Age-related differences in the neural correlates mediating false recollection.

The current study investigated the effects of aging on the neural basis underlying true and false recollection. Although older adults, compared with younger adults, exhibited equivalent rates of true recollection, age differences in true recollection showed a pattern of activity commonly found among previous memory studies (e.g., age-related decreases in occipital and increases in prefrontal cortices), suggesting reduced retrieval of perceptual details associated with encoding items and a greater reliance on top-down compensatory processing. With regard to false recollection, older adults exhibited significantly greater false recollection yet did not exhibit increased neural processing. They did exhibit decreased activity in prefrontal, parahippocampal gyrus, and occipitoparietal cortex, suggesting a reduced reliance on reconstruction processes mediating false recollection in young. An individual differences analysis in older adults found false recollection rates predicted activity in several regions. including bilateral middle/superior temporal gyrus. Taken together, these results indicate that increases in false recollection in aging may be mediated by reduced access to encoding-related details as well as reliance on semantic gist and familiarity-related neural activity.

Dennis NA ，Bowman CR ，Peterson KM 《-》

What's the gist? The influence of schemas on the neural correlates underlying true and false memories.

The current study used a novel scene paradigm to investigate the role of encoding schemas on memory. Specifically, the study examined the influence of a strong encoding schema on retrieval of both schematic and non-schematic information, as well as false memories for information associated with the schema. Additionally, the separate roles of recollection and familiarity in both veridical and false memory retrieval were examined. The study identified several novel results. First, while many common neural regions mediated both schematic and non-schematic retrieval success, schematic recollection exhibited greater activation in visual cortex and hippocampus, regions commonly shown to mediate detailed retrieval. More effortful cognitive control regions in the prefrontal and parietal cortices, on the other hand, supported non-schematic recollection, while lateral temporal cortices supported familiarity-based retrieval of non-schematic items. Second, both true and false recollection, as well as familiarity, were mediated by activity in left middle temporal gyrus, a region associated with semantic processing and retrieval of schematic gist. Moreover, activity in this region was greater for both false recollection and false familiarity, suggesting a greater reliance on lateral temporal cortices for retrieval of illusory memories, irrespective of memory strength. Consistent with previous false memory studies, visual cortex showed increased activity for true compared to false recollection, suggesting that visual cortices are critical for distinguishing between previously viewed targets and related lures at retrieval. Additionally, the absence of common visual activity between true and false retrieval suggests that, unlike previous studies utilizing visual stimuli, when false memories are predicated on schematic gist and not perceptual overlap, there is little reliance on visual processes during false memory retrieval. Finally, the medial temporal lobe exhibited an interesting dissociation, showing greater activity for true compared to false recollection, as well as for false compared to true familiarity. These results provided an indication as to how different types of items are retrieved when studied within a highly schematic context. Results both replicate and extend previous true and false memory findings, supporting the Fuzzy Trace Theory.

Webb CE ，Turney IC ，Dennis NA 《-》

True and phantom recollection: an fMRI investigation of similar and distinct neural correlates and connectivity.

Although research suggests that most false memories are mediated by a sense of familiarity, behavioral evidence indicates that some are characterized by retrieval of item-specific details associated with recollection. However, neuroimaging studies have yet to isolate and analyze the neural correlates of false (or phantom) recollection, focusing instead on general recognition processes. In doing so, results are mixed with respect to the role of the medial temporal lobes (MTL) in distinguishing between true and false retrieval. The present study sought to investigate the neural basis of true and phantom recollection and clarify the role of the MTL in dissociating between the two processes. Results showed that true and phantom recollection were associated with a largely overlapping retrieval network including activity in bilateral anterior parahippocampal gyrus, fusiform gyrus, anterior cingulate cortex, and right superior parietal cortex. However, connectivity analyses using two common MTL seeds revealed a more inferior network (fusiform gyrus, hippocampus, middle temporal gyrus) associated with true recollection and a more superior network (superior parietal, superior frontal gyrus, posterior cingulate cortex) associated with false recollection. Finally, direct comparisons between true and phantom recollection showed greater activity in right hippocampus and early visual cortex for true recollection, whereas no region exhibited greater activity for false recollection. Results indicate that while both true and phantom recollection show similar patterns of activation, there are also distinctions in the neural networks contributing to the two recollection processes. Moreover, results conclude that within the MTL, the hippocampus proper can distinguish between true and phantom recollection.

Dennis NA ，Bowman CR ，Vandekar SN 《-》

Encoding- and retrieval-related brain activity underlying false recognition.

We examined the neural activity associated with true and false recognition during both encoding and retrieval using the Remember/Know procedure to separate recollection (i.e., mental reinstatement of experienced events during which unique details of a memory are recalled) and familiarity (i.e., mental awareness that an event has been experienced previously without the unique details of the event) in recognition memory. Neuroimaging data at retrieval revealed that the right parahippocampal gyrus was activated during recollection-based true recognition compared with familiarity-based true recognition, indicating the item-specific retrieval of visual details. This effect in the right parahippocampal gyrus was not observed for false recognition. Contrary to our expectation, the reactivation effect in early visual cortex was not observed during true recognition, as opposed to false recognition. Neuroimaging data at encoding revealed that the right visual cortex (the right occipitotemporal sulcus) was activated during the encoding of items that yielded recollection-based true recognition compared with familiarity-based true recognition, indicating item-specific visual processing. This effect in the right visual cortex was not observed for false recognition. These results suggest that the subjective feeling of Remember/Know with respect to both veridical and false memories varies with the neural activity during both encoding and retrieval.

Abe N ，Fujii T ，Suzuki M ，Ueno A ，Shigemune Y ，Mugikura S ，Takahashi S ，Mori E ... -  《-》

Event congruency and episodic encoding: a developmental fMRI study.

A known contributor to adults' superior memory performance compared to children is their differential reliance on an existing knowledge base. Compared to those of adults, children's semantic networks are less accessible and less established, a difference that is also thought to contribute to children's relative resistance to semantically related false alarms. Using the "congruency effect" - the memory advantage of congruity, we manipulated the encoded stimuli in the present experiment such that the use of the knowledge base at encoding was more - or less - accessible in both children and adults. While being scanned, 15 children (ages 8-11) and 18 young adults saw printed noun/color combinations and were asked to indicate whether each combination existed in nature. A subsequent recognition test was administered outside of the scanner. Behaviorally, although overall memory was higher in the adult group compared to the children, both age groups showed the congruency effect to the same extent. A comparison of the neural substrates supporting the congruency effect between adults and children revealed that whereas adults recruited regions primarily associated with semantic-conceptual processing (e.g., the left PFC and parietal and occipito-temporal cortices), children recruited regions earlier in the processing stream (e.g., the right occipital cortex). This evidence supports the hypothesis that early in development, episodic encoding depends more on perceptual systems, whereas top-down frontal control and parietal structures become more prominent in the encoding process with age. This developmental switch contributes to adults' superior memory performance but may render adults more vulnerable to committing semantically based errors.

Maril A ，Avital R ，Reggev N ，Zuckerman M ，Sadeh T ，Ben Sira L ，Livneh N ... -  《-》