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N200 (neuroscience)
The N200, or N2, is an event-related potential (ERP) component. An ERP can be monitored using a non-invasive electroencephalography (EEG) cap that is fitted over the scalp on human subjects. An EEG cap allows researchers and clinicians to monitor the minute electrical activity that reaches the surface of the scalp from post-synaptic potentials in neurons, which fluctuate in relation to cognitive processing. EEG provides millisecond-level temporal resolution and is therefore known as one of the most direct measures of covert mental operations in the brain. The N200 in particular is a negative-going wave that peaks 200-350ms post-stimulus and is found primarily over anterior scalp sites. Past research focused on the N200 as a mismatch detector, but it has also been found to reflect executive cognitive control functions, and has recently been used in the study of language (Folstein & Van Petten, 2008; Schmitt, Münte, & Kutas, 2000). History The N2 component starts with the discove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event-related Potential
An event-related potential (ERP) is the measured brain response that is the direct result of a specific sense, sensory, cognition, cognitive, or motor system, motor event. More formally, it is any stereotyped electrophysiology, electrophysiological response to a stimulus. The study of the brain in this way provides a Invasiveness of surgical procedures, noninvasive means of evaluating brain functioning. ERPs are measured by means of electroencephalography (EEG). The magnetoencephalography (MEG) equivalent of ERP is the ERF, or event-related field. Evoked potentials and induced potentials are subtypes of ERPs. History With the discovery of the electroencephalogram (EEG) in 1924, Hans Berger revealed that one could measure the electrical activity of the human brain by placing electrodes on the scalp and amplifying the signal. Changes in voltage can then be plotted over a period of time. He observed that the voltages could be influenced by external events that stimulated the sens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Left Anterior Negativity
The early left anterior negativity (commonly referred to as ELAN) is an event-related potential in electroencephalography (EEG), or component of brain activity that occurs in response to a certain kind of stimulus. It is characterized by a negative-going wave that peaks around 200 milliseconds or less after the onset of a stimulus, and most often occurs in response to linguistic stimuli that violate word-category or phrase structure rules (as in *''the in room'' instead of ''in the room''). As such, it is frequently a topic of study in neurolinguistics experiments, specifically in areas such as sentence processing. While it is frequently used in language research, there is no evidence yet that it is necessarily a language-specific phenomenon. More recent work has criticized the design of many of the foundational studies that characterized the ELAN, such that apparent ELAN effects might be the result of spillover from words prior to the onset of the critical word. This raises impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somatosensory Evoked Potential
Somatosensory evoked potential (SEP or SSEP) is the electrical activity of the brain that results from the stimulation of touch. SEP tests measure that activity and are a useful, noninvasive means of assessing somatosensory system functioning. By combining SEP recordings at different levels of the somatosensory pathways, it is possible to assess the transmission of the afferent volley from the periphery up to the cortex. SEP components include a series of positive and negative deflections that can be elicited by virtually any sensory stimuli. For example, SEPs can be obtained in response to a brief mechanical impact on the fingertip or to air puffs. However, SEPs are most commonly elicited by bipolar transcutaneous electrical stimulation applied on the skin over the trajectory of peripheral nerves of the upper limb (e.g., the median nerve) or lower limb (e.g., the posterior tibial nerve), and then recorded from the scalp. In general, somatosensory stimuli evoke early cortical compone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P600 (neuroscience)
The P600 is an event-related potential (ERP) component, or peak in electrical brain activity measured by electroencephalography (EEG). It is a language-relevant ERP component and is thought to be elicited by hearing or reading grammatical errors and other syntactic anomalies. Therefore, it is a common topic of study in neurolinguistic experiments investigating sentence processing in the human brain. The P600 can be elicited in both visual (reading) and auditory (listening) experiments, and is characterized as a positive-going deflection with an onset around 500 milliseconds after the stimulus that elicits it; it often reaches its peak around 600 milliseconds after presentation of the stimulus (hence its name), and lasts several hundred milliseconds.Different authors give slightly different time periods for the P600; for example, claim it may start as early as 400 milliseconds, and describes it as occurring "between 600–1000 ms. In other words, in the EEG waveform it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P200
In neuroscience, the visual P200 or P2 is a waveform component or feature of the event-related potential (ERP) measured at the human scalp. Like other potential changes measurable from the scalp, this effect is believed to reflect the post-synaptic activity of a specific neural process. The P2 component, also known as the P200, is so named because it is a positive going electrical potential that peaks at about 200 milliseconds (varying between about 150 and 275 ms) after the onset of some external stimulus. This component is often distributed around the centro-frontal and the parieto-occipital areas of the scalp. It is generally found to be maximal around the vertex (frontal region) of the scalp, however there have been some topographical differences noted in ERP studies of the P2 in different experimental conditions. Research on the visual P2 is at an early stage compared to other more established ERP components and there is much that we still do not know about it. Part of the dif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N400 (neuroscience)
The N400 is a component of time-locked EEG signals known as event-related potentials (ERP). It is a negative-going deflection that peaks around 400 milliseconds post-stimulus onset, although it can extend from 250-500 ms, and is typically maximal over centro-parietal electrode sites. The N400 is part of the normal brain response to words and other meaningful (or potentially meaningful) stimuli, including visual and auditory words, sign language signs, pictures, faces, environmental sounds, and smells. History The N400 was first discovered by Marta Kutas and Steven Hillyard in 1980. They conducted the first experiment looking at the response to unexpected words in read sentences, expecting to elicit a P300 component. The P300 had previously been shown to be elicited by unexpected stimuli. Kutas and Hillyard therefore used sentences with anomalous endings (i.e.''I take coffee with cream and dog''), expecting to see a P300 to the unexpected sentence-final words. However, instead of el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N170
The N170 is a component of the event-related potential (ERP) that reflects the neural processing of faces, familiar objects or words. Furthermore, the N170 is modulated by prediction error processes. When potentials evoked by images of faces are compared to those elicited by other visual stimuli, the former show increased negativity 130-200 ms after stimulus presentation. This response is maximal over occipito-temporal electrode sites, which is consistent with a source located at the fusiform and inferior-temporal gyri, confirmed by electrocorticography. The N170 generally displays right-hemisphere lateralization and has been linked with the structural encoding of faces, hence is considered to be primarily sensitive to faces. A study, employing transcranial magnetic stimulation combined with EEG, found that N170 can be modulated by top-down influences from prefrontal cortex. History The N170 was first described by Shlomo Bentin and colleagues in 1996, who measured ERPs from parti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N100 (neuroscience)
In neuroscience, the N100 or N1 is a large, negative-going evoked potential measured by electroencephalography (its equivalent in magnetoencephalography is the M100); it peaks in adults between 80 and 120 milliseconds after the onset of a stimulus, and is distributed mostly over the fronto-central region of the scalp. It is elicited by any unpredictable stimulus in the absence of task demands. It is often referred to with the following P200 evoked potential as the "N100-P200" or "N1-P2" complex. While most research focuses on auditory stimuli, the N100 also occurs for visual (see visual N1, including an illustration), olfactory, heat, pain, balance, respiration blocking, and somatosensory stimuli. The auditory N100 is generated by a network of neural populations in the primary and association auditory cortices in the superior temporal gyrus in Heschl's gyrus and planum temporale. It also could be generated in the frontal and motor areas. The area generating it is larger in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N2pc
N2pc refers to an ERP component linked to selective attention.Luck, S. J. (2005). "The operation of attention—millisecond by millisecond—over the first half second." In H. Ogmen & B. G. Breitmeyer (Eds.), ''The first half second: The microgenesis and temporal dynamics of unconscious and conscious visual processes.'' Cambridge, MA: MIT Press The N2pc appears over visual cortex contralateral to the location in space to which subjects are attending; if subjects pay attention to the left side of the visual field, the N2pc appears in the right hemisphere of the brain, and vice versa. This characteristic makes it a useful tool for directly measuring the general direction of a person's attention (either left or right) with fine-grained temporal resolution. History Luck and Hillyard (1990) first observed the N2pc while seeking to document electrophysiological correlates of focused attention during visual search using ERPs. Subjects viewed arrays containing 4-12 items, one of which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateralized Readiness Potential
In neuroscience, the lateralized readiness potential (LRP) is an event-related brain potential, or increase in electrical activity at the surface of the brain, that is thought to reflect the preparation of motor activity on a certain side of the body; in other words, it is a spike in the electrical activity of the brain that happens when a person gets ready to move one arm, leg, or foot. It is a special form of bereitschaftspotential (a general pre-motor potential). LRPs are recorded using electroencephalography (EEG) and have numerous applications in cognitive neuroscience. History Kornhuber and Deecke's discovery of the Bereitschaftspotential (German for readiness potential) led to research on the now extensively used LRP, which has often been investigated in the context of the mental chronometry paradigm.Coles, M. G. H., 1988. Modern Mind-brain Reading: Psychophysiology, Physiology, and Cognition. 26, 251–269. In the basic chronometric paradigm, the subject experiences a war ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Positive Component
The late positive component or late positive complex (LPC) is a positive-going event-related brain potential (ERP) component that has been important in studies of explicit recognition memory.Munte, T. F., Urbach, T. P., Duzel, E., & Kutas, M., (2000). Event-related brain potentials in the study of human cognition and neuropsychology, In: F. Boller, J. Grafman, and G. Rizzolatti (Eds.) Handbook of Neuropsychology, Vol. 1, 2nd edition, Elsevier Science Publishers B.V., 97. It is generally found to be largest over parietal scalp sites (relative to reference electrodes placed on the mastoid processes), beginning around 400–500 ms after the onset of a stimulus and lasting for a few hundred milliseconds. It is an important part of the ERP "old/new" effect, which may also include modulations of an earlier component similar to an N400. Similar positivities have sometimes been referred to as the P3b, P300, and P600.Finnigan, S., Humphreys, M.S., Dennis, S., Geffen, G. (2002). ERP 'old ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
