Effects of cortical thickness, volume, and memory performance on age differences in neural reinstatement of scene information.

The strength of neural reinstatement, a correlate of episodic memory retrieval, reportedly reflects the amount and fidelity of mnemonic content and is weaker in older than younger adults, especially for scene memoranda. Based on evidence that age-related declines in cortical thickness and volume contribute to age-related cognitive decline, we analyzed functional magnetic resonance imaging data acquired from healthy young and older adults to examine relationships between cortical thickness, cortical volume, age, and scene-related reinstatement in 3 cortical regions implicated in scene processing: the parahippocampal place area, medial place area, and occipital place area. A "reinstatement index" was estimated from functional magnetic resonance imaging data collected during tests of source memory for scene images, and multiple regression analyses were employed to examine the effects of the variables of interest on scene reinstatement.

fMRI BOLD signals in the left angular gyrus and hippocampus are associated with memory precision.

Prior functional magnetic resonance (fMRI) studies examining the neural correlates of retrieval success and precision have reported inconsistent results. Here, we examined the neural correlates of success and precision in a test of memory for spatial location. The present study extended prior findings by employing an experimental design that minimized temporal overlap between mnemonic and visuomotor processing.

Repetition-related reductions in neural activity support improved behavior through increases in oscillatory power.

Repeatedly processing an object leads to subsequent behavioral improvements in its identification and reductions in associated neural activity, a form of neural processing efficiency that multiple theoretical models have attempted to explain. Using simultaneous fMRI-EEG in humans during object naming, we find that stimulus-driven oscillatory power from high (gamma) to low frequencies (theta) increases and resolves earlier with repetition in task-engaged frontal and occipitotemporal brain regions identified as showing repetition suppression in fMRI. Changes in gamma oscillatory power in these regions were correlated with behavioral priming across subjects and additionally with fMRI repetition suppression in left frontal cortex, providing multimodal support for a novel mixture of the previously proposed Synchrony and Facilitation models.

Effects of age on the strategic control of recollected content as reflected by modulation of neural correlates of scene retrieval.

A previous study employing fMRI measures of retrieval-related neural selectivity reported that young, but not older, adults employ 'retrieval gating' to attenuate aspects of an episodic memory that are irrelevant to the retrieval goal. We examined whether the weak memories of the older adults in that study rendered goal-irrelevant memories insufficiently intrusive to motivate retrieval gating. Young and older participants studied words superimposed on rural or urban scenes, or on scrambled backgrounds.

Effects of cortical thickness, volume, and memory performance on age differences in neural reinstatement of scene information.

The strength of neural reinstatement, a correlate of episodic memory retrieval, reportedly reflects the amount and fidelity of mnemonic content and is weaker in older than younger adults, especially for scene memoranda. Based on evidence that age-related declines in cortical thickness and volume contribute to age-related cognitive decline, we analyzed fMRI data acquired from healthy young and older adults to examine relationships between cortical thickness, cortical volume, age, and scene-related reinstatement in three cortical regions implicated in scene processing: the parahippocampal place area (PPA), medial place area (MPA), and occipital place area (OPA). A 'reinstatement index' was estimated from fMRI data collected during tests of source memory for scene images, and multiple regression analyses were employed to examine the effects of the variables of interest on scene reinstatement.

Effects of age in the strategic control of recollected content as reflected by modulation of scene reinstatement.

A previous study employing fMRI measures of retrieval-related cortical reinstatement reported that young, but not older, adults employ 'retrieval gating' to attenuate aspects of an episodic memory that are irrelevant to the retrieval goal. We examined whether the weak memories of the older adults in that study rendered goal-irrelevant memories insufficiently intrusive to motivate retrieval gating. Young and older participants studied words superimposed on rural or urban scenes, or on pixelated backgrounds.

Recollection-related fMRI effects in entorhinal cortex predict longitudinal memory change in healthy older adults.

The present study examines whether structural and functional variability in medial temporal lobe (MTL) neocortical regions correlate with individual differences in episodic memory and longitudinal memory change in cognitively healthy older adults. To address this question, older adults were administered a battery of neuropsychological tests on three occasions: the second occasion one month after the first test session, and a third session three years later. Structural and functional MRI data were acquired between the first two sessions and included an in-scanner associative recognition procedure enabling estimation of MTL encoding and recollection fMRI BOLD effects.

Neural Correlates of Retrieval Success and Precision: A Functional Magnetic Resonance Imaging Study.

Prior studies examining the neural mechanisms underlying retrieval success and precision have yielded inconsistent results. Here, the neural correlates of success and precision were examined with a memory task that assessed precision for spatial location. A sample of healthy young adults underwent fMRI scanning during a single study-test cycle.

Free water-corrected fractional anisotropy of the fornix and parahippocampal cingulum predicts longitudinal memory change in cognitively healthy older adults.

Prior studies have reported inconsistent results regarding the relationships between the integrity of the fornix and parahippocampal cingulum and both memory performance and longitudinal change in performance. In the present study, we examined associations in a sample of cognitively healthy older adults between free water-corrected fractional anisotropy (FA) metrics derived from the fornix and cingulum, baseline memory performance, and 3-year memory change. Neither fornix nor cingulum FA correlated with memory performance at baseline.

Neural correlates of retrieval success and precision: an fMRI study.

Prior studies examining the neural mechanisms underlying retrieval success and precision have yielded inconsistent results. Here, their neural correlates were examined using a memory task that assessed precision for spatial location. A sample of healthy young adults underwent fMRI scanning during a single study-test cycle.

Dissociative Effects of Age on Neural Differentiation at the Category and Item Levels.

Increasing age is associated with age-related neural dedifferentiation, a reduction in the selectivity of neural representations, which has been proposed to contribute to cognitive decline in older age. Recent findings indicate that when operationalized in terms of selectivity for different perceptual categories, age-related neural dedifferentiation and the apparent age-invariant association of neural selectivity with cognitive performance are largely restricted to the cortical regions typically recruited during scene processing. It is currently unknown whether this category-level dissociation extends to metrics of neural selectivity defined at the level of individual stimulus items.

Relationships between age, fMRI correlates of familiarity and familiarity-based memory performance under single and dual task conditions.

Using fMRI, we investigated the effects of age and divided attention on the neural correlates of familiarity and their relationship with memory performance. At study, word pairs were visually presented to young and older participants under the requirement to make a relational judgment on each pair. Participants were then scanned while undertaking an associative recognition test under single and dual (auditory tone detection) task conditions.

Age differences in the neural correlates of recollection: transient versus sustained fMRI effects.

Prior functional magnetic resonance imaging findings in young adults indicate that recollection-sensitive neural regions dissociate according to the time courses of their respective recollection effects. Here, we examined whether such dissociations are also evident in older adults. Young and older participants encoded a series of word-image pairs, judging which of the denoted objects was the smaller.

Supervised machine learning classification of psychosis biotypes based on brain structure: findings from the Bipolar-Schizophrenia network for intermediate phenotypes (B-SNIP).

Traditional diagnostic formulations of psychotic disorders have low correspondence with underlying disease neurobiology. This has led to a growing interest in using brain-based biomarkers to capture biologically-informed psychosis constructs. Building upon our prior work on the B-SNIP Psychosis Biotypes, we aimed to examine whether structural MRI (an independent biomarker not used in the Biotype development) can effectively classify the Biotypes.

A meta-analysis of event-related potential correlates of recognition memory.

A longstanding question in memory research is whether recognition is supported by more than one mnemonic process. Dual-process models distinguish recollection of episodic detail from familiarity, while single-process models explain recognition in terms of one process that varies in strength. Dual process models have drawn support from findings that recollection and familiarity elicit distinct electroencephalographic event-related potentials (ERPs): a mid-frontal ERP effect that occurs at around 300-500 ms post-stimulus onset and is often larger for familiarity than recollection contrasts, and a parietal ERP effect that occurs at around 500-800 ms and is larger for recollection than familiarity contrasts.

Relationships between age, fMRI correlates of familiarity and familiarity-based memory performance under single and dual task conditions.

Using fMRI, we investigated the effects of age and divided attention on the neural correlates of familiarity and their relationship with memory performance. At study, word pairs were visually presented to young and older participants under the requirement to make a relational judgment on each pair. Participants were then scanned while undertaking an associative recognition test under single and dual (auditory tone detection) task conditions.

Dissociative effects of age on neural differentiation at the category and item level.

Increasing age is associated with age-related neural dedifferentiation, a reduction in the selectivity of neural representations which has been proposed to contribute to cognitive decline in older age. Recent findings indicate that when operationalized in terms of selectivity for different perceptual categories, age-related neural dedifferentiation, and the apparent age-invariant association of neural selectivity with cognitive performance, are largely restricted to the cortical regions typically recruited during scene processing. It is currently unknown whether this category-level dissociation extends to metrics of neural selectivity defined at the level of individual stimulus items.

The effects of age on neural correlates of recollection: transient versus sustained fMRI effects.

Prior fMRI findings in young adults indicate that recollection-sensitive neural regions dissociate according to the time courses of their respective recollection effects. Here, we examined whether such dissociations are also evident in older adults. Young and older participants encoded a series of word-object image pairs, judging which of the denoted objects was the smaller.

Cortical thickness, gray matter volume, and cognitive performance: a crosssectional study of the moderating effects of age on their interrelationships.

In a sample comprising younger, middle-aged, and older cognitively healthy adults (N = 375), we examined associations between mean cortical thickness, gray matter volume (GMV), and performance in 4 cognitive domains-memory, speed, fluency, and crystallized intelligence. In almost all cases, the associations were moderated significantly by age, with the strongest associations in the older age group. An exception to this pattern was identified in a younger adult subgroup aged <23 years when a negative association between cognitive performance and cortical thickness was identified.

Effects of age on the neural correlates of encoding source and item information: An fMRI study.

The effects of age on encoding-related neural activity predictive of accurate item and source memory judgments were examined with fMRI, with an a priori focus of the inferior frontal gyrus (IFG) and hippocampus. During a scanned study phase, young and older adults viewed a series of pictures of objects and made one of two judgments on each object. At test, which occurred outside of the scanner, an 'old/new' judgment on each test item was followed, for those items endorsed old, by a source judgment querying the study task.

Patterns of retrieval-related cortico-striatal connectivity are stable across the adult lifespan.

Memory retrieval effects in the striatum are well documented and robust across experimental paradigms. However, the functional significance of these effects, and whether they are moderated by age, remains unclear. We used functional magnetic resonance imaging paired with an associative recognition task to examine retrieval effects in the striatum in a sample of healthy young, middle-aged, and older adults.

Transcranial magnetic stimulation of right dorsolateral prefrontal cortex does not affect associative retrieval in healthy young or older adults.

We examined whether post-retrieval monitoring processes supporting memory performance are more resource limited in older adults than younger individuals. We predicted that older adults would be more susceptible to an experimental manipulation that reduced the neurocognitive resources available to support post-retrieval monitoring. Young and older adults received transcranial magnetic stimulation (TMS) to the right dorsolateral prefrontal cortex (DLPFC) or a vertex control site during an associative recognition task.

Sensitivity of the hippocampus to objective but not subjective episodic memory judgments.

We assessed whether neural activity in the hippocampus dissociates according to whether memory test items elicit a subjective sense of recollection or accurate retrieval of contextual information. We reanalyzed a previously acquired dataset from a study in which participants made both objective (source memory for spatial context) and subjective (Remember-Know) judgments for each test item. Results indicated that the hippocampus was exclusively sensitive to the amount of contextual information retrieved, such that accurate source memory judgments were associated with greater activity than inaccurate judgments, regardless of Remember/Know status.

Divided attention at retrieval does not influence neural correlates of recollection in young or older adults.

Age-related decline in episodic memory has been partially attributed to older adults' reduced domain general processing resources. In the present study, we examined the effects of divided attention (DA) - a manipulation assumed to further deplete the already limited processing resources of older adults - on the neural correlates of recollection in young and older adults. Participants underwent fMRI scanning while they performed an associative recognition test in single and dual (tone detection) task conditions.

The Retrieval-Related Anterior Shift Is Moderated by Age and Correlates with Memory Performance.

Recent research suggests that episodic memory is associated with systematic differences in the localization of neural activity observed during memory encoding and retrieval. The retrieval-related anterior shift is a phenomenon whereby the retrieval of a stimulus event (e.g.