title: Sparse and distributed coding of episodic memory in neurons of the human hippocampus.
abstract: Neurocomputational models hold that sparse distributed coding is the most efficient way for hippocampal neurons to encode episodic memories rapidly. We investigated the representation of episodic memory in hippocampal neurons of nine epilepsy patients undergoing intracranial monitoring as they discriminated between recently studied words (targets) and new words (foils) on a recognition test. On average, single units and multiunits exhibited higher spike counts in response to targets relative to foils, and the size of this effect correlated with behavioral performance. Further analyses of the spike-count distributions revealed that (i) a small percentage of recorded neurons responded to any one target and (ii) a small percentage of targets elicited a strong response in any one neuron. These findings are consistent with the idea that in the human hippocampus episodic memory is supported by a sparse distributed neural code.
authors: Departments of Psychology, jwixted@ucsd.edu lsquire@ucsd.edu.
authors: John T
authors: JT
authors: Wixted
authors: Departments of Psychology,Psychiatry, andNeurosciences, University of California, San Diego, La Jolla, CA 92093;Veterans Affairs Medical Center, San Diego, CA 92161; jwixted@ucsd.edu lsquire@ucsd.edu.
authors: Larry R
authors: LR
authors: Squire
authors: Department of Psychology, University of Montana, Missoula, MT 59812;
authors: Yoonhee
authors: Y
authors: Jang
authors: Department of Psychology, Louisiana State University, Baton Rouge, LA 70803;
authors: Megan H
authors: MH
authors: Papesh
authors: Department of Psychology, Arizona State University, Tempe, AZ 85287; and.
authors: Stephen D
authors: SD
authors: Goldinger
authors: Departments of Psychology.
authors: Joel R
authors: JR
authors: Kuhn
authors: Departments of Neurosurgery and.
authors: Kris A
authors: KA
authors: Smith
authors: Neurology, Barrow Neurological Institute, Phoenix, AZ 85013.
authors: David M
authors: DM
authors: Treiman
authors: Departments of Neurosurgery andNeurology, Barrow Neurological Institute, Phoenix, AZ 85013.
authors: Peter N
authors: PN
authors: Steinmetz
mesh_terms: D004827:Epilepsy / Q000503:physiopathology*; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D061212:Memory, Episodic; D008959:Models, Neurological; D064926:Neurophysiological Monitoring; D009483:Neuropsychological Tests
keywords: amygdala; intracranial recording; recognition memory