title: The brain-derived neurotrophic factor Val66Met polymorphism affects encoding of object locations during active navigation.
abstract: The brain-derived neurotrophic factor (BDNF) was shown to be involved in spatial memory and spatial strategy preference. A naturally occurring single nucleotide polymorphism of the BDNF gene (Val66Met) affects activity-dependent secretion of BDNF. The current event-related fMRI study on preselected groups of 'Met' carriers and homozygotes of the 'Val' allele investigated the role of this polymorphism on encoding and retrieval in a virtual navigation task in 37 healthy volunteers. In each trial, participants navigated toward a target object. During encoding, three positional cues (columns) with directional cues (shadows) were available. During retrieval, the invisible target had to be replaced while either two objects without shadows (objects trial) or one object with a shadow (shadow trial) were available. The experiment consisted of blocks, informing participants of which trial type would be most likely to occur during retrieval. We observed no differences between genetic groups in task performance or time to complete the navigation tasks. The imaging results show that Met carriers compared to Val homozygotes activate the left hippocampus more during successful object location memory encoding. The observed effects were independent of non-significant performance differences or volumetric differences in the hippocampus. These results indicate that variations of the BDNF gene affect memory encoding during spatial navigation, suggesting that lower levels of BDNF in the hippocampus results in less efficient spatial memory processing.
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, Nijmegen, 6500 HE, The Netherlands.|Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, PO Box 9101, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Wegman
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, Nijmegen, 6500 HE, The Netherlands.|Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, PO Box 9101, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Anna
authors.initials: A
authors.lastname: Tyborowska
authors.affiliation: Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.|Department of Language and Genetics, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands.
authors.forename: Martine
authors.initials: M
authors.lastname: Hoogman
authors.affiliation: Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.|Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Arias Vásquez
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, Nijmegen, 6500 HE, The Netherlands.|Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, PO Box 9101, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Janzen
mesh_terms: D000328:Adult; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D006624:Hippocampus / Q000502:physiology; D006720:Homozygote; D006801:Humans; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide; D065854:Spatial Navigation
chemical_list: D019208:Brain-Derived Neurotrophic Factor
keywords: 
  fMRI
  ; BDNF Val66Met polymorphism; hippocampus; imaging genomics; spatial memory