Functional neuroimaging

Functional neuroimaging

Functional neuroimaging is the use of neuroimaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions. It is primarily used as a research tool in cognitive neuroscience, cognitive psychology and neuropsychology...

Overview

Common methods of functional neuroimaging include
* Positron emission tomography (PET),
* Functional magnetic resonance imaging (fMRI),
* multichannel electroencephalography (EEG),
* magnetoencephalography (MEG), and
* near infrared spectroscopic imaging (NIRSI). PET, fMRI and NIRSI can measure localized changes in cerebral blood flow related to neural activity. These changes are referred to as "activations". Regions of the brain which are activated when a subject performs a particular task may play a role in the neural computations which contribute to the behaviour. For instance, widespread activation of the occipital lobe is typically seen in tasks which involve visual stimulation (compared with tasks that do not). This part of the brain receives signals from the retina and is believed to play a role in visual perception.

Functional neuroimaging topics

The measure used in a particular study is generally related to the particular question being addressed. Measurement limitations vary amongst the techniques. For instance, MEG and EEG record the magnetic or electrical fluctuations that occur when a population of neurons is active. These methods are excellent for measuring the time-course of neural events (on the order of milliseconds,) but generally bad at measuring where those events happen. PET and fMRI measure changes in the composition of blood near a neural event. Because measurable blood changes are slow (on the order of seconds), these methods are much worse at measuring the time-course of neural events, but are generally better at measuring the location.

Traditional "activation studies" focus on determining distributed patterns of brain activity associated with specific tasks. However, scientists are able to more thoroughly understand brain function by studying the interaction of distinct brain regions, as a great deal of neural processing is performed by an integrated network of several regions of the brain. An active area of neuroimaging research involves examining the functional connectivity of spatially remote brain regions. Functional connectivity analyses allow the characterization of interregional neural interactions during particular cognitive or motor tasks or merely from spontaneous activity during rest. FMRI and PET enable creation of functional connectivity maps of distinct spatial distributions of temporally correlated brain regions called functional networks.

A direct method to measure functional connectivity is to observe how stimulation of one part of the brain will affect other areas. This can be done noninvasively in humans by combining transcranial magnetic stimulation with one of the neuroimaging tools such as PET, fMRI, or EEG. Massimini et al. ("Science", September 30, 2005) used EEG to record how activity spreads from the stimulated site. They reported that in non-REM sleep, although the brain responds vigorously to stimulation, functional connectivity is much attenuated from its level during wakefulness. Thus, during deep sleep, "brain areas do not talk to each other".

Functional neuroimaging draws on data from many areas other than cognitive neuroscience, including biological sciences (such as neuroanatomy and neurophysiology), physics and maths, to further develop and refine the technology.

Critique and careful interpretation

Functional neuroimaging studies have to be carefully designed and interpreted with care.Statistical analysis (often using a technique called statistical parametric mapping) is often needed so that the different sources of activation within the brain can be distinguished from one another.This can be particularly challenging when considering processes which are difficult to conceptualise or have no easily definable task associated with them (for example belief and consciousness).

Functional neuroimaging of interesting phenomena often gets cited in the press. In one case a group of prominent functional neuroimaging researchers felt compelled to write a letter to New York Times in response to an op-ed article about a study of so-called neuropolitics. [Marco Iacoboni et al. (2007). [http://www.nytimes.com/2007/11/11/opinion/11freedman.html "This Is Your Brain on Politics"] . In: "The New York Times" 11 November 2007.] They argued that the some of the intepretation of the study were "scientifically unfounded". [Chris Frith et al. (2007). [http://www.nytimes.com/2007/11/14/opinion/lweb14brain.html "Politics and the Brain"] . In: The New York Times, 14 November 2007.]

ee also

* Analysis of Functional NeuroImages
* EEG topography
* Electroencephalography
* Event related potential
* FMRIB Software Library
* FreeSurfer
* Magnetoencephalography
* Perfusion Scanning
* Single photon emission computed tomography
* Statistical Parametric Mapping

References

Further reading

* Roberto Cabeza and Alan Kingstone (eds.) (2006). "Handbook of Functional Neuroimaging of Cognition". MIT Press.
* Frank G. Hillary, John DeLuca (2007). "Functional Neuroimaging in Clinical Populations".
* Nancy Kanwisher, John Duncan (2004). "Functional Neuroimaging of Visual Cognition".
* Roger E. Kelley (1994). "Functional Neuroimaging".
* David Silbersweig and Emily Stern (2001). "Functional Neuroimaging and Neuropsychology Fundamentals and Practice".
* Robert W. Thatcher (1994). "Functional Neuroimaging: Technical Foundations."

External links

* [http://www.med.harvard.edu/AANLIB/home.html The Whole Brain Atlas @ Harvard]
* [http://www.asnweb.org/ The American Society of Neuroimaging (ASN)] .
* [http://www.brainmapping.org/NITP UCLA Neuroimaging Training Program] .
* [http://www.brainmapping.org/ BrainMapping.org, "a free BrainMapping community information portal"]


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Functional magnetic resonance imaging — Functional MRI or functional Magnetic Resonance Imaging (fMRI) is a type of specialized MRI scan. It measures the haemodynamic response related to neural activity in the brain or spinal cord of humans or other animals. It is one of the most… …   Wikipedia

  • Neuroimaging — Para sagittal MRI of the head in a patient with benign familial macrocephaly. 3 D MRI o …   Wikipedia

  • Neuroimaging —    The radiological imaging of the brain is important because it occasionally permits the linking of psychiatric symptoms to underlying brain lesions. Neuroradiology: plain film studies of the skull and spine (from 1896). This story begins with… …   Historical dictionary of Psychiatry

  • Functional specialization (brain) — This article is about specialization of function among regions of the brain generally. For the particular topic of left right brain specialization, see Lateralization of brain function. Functional specialization suggests that different areas in… …   Wikipedia

  • functional magnetic resonance imaging — ▪ medicine       neuroimaging technique used in biomedical research and in diagnosis that detects changes in blood flow in the brain. This technique compares brain activity under resting and activated conditions. It combines the high spatial… …   Universalium

  • List of neuroimaging software — Neuroimaging software is used to study the structure and function of the brain. To see an NIH Blueprint for Neuroscience Research funded clearinghouse of many of these software applications, as well as hardware, etc. go to the NITRC web site. 3D… …   Wikipedia

  • History of neuroimaging — The history of neuroimaging, began in the early 1900s with a technique called pneumoencephalography. This process involved draining the cerebrospinal fluid from around the brain and replacing it with air, altering the relative density of the… …   Wikipedia

  • Wellcome Trust Centre for Neuroimaging — The Wellcome Trust Centre for Neuroimaging at University College London (incorporating the Leopold Muller Functional Imaging Laboratory and the Wellcome Department of Imaging Neuroscience) is an interdisciplinary centre for neuroimaging… …   Wikipedia

  • Analysis of Functional NeuroImages — Infobox Software name = AFNI caption = AFNI displaying a statistical parametric map generated from a finger tapping FMRI experiment. operating system = Cross platform [http://afni.nimh.nih.gov/afni/download/afni/releases/latest (list)] author =… …   Wikipedia

  • Educational neuroscience — (also called Mind Brain and Education; MBE) is an emerging scientific field that brings together researchers in cognitive neuroscience, developmental cognitive neuroscience, educational psychology, educational technology, education theory and… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”