N100

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),^[1] olfactory,^[2] heat,^[3] pain,^[3] balance,^[4] respiration blocking,^[5] and somatosensory stimuli.^[6]

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^[7] and planum temporale.^[8] It also could be generated in the frontal and motor areas.^[9] The area generating it is larger in the right hemisphere than the left.^[7]

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,^[10] its loudness,^[11] interstimulus interval with other sounds,^[12] 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.^[13] Neuromagnetic research has linked it further to perception by finding that the auditory cortex has a tonotopic organization to N100.^[14] However, it also shows a link to a person's arousal^[15] and selective attention.^[16] N100 is decreased when a person controls the creation of auditory stimuli,^[17] such as their own voice.^[18]