title: Maintaining vs. enhancing motor sequence memories: respective roles of striatal and hippocampal systems.
abstract: It is now accepted that hippocampal- and striatal-dependent memory systems do not act independently, but rather interact during both memory acquisition and consolidation. However, the respective functional roles of the hippocampus and the striatum in these processes remain unknown. Here, functional magnetic resonance imaging (fMRI) was used in a daytime sleep/wake protocol to investigate this knowledge gap. Using a protocol developed earlier in our lab (Albouy et al., 2013a), the manipulation of an explicit sequential finger-tapping task, allowed us to isolate allocentric (spatial) and egocentric (motor) representations of the sequence, which were supported by distinct hippocampo- and striato-cortical networks, respectively. Importantly, a sleep-dependent performance enhancement emerged for the hippocampal-dependent memory trace, whereas performance was maintained for the striatal-dependent memory trace, irrespective of the sleep condition. Regression analyses indicated that the interaction between these two systems influenced subsequent performance improvements. While striatal activity was negatively correlated with performance enhancement after both sleep and wakefulness in the allocentric representation, hippocampal activity was positively related to performance improvement for the egocentric representation, but only if sleep was allowed after training. Our results provide the first direct evidence of a functional dissociation in consolidation processes whereby memory stabilization seems supported by the striatum in a time-dependent manner whereas memory enhancement seems linked to hippocampal activity and sleep-dependent processes.
authors.affiliation: Functional Neuroimaging Unit, C.R.I.U.G.M., Montreal, QC, Canada; Psychology Department, University of Montreal, Montreal, QC, Canada.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Albouy
authors.affiliation: Functional Neuroimaging Unit, C.R.I.U.G.M., Montreal, QC, Canada; Psychology Department, University of Montreal, Montreal, QC, Canada; Brain & Mind Institute, Department of Psychology, Western University, London, ON, Canada.
authors.forename: Stuart
authors.initials: S
authors.lastname: Fogel
authors.affiliation: Functional Neuroimaging Unit, C.R.I.U.G.M., Montreal, QC, Canada; Psychology Department, University of Montreal, Montreal, QC, Canada.
authors.forename: Bradley R
authors.initials: BR
authors.lastname: King
authors.affiliation: Functional Neuroimaging Unit, C.R.I.U.G.M., Montreal, QC, Canada; Psychology Department, University of Montreal, Montreal, QC, Canada.
authors.forename: Samuel
authors.initials: S
authors.lastname: Laventure
authors.affiliation: Unité Mixte de Recherche-S 678, Institut National de la Santé et de la Recherche Médicale/University of Paris 6, Centre Hospitalier Universitaire Pitié-Salpêtrière, Paris, France.
authors.forename: Habib
authors.initials: H
authors.lastname: Benali
authors.affiliation: Laboratory for Human Brain & Learning, Sagol Department of Neurobiology & E.J. Safra Brain Research Center, University of Haifa, Haifa, Israel.
authors.forename: Avi
authors.initials: A
authors.lastname: Karni
authors.affiliation: Functional Neuroimaging Unit, C.R.I.U.G.M., Montreal, QC, Canada; Psychology Department, University of Montreal, Montreal, QC, Canada; Centre of Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montreal, Montreal, QC, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Carrier
authors.affiliation: Harvard Center for Noninvasive Brain Stimulation, Harvard Medical School and Beth Israel Deaconess Medical Center, Neurology Department, Boston, MA, USA.
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Robertson
authors.affiliation: Functional Neuroimaging Unit, C.R.I.U.G.M., Montreal, QC, Canada; Psychology Department, University of Montreal, Montreal, QC, Canada. Electronic address: julien.doyon@umontreal.ca.
authors.forename: Julien
authors.initials: J
authors.lastname: Doyon
mesh_terms: D003342:Corpus Striatum / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D012890:Sleep; D014851:Wakefulness; D055815:Young Adult
keywords: Hippocampus; Memory consolidation; Motor sequence learning; Sleep; Striatum