Activating the Medial Temporal Lobe during Oddity Judgment for Faces and Scenes

• Published in: Cerebral cortex (New York, N.Y. 1991) Vol. 18; no. 3; pp. 683 - 696
• Main Authors: Lee, Andy C. H., Scahill, Victoria L., Graham, Kim S.
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.03.2008; Oxford Publishing Limited (England)
• Subjects: Adult; Discrimination Learning - physiology; Face; Female; hippocampus; Humans; Judgment - physiology; Male; memory; Memory - physiology; Pattern Recognition, Visual - physiology; perception; perirhinal cortex; Photic Stimulation - methods; Reaction Time - physiology; Temporal Lobe - physiology; visual discrimination; memory; hippocampus; visual discrimination; perception; perirhinal cortex
• ISSN: 1047-3211; 1460-2199
• DOI: 10.1093/cercor/bhm104

Impairments in visual discrimination beyond long-term declarative memory have been found in amnesic individuals, with hippocampal lesions resulting in deficits in scene discrimination and perirhinal cortex damage affecting object discrimination. To complement these findings, the present functional magnetic resonance imaging study found that in healthy participants oddity judgment for novel trial-unique scenes, compared with face or size oddity, was associated with increased posterior hippocampus and parahippocampal cortex activity. In contrast, perirhinal and anterior hippocampus activity was observed during unfamiliar trial-unique face oddity judgment, when contrasted with scene or size oddity tasks. Activity in all of these regions decreased as the stimuli were repeated across trials, reflecting the participants' increasing familiarity with the stimuli. This change was significant in all areas, with the exception of the perirhinal cortex, right anterior hippocampus, and to a lesser extent the left anterior hippocampus during face oddity judgment. One possibility is that the activity in these regions may not reflect entirely episodic memory encoding but, in part, processes beyond the mnemonic domain. Thus, the perirhinal cortex, and possibly anterior hippocampus, may play a more generic role in the discrimination and processing of objects.