View source for N100

{{short description|Evoked potential in the brain}}
{{for|the air filtration rating|NIOSH air filtration rating#NIOSH classifications}}
{{other uses}}
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 (physiology)|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 [[Sound|auditory]] stimuli, the N100 also occurs for [[visual]] (see [[visual N1]], including an illustration),<ref>{{Cite journal 
| last1 = Warnke | first1 = A. 
| last2 = Remschmidt | first2 = H. 
| last3 = Hennighausen | first3 = K. 
| title = Verbal information processing in dyslexia--data from a follow-up experiment of neuro-psychological aspects and EEG 
| journal = Acta Paedopsychiatrica 
| volume = 56 
| issue = 3 
| pages = 203–208 
| year = 1994 
| pmid = 7521558
}}</ref> [[olfactory]],<ref>{{Cite journal 
| last1 = Pause | first1 = B. M. 
| last2 = Sojka | first2 = B. 
| last3 = Krauel | first3 = K. 
| last4 = Ferstl | first4 = R. 
| title = The nature of the late positive complex within the olfactory event-related potential (OERP) 
| journal = Psychophysiology 
| volume = 33 
| issue = 4 
| pages = 376–384 
| year = 1996 
| pmid = 8753937 | doi=10.1111/j.1469-8986.1996.tb01062.x
}}</ref> [[Thermoception|heat]],<ref name="Greffrath">{{Cite journal 
| last1 = Greffrath | first1 = W. 
| last2 = Baumgärtner | first2 = U. 
| last3 = Treede | first3 = R. D. 
| doi = 10.1016/j.pain.2007.04.026 
| title = Peripheral and central components of habituation of heat pain perception and evoked potentials in humans 
| journal = Pain 
| volume = 132 
| issue = 3 
| pages = 301–311 
| year = 2007 
| pmid = 17533117 
| pmc = 
| s2cid = 29266108 
}}</ref> [[pain]],<ref name="Greffrath"/> [[Senses#Balance and acceleration|balance]],<ref>{{Cite journal 
| last1 = Quant | first1 = S. 
| last2 = Maki | first2 = B. E. 
| last3 = McIlroy | first3 = W. E. 
| doi = 10.1016/j.neulet.2005.02.015 
| title = The association between later cortical potentials and later phases of postural reactions evoked by perturbations to upright stance 
| journal = Neuroscience Letters 
| volume = 381 
| issue = 3 
| pages = 269–274 
| year = 2005 
| pmid = 15896482 
| pmc = 
| s2cid = 24770418 
}}</ref> [[pulmonary stretch receptors|respiration blocking]],<ref>{{Cite journal 
| last1 = Chan | first1 = P. -Y. S. 
| last2 = Davenport | first2 = P. W. 
| doi = 10.1152/japplphysiol.90722.2008 
| title = Respiratory-related evoked potential measures of respiratory sensory gating 
| journal = Journal of Applied Physiology 
| volume = 105 
| issue = 4 
| pages = 1106–1113 
| year = 2008 
| pmid = 18719232 
| pmc = 4347743
}}</ref> and [[Touch|somatosensory]] stimuli.<ref name="wang">{{Cite journal 
| last1 = Wang | first1 = A. L. 
| last2 = Mouraux | first2 = A. 
| last3 = Liang | first3 = M. 
| last4 = Iannetti | first4 = G. D. 
| editor1-last = Lauwereyns 
| editor1-first = Jan 
| title = The Enhancement of the N1 Wave Elicited by Sensory Stimuli Presented at Very Short Inter-Stimulus Intervals is a General Feature across Sensory Systems 
| doi = 10.1371/journal.pone.0003929 
| journal = PLOS ONE 
| volume = 3 
| issue = 12 
| pages = e3929 
| year = 2008 
| pmid = 19081790 
| pmc =2597742 
| bibcode = 2008PLoSO...3.3929W 
| doi-access = free 
}}</ref>

The auditory N100 is generated by a network of [[neural population]]s in the [[primary auditory cortex|primary]] and association auditory cortices in the [[superior temporal gyrus]] in [[Heschl's gyrus]]<ref name="Zouridakis ">{{Cite journal 
| last1 = Zouridakis | first1 = G. 
| last2 = Simos | first2 = P. G. 
| last3 = Papanicolaou | first3 = A. C. 
| title = Multiple bilaterally asymmetric cortical sources account for the auditory N1m component 
| journal = Brain Topography 
| volume = 10 
| issue = 3 
| pages = 183–189 
| year = 1998 
| pmid = 9562539
| doi = 10.1023/A:1022246825461 
| s2cid = 1743975 
}}</ref> and [[planum temporale]].<ref>{{Cite journal 
| last1 = Godey | first1 = B. 
| last2 = Schwartz | first2 = D. 
| last3 = De Graaf | first3 = J. B. 
| last4 = Chauvel | first4 = P. 
| last5 = Liégeois-Chauvel | first5 = C. 
| title = Neuromagnetic source localization of auditory evoked fields and intracerebral evoked potentials: A comparison of data in the same patients 
| journal = Clinical Neurophysiology 
| volume = 112 
| issue = 10 
| pages = 1850–1859 
| year = 2001 
| pmid = 11595143 | doi=10.1016/s1388-2457(01)00636-8
| s2cid = 6501656 
| url = https://hal.archives-ouvertes.fr/hal-01454201/file/ClinNeuroPhysiol2001.pdf 
}}</ref> It also could be generated in the [[frontal lobe|frontal]] and [[motor cortex|motor]] areas.<ref name="Näätänen">{{Cite journal 
| last1 = Näätänen | first1 = R. 
| last2 = Picton | first2 = T. 
| title = The N1 wave of the human electric and magnetic response to sound: A review and an analysis of the component structure 
| journal = Psychophysiology 
| volume = 24 
| issue = 4 
| pages = 375–425 
| year = 1987 
| pmid = 3615753
 | doi=10.1111/j.1469-8986.1987.tb00311.x
}}</ref> The area generating it is larger in the right hemisphere than the left.<ref name="Zouridakis "/>

The N100 is preattentive and involved in perception because its [[amplitude]] is strongly dependent upon such things as the rise time of the onset of a sound,<ref>{{Cite journal 
| last1 = Spreng | first1 = M. 
| title = Influence of impulsive and fluctuating noise upon physiological excitations and short-time readaptation 
| journal = Scandinavian Audiology. Supplementum 
| issue = Suppl 12 
| pages = 299–306 
| year = 1980 
| pmid = 6939101
}}</ref> its loudness,<ref>{{Cite journal 
| last1 = Keidel | first1 = W. D. 
| last2 = Spreng | first2 = M. 
| title = Neurophysiological Evidence for the Stevens Power Function in Man 
| journal = The Journal of the Acoustical Society of America 
| volume = 38 
| issue = 2 
| pages = 191–195 
| year = 1965 
| pmid = 14341718
 | doi=10.1121/1.1909629
| bibcode = 1965ASAJ...38..191K 
}}</ref>   [[interstimulus interval]] with other sounds,<ref>{{Cite journal 
| last1 = Davis | first1 = H. 
| last2 = Mast | first2 = T. 
| last3 = Yoshie | first3 = N. 
| last4 = Zerlin | first4 = S. 
| title = The slow response of the human cortex to auditory stimuli: Recovery process 
| journal = Electroencephalography and Clinical Neurophysiology 
| volume = 21 
| issue = 2 
| pages = 105–113 
| year = 1966 
| pmid = 4162003 | doi=10.1016/0013-4694(66)90118-0
}}</ref> and the comparative [[frequency]] of a sound as its amplitude increases in proportion to how much a sound differs in frequency from a preceding one.<ref>{{Cite journal 
| doi = 10.1121/1.1911233 
| last1 = Butler | first1 = R. A. 
| title = Effect of changes in stimulus frequency and intensity on habituation of the human vertex potential 
| journal = The Journal of the Acoustical Society of America 
| volume = 44 
| issue = 4 
| pages = 945–950 
| year = 1968 
| pmid = 5683660
| bibcode = 1968ASAJ...44..945B }}</ref> [[Magnetoencephalography|Neuromagnetic]] research has linked it further to perception by finding that the [[auditory cortex]] has a [[Tonotopy|tonotopic]] organization to N100.<ref>{{Cite journal 
| doi = 10.1016/0013-4694(88)90211-8 
| last1 = Pantev | first1 = C. 
| last2 = Hoke | first2 = M. 
| last3 = Lehnertz | first3 = K. 
| last4 = Lütkenhöner | first4 = B. 
| last5 = Anogianakis | first5 = G. 
| last6 = Wittkowski | first6 = W. 
| title = Tonotopic organization of the human auditory cortex revealed by transient auditory evoked magnetic fields 
| journal = Electroencephalography and Clinical Neurophysiology 
| volume = 69 
| issue = 2 
| pages = 160–170 
| year = 1988 
| pmid = 2446835
}}</ref> However, it also shows a link to a person's arousal<ref>{{Cite journal 
| last1 = Nash | first1 = A. J. 
| last2 = Williams | first2 = C. S. 
| title = Effects of preparatory set and task demands on auditory event-related potentials 
| journal = Biological Psychology 
| volume = 15 
| issue = 1–2 
| pages = 15–31 
| year = 1982 
| pmid = 7138998
 | doi=10.1016/0301-0511(82)90028-x
| s2cid = 43038773 
}}</ref> and selective [[attention]].<ref>{{Cite journal 
| last1 = Hillyard | first1 = S. A. 
| last2 = Hink | first2 = R. F. 
| last3 = Schwent | first3 = V. L. 
| last4 = Picton | first4 = T. W. 
| title = Electrical signs of selective attention in the human brain 
| journal = Science 
| volume = 182 
| issue = 4108 
| pages = 177–180 
| year = 1973 
| pmid = 4730062 | doi=10.1126/science.182.4108.177
| bibcode = 1973Sci...182..177H 
| citeseerx = 10.1.1.465.3727 
| s2cid = 14430569 
}}</ref> N100 is decreased when a person controls the creation of auditory stimuli,<ref name="Schafer">{{Cite journal 
| doi = 10.1126/science.181.4095.175 
| last1 = Schafer | first1 = E. W. 
| last2 = Marcus | first2 = M. M. 
| title = Self-stimulation alters human sensory brain responses 
| journal = Science 
| volume = 181 
| issue = 4095 
| pages = 175–177 
| year = 1973 
| pmid = 4711735
| bibcode = 1973Sci...181..175S | s2cid = 145362025 }}</ref> such as their own voice.<ref name="Curio">{{Cite journal 
| last1 = Curio | first1 = G. 
| last2 = Neuloh | first2 = G. 
| last3 = Numminen | first3 = J. 
| last4 = Jousmäki | first4 = V. 
| last5 = Hari | first5 = R. 
| title = Speaking modifies voice-evoked activity in the human auditory cortex 
| doi = 10.1002/(SICI)1097-0193(200004)9:4<183::AID-HBM1>3.0.CO;2-Z 
| journal = Human Brain Mapping 
| volume = 9 
| issue = 4 
| pages = 183–191 
| year = 2000 
| pmid = 10770228 
| pmc =6871984 
}}</ref>

==Types==
There are three subtypes of adult auditory N100.<ref name="Näätänen"/>

* N100b or vertex N100, peaking at 100 ms.
* T-complex N100a, largest at temporal [[electrodes]] at 75 ms
* T-complex N100c, follows N100a and peaks at about 130 ms.  The two T-complex N100 evoked potentials are created by auditory association cortices in the [[Superior temporal gyrus|superior temporal gyri]].

==Elicitation==
The N100 is often known as the "auditory N100" because it is elicited by perception of auditory stimuli.  Specifically, it has been found to be sensitive to things such as the predictability of an auditory stimulus, and special features of speech sounds such as [[voice onset time]].

===During sleep===
It occurs during both [[rapid eye movement sleep|REM]] and [[NREM]] stages of sleep though its time is slightly delayed.<ref>{{Cite journal 
| doi = 10.1097/00001756-199604100-00026 
| last1 = Nordby | first1 = H. 
| last2 = Hugdahl | first2 = K. 
| last3 = Stickgold | first3 = R. 
| last4 = Bronnick | first4 = K. S. 
| last5 = Hobson | first5 = J. A. 
| title = Event-related potentials (ERPs) to deviant auditory stimuli during sleep and waking 
| journal = NeuroReport 
| volume = 7 
| issue = 5 
| pages = 1082–1086 
| year = 1996 
| pmid = 8804056
| s2cid = 40303719 }}</ref> During stage 2 [[NREM]] it seems responsible for the production of [[K-complex]]es.<ref>{{Cite journal 
| doi = 10.1016/0013-4694(96)95103-2 
| last1 = Niiyama | first1 = Y. 
| last2 = Satoh | first2 = N. 
| last3 = Kutsuzawa | first3 = O. 
| last4 = Hishikawa | first4 = Y. 
| title = Electrophysiological evidence suggesting that sensory stimuli of unknown origin induce spontaneous K-complexes 
| journal = Electroencephalography and Clinical Neurophysiology 
| volume = 98 
| issue = 5 
| pages = 394–400 
| year = 1996 
| pmid = 8647042
}}</ref> N100 is reduced following [[total sleep deprivation]] and this associates with an impaired ability to consolidate [[memories]].<ref>{{Cite journal 
| doi = 10.1016/j.nlm.2009.01.008 
| last1 = Mograss | first1 = M. A. 
| last2 = Guillem | first2 = F. 
| last3 = Brazzini-Poisson | first3 = V. 
| last4 = Godbout | first4 = R. 
| title = The effects of total sleep deprivation on recognition memory processes: A study of event-related potential 
| journal = Neurobiology of Learning and Memory 
| volume = 91 
| issue = 4 
| pages = 343–352 
| year = 2009 
| pmid = 19340944
| s2cid = 35985772 }}</ref>

===Stimulus repetition===
The N100 depends upon unpredictability of stimulus: it is weaker when stimuli are repetitive, and stronger when they are random. When subjects are allowed to control stimuli, using a switch, the N100 may decrease.<ref name="Schafer"/> This effect has been linked to intelligence, as the N100 attenuation for self-controlled stimuli occurs the most strongly (i.e., the N100 shrinks the most) in individuals who are also evaluated as having high intelligence. Indeed, researchers have found that in those with [[Down syndrome]] "the amplitude of the self-evoked response actually exceeded that of the machine-evoked potential".<ref name="Schafer"/> Being warned about an upcoming stimulus also reduces its N100.<ref>{{Cite journal 
| doi = 10.1016/0013-4694(81)90183-8 
| last1 = Schafer | first1 = E. W. 
| last2 = Amochaev | first2 = A. 
| last3 = Russell | first3 = M. J. 
| title = Knowledge of stimulus timing attenuates human evoked cortical potentials 
| journal = Electroencephalography and Clinical Neurophysiology 
| volume = 52 
| issue = 1 
| pages = 9–17 
| year = 1981 
| pmid = 6166459
}}</ref>

The amplitude of N100 shows refractoriness upon repetition of a stimulus; in other words, it decreases at first upon repeated presentations of the stimulus, but after a short period of silence it returns to its previous level.<ref name="Näätänen"/> Paradoxically, at short repetition the second N100 is enhanced both for sound<ref>{{Cite journal 
| doi = 10.1097/00001756-199412000-00027 
| last1 = Budd | first1 = T. W. 
| last2 = Michie | first2 = P. T. 
| title = Facilitation of the N1 peak of the auditory ERP at short stimulus intervals 
| journal = NeuroReport 
| volume = 5 
| issue = 18 
| pages = 2513–2516 
| year = 1994 
| pmid = 7696592
}}</ref> and somatosensory stimuli.<ref name="wang"/>

With paired clicks, the second N100 is reduced due to [[sensory gating]].<ref name="Hanlon">{{Cite journal 
| last1 = Hanlon | first1 = F. M. 
| last2 = Miller | first2 = G. A. 
| last3 = Thoma | first3 = R. J. 
| last4 = Irwin | first4 = J. 
| last5 = Jones | first5 = A. 
| last6 = Moses | first6 = S. N. 
| last7 = Huang | first7 = M. 
| last8 = Weisend | first8 = M. P. 
| last9 = Paulson | first9 = K. M. 
| last10 = Edgar 
| doi = 10.1111/j.1469-8986.2005.00299.x | first10 = J. C. 
| last11 = Adler | first11 = L. E. 
| last12 = Cañive | first12 = J. M. 
| title = Distinct M50 and M100 auditory gating deficits in schizophrenia 
| journal = Psychophysiology 
| volume = 42 
| issue = 4 
| pages = 417–427 
| year = 2005 
| pmid = 16008770 
| pmc = 
}}</ref>

===Voice onset time===
The difference between many [[consonant]]s is their [[voice onset time]] (VOT), the interval between consonant release (onset) and the start of rhythmic vocal cord vibrations in the [[vowel]]. The voiced stop consonants /b/, /d/ and /g/ have a short VOT, and unvoiced stop consonants /p/, /t/ and /k/ long VOTs. The N100 plays a role in recognizing the difference and categorizing these sounds: speech stimuli with a short 0 to +30 ms voice onset time evoke a single N100 response but those with a longer (+30 ms and longer) evoked two N100 peaks and these are linked to the consonant release and vocal cord vibration onset.<ref>{{Cite journal 
| last1 = Steinschneider | first1 = M. 
| last2 = Volkov | first2 = I. O. 
| last3 = Fishman | first3 = Y. I. 
| last4 = Oya | first4 = H. 
| last5 = Arezzo | first5 = J. C. 
| last6 = Howard III | first6 = M. A. 
| title = Intracortical Responses in Human and Monkey Primary Auditory Cortex Support a Temporal Processing Mechanism for Encoding of the Voice Onset Time Phonetic Parameter 
| doi = 10.1093/cercor/bhh120 
| journal = Cerebral Cortex 
| volume = 15 
| issue = 2 
| pages = 170–186 
| year = 2004 
| pmid = 15238437 
| pmc = 
| doi-access = free 
}}</ref><ref>{{Cite journal 
| last1 = Steinschneider | first1 = M. 
| last2 = Volkov | first2 = I. O. 
| last3 = Noh | first3 = M. D. 
| last4 = Garell | first4 = P. C. 
| last5 = Howard III | first5 = M. A. 
| title = Temporal encoding of the voice onset time phonetic parameter by field potentials recorded directly from human auditory cortex 
| journal = Journal of Neurophysiology 
| volume = 82 
| issue = 5 
| pages = 2346–2357 
| year = 1999 
| pmid = 10561410
| doi = 10.1152/jn.1999.82.5.2346 
}}</ref>

==Top-down influences==
Traditionally, 50 to 150 ms evoked potentials were considered too short to be influenced by top-down influences from the [[prefrontal cortex]]. However, it is now known that sensory input is processed by the [[occipital cortex]] by 56&nbsp;ms and this is communicated to the dorsolateral frontal cortex where it arrives by 80&nbsp;ms.<ref>{{Cite journal 
| last1 = Foxe | first1 = J. 
| last2 = Simpson | first2 = G. 
| doi = 10.1007/s00221-001-0906-7 
| title = Flow of activation from V1 to frontal cortex in humans 
| journal = Experimental Brain Research 
| volume = 142 
| issue = 1 
| pages = 139–150 
| year = 2002 
| pmid = 11797091 
| pmc = 
| s2cid = 25506401 
}}</ref> Research also finds that the modulation effects upon N100 are affected by prefrontal cortex lesions.<ref>{{Cite journal 
| doi = 10.3109/00207459408986053 
| last1 = Blenner | first1 = J. L. 
| last2 = Yingling | first2 = C. D. 
| title = Effects of prefrontal cortex lesions on visual evoked potential augmenting/reducing 
| journal = The International Journal of Neuroscience 
| volume = 78 
| issue = 3–4 
| pages = 145–156 
| year = 1994 
| pmid = 7883451
}}</ref> These higher-level areas create the attentive, repetition, and arousal modulations upon the sensory area processing reflected in N100.<ref>{{Cite journal 
| doi = 10.1016/S0301-0082(98)00011-2 
| last1 = Coull | first1 = J. T. 
| title = Neural correlates of attention and arousal: Insights from electrophysiology, functional neuroimaging and psychopharmacology 
| journal = Progress in Neurobiology 
| volume = 55 
| issue = 4 
| pages = 343–361 
| year = 1998 
| pmid = 9654384
| s2cid = 26194262 }} [http://sites.univ-provence.fr/lnc/intranet/user/biblio/images/ProgNeurobiol98.pdf PDF]</ref>

Another top-down influence upon N100 has been suggested to be [[Efference copy|efference copies]] from a person's intended movements so that the stimulation that results from them are not processed.<ref>{{Cite journal 
| doi = 10.1016/j.neures.2003.09.008 
| last1 = Kudo | first1 = N. 
| last2 = Nakagome | first2 = K. 
| last3 = Kasai | first3 = K. 
| last4 = Araki | first4 = T. 
| last5 = Fukuda | first5 = M. 
| last6 = Kato | first6 = N. 
| last7 = Iwanami | first7 = A. 
| title = Effects of corollary discharge on event-related potentials during selective attention task in healthy men and women 
| journal = Neuroscience Research 
| volume = 48 
| issue = 1 
| pages = 59–64 
| year = 2004 
| pmid = 14687881
| s2cid = 37957344 }}</ref> A person's own voice produces a reduced N100<ref name="Curio"/> as does the effect of a self-initiated compared to externally created perturbation upon balance.<ref>{{Cite journal 
| last1 = Mochizuki | first1 = G. 
| last2 = Sibley | first2 = K. M. 
| last3 = Cheung | first3 = H. J. 
| last4 = McIlroy | first4 = W. E. 
| title = Cortical activity prior to predictable postural instability: Is there a difference between self-initiated and externally-initiated perturbations? 
| doi = 10.1016/j.brainres.2009.04.050 
| journal = Brain Research 
| volume = 1279 
| pages = 29–36 
| year = 2009 
| pmid = 19422812 
| pmc = 
| s2cid = 12170405 
}}</ref>

==Development in children==
The N100 is a slow-developing evoked potential. From one to four years of age, a positive evoked potential, P100, is the predominant peak.<ref>{{Cite journal 
| doi = 10.1097/00001756-200201210-00014 
| last1 = Kushnerenko | first1 = E. 
| last2 = Ceponiene | first2 = R. 
| last3 = Balan | first3 = P. 
| last4 = Fellman | first4 = V. 
| last5 = Huotilaine | first5 = M. 
| last6 = Näätäne | first6 = R. 
| title = Maturation of the auditory event-related potentials during the first year of life 
| journal = NeuroReport 
| volume = 13 
| issue = 1 
| pages = 47–51 
| year = 2002 
| pmid = 11924892
| s2cid = 33934033 }}</ref> Older children start to develop a negative evoked potential at 200 ms that dominates evoked potentials until [[adolescence]];<ref name="Pang">{{Cite journal 
| doi = 10.1016/S1388-2457(99)00259-X 
| last1 = Pang | first1 = E. W. 
| last2 = Taylor | first2 = M. J. 
| title = Tracking the development of the N1 from age 3 to adulthood: An examination of speech and non-speech stimuli 
| journal = Clinical Neurophysiology 
| volume = 111 
| issue = 3 
| pages = 388–397 
| year = 2000 
| pmid = 10699397
| s2cid = 37029252 }}</ref> this potential is identical to the adult N100 in scalp topography and elicitation, but with a much later onset. The magnetic M100 (measured by [[Magnetoencephalography|MEG]] rather than [[EEG]]) is, likewise, less robust in children than in adults.<ref>{{Cite journal 
| doi = 10.1097/00004691-199503000-00008 
| last1 = Paetau | first1 = R. 
| last2 = Ahonen | first2 = A. 
| last3 = Salonen | first3 = O. 
| last4 = Sams | first4 = M. 
| title = Auditory evoked magnetic fields to tones and pseudowords in healthy children and adults 
| journal = Journal of Clinical Neurophysiology 
| volume = 12 
| issue = 2 
| pages = 177–185 
| year = 1995 
| pmid = 7797632
| s2cid = 33059979 }}</ref> An adult-like N100-P200 complex only develops after 10 years of age.<ref>{{Cite journal 
| doi = 10.1097/00004691-199207010-00007 
| last1 = Shibasaki | first1 = H. 
| last2 = Miyazaki | first2 = M. 
| title = Event-related potential studies in infants and children 
| journal = Journal of Clinical Neurophysiology 
| volume = 9 
| issue = 3 
| pages = 408–418 
| year = 1992 
| pmid = 1517407
}}</ref>

The various types of N100 mature at different times. Their maturation also varies with the side of the brain: N100a in the left hemisphere is mature before three years of age but this does not happen in the right hemisphere until seven or eight years of age.<ref name="Pang"/>

==Clinical use==
The N100 may be used to test for abnormalities in the auditory system where verbal or behavioral responses cannot be used,<ref>{{Cite journal 
| doi = 10.1159/000259253 
| last1 = Hyde | first1 = M. 
| title = The N1 response and its applications 
| journal = Audiology and Neuro-Otology  
| volume = 2 
| issue = 5 
| pages = 281–307 
| year = 1997 
| pmid = 9390837
}}</ref> such with individuals in [[coma]]; in such cases, it can help predict the probability of recovery.<ref>{{Cite journal 
| doi = 10.1159/000013880 
| last1 = Fischer | first1 = C. 
| last2 = Morlet | first2 = D. 
| last3 = Giard | first3 = M. 
| title = Mismatch negativity and N100 in comatose patients 
| journal = Audiology and Neuro-Otology  
| volume = 5 
| issue = 3–4 
| pages = 192–197 
| year = 2000 
| pmid = 10859413
| s2cid = 42959451 }}</ref><ref>{{Cite journal 
| last1 = Fischer | first1 = C. 
| last2 = Luauté | first2 = J. 
| last3 = Adeleine | first3 = P. 
| last4 = Morlet | first4 = D. 
| title = Predictive value of sensory and cognitive evoked potentials for awakening from coma 
| journal = Neurology 
| volume = 63 
| issue = 4 
| pages = 669–673 
| year = 2004 
| pmid = 15326240 | doi=10.1212/01.wnl.0000134670.10384.e2
| s2cid = 31825723 
}}</ref> Another application is in assessing the optimal level of [[sedation]] in intensive [[intensive-care medicine|critical care]].<ref>{{Cite journal 
| last1 = Yppärilä | first1 = H. 
| last2 = Nunes | first2 = S. 
| last3 = Korhonen | first3 = I. 
| last4 = Partanen | first4 = J. 
| last5 = Ruokonen | first5 = E. 
| title = The effect of interruption to propofol sedation on auditory event-related potentials and electroencephalogram in intensive care patients 
| journal = Critical Care 
| volume = 8 
| issue = 6 
| pages = R483–R490 
| year = 2004 
| doi = 10.1186/cc2984 
| pmid = 15566595 
| pmc =1065074 
| doi-access = free 
}}</ref>

High density mapping of the location of the generators of M100 is being researched as a means of presurgical [[Neuroimaging#Magnetoencephalography|neuromapping]] needed for [[neurosurgery]].<ref name="Cheyne">{{Cite journal 
| last1 = Cheyne | first1 = D. 
| last2 = Bostan | first2 = A. C. 
| last3 = Gaetz | first3 = W. 
| last4 = Pang | first4 = E. W. 
| title = Event-related beamforming: A robust method for presurgical functional mapping using MEG 
| doi = 10.1016/j.clinph.2007.05.064 
| journal = Clinical Neurophysiology 
| volume = 118 
| issue = 8 
| pages = 1691–1704 
| year = 2007 
| pmid = 17587643 
| pmc = 
| s2cid = 5900519 
}}</ref>

Many cognitive or other mental impairments are associated with changes in the N100 response, including the following:
*There is some evidence that the N100 is affected in those with [[dyslexia]] and [[specific language impairment]].<ref>Shaul S. (2007). Evoked response potentials (ERPs) in the study of dyslexia: A review. pp. 51–91. In (Breznitz Z. Editor) Brain Research in Language. Springer {{ISBN|978-0-387-74979-2}}</ref>
*The sensory gating effect upon N100 with paired clicks is reduced in those with [[schizophrenia]].<ref name="Hanlon"/>
*In individuals with [[tinnitus]], those with smaller N100 are less distressed than those with larger amplitudes.<ref>{{Cite journal 
| last1 = Delb | first1 = W. 
| last2 = Strauss | first2 = D. J. 
| last3 = Low | first3 = Y. F. 
| last4 = Seidler | first4 = H. 
| last5 = Rheinschmitt | first5 = A. 
| last6 = Wobrock | first6 = T. 
| last7 = d’Amelio | first7 = R. 
| doi = 10.1007/s10484-008-9065-y 
| title = Alterations in Event Related Potentials (ERP) Associated with Tinnitus Distress and Attention 
| journal = Applied Psychophysiology and Biofeedback 
| volume = 33 
| issue = 4 
| pages = 211–221 
| year = 2008 
| pmid = 18836827 
| pmc = 
| doi-access = free 
}}</ref>
*[[Migraine]] is associated with an increase rather than decrease in N100 amplitude with repetition of the high-intensity stimulation.<ref>{{Cite journal 
| last1 = Wang | first1 = W. 
| last2 = Timsit-Berthier | first2 = M. 
| last3 = Schoenen | first3 = J. 
| title = Intensity dependence of auditory evoked potentials is pronounced in migraine: An indication of cortical potentiation and low serotonergic neurotransmission? 
| journal = Neurology 
| volume = 46 
| issue = 5 
| pages = 1404–1409 
| year = 1996 
| pmid = 8628490
 | doi=10.1212/wnl.46.5.1404
| s2cid = 2645081 
}}</ref>
*[[Headache]] sufferers also have more reactive N100 to somatosensory input than nonsufferers<ref>{{Cite journal 
| last1 = Marlowe | first1 = N. 
| title = Somatosensory evoked potentials and headache: A further examination of the central theory 
| journal = Journal of Psychosomatic Research 
| volume = 39 
| issue = 2 
| pages = 119–131 
| year = 1995 
| pmid = 7595870
 | doi=10.1016/0022-3999(94)00072-d
}}</ref>

The N100 is 10 to 20% larger than normal when the auditory stimulus is synchronized with the [[diastole|diastolic phase]] of the cardiac blood pressure pulse.<ref>{{Cite journal 
| doi = 10.1126/science.6729458 
| last1 = Sandman | first1 = C. A. 
| last2 = O'Halloran | first2 = J. P. 
| last3 = Isenhart | first3 = R. 
| title = Is there an evoked vascular response? 
| journal = Science 
| volume = 224 
| issue = 4655 
| pages = 1355–1357 
| year = 1984 
| pmid = 6729458
| bibcode = 1984Sci...224.1355S | url = http://www.escholarship.org/uc/item/1889h4km }}</ref>

==Relationship to mismatch negativity==
The [[Mismatch negativity]] (MMN) is an evoked potential that occurs at roughly the same time as N100 in response to rare auditory events. It differs from the N100 in that:
* They are generated in different locations.<ref>{{Cite journal 
| last1 = Alho | first1 = K. 
| title = Cerebral generators of mismatch negativity (MMN) and its magnetic counterpart (MMNm) elicited by sound changes 
| journal = Ear and Hearing 
| volume = 16 
| issue = 1 
| pages = 38–51 
| year = 1995 
| pmid = 7774768
 | doi=10.1097/00003446-199502000-00004
| s2cid = 31698419 
}}</ref>
* The MMN occurs too late to be an N100.<ref>{{Cite journal 
| last1 = Näätänen | first1 = R. 
| last2 = Alho | first2 = K. 
| title = Mismatch negativity—a unique measure of sensory processing in audition 
| journal = The International Journal of Neuroscience 
| volume = 80 
| issue = 1–4 
| pages = 317–337 
| year = 1995 
| pmid = 7775056
 | doi=10.3109/00207459508986107
}}</ref>
* The MMN, unlike N100, may be elicited by stimulus omissions (i.e., not hearing a stimulus when you expect to hear one).<ref>{{Cite journal 
| last1 = Yabe | first1 = H. 
| last2 = Tervaniemi | first2 = M. 
| last3 = Sinkkonen | first3 = J. 
| last4 = Huotilainen | first4 = M. 
| last5 = Ilmoniemi | first5 = R. J. 
| last6 = Näätänen | first6 = R. 
| title = Temporal window of integration of auditory information in the human brain 
| journal = Psychophysiology 
| volume = 35 
| issue = 5 
| pages = 615–619 
| year = 1998 
| pmid = 9715105 | doi=10.1017/s0048577298000183
}}</ref>

Though this suggests that they are separate processes, arguments have been made that this is not necessarily so and that they are created by the "relative activation of multiple cortical areas contributing to both of these 'components'".<ref>{{Cite journal 
| last1 = May | first1 = P. J. 
| last2 = Tiitinen | first2 = H. 
| title = The MMN is a derivative of the auditory N100 response 
| journal = Neurology & Clinical Neurophysiology 
| volume = 2004 
| pages = 20 
| year = 2004 
| pmid = 16012601
}}</ref>

==History==
Pauline A. Davis at [[Harvard University]] first recorded the wave peak now identified with N100.<ref>Davis PA. (1939).  Effects of acoustic stimuli on the waking human brain. J Neurophysiol 2: 494–499 [http://jn.physiology.org/cgi/content/citation/2/6/494 abstract]</ref> The present use of the N1 to describe this peak originates in 1966<ref>{{cite journal|pmid=5904525|year=1966|last1=Davis|first1=H|title=Acoustic relations of the human vertex potential|journal=The Journal of the Acoustical Society of America|volume=39|issue=1|pages=109–16|last2=Zerlin|first2=S|doi=10.1121/1.1909858|bibcode=1966ASAJ...39..109D}}</ref> and N100 later in the mid 1970s.<ref>{{Cite journal 
| last1 = Donchin | first1 = E. 
| last2 = Tueting | first2 = P. 
| last3 = Ritter | first3 = W. 
| last4 = Kutas | first4 = M. 
| last5 = Heffley | first5 = E. 
| title = On the independence of the CNV and the P300 components of the human averaged evoked potential 
| journal = Electroencephalography and Clinical Neurophysiology 
| volume = 38 
| issue = 5 
| pages = 449–461 
| year = 1975 
| pmid = 50170 | doi=10.1016/0013-4694(75)90187-x
}}</ref> The origin of the wave for a long time was unknown and only linked to the auditory cortex in 1970.<ref name="Näätänen"/><ref>{{Cite journal 
| last1 = Vaughan Jr | first1 = H. G. 
| last2 = Ritter | first2 = W. 
| title = The sources of auditory evoked responses recorded from the human scalp 
| journal = Electroencephalography and Clinical Neurophysiology 
| volume = 28 
| issue = 4 
| pages = 360–367 
| year = 1970 
| pmid = 4191187
 | doi=10.1016/0013-4694(70)90228-2
}}</ref>

Due to [[magnetoencephalography]], research is increasingly done upon M100, the magnetic counterpart of the [[electroencephalographic]] N100. Unlike [[electrical field]]s which face the high resistance of the [[Human skull|skull]] and generate secondary or volume currents, [[magnetic field]]s which are [[orthogonal]] to them have a homogeneous permeability through the skull. This enables the location of sources generating fields that are tangent to the head surface with an accuracy of a few millimeters.<ref>Hämäläinen M, Hari R, Ilmoniemi RJ, Knuutila J. (1993). Magnetoencephalography-theory, instrumentation, and applications to noninvasive studies of the working human brain. Reviews of modern Physics.  65: 413–497. {{OCLC|197237696}}</ref> New techniques, such as event-related beam-forming with magnetoencephalography, allow sufficiently accurate location of M100 sources to be clinically useful for preparing surgery upon the brain.<ref name="Cheyne"/>

==See also==
{{div col|colwidth=22em}}
* [[Bereitschaftspotential]]
* [[C1 and P1 (neuroscience)|C1 and P1]]
* [[Contingent negative variation]]
* [[Difference due to memory]]
* [[Early left anterior negativity]]
* [[Error-related negativity]]
* [[Late positive component]]
* [[Lateralized readiness potential]]
* [[Mismatch negativity]]
* [[N2pc]]
* [[N170]]
* [[N200 (neuroscience)|N200]]
* [[N400 (neuroscience)|N400]]
* [[P3a]]
* [[P3b]]
* [[P200]]
* [[P300 (neuroscience)]]
* [[P600 (neuroscience)|P600]]
* [[Somatosensory evoked potential]]
* [[Visual N1]]
{{div col end}}

==References==
{{Reflist|2}}
{{Use dmy dates|date=April 2020}}

{{EEG}}

{{Authority control}}

[[Category:Electroencephalography]]
[[Category:Evoked potentials]]