Scand J Psychol 43 (2002) Duration of auditory memory 33 © 2002 The Scandinavian Psychological Associations. Scandinavian Journal of Psychology, 2002, 43, 33–39 The auditory sensory memory trace decays rapidly in newborns MARIE CHEOUR 1,2 , RITA C ˚ EPONIENÉ 2 , PAAVO LEPPÄNEN 3 , KIMMO ALHO 2 , TEIJA KUJALA 2 , MARTIN RENLUND 4,5 , VINETA FELLMAN 5 and RISTO NÄÄTÄNEN 2 1 Language and the Developing Brain Laboratory, Center for Cognitive Neuroscience, University of Turku, Finland 2 Cognitive Brain Research Unit, University of Helsinki, Finland 3 Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, USA 4 Department of Obstetrics and Gynecology, University of Helsinki, Finland 5 Hospital for Children and Adolescents, Helsinki University Hospital, Finland Cheour M., C · eponiené, R., Leppänen, P., Alho, K., Kujala, T., Renlund, M., Fellman, V. and Näätänen, R. (2002). The auditory sensory memory trace decays rapidly in newborns. Scandinavian Journal of Psychology, 43, 33–39. The present study investigated the temporal dynamics of auditory sensory memory in newborns as reflected by the mismatch negativity (MMN), a preattentive electric change-detection response. MMN was obtained from 24 full-term healthy newborns who were either awake or asleep (quiet or active sleep) during the experiments. Stimuli were 1,000 Hz tones (standards) that were occasionally replaced by 1,100 Hz tones (deviants). The constant stimulus onset asynchrony (SOA) was, in separate blocks, either 450, 800, or 1,500 ms. A prominent MMN was obtained at the 800 ms SOA in all three sleep or waking states, whereas no MMN occurred at 450 and 1,500 ms SOAs. In view of the fact that in adults MMN is elicited even with a 10s SOA, these results imply that the time span of auditory memory is considerably shorter in neonates than in adults and 8–12-year-old children. Key words: Auditory sensory memory, event-related potentials (ERPs), infants, mismatch negativity (MMN). Marie Cheour, Language and the Developing Brain Laboratory, Center for Cognitive Neuroscience, Lemminkäisenk. 14 A, 20014 University of Turku, Finland. E-mail: Marie.Cheour@utu.fi © 2002 The Scandinavian Psychological Associations. Published by Blackwell Publishers, 108 Cowley Road, Oxford OX4 1JF, UK and 350 Main Street, Malden, MA 02148, USA. ISSN 0036-5564. stores can be studied by using MMN (Näätänen & Winkler, 1999). By varying stimulus onset asychrony (SOA), one can determine the time span of this longer-duration auditory sensory memory, since a stimulus change cannot elicit MMN if the trace of the repetitive stimulus has already decayed (Näätänen, 1992). In adults, the temporal dynamics of auditory sensory memory have been investigated in several MMN studies (Cowan et al., 1993; Mäntysalo & Näätänen, 1987; Winkler & Näätänen, 1992). A prominent MMN can be recorded with SOAs ranging from a continuous tone (Lavikainen, Huotilainen, Ilmoniemi, Simola & Näätänen, 1995) to about 10 s (Böttcher-Gandor & Ullsperger, 1992; Sams, Hari, Rif & Knuutila, 1993). The MMN amplitude decreases as the interval between stimuli is prolonged, demonstrating the weakening of the memory trace as a function of time (Mäntysalo & Näätänen, 1987; Sams et al., 1993). It is clinically interesting that the duration of auditory sensory memory, as determined with the MMN procedure, is considerably shorter in patients with Alzheimer’s disease suffering from progressive memory dysfunction than in age- matched control subjects (Pekkonen, Jousmäki, Könönen, Reinikainen & Partanen, 1994). Surprisingly, although the MMN is well documented in adults, children, and especially infants, MMN studies are still relatively rare (see, however, Alho, Sainio, Sajaniemi, Reinikainen & Näätänen, 1990; Cheour-Luhtanen et al., INTRODUCTION Mismatch negativity (MMN) is a preattentive component of the auditory event-related potential (ERP) that is eli- cited when a repetitive “standard” stimulus is occasionally replaced by a physically “deviant” stimulus (Näätänen, 1992; Näätänen, Gaillard & Mäntysalo, 1978). MMN is evoked by any discriminable change in auditory stimuli, involving parameters such as frequency, intensity, duration, location, or phonetic features (Näätänen, 1992; Näätänen & Winkler, 1999). However, an infrequent stimulus presented alone (without intervening standard stimuli) elicits no MMN kind of response (Lounasmaa, Hari, Joutsniemi & Hämäläinen, 1989; Näätänen, 1985; Sams, Hämäläinen, et al., 1985). This suggests that MMN elicitation depends on the presence of a memory trace formed by the standard stimulus in the auditory system when the deviant stimulus is presented. Consequently, it has been proposed that MMN reflects the operation of auditory sensory memory (Cowan, Winkler, Teder & Näätänen, 1993; Tiitinen, May, Reinikainen & Näätänen, 1994) that can store large amounts of sensory data for a relatively short time (Neisser, 1967). This memory system, in turn, is suggested to consist of two separate stores. One has a short duration of about 250 ms, and serves mainly auditory perception. The other is proposed to be memory proper and is considerably longer in duration (Cowan, 1984). With appropriate experimental paradigms both memory