Unconscious relational encoding depends on hippocampus

Duss, Simone; Reber, Thomas P; Hänggi, Jürgen; Schwab, Simon; Wiest, Roland; Müri, René Martin; Brugger, Peter; Gutbrod, Klemens; Henke, Katharina (2014). Unconscious relational encoding depends on hippocampus. Brain, 137(12), pp. 3355-3370. Oxford University Press 10.1093/brain/awu270

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Textbooks divide between human memory systems based on consciousness. Hippocampus is thought to support only conscious encoding, while neocortex supports both conscious and unconscious encoding. We tested whether processing modes, not consciousness, divide between memory systems in three neuroimaging experiments with 11 amnesic patients (mean age = 45.55 years, standard deviation = 8.74, range = 23-60) and 11 matched healthy control subjects. Examined processing modes were single item versus relational encoding with only relational encoding hypothesized to depend on hippocampus. Participants encoded and later retrieved either single words or new relations between words. Consciousness of encoding was excluded by subliminal (invisible) word presentation. Amnesic patients and controls performed equally well on the single item task activating prefrontal cortex. But only the controls succeeded on the relational task activating the hippocampus, while amnesic patients failed as a group. Hence, unconscious relational encoding, but not unconscious single item encoding, depended on hippocampus. Yet, three patients performed normally on unconscious relational encoding in spite of amnesia capitalizing on spared hippocampal tissue and connections to language cortex. This pattern of results suggests that processing modes divide between memory systems, while consciousness divides between levels of function within a memory system.

Item Type: Journal Article (Original Article)
Division/Institute: 04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology
04 Faculty of Medicine > University Psychiatric Services > University Hospital of Psychiatry and Psychotherapy > Psychiatric Neurophysiology (discontinued)
07 Faculty of Human Sciences > Institute of Psychology
04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic and Interventional Neuroradiology
07 Faculty of Human Sciences > Institute of Psychology > Experimental Psychology and Neuropsychology
10 Strategic Research Centers > Center for Cognition, Learning and Memory (CCLM)
UniBE Contributor: Duss, Simone; Schwab, Simon; Wiest, Roland; Müri, René Martin; Brugger, Peter; Gutbrod, Klemens and Henke, Katharina
Subjects: 100 Philosophy > 150 Psychology
600 Technology > 610 Medicine & health
ISSN: 0006-8950
Publisher: Oxford University Press
Language: English
Submitter: Valentina Rossetti
Date Deposited: 13 Oct 2014 13:05
Last Modified: 06 Jan 2015 09:02
Publisher DOI: 10.1093/brain/awu270
PubMed ID: 25273998
Uncontrolled Keywords: flexible implicit nondeclarative relational subliminal
BORIS DOI: 10.7892/boris.59084
URI: http://boris.unibe.ch/id/eprint/59084

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