title: Repetition suppression and repetition enhancement underlie auditory memory-trace formation in the human brain: an MEG study.
abstract: The formation of echoic memory traces has traditionally been inferred from the enhanced responses to its deviations. The mismatch negativity (MMN), an auditory event-related potential (ERP) elicited between 100 and 250ms after sound deviation is an indirect index of regularity encoding that reflects a memory-based comparison process. Recently, repetition positivity (RP) has been described as a candidate ERP correlate of direct memory trace formation. RP consists of repetition suppression and enhancement effects occurring in different auditory components between 50 and 250ms after sound onset. However, the neuronal generators engaged in the encoding of repeated stimulus features have received little interest. This study intends to investigate the neuronal sources underlying the formation and strengthening of new memory traces by employing a roving-standard paradigm, where trains of different frequencies and different lengths are presented randomly. Source generators of repetition enhanced (RE) and suppressed (RS) activity were modeled using magnetoencephalography (MEG) in healthy subjects. Our results show that, in line with RP findings, N1m (~95-150ms) activity is suppressed with stimulus repetition. In addition, we observed the emergence of a sustained field (~230-270ms) that showed RE. Source analysis revealed neuronal generators of RS and RE located in both auditory and non-auditory areas, like the medial parietal cortex and frontal areas. The different timing and location of neural generators involved in RS and RE points to the existence of functionally separated mechanisms devoted to acoustic memory-trace formation in different auditory processing stages of the human brain.
authors.affiliation: Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Barcelona, 08035, Spain; Cognitive Neuroscience Research Group, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, 08035, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Recasens
authors.affiliation: Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Barcelona, 08035, Spain; Cognitive Neuroscience Research Group, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, 08035, Spain.
authors.forename: Sumie
authors.initials: S
authors.lastname: Leung
authors.affiliation: Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Barcelona, 08035, Spain; Cognitive Neuroscience Research Group, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, 08035, Spain.
authors.forename: Sabine
authors.initials: S
authors.lastname: Grimm
authors.affiliation: Unidad de Magnetoencefalografía, Hospital Quirón Teknon, Barcelona, 08022, Spain.
authors.forename: Rafal
authors.initials: R
authors.lastname: Nowak
authors.affiliation: Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Barcelona, 08035, Spain; Cognitive Neuroscience Research Group, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, 08035, Spain. Electronic address: cescera@ub.edu.
authors.forename: Carles
authors.initials: C
authors.lastname: Escera
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008568:Memory / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: Auditory cortex; Echoic memory; Magnetoencephalography; Mismatch negativity; Repetition enhancement; Repetition suppression