title: Electrophysiological correlates of deficient encoding in a case of post-anoxic amnesia.
abstract: Little is known about the initial stages of information processing in amnesia as compared to normal memory. In this study, we used electrical spatiotemporal mapping to compare cortical activation during encoding and recognition in a 56-year-old patient with severe, chronic post-anoxic amnesia and an age-matched control group. Event-related potentials were recorded as the subjects performed a continuous recognition task composed of meaningful designs. Activation in the control group rapidly progressed through eight different electrocortical configurations over 700 ms after onset of new stimuli. In contrast, activation in the amnesic patient was highly monotonous: it showed varying electrocortical patterns only during the first 150 ms but then remained abnormally stable for the remainder of the analysed time window. Electrical source localisation revealed that the patient failed to activate distributed cortical networks and that his processing was confined to visual areas. The present study suggests that the rapid activation of distributed cortical networks is critical for efficient encoding.
authors.affiliation: Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital, CH-1211 Geneva 14, Switzerland.
authors.forename: Sandra
authors.initials: S
authors.lastname: Lehmann
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Morand
authors.forename: Clara
authors.initials: C
authors.lastname: James
authors.forename: Armin
authors.initials: A
authors.lastname: Schnider
mesh_terms: D000647:Amnesia / Q000209:etiology / Q000503:physiopathology*; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000150:complications; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time; D021641:Recognition, Psychology; D013057:Spectrum Analysis; D013997:Time Factors