Abstract
The ability to detect small changes in one's visual environment is important for effective adaptation to and interaction with a wide variety of external stimuli. Much research has studied the auditory mismatch negativity (MMN), or the brain's automatic response to rare changes in a series of repetitive auditory stimuli. But recent studies indicate that a visual homolog to this component of the event-related potential (ERP) can also be measured. While most visual mismatch response (vMMR) studies have focused on adult populations, few studies have investigated this response in healthy children, and little is known about the developmental nature of this phenomenon. We recorded EEG data in 22 healthy children (ages 8–12) and 20 healthy adults (ages 18–42). Participants were presented with two types of task irrelevant background images of black and gray gratings while performing a visual target detection task. Spatial frequency of the background gratings was varied with 85% of the gratings being of high spatial frequency (HSF; i.e., standard background stimulus) and 15% of the images being of low spatial frequency (LSF; i.e., deviant background stimulus). Results in the adult group showed a robust mismatch response to deviant (non-target) background stimuli at around 150 ms post-stimulus at occipital electrode locations. In the children, two negativities around 150 and 230 ms post-stimulus at occipital electrode locations and a positivity around 250 ms post-stimulus at fronto-central electrode locations were observed. In addition, larger amplitudes of P1 and longer latencies of P1 and N1 to deviant background stimuli were observed in children vs. adults. These results suggest that processing of deviant stimuli presented outside the focus of attention in 8–12-year-old children differs from those in adults, and are in agreement with previous research. They also suggest that the vMMR may change across the lifespan in accordance with other components of the visual ERP.
Highlights
The human brain is constantly responding to changes in sensory stimuli, even if these changes do not pass into conscious awareness
Visual mismatch negativity (MMN) is an occipital-parietal negativity computed by subtracting the Event-Related Potential (ERP) to a frequentlyoccurring standard stimulus from the ERP to a rarely-occurring deviant stimulus in the visual modality. vMMN usually occurs around 100–250 ms post-stimulus presentation and to date has been primarily studied in typically-developing adults
There was a significant difference in the response accuracy between the children and the adults for the deviant background target condition (t = 2.38, p = 0.022), whereas response accuracy for the standard background target condition did not differ (p > 0.08)
Summary
The human brain is constantly responding to changes in sensory stimuli, even if these changes do not pass into conscious awareness. MMN is typically measured when the subject’s attention is directed away from the stimulus, and manifests as a difference wave computed by subtracting the ERP to a frequently-occurring standard stimulus from the ERP to a rarely-occurring deviant stimulus. MMN has mainly been investigated in the auditory modality, but recent studies have characterized this difference wave in the visual modality as well (see Pazo-Alvarez et al, 2003; Czigler, 2007, for reviews). Visual MMN (vMMN) is an occipital-parietal negativity computed by subtracting the ERP to a frequentlyoccurring standard stimulus from the ERP to a rarely-occurring deviant stimulus in the visual modality. 498 ms 50 ms 590 ms 70 ms 512 ms 50 ms 598 ms 58 ms Percentage of correct responses (accuracy) and reaction times in ms [as well as standard deviations (SD)] are indicated for both standard background (Std) and deviant background (Dev) target stimulus conditions
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