Absence of a mere-exposure effect in older and younger adults.

The mere-exposure effect, in which repeated stimuli are liked more than novel stimuli, is a well-known effect. However, little research has studied adult age differences in mere-exposure effects, despite possible applications in helping older adults transition to new living environments. Here, we report four experiments assessing mere-exposure to neutral-face stimuli in groups of older and younger adult participants tested online.

Neural reactivation and judgements of vividness reveal separable contributions to mnemonic representation.

Mnemonic representations vary in fidelity, sharpness, and strength-qualities that can be examined using both introspective judgements of mental states and objective measures of brain activity. Subjective and objective measures are both valid ways of "reading out" the content of someone's internal mnemonic states, each with different strengths and weaknesses. St-Laurent and colleagues (2015) compared the neural correlates of memory vividness ratings with patterns of neural reactivation evoked during memory recall and found considerable overlap between the two, suggesting a common neural basis underlying these different markers of representational quality.

Influence of target-distractor neural similarity on working memory performance in older and younger adults.

According to the inhibitory deficit hypothesis, older adults often fail to selectively inhibit distractors and attend to relevant information in working memory, leading to poorer memory of target items but better recall of irrelevant distractors compared to younger adults. Here, we explored how neural similarity of activity patterns between relevant and irrelevant stimulus categories impacts memory performance. We found evidence that older adults may benefit from failing to inhibit distractors that are similar to targets, perhaps because sustained neural activation of distractors partially supports maintenance of targets when they share neural resources, allowing for better subsequent recognition of studied target items.

Four-modality imaging of unmedicated subjects with schizophrenia: F-fluorodeoxyglucose and F-fallypride PET, diffusion tensor imaging, and MRI.

Diminished prefrontal function, dopaminergic abnormalities in the striatum and thalamus, reductions in white matter integrity and frontotemporal gray matter deficits are the most replicated findings in schizophrenia. We used four imaging modalities (F-fluorodeoxyglucose and F-fallypride PET, diffusion tensor imaging, structural MRI) in 19 healthy and 25 schizophrenia subjects to assess the relationship between functional (dopamine D/D receptor binding potential, glucose metabolic rate) and structural (fractional anisotropy, MRI) correlates of schizophrenia and their additive diagnostic prediction potential. Multivariate ANOVA was used to compare structural and functional image sets for identification of schizophrenia.

Multivariate FMRI Signatures of Learning in a Hebb Repetition Paradigm With Tone Sequences.

Important information from the environment often arrives to the brain in temporally extended sequences. Language, music, actions, and complex events generally unfold over time. When such informational sequences exceed the limited capacity of working memory, the human brain relies on its ability to accumulate information in long-term memory over several encounters with a complex stimulus.

Reading abilities and dopamine D/D receptor availability: An inverted U-shaped association in subjects with schizophrenia.

Reading impairments are prominent trait-like features of cognitive deficits in schizophrenia, predictive of overall cognitive functioning and presumably linked to dopaminergic abnormalities. To evaluate this, we used F-fallypride PET in 19 healthy and 21 antipsychotic-naïve schizophrenia subjects and correlated dopamine receptor binding potentials in relevant AFNI-derived regions and voxelwise with group performance on WRAT4 single-word reading subtest. Healthy subjects' scores were positively and linearly associated with D/D receptor availability in the rectus, orbital and superior frontal gyri, fusiform and middle temporal gyri, as well as middle occipital gyrus and precuneus, all predominantly in the left hemisphere and previously implicated in reading, hence suggesting that higher dopamine receptor density is cognitively advantageous.

Detailed Episodic Memory Depends on Concurrent Reactivation of Basic Visual Features within the Posterior Hippocampus and Early Visual Cortex.

The hippocampus is a key brain region for the storage and retrieval of episodic memories, but how it performs this function is unresolved. Leading theories posit that the hippocampus stores a sparse representation, or "index," of the pattern of neocortical activity that occurred during perception. During retrieval, reactivation of the index by a partial cue facilitates the reactivation of the associated neocortical pattern.

The influence of long-term memory on working memory: Age-differences in proactive facilitation and interference.

Prior learning can hinder subsequent memory, especially when there is conflict between old and new information. The ability to handle this proactive interference is an important source of differences in memory performance between younger and older adults. In younger participants, Oberauer et al.

Encoding and retrieval eye movements mediate age differences in pattern completion.

Older adults often mistake new information as 'old', yet the mechanisms underlying this response bias remain unclear. Typically, false alarms by older adults are thought to reflect pattern completion - the retrieval of a previously encoded stimulus in response to partial input. However, other work suggests that age-related retrieval errors can be accounted for by deficient encoding processes.

Effects of temporal order and intentionality on reflective attention to words in noise.

Speech perception in noise is a cognitively demanding process that challenges not only the auditory sensory system, but also cognitive networks involved in attention. The predictive coding theory has been influential in characterizing the influence of prior context on processing incoming auditory stimuli, with comparatively less research dedicated to "postdictive" processes and subsequent context effects on speech perception. Effects of subsequent semantic context were evaluated while manipulating the relationship of three target words presented in noise and the temporal position of targets compared to the subsequent contextual cue, demonstrating that subsequent context benefits were present regardless of whether the targets were related to each other and did not depend on the position of the target.

Orienting Attention to Short-Term Memory Representations via Sensory Modality and Semantic Category Retro-Cues.

There is growing interest in characterizing the neural mechanisms underlying the interactions between attention and memory. Current theories posit that reflective attention to memory representations generally involves a fronto-parietal attentional control network. The present study aimed to test this idea by manipulating how a particular short-term memory (STM) representation is accessed, that is, based on its input sensory modality or semantic category, during functional magnetic resonance imaging (fMRI).

The role of anterior and medial dorsal thalamus in associative memory encoding and retrieval.

A growing body of work has revealed a role for the anterior and medial dorsal thalamus in memory. Very few studies, however, have used neuroimaging to test hypotheses regarding these structures' predicted roles in associative memory encoding and retrieval. To fill this gap, our study used fMRI in a group of healthy adults as they performed a face-scene associative memory task.

Holding On to the Past: Older Adults Show Lingering Neural Activation of No-Longer-Relevant Items in Working Memory.

Goal-relevant information can be maintained in working memory over a brief delay interval to guide an upcoming decision. There is also evidence suggesting the existence of a complementary process: namely, the ability to suppress information that is no longer relevant to ongoing task goals. Moreover, this ability to suppress or inhibit irrelevant information appears to decline with age.

Beware (Surprisingly Common) Left-Right Flips in Your MRI Data: An Efficient and Robust Method to Check MRI Dataset Consistency Using AFNI.

Knowing the difference between left and right is generally assumed throughout the brain MRI research community. However, we note widespread occurrences of left-right orientation errors in MRI open database repositories where volumes have contained systematic left-right flips between subject EPIs and anatomicals, due to having incorrect or missing file header information. Here we present a simple method in AFNI for determining the consistency of left and right within a pair of acquired volumes for a particular subject; the presence of EPI-anatomical inconsistency, for example, is a sign that dataset header information likely requires correction.

Feature-specific neural reactivation during episodic memory.

We present a multi-voxel analytical approach, feature-specific informational connectivity (FSIC), that leverages hierarchical representations from a neural network to decode neural reactivation in fMRI data collected while participants performed an episodic visual recall task. We show that neural reactivation associated with low-level (e.g.

Representation of viewed and recalled film clips in patterns of brain activity in a person with developmental amnesia.

As clear memories transport us back into the past, the brain also revives prior patterns of neural activity, a phenomenon known as neural reactivation. While growing evidence indicates a link between neural reactivation and typical variations in memory performance in healthy individuals, it is unclear how and to what extent reactivation is disrupted by a memory disorder. The current study characterizes neural reactivation in a case of amnesia using Multivoxel Pattern Analysis (MVPA).

Relationship between white matter glucose metabolism and fractional anisotropy in healthy and schizophrenia subjects.

Decreased fractional anisotropy and increased glucose utilization in the white matter have been reported in schizophrenia. These findings may be indicative of an inverse relationship between these measures of white matter integrity and metabolism. We used F-fluorodeoxyglucose positron emission tomography and diffusion-tensor imaging in 19 healthy and 25 schizophrenia subjects to assess and compare coterritorial correlation patterns between glucose utilization and fractional anisotropy on a voxel-by-voxel basis and across a range of automatically placed representative white matter regions of interest.

Eye movements support behavioral pattern completion.

The ability to recall a detailed event from a simple reminder is supported by pattern completion, a cognitive operation performed by the hippocampus wherein existing mnemonic representations are retrieved from incomplete input. In behavioral studies, pattern completion is often inferred through the false endorsement of lure (i.e.

Eyes Wide Shut: Gaze dynamics without vision, Symposium 6 at the 20th European Conference on Eye Movement Research (ECEM) in Alicante, 21.8.2019.

The human ability for visualization extends far beyond the physical items that surround us. We are able to dismiss the constant influx of photons hitting our retinas, and instead picture the layout of our kindergarten classroom, envision the gently swaying palm trees of our dream vacation, or foresee the face of a yet-to-be-born child. As we inspect imaginary objects and people with our mind's eye, our corporeal eyeballs latch onto the fantasy.

Positive association between cerebral grey matter metabolism and dopamine D/D receptor availability in healthy and schizophrenia subjects: An F-fluorodeoxyglucose and F-fallypride positron emission tomography study.

Overlapping decreases in extrastriatal dopamine D/D-receptor availability and glucose metabolism have been reported in subjects with schizophrenia. It remains unknown whether these findings are physiologically related or coincidental. To ascertain this, we used two consecutive F-fluorodeoxyglucose and F-fallypride positron emission tomography scans in 19 healthy and 25 unmedicated schizophrenia subjects.

How Multiple Retrievals Affect Neural Reactivation in Young and Older Adults.

Objectives: Aging can reduce the specificity with which memory episodes are represented as distributed patterns of brain activity. It remains unclear, however, whether repeated encoding and retrieval of stimuli modulate this decline. Memory repetition is thought to promote semanticization, a transformative process during which episodic memory becomes gradually decontextualized and abstracted.

A sensorimotor view of verbal working memory.

The divide-and-conquer approach to the study of human cognition has succeeded in focusing researchers' efforts on behavioral phenomena that fall under well-defined categories such as attention, perception, language, memory, emotion, and motor control. The result has been the development of coherent bodies of work in each area replete with successful explanatory theories and a rich collection of paradigms, tasks, and analytic techniques. There has been a renewed in recent years in combining and integrating ideas across these domains, as well as in incorporating neuroscientific data, as a way to build more powerful and general models of cognition.

Dopamine receptor density and white mater integrity: F-fallypride positron emission tomography and diffusion tensor imaging study in healthy and schizophrenia subjects.

Dopaminergic dysfunction and changes in white matter integrity are among the most replicated findings in schizophrenia. A modulating role of dopamine in myelin formation has been proposed in animal models and healthy human brain, but has not yet been systematically explored in schizophrenia. We used diffusion tensor imaging and F-fallypride positron emission tomography in 19 healthy and 25 schizophrenia subjects to assess the relationship between gray matter dopamine D/D receptor density and white matter fractional anisotropy in each diagnostic group.

Fixation reinstatement supports visuospatial memory in older adults.

Research using eye movement monitoring suggests that recapitulating the pattern of eye movements made during stimulus encoding at subsequent retrieval supports memory by reinstating the spatial layout of the encoded stimulus. In the present study, the authors investigated whether recapitulation of encoding fixations during a poststudy, stimulus-free delay period-an effect that has been previously linked to memory maintenance in younger adults-can support mnemonic performance in older adults. Older adults showed greater delay-period fixation reinstatement than younger adults, and this reinstatement supported age-equivalent performance on a subsequent visuospatial-memory-based change detection task, whereas in younger adults, the performance-enhancing effects of fixation reinstatement increased with task difficulty.

The Primacy of Spatial Context in the Neural Representation of Events.

Some theories of episodic memory hypothesize that spatial context plays a fundamental role in episodic memory, acting as a scaffold on which episodes are constructed. A prediction based on this hypothesis is that spatial context should play a primary role in the neural representation of an event. To test this hypothesis in humans, male and female participants imagined events, composed of familiar locations, people, and objects, during an fMRI scan.