Academic journal article Canadian Journal of Experimental Psychology

Dissociating the Neural Correlates of Item and Context Memory: An ERP Study of Face Recognition

Academic journal article Canadian Journal of Experimental Psychology

Dissociating the Neural Correlates of Item and Context Memory: An ERP Study of Face Recognition

Article excerpt

Abstract We investigated the neural correlates of item and context retrieval using event-related potentials (ERPs). Particpants studied unfamiliar faces with happy or neutral expressions, and at test, they decided whether test faces were studied in the same or in a different expression, or were new. The parietal ERP effect, which is hypothesized to indirectly reflect medial-temporal lobe (MTL) function, was sensitive to item retrieval, whereas the frontal ERP effect, which is thought to reflect prefrontal cortex (PFC) function, was sensitive to context retrieval. Converging with lesion, functional neuroimaging (PET and fMRI), and ERP evidence, these results support the notion that item retrieval is primarily associated with MTL function whereas context retrieval is primarily associated by PFC function.

Resume Nous avons examine les correlate neuronaux du recouvrement des items et du contexte a l'aide de potentiels evoques. Les participants ont memorise des visages non familiers qui affichaient des expressions joyeuses ou neutres; lors de la reconnaissance, ils devaient decider si les visages presentes affichaient la meme expression ou non, ou encore s'ils etaient nouveaux. Le potentiel evoque parietal, que Pon suppose refleter indirectement la fonction du lobe medio-temporal, etait sensible au recouvrement des items, tandis que le frontal, qui refleterait la fonction du cortex prefrontal, 1'etait au recouvrement du contexte. Ces resultats, qui vont dans le meme sens que les informations decoulant d'etudes sur les lesions cerebrales, de la neuro-imagerie fonctionnelle (PET et IRMF) et des potentiels evoques, appuient l'idee selon laquelle le recouvrement des items est principalement associe a la fonction du lobe medio-temporal, alors que le recouvrement du contexte l'est a celle du cortex prefrontal.

Remembering personally experienced past events, or episodic memory retrieval, involves both item and context retrieval. Item retrieval refers to remembering what events happened, and context retrieval, to remembering when (temporal-order memory), where (spatial memory) or how (source memory) they happened. The distinction between item and context retrieval is important because lesion, functional neuroimaging, and electrophysiological evidence suggests that these two components of episodic retrieval involve different neural mechanisms. In the present study, we investigated the neural correlates of item and context retrieval using event-related potentials.

Lesion evidence has associated item retrieval with the medial-temporal lobe, and context retrieval with the prefrontal cortex. In a classic study by Corsi and Milner (cited by Milner, 1971), patients with MTL lesions were impaired in item retrieval (recognition test) but not in context retrieval (temporal-order test) whereas patients with PFC lesions were impaired in context but not in item retrieval. Although this double dissociation may not be generalizable to other forms of item and context memory, numerous studies with human (e.g., Janowsky, Shimamura, & Squire, 1989; Shimamura, Janowsky, & Squire, 1990) and nonhuman primates (e.g., Petrides, 1991) have found that PFC lesions produce greater deficits in context retrieval than in item retrieval.

Functional neuroimaging evidence is also consistent with the idea that item retrieval is primarily associated with MTL function, and context retrieval, with PFC function. A positron emission tomography (PET) study found that MTL was more activated for item retrieval than for context retrieval, whereas PFC was more activated for context than for item retrieval (Cabeza et al., 1997). This double dissociation was significant when differences in task difficulty were statistically removed, and when item and context conditions with similar levels of performance were compared. Greater PFC activity for context than for item retrieval was also found in several functional magnetic resonance imaging (fMRI) studies (e. …

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