title: Pre-stimulus thalamic theta power predicts human memory formation.
abstract: Pre-stimulus theta (4-8Hz) power in the hippocampus and neocortex predicts whether a memory for a subsequent event will be formed. Anatomical studies reveal thalamus-hippocampal connectivity, and lesion, neuroimaging, and electrophysiological studies show that memory processing involves the dorsomedial (DMTN) and anterior thalamic nuclei (ATN). The small size and deep location of these nuclei have limited real-time study of their activity, however, and it is unknown whether pre-stimulus theta power predictive of successful memory formation is also found in these subcortical structures. We recorded human electrophysiological data from the DMTN and ATN of 7 patients receiving deep brain stimulation for refractory epilepsy. We found that greater pre-stimulus theta power in the right DMTN was associated with successful memory encoding, predicting both behavioral outcome and post-stimulus correlates of successful memory formation. In particular, significant correlations were observed between right DMTN theta power and both frontal theta and right ATN gamma (32-50Hz) phase alignment, and frontal-ATN theta-gamma cross-frequency coupling. We draw the following primary conclusions. Our results provide direct electrophysiological evidence in humans of a role for the DMTN as well as the ATN in memory formation. Furthermore, prediction of subsequent memory performance by pre-stimulus thalamic oscillations provides evidence that post-stimulus differences in thalamic activity that index successful and unsuccessful encoding reflect brain processes specifically underpinning memory formation. Finally, the findings broaden the understanding of brain states that facilitate memory encoding to include subcortical as well as cortical structures.
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: catherine.sweeney-reed@med.ovgu.de.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Sweeney-Reed
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: tino.zaehle@ovgu.de.
authors.forename: Tino
authors.initials: T
authors.lastname: Zaehle
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: juergen.voges@med.ovgu.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Voges
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: fc.schmitt@med.ovgu.de.
authors.forename: Friedhelm C
authors.initials: FC
authors.lastname: Schmitt
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: lars.buentjen@med.ovgu.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Buentjen
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: klaus.kopitzki@med.ovgu.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kopitzki
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: alan.richardson-klavehn@med.ovgu.de.
authors.forename: Alan
authors.initials: A
authors.lastname: Richardson-Klavehn
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany; German Centre for Neurodegenerative Diseases (DZNE), Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: hermann.hinrichs@med.ovgu.de.
authors.forename: Hermann
authors.initials: H
authors.lastname: Hinrichs
authors.affiliation: Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany; German Centre for Neurodegenerative Diseases (DZNE), Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Electronic address: hans-jochen.heinze@med.ovgu.de.
authors.forename: Hans-Jochen
authors.initials: HJ
authors.lastname: Heinze
authors.affiliation: Helen Wills Neuroscience Institute and Department of Psychology, University of California, Tolman Hall, MC 3192, Berkeley, CA 94720, USA. Electronic address: rtknight@berkeley.edu.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Knight
authors.affiliation: Center for Vital Longevity and School of Behavioral and Brain Sciences, University of Texas, Dallas, TX 75235, USA. Electronic address: mdr104020@utdallas.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Rugg
mesh_terms: D000328:Adult; D020643:Anterior Thalamic Nuclei / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D003210:Concept Formation / Q000502:physiology*; D046690:Deep Brain Stimulation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D020645:Mediodorsal Thalamic Nucleus / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Anterior thalamic nucleus; Dorsomedial thalamic nucleus; Encoding; Memory; Pre-stimulus theta; Thalamus