| |
Abstract:
Separate but overlapping components of event-related brain
potentials (ERPs) may obscure aging effects on the mismatch
negativity. One method to disentangle these components is to use
event-related optical signal (EROS), which is a noninvasive measure
of cortical activation that provides both high spatial and temporal
resolution. In this study, both EROS and ERPs were recorded during
an oddball paradigm in 16 young and 16 old adults with normal
hearing. 500 Hz tones were binaurally presented at 70 dB above
hearing threshold while subjects were reading text of their own
choice under the instruction to ignore the tones. Standard tones
were 75 ms in duration; deviant tones were 25 ms in duration. ERPs
were recorded from 5 locations and EROS was recorded in locations
that covered the scalp projection of the auditory cortex of the
right hemisphere. ERP results indicated that the older adults
responded differently from younger adults to the standard stimuli.
EROS results indicated that both groups showed a response to
standard stimuli at area 42 with a latency of 120 ms and a response
to deviant stimuli at area 21 with a latency of 180 ms. These data
suggest that although older adults may have difficulty maintaining
a template of the standard tones, the neural generators for
stimulus detection and change detection for both groups are
similar.
|
