EEG Reveals Alterations in Motor Imagery in People With Amnestic Mild Cognitive Impairment.

OBJECTIVES: Motor imagery has been used to investigate the cognitive mechanism of motor control. Although behavioral and electrophysiological changes in motor imagery in people with amnestic mild cognitive impairment (aMCI) have been reported, deficits in different types of imagery remain unclear. To explore this question, we used electroencephalography (EEG) to study neural correlates of visual imagery (VI) and kinesthetic imagery (KI) and their relationship to cognitive function in people with aMCI. METHODS: A hand laterality judgment task was used to induce implicit motor imagery in 29 people with aMCI and 40 healthy controls during EEG recording. Mass univariate and multivariate EEG analysis was applied to explore group differences in a data-driven manner. RESULTS: Modulation of stimuli orientation to event-related potential (ERP) amplitudes differed significantly between groups at 2 clusters located in the posterior-parietal and frontal areas. Multivariate decoding revealed sufficient representation of VI-related orientation features in both groups. Relative to healthy controls, the aMCI group lacked accurate representation of KI-related biomechanical features, suggesting deficits in automatic activation of KI strategy. Electrophysiological correlates were associated with episodic memory, visuospatial function, and executive function. Higher decoding accuracy of biomechanical features predicted better executive function via longer response time in the imagery task in the aMCI group. DISCUSSION: These findings reveal electrophysiological correlates related to motor imagery deficits in aMCI, including local ERP amplitudes and large-scale activity patterns. Alterations in EEG activity are related to cognitive function in multiple domains, including episodic memory, suggesting the potential of these EEG indices as biomarkers of cognitive impairment.

Working Memory for Spatial Sequences: Developmental and Evolutionary Factors in Encoding Ordinal and Relational Structures.

Sequence learning is a ubiquitous facet of human and animal cognition. Here, using a common sequence reproduction task, we investigated whether and how the ordinal and relational structures linking consecutive elements are acquired by human adults, children, and macaque monkeys. While children and monkeys exhibited significantly lower precision than adults for spatial location and temporal order information, only monkeys appeared to exceedingly focus on the first item. Most importantly, only humans, regardless of age, spontaneously extracted the spatial relations between consecutive items and used a chunking strategy to compress sequences in working memory. Monkeys did not detect such relational structures, even after extensive training. Monkey behavior was captured by a conjunctive coding model, whereas a chunk-based conjunctive model explained more variance in humans. These age- and species-related differences are indicative of developmental and evolutionary mechanisms of sequence encoding and may provide novel insights into the uniquely human cognitive capacities.SIGNIFICANCE STATEMENT Sequence learning, the ability to encode the order of discrete elements and their relationships presented within a sequence, is a ubiquitous facet of cognition among humans and animals. By exploring sequence-processing abilities at different human developmental stages and in nonhuman primates, we found that only humans, regardless of age, spontaneously extracted the spatial relations between consecutive items and used an internal language to compress sequences in working memory. The findings provided insights into understanding the origins of sequence capabilities in humans and how they evolve through development to identify the unique aspects of human cognitive capacity, which includes the comprehension, learning, and production of sequences, and perhaps, above all, language processing.

Onset Time of Inhibition of Return Is a Promising Index for Assessing Cognitive Functions in Older Adults.

OBJECTIVES: Developing efficient tools for assessing general cognitive functions in older adults is essential. Previous studies found that inhibition of return (IOR) occurred later in the older adults than in the younger. However, little is known about the relationship between the onset time of IOR (IOR-OT) and cognitive functions in the aging population. The present study examined this issue and investigated the potential of using IOR-OT as an index of cognitive functioning in older adults. METHODS: In two studies, the IOR-OT of healthy younger and older adults was measured by a modified Posner peripheral cueing task, and cognitive functions of the older adults were evaluated with the Addenbrooke's Cognitive Examination Revised (ACE-R). RESULTS: Both studies showed a significant correlation (r = ~.5) between IOR-OT and cognitive functions as assessed by ACE-R in older individuals: later IOR-OT was accompanied by a lower ACE-R score. DISCUSSION: To our knowledge, the present studies are the first to discover a relatively strong correlation between IOR-OT and cognitive functions in older adults. These findings provide new evidence supporting the inhibition deficit theory of aging and lay the foundation of using IOR-OT as an objective measure of cognitive functions in the aging population.

Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans.

Orientation contrast is formed when some elements orient differently from their surroundings. Although orientation contrast can be processed in the absence of top-down attention, the underlying neural mechanism for this automatic processing in humans is controversial. In particular, whether automatic detection of orientation contrast occurs at the initial feedforward stage in the primary visual cortex (i.e., V1) remains unclear. Here, we used event-related potentials (ERPs) to examine the automatic processing of orientation contrast in humans. In three experiments, participants completed a task at fixation while orientation contrasts were presented in the periphery, either in the upper visual field (UVF) or the lower visual field (LVF). All experiments showed significant positive potentials evoked by orientation contrasts over occipital areas within 100 ms after stimulus onset. These contrast effects occurred 10-20 ms later than the C1 components evoked by identically located abrupt onset stimuli which indexes the initial feedforward activity in V1. Compared with those in the UVF, orientation contrasts in the LVF evoked earlier and stronger activities, probably reflecting a LVF advantage in processing of orientation contrast. Even when orientation contrasts were rendered almost invisible by backward masking (in Experiment 2), the early contrast effect in the LVF was not disrupted. These findings imply that automatic processing of orientation contrast could occur at early visual cortical processing stages, but was slightly later than the initial feedforward processing in human V1; such automatic processing may involve either recurrent processing in V1 or feedforward processing in early extrastriate visual cortex. Highlights -We examined the earliest automatic processing of orientation contrast in humans with ERPs.-Significant orientation contrast effect started within 100 ms in early visual areas.-The earliest orientation contrast effect occurred later than the C1 evoked by abrupt onset stimuli.-The earliest orientation contrast effect was independent of top-down attention and awareness.-Automatic detection of orientation contrast arises slightly after the initial feedforward processing in V1.

The role of top-down spatial attention in contingent attentional capture.

It is well known that attentional capture by an irrelevant salient item is contingent on top-down feature selection, but whether attentional capture may be modulated by top-down spatial attention remains unclear. Here, we combined behavioral and ERP measurements to investigate the contribution of top-down spatial attention to attentional capture under modified spatial cueing paradigms. Each target stimulus was preceded by a peripheral circular cue array containing a spatially uninformative color singleton cue. We varied target sets but kept the cue array unchanged among different experimental conditions. When participants' task was to search for a colored letter in the target array that shared the same peripheral locations with the cue array, attentional capture by the peripheral color cue was reflected by both a behavioral spatial cueing effect and a cue-elicited N2pc component. When target arrays were presented more centrally, both the behavioral and N2pc effects were attenuated but still significant. The attenuated cue-elicited N2pc was found even when participants focused their attention on the fixed central location to identify a colored letter among an RSVP letter stream. By contrast, when participants were asked to identify an outlined or larger target, neither the behavioral spatial cueing effect nor the cue-elicited N2pc was observed, regardless of whether the target and cue arrays shared same locations or not. These results add to the evidence that attentional capture by salient stimuli is contingent upon feature-based task sets, and further indicate that top-down spatial attention is important but may not be necessary for contingent attentional capture.

Brain mechanisms underlying behavioral specificity and generalization of short-term texture discrimination learning.

In this study, we used high-density event-related potentials (ERPs) to investigate the brain mechanisms underlying behavioral specificity and generalization of short-term learning of texture discrimination task (TDT). Human adults were trained with TDT for a single session of 1.5 h and their ERPs were measured on the following day. Behavioral performance showed that, after a same amount of exposure of the trained and untrained conditions during EEG session, learning effects were specific to the trained background orientation but generalized across target locations. ERP data, however, revealed both target-location and background-orientation specific changes. While the behavioral background-orientation specificity mainly involved amplitude enhancement of early N2pc over occipital cortex, behavioral target-location generalization was associated with modulation of tempo-spatial configurations of the N2pc component (early-occipital vs. late-parietal/temporal pattern) and decrease of frontal P2 amplitudes for the trained relative to the untrained condition. The earliest visual component C1 did not show specific effects for either background orientation or target location. These results indicated different brain mechanisms underlying the behavioral specificity and generalization of TDT learning. Based on the present findings and literatures, we propose that perceptual learning may induce not only enhancement of relatively early visual selection of the trained target among distractors but also decreases of top-down attention originating from high-level brain center. The reactivation of top-down attention control in some conditions (e.g., the untrained target-location condition) may compensate for the specific effect induced by the early visual selective attention mechanism, leading to generalization or less specificity of perceptual learning in behavioral performance.

[Serum levels of 25-(OH)D(3) and total IgE in children with asthma].

OBJECTIVE: To study the changes and clinical significance of serum levels of 25-(OH)D(3) and total IgE in children with asthma. METHODS: Thirty children with asthma, 40 children with asthmatic bronchitis, and 40 healthy children were enrolled. Double-antibody radioimmunoassay was used to detect the levels of serum 25-(OH)D(3) and total IgE. RESULTS: Serum 25-(OH)D(3) levels (18±3 ng/Ml)decreased significantly in the asthmatic group compared with those in the asthmatic bronchitis group (43±3 ng/mL) and the control group (43±3 ng/mL) (P<0.01). In contrast, serum total IgE levels (192±16 IU/mL) increased significantly in the asthmatic group compared with those in the asthmatic bronchitis group (123±14 IU/mL) and the control group (118±15 IU/mL) (P<0.01). Serum 25-(OH)D(3) levels were negatively correlated with serum total IgE levels in asthmatic children (r=-0.783, P<0.01). There were no correlation between serum 25-(OH)D(3) levels and serum total IgE level in the asthmatic bronchitis and the control groups. CONCLUSIONS: 25-(OH)D(3) may play an important role in the pathogenesis of asthma. The increased serum 25-(OH)D(3) level may inhibit total IgE expression, suggesting that increasing serum 25-(OH)D(3) level might be a new option for the prevention and treatment of asthma.