electrical neuronal activity, it is possible to detect signals from the brain on a sub-millisecond time scale. This makes MEG fundamentally different from imaging technologies like functional magnetic resonance imaging (fMRI), which measures blood flow changes occurring on a much slower time-scale. The activity measured by MEG may be the result of an evoked response, such as visual stimulation, or spontaneous oscillatory activity such as alpha rhythms.

When analyzing the data measured by a whole-head MEG system it is often possible to identify the brain areas generating the measures MEG signals (source localization). Magnetic fields are less distorted by tissues of different conductivity compared to the electric potentials measured with electroencephalography (EEG). Consequently, source localization can be obtained with simpler volume conduction models and may result in more accurate source models. In addition, MEG does not require a reference electrode that is needed for EEG recordings. Another important difference between MEG and EEG is that MEG is insensitive to current flows oriented perpendicularly to the scalp. Only the tangential component of a current flow will produce a measurable field. This in fact makes EEG and MEG complementary techniques, and MEG and EEG signals are often recorded simultaneously.
http://megcommunity.org/what-is-meg

JM

[JM]

Äntligen!

Nobellpris?

JM