title: Stimulation of the Posterior Cortical-Hippocampal Network Enhances Precision of Memory Recollection.
abstract: Episodic memory is thought to critically depend on interaction of the hippocampus with distributed brain regions [1-3]. Specific contributions of distinct networks have been hypothesized, with the hippocampal posterior-medial (HPM) network implicated in the recollection of highly precise contextual and spatial information [3-6]. Current evidence for HPM specialization is mostly indirect, derived from correlative measures such as neural activity recordings. Here we tested the causal role of the HPM network in recollection using network-targeted noninvasive brain stimulation in humans, which has previously been shown to increase functional connectivity within the HPM network [7]. Effects of multiple-day electromagnetic stimulation were assessed using an object-location memory task that segregated recollection precision from general recollection success. HPM network-targeted stimulation produced lasting (∼24 hr) enhancement of recollection precision, without effects on general success. Canonical neural correlates of recollection [8-10] were also modulated by stimulation. Late-positive evoked potential amplitude and theta-alpha oscillatory power were reduced, suggesting that stimulation can improve memory through enhanced reactivation of detailed visuospatial information at retrieval. The HPM network was thus specifically implicated in the processing of fine-grained memory detail, supporting functional specialization of hippocampal-cortical networks. These findings demonstrate that brain networks can be causally linked to distinct and specific neurocognitive functions and suggest mechanisms for long-lasting changes in memory due to network-targeted stimulation.
authors.affiliation: Department of Medical Social Sciences and Interdepartmental Neuroscience Program, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Aneesha S
authors.initials: AS
authors.lastname: Nilakantan
authors.affiliation: Department of Medical Social Sciences and Interdepartmental Neuroscience Program, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Donna J
authors.initials: DJ
authors.lastname: Bridge
authors.affiliation: Department of Medical Social Sciences and Interdepartmental Neuroscience Program, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Elise P
authors.initials: EP
authors.lastname: Gagnon
authors.affiliation: Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: VanHaerents
authors.affiliation: Department of Medical Social Sciences and Interdepartmental Neuroscience Program, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. Electronic address: joel-voss@northwestern.edu.
authors.forename: Joel L
authors.initials: JL
authors.lastname: Voss
mesh_terms: D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005071:Evoked Potentials; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D011939:Mental Recall / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009434:Neural Pathways
keywords: EEG; hippocampus; precision; retrieval; spatial memory; theta; transcranial magnetic stimulation