Functional neuroimaging is the use of neuroimaging Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/pharmacology of the brain. It is a relatively new discipline within medicine and neuroscience/psychology technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all. In vertebrates, the brain is located in the head, protected by the skull and close to the primary areas and specific mental functions. It is primarily used as a research tool in cognitive neuroscience Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain. Cognitive neuroscience is a branch of both psychology and, cognitive psychology Cognitive psychology is a discipline within psychology that investigates the internal mental processes of thought such as visual processing, memory, thinking, learning, feeling, problem solving, and language, neuropsychology Neuropsychology is the basic scientific discipline that studies the structure and function of the brain related to specific psychological processes and overt behaviors. The term neuropsychology has been applied to lesion studies in humans and animals. It has also been applied to efforts to record electrical activity from individual cells in higher, and social neuroscience Social neuroscience is an interdisciplinary field devoted to understanding how biological systems implement social processes and behavior, and to using biological concepts and methods to inform and refine theories of social processes and behavior. Humans are fundamentally a social species, rather than individualists. As a social species, Homo.

Contents

Overview

Common methods of functional neuroimaging include

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 Computational neuroscience is the study of brain function in terms of the information processing properties of the structures that make up the nervous system. It is an interdisciplinary science that links the diverse fields of neuroscience, cognitive science and psychology with electrical engineering, computer science, mathematics and physics which contribute to the behaviour. For instance, widespread activation of the occipital lobe The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1 . Human V1 is located on the medial side of the occipital lobe within the calcarine sulcus; the full extent of V1 often continues onto the is typically seen in tasks which involve visual The visual system is the part of the central nervous system which enables organisms to see, as well as enabling several non-image forming photoresponse functions. It interprets information from visible light to build a representation of the surrounding world. The visual system accomplishes a number of complex tasks, including the reception of stimulation (compared with tasks that do not). This part of the brain receives signals from the retina The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These and is believed to play a role in visual perception Visual perception is the ability to interpret information and surroundings from visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision . The various physiological components involved in vision are referred to collectively as the visual system, and are the focus of much research in psychology, cognitive.

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 Transcranial magnetic stimulation is a noninvasive method to excite the elementary unit of the nervous system; neurons in the brain: weak electric currents are induced in the tissue by rapidly changing magnetic fields (electromagnetic induction). This way, brain activity can be triggered with minimal discomfort, and the functionality of the 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 The sleep stages 1 through 3, previously known as stages 1 through 4, are collectively referred to as NREM, non-rapid eye movement, sleep. Rapid eye movement is not included. There are distinct electroencephalographic and other characteristics seen in each stage. Unlike REM sleep, there is usually little or no eye movement during this stage, 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 Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain. Cognitive neuroscience is a branch of both psychology and and social neuroscience Social neuroscience is an interdisciplinary field devoted to understanding how biological systems implement social processes and behavior, and to using biological concepts and methods to inform and refine theories of social processes and behavior. Humans are fundamentally a social species, rather than individualists. As a social species, Homo, including biological sciences (such as neuroanatomy Neuroanatomy is the study of the anatomy of nervous tissue and neural structures of the nervous system. In vertebrates the routes that the myriad nerves take from the brain to the rest of the body , and the internal structure of the brain in particular, are both extremely elaborate. As a result, the study of neuroanatomy has developed into a and neurophysiology Neurophysiology is a part of physiology. Neurophysiology is the study of nervous system function. Primarily, it is connected with neurobiology, psychology, neurology, clinical neurophysiology, electrophysiology, biophysical neurophysiology, ethology, neuroanatomy, cognitive science and other brain sciences), physics Physics is a natural science that involves the study of matter and its motion through space-time, as well as all applicable concepts, such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves and maths Mathematics is the study of quantity, structure, space, and change. Mathematicians seek out patterns, formulate new conjectures, and establish truth by rigorous deduction from appropriately chosen axioms and definitions, 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 Belief is the psychological state in which an individual holds a proposition or premise to be true and consciousness Consciousness is variously defined as subjective experience, or awareness, or wakefulness, or the executive control system of the mind. It is an umbrella term that may refer to a variety of mental phenomena. Although humans realize what everyday experiences are, consciousness refuses to be defined, philosophers note :).

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 The New York Times is an American daily newspaper founded and continuously published in New York City since 1851. Although it remains both the largest local metropolitan newspaper in the United States as well as being third largest overall, behind The Wall Street Journal and USA Today, the weekday circulation of the paper has fallen precipitously in response to an op-ed An op-ed, abbreviated from opposite the editorial page , is a newspaper article that expresses the opinions of a named writer who is usually unaffiliated with the newspaper's editorial board. These are different from editorials, which are usually unsigned and written by editorial board members article about a study of so-called neuropolitics.[1]

They argued that some of the interpretations of the study were "scientifically unfounded".[2]

See also

References

  1. ^ Marco Iacoboni et al. (2007). "This Is Your Brain on Politics". In: The New York Times 11 November 2007.
  2. ^ Chris Frith et al. (2007). "Politics and the Brain". In: The New York Times, 14 November 2007.

Further reading

External links

Categories: Neuroimaging Neuroimaging is a means through which the structure, function, or pharmacology of the brain is visualized | Cognitive neuroscience

 

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