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Activation and deactivation in response to visual stimulation in the occipital cortex of 6‐month‐old human infants
Author(s) -
Watanabe Hama,
Homae Fumitaka,
Taga Gentaro
Publication year - 2012
Publication title -
developmental psychobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 93
eISSN - 1098-2302
pISSN - 0012-1630
DOI - 10.1002/dev.20569
Subject(s) - stimulus (psychology) , visual cortex , neuroscience , functional magnetic resonance imaging , photic stimulation , psychology , occipital lobe , stimulation , prefrontal cortex , visual n1 , visual perception , audiology , cognition , medicine , cognitive psychology , perception
In an infant's developing cortex, the explanation for the mechanisms underlying the activations and deactivations in response to visual stimuli remains controversial. While previous near‐infrared spectroscopy (NIRS) studies in awake infants have demonstrated cortical activations in response to meaningful/attractive visual stimuli, functional magnetic resonance imaging (fMRI) studies performed on sleeping infants showed negative blood oxygenation level‐dependent (BOLD) responses to high‐luminance unpatterned stimulations, such as a photic stimulation. To examine the effect of the characteristics of visual stimuli on cortical processing in awake infants, we measured cortical hemodynamic responses in 6‐month‐old infants during the presentation of a high‐luminance unpatterned stimulus by using a NIRS system with 94 measurement channels. Results from 35 infants showed dissociated cortical responses between the occipital region and the other parts of the cortex, including the temporal and prefrontal regions. Although the visual stimulus produced sustained increases in oxygenated hemoglobin (oxy‐Hb) signals in the temporal and prefrontal regions, it produced a transient increase in oxy‐Hb signals followed by a salient decrease in oxy‐Hb signals during a trial in a focal region of the occipital visual region. This suggests that the deactivation of the occipital visual region in response to visual stimulation is not a phenomenon that occurs only in the sleeping state, but that a high‐luminance unpatterned stimulus can induce deactivation even in the awake infants. © 2011 Wiley Periodicals, Inc. Dev Psychobiol 54:1–15, 2012.