Age-related qualitative differences in auditory cortical responses during short-term memory

Abstract

Objective: To examine the affects of aging on auditory cortical activity during a short-term memory task. Methods: Young and elderly subjects performed a working memory task using acoustically presented digits while evoked potential components (N100, P200) generated by auditory cortex were recorded. Reaction time and N100/P200 amplitudes and latency were analyzed as a function of memory load.Results: N100 amplitude to probes decreased as a function of memory load in young subjects, but increased as a function of memory load in the elderly. Young subjects also exhibited changes in N100 latency during memorization of list items, a result not found in elderly subjects.Conclusions: We conclude that normal aging is associated with a qualitatively different pattern of N100 responses during memory retrieval, and a static N100 response during encoding. The ®ndings suggest that aging is accompanied by functional reorganization of the neural network that supports retrieval in auditory working memory. q

Serial Position Effects in Auditory Event-related Potentials during Working Memory Retrieval

“…The finding that N100 amplitude to probes covaries with memory load is consistent with the notion that sensory areas contribute to retrieval because the neural generators of the N100 have been localized to the primary/secondary auditory cortex (Zouridakis, Simos, & Papanicolaou, 1998;Pantev et al, 1995;LiegeoisChauvel, Musolino, Badier, Marquis, & Chauvel, 1994). In addition, decreases in N100 amplitude following increases in memory load have also been reported during encoding (Golob & Starr, 2000;Conley et al, 1999), which also suggests similar patterns of auditory cortical activation during encoding and retrieval as a function of memory load. N100 amplitudes during encoding showed no significant effect as a function of serial position (Golob & Starr, 2000), a result that was replicated in the present study (data not shown).…”

“…In addition, decreases in N100 amplitude following increases in memory load have also been reported during encoding (Golob & Starr, 2000;Conley et al, 1999), which also suggests similar patterns of auditory cortical activation during encoding and retrieval as a function of memory load. N100 amplitudes during encoding showed no significant effect as a function of serial position (Golob & Starr, 2000), a result that was replicated in the present study (data not shown). Thus, differences in N100 amplitude during retrieval, as a function of serial position, do not reflect the initial N100 response during encoding.…”

“…When auditory stimuli are presented the N100 component, a prominent negative wave generated in the auditory cortex having a peak latency $100 msec after stimulus presentation, exhibits linear amplitude reductions in response to increases in memory load (Golob & Starr, 2000;Conley, Michalewski, Starr, 1999;cf. Kaufman, Curtis, Wang, & Williamson, 1992).…”

Linking Brainwaves to the Brain: An ERP Primer

“…The P2 component has been identified in many different cognitive tasks, including selective attention (Hackley, Woldorff, & Hillyard, 1990;Hillyard et al, 1973;Johnson, 1989), stimulus change (Naatanen, 1990), feature detection processes , and short-term memory (Golob & Starr, 2000;Starr & Barrett, 1987). Similar to N1, P2 has been consistently identified by principal components analysis factor scores (Beauducel et al, 2000), baseline-to-peak amplitude (Beauducel et al, 2000;, and latency measures (Segalowitz & Barnes, 1993).…”

Effects of aging on slowing of motor-response generation

“…For example, impaired performance of old individuals in a variety of visual tasks has been attributed to a decline in working memory but not to a decrease of sensorimotor speed Raz et al, 1999). Auditory working memory has also been proposed to vary with aging (Golob and Starr, 2000). However, an impaired transmission of visuomotor information from parietal to motor cortical areas has been suggested to produce a response delay in aged people (van der Lubbe and Verleger, 2002), although no evidence exists for transmission deficits in the auditory modality (Amenedo and Diaz, 1998).…”