Recognition memory is thought to be supported by two processes: the recollection of contextual information and an acontextual sense of familiarity from a previously experienced episode. There has been considerable interest in whether the hippocampus selectively supports recollection or whether the hippocampus contributes to both recollection and familiarity when memories are strong. Here, I briefly review results from event-related functional magnetic resonance imaging (fMRI) studies investigating the relationship between retrieval-related hippocampal activity and the recollection of contextual (source) information. On the basis of these findings, I argue that retrieval-related activity in the hippocampus is not modulated by differences in the undifferentiated memory strength elicited by test items. Instead, hippocampal activity is more likely to be sensitive to recollection success or to the amount of contextual information that is recollected in response to a test item.

抄録全体を表示

What are the neural markers of encoding and retrieving emotional events with increased efficacy? In recent years, this question has captured the attention of cognitive neuroscientists who fervently engaged in addressing it using a multitude of approaches. The present review discusses evidence from brain imaging studies investigating the neural correlates of the memory-enhancing effect of emotion in healthy human participants. The available evidence points to two main mechanisms: one direct involving the medial temporal lobe (MTL), and the other indirect involving the prefrontal cortex (PFC), among other brain regions. Recent studies also showed that these mechanisms are sensitive to aspects relevant to social interactions, as well as to personality-, sex- and age-related differences. Overall, this evidence provides insights into the brain mechanisms that make emotional memories special, and points to possible alterations that could lead to negative affective biases in encoding and remembering emotional memories observed in affective disorders.

抄録全体を表示

Recent advances in fMRI methodology have allowed researchers to examine age-related neural differences underlying episodic memory from both a quantitative and network level approach. Specifically, BOLD (blood-oxygen-level-dependent) contrasts have observed age-related decreases and increases in overall neural activation. Regarding increases, the pattern of activity often results in more bilateral frontal activation (described as Hemispheric Asymmetry Reduction in OLDer adults; HAROLD) or greater recruitment of frontal regions (described as Posterior to Anterior Shift in Aging; PASA) in aging. These increases are largely interpreted as compensatory and beneficial to memory performance. Similar to BOLD findings, connectivity analyses showed age-related plasticity within the episodic memory network, with results converging on a similar posterior-to-anterior shift in the coherence of regions associated with medial temporal lobe activity during episodic encoding and retrieval. This paper reviews the latest neuroimaging findings across both BOLD and connectivity results associated with age-related differences in episodic memory.

抄録全体を表示

It is widely recognized that human memory is an imperfect process that sometimes causes various kinds of distortions and illusions. Recently, some light has been shed on the brain mechanisms involved in this false memory phenomenon as a result of research into its neural basis embarked on by cognitive neuroscientists. This article reviews neuroimaging studies that have attempted to distinguish between true and false memory retrieval. It also reviews neuroimaging studies that have measured neural activity during encoding and addresses the question of whether the encoding-related neural activity predicts subsequent memory distortions. Finally, there is a brief discussion from the cognitive neuroscience perspective about whether the memory distortion reflects deficient cognitive processing or is a by-product of adaptive cognitive processing.

抄録全体を表示

Recent studies have documented cognitive and neural processes related to human abilities for prospection and prospective memory. In this review article, I discuss functional neuroimaging findings on these two inter-related neurocognitive processes in humans, which are both thought to develop in relation to episodic memory. Prospection is the ability to construct ideas about possible future events, whereas prospective memory involves the formation and encoding of personal behavioural plans that are then maintained and retrieved at a planned time (or condition) during other ongoing activities. A growing body of neuroimaging studies investigating human prospection has consistently identified a core brain network consisting of medial regions of the frontal, temporal, and parietal lobes. The medial prefrontal cortex has also been identified to play a significant role for executive processes in prospective memory. Further investigations will be needed to disambiguate the contributions of the medial temporal lobe in constructing, encoding, and remembering future plans.

抄録全体を表示