title: Hippocampal glutamate concentration predicts cerebral theta oscillations during cognitive processing.
abstract: BACKGROUND
  Brain waves reflect collective behavior of neurons and provide insight into distributed network processing. Frontal and hippocampal theta oscillations (4-7 Hz) were linked to cognitive tasks and animal studies have suggested an involvement of glutamatergic neurotransmission in integrative frontal-hippocampal processing. Human evidence for such relationships is lacking.
  
  
  METHODS
  Here, we studied the associations between glutamate concentrations in the hippocampal region, measured by a 3-T proton magnetic resonance spectroscopy (1H-MRS), and EEG theta activity during an auditory target detection paradigm.
  
  
  RESULTS
  A robust relationship between hippocampal glutamate and frontal theta activity during stimulus processing was found. Moreover, frontal theta oscillations were related to response speed.
  
  
  CONCLUSIONS
  The results suggest a functional coupling between the frontal cortex and hippocampal region during stimulus processing and support the idea of the hippocampus as a neural rhythm generator driven by glutamatergic neurotransmission. These preliminary data show, for the first time, a relationship between in vivo measured glutamate and basic cerebral information processing in humans.
authors.affiliation: Clinic for Psychiatry and Psychotherapy (PUK im SHK), Charité-University Medicine Berlin, Campus Mitte, St. Hedwig Krankenhaus, Turmstrasse 21, 10559 Berlin, Germany. juergen.gallinat@charite.de
authors.forename: J
authors.initials: J
authors.lastname: Gallinat
authors.forename: D
authors.initials: D
authors.lastname: Kunz
authors.forename: D
authors.initials: D
authors.lastname: Senkowski
authors.forename: T
authors.initials: T
authors.lastname: Kienast
authors.forename: F
authors.initials: F
authors.lastname: Seifert
authors.forename: F
authors.initials: F
authors.lastname: Schubert
authors.forename: A
authors.initials: A
authors.lastname: Heinz
mesh_terms: D000328:Adult; D003071:Cognition / Q000502:physiology*; D005260:Female; D018698:Glutamic Acid / Q000032:analysis / Q000502:physiology*; D006624:Hippocampus / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D011930:Reaction Time; D013826:Theta Rhythm
chemical_list: D018698:Glutamic Acid