Search

Abstract: Semantic richness refers to the amount of semantic information associated with a concept. Reaction-time (RT) studies have shown that words referring to rich concepts elicit faster responses than those referring to impoverished ones, suggesting that richer concepts are activated more quickly. In a recent functional neuroimaging study, richer concepts evoked less neural activity, which was interpreted as faster activation. The interpretations of these findings appear to conflict with event-related potential (ERP) studies showing no evidence that speed of concept activation is influenced by typical semantic variables. Resolution of this apparent contradiction is important because the interpretation of 40 years of semantic-memory RT studies depends on whether factors such as semantic richness influence the duration of initial concept activation or later decision and response processes. Consistent with previous studies of the effects of semantic factors on ERP, the present study shows that richness influences the magnitude, but not the latency, of the P2 and N400 ERP components (which are early relative to behavioral responses), suggesting that effects of richness on RT reflect temporal effects on downstream decision or response mechanisms rather than on upstream concept activation. [Copyright &y& Elsevier]

Abstract: Accumulating evidence suggests that top-down processes, reflected by frontal-midline theta-band (4–8 Hz) electroencephalogram (EEG) oscillations, strengthen the activation of a memory set during short-term memory (STM) retention. In addition, the amplitude of posterior alpha-band (8–13 Hz) oscillations during STM retention is thought to reflect a mechanism that protects fragile STM activations from interference by gating bottom-up sensory inputs. The present study addressed two important questions about these phenomena. First, why have previous studies not consistently found memory set-size effects on frontal-midline theta? Second, how does posterior alpha participate in STM retention? To answer these questions, large-scale network connectivity during STM retention was examined by computing EEG wavelet coherence during the retention period of a modified Sternberg task using visually-presented letters as stimuli. The results showed (a) increasing theta-band coherence between frontal-midline and left temporal-parietal sites with increasing memory load, and (b) increasing alpha-band coherence between midline parietal and left temporal/parietal sites with increasing memory load. These findings support the view that theta-band coherence, rather than amplitude, is the key factor in selective top-down strengthening of the memory set and demonstrate that posterior alpha-band oscillations associated with sensory gating are involved in STM retention by participating in the STM network. [Copyright &y& Elsevier]

Abstract: People can solve problems in more than one way. Two general strategies involve (A) methodical, conscious, search of problem-state transformations, and (B) sudden insight, with abrupt emergence of the solution into consciousness. This study elucidated the influence of initial resting brain-state on subjects’ subsequent strategy choices. High-density electroencephalograms (EEGs) were recorded from subjects at rest who were subsequently directed to solve a series of anagrams. Subjects were divided into two groups based on the proportion of anagram solutions derived with self-reported insight versus search. Reaction time and accuracy results were consistent with different cognitive problem-solving strategies used for solving anagrams with versus without insight. Spectral analyses yielded group differences in resting-state EEG supporting hypotheses concerning insight-related attentional diffusion and right-lateralized hemispheric asymmetry. These results reveal a relationship between resting-state brain activity and problem-solving strategy, and, more generally, a dependence of event-related neural computations on the preceding resting state. [Copyright &y& Elsevier]

Effects of conceptual fusion on episodic associative retrieval were examined. Subjects attempted to fuse sequentially displayed (800 ms offset) word pairs; pairs subjects were unable to fuse were instead considered associated by juxtaposition. Next, dense-array event-related potentials (ERPs) were recorded while the pairs were redisplayed, half reversed in order. Subjects pressed a button to indicate whether each pair was presented in the previous order. Behavioral results showed that retrieval of fused pairs was faster and more accurate than for juxtaposed pairs. ERP topography to the first word of fused pairs was different from juxtaposed pairs, indicating that fusion can mediate associative retrieval of constituent items. Estimates of current source density at the cortical surface showed that fusion-mediated retrieval elicited left inferior-prefrontal/anterior-temporal activity not typically observed in episodic memory retrieval studies. [Copyright &y& Elsevier]

Semantic memory consolidation was studied by comparing medial temporal lobe (MTL) fMRI activation to ANIMAL, IMPLEMENT and ABSTRACT nouns in healthy seniors to that of young adults. Relative to healthy seniors, young adults were predicted to show greater MTL activation for IMPLEMENTS, but not ANIMALS, because the ANIMALS category consists of highly intercorrelated and overlapping features that should require less MTL-mediated binding than IMPLEMENTS over a shorter period of time during concept consolidation. ABSTRACT meanings are context-dependent and do not consist of fixed feature sets. Thus it was predicted that ABSTRACT words would not involve age-related feature binding mediated by the MTL. These predictions were confirmed by the results. Our observations are consistent with the hypothesis that the structure of a category influences the consolidation of knowledge in semantic memory. [Copyright &y& Elsevier]

Sometimes, a thousand words isn''t worth a picture. A recent study by West and Holcomb used event-related potentials to examine non-verbal, discourse-level processing of stories presented as picture sequences. These complex pictures were presented at a rapid rate, thereby minimizing linguistic mediation. The ERP showed N300 and N400 deflections, hypothesized to reflect image activation and amodal semantic integration, respectively. [ABSTRACT FROM AUTHOR]

A history of dieting to lose weight has been shown to be a robust predictor of future weight gain. A potential factor in propensity towards weight gain is the nature of people's reactions to the abundance of highly palatable food cues in the environment. Event Related Potentials (ERPs) have revealed differences in how the brain processes food cues between obese and normal weight individuals, as well as between restrained and unrestrained eaters. However, comparisons by weight status are not informative regarding whether differences predate or follow weight gain in obese individuals and restrained eating has not consistently been found to predict future weight gain. The present study compared ERP responses to food cues in non-obese historic dieters (HDs) to non-obese never dieters (NDs). HDs showed a blunted N1 component relative to NDs overall, and delayed N1 and P2 components compared to NDs in the hungry state, suggesting that early, perceptual processing of food cues differs between these groups, especially when food-deprived. HDs also showed a more hunger-dependent sustained ERP (LPP) compared to NDs. Future research should test ERP-based food cue responsivity as a mediator between dieting history and future weight gain to better identify those most at risk for weight gain as well as the nature of their vulnerability. [ABSTRACT FROM AUTHOR]

Using a creative production task, jazz improvisation, we tested alternative hypotheses about the flow experience: (A) that it is a state of domain-specific processing optimized by experience and characterized by minimal interference from task-negative default-mode network (DMN) activity versus (B) that it recruits domain-general task-positive DMN activity supervised by the fronto-parietal control network (FPCN) to support ideation. We recorded jazz guitarists' electroencephalograms (EEGs) while they improvised to provided chord sequences. Their flow-states were measured with the Core Flow State Scale. Flow-related neural sources were reconstructed using SPM12. Over all musicians, high-flow (relative to low-flow) improvisations were associated with transient hypofrontality. High-experience musicians' high-flow improvisations showed reduced activity in posterior DMN nodes. Low-experience musicians showed no flow-related DMN or FPCN modulation. High-experience musicians also showed modality-specific left-hemisphere flow-related activity while low-experience musicians showed modality-specific right-hemisphere flow-related deactivations. These results are consistent with the idea that creative flow represents optimized domain-specific processing enabled by extensive practice paired with reduced cognitive control. • The flow state has been described as effortless attention to a task. • Few studies have examined the neural basis of flow during creative production. • We examined flow-related neural activity by recording EEGs during jazz improvisation. • High-flow versus low-flow is associated with greater left-hemisphere activity and reduced frontal and default-mode activity. • The results support the view that creative flow is a state of optimized, domain-specific processing. [ABSTRACT FROM AUTHOR]

Abstract Anecdotal reports suggest the existence of individual differences in peoples' cognitive styles for solving problems, in particular, the tendency to rely on insight (the "aha" phenomenon) versus deliberate analytical thought. We hypothesized that such stable individual differences exist and are associated with trait-like individual differences in resting-state brain activity. We tested this idea by recording participants' resting-state electroencephalograms (RS-EEGs) on 4 occasions over approximately 7 weeks and then tasking them with solving anagrams and compound remote associates problems that are solvable by either strategy. We found that peoples' tendency to solve problems consistently by insight or by analysis spans both tasks and time. Moreover, we discovered trait-like individual differences in the balance between frontal and posterior resting-state brain activity and in temporal-lobe hemispheric asymmetries that predict, at least weeks in advance, the tendency to solve by insight versus analysis. The discovery of an insight-analytic dimension of cognitive style and its neural basis in resting state brain activity suggests new avenues for the development of neuroscience-based methods for intellectual, educational, and vocational assessment. Highlights • The tendency to use insight or analytic thinking to solve problems is trait-like. • Individuals' resting brainwave patterns predict which method they use more. • Analytic solvers exhibit greater frontal resting-state beta-band power. • Insightful solvers exhibit more left parietal beta and left-temporal theta/alpha. • A brainwave model can predict which strategy a person relies on weeks in advance. [ABSTRACT FROM AUTHOR]

Introduction Reductions of cerebrospinal fluid (CSF) amyloid-beta (Aβ42) and elevated phosphorylated-tau (p-Tau) reflect in vivo Alzheimer׳s disease (AD) pathology and show utility in predicting conversion from mild cognitive impairment (MCI) to dementia. We investigated the P50 event-related potential component as a noninvasive biomarker of AD pathology in non-demented elderly. Methods 36 MCI patients were stratified into amyloid positive (MCI-AD, n =17) and negative (MCI-Other, n =19) groups using CSF levels of Aβ42. All amyloid positive patients were also p-Tau positive. P50s were elicited with an auditory oddball paradigm. Results MCI-AD patients yielded larger P50s than MCI-Other. The best amyloid-status predictor model showed 94.7% sensitivity, 94.1% specificity and 94.4% total accuracy. Discussion P50 predicted amyloid status in MCI patients, thereby showing a relationship with AD pathology versus MCI from another etiology. The P50 may have clinical utility for inexpensive pre-screening and assessment of Alzheimer׳s pathology. [ABSTRACT FROM AUTHOR]

There are two general strategies for solving a problem. Insight is the sudden realization of a novel idea or problem solution accompanied by an "aha" experience. Analysis occurs in a conscious, deliberate fashion without an "aha" experience. Previous research has shown that brain activity during a preparatory period immediately before a problem is presented can predict whether the subsequently presented problem will be solved by insight or by analysis. Those prior studies used a type of brief verbal problem called compound remote associates (CRA). To determine whether prestimulus activity predicts subsequent insight versus analytic solving for other types of problems, the present study used an anagram task. We examined high-density electroencephalograms (EEGs) immediately preceding the presentation of anagrams and found that during the 2-s prestimulus interval there was greater beta-band activity recorded over right central-parietal cortex prior to analytic solving compared with insightful solving. EEG source reconstruction showed that this activity originated in left mid-cingulate cortex (MCC) and the right postcentral gyrus. In contrast to prior work, we found no evidence of a significant interaction between insight-related prestimulus brain activity and positive mood, although positive mood was associated with greater activity in anterior cingulate cortex and with a larger number of insight solutions. The present MCC results suggest that participants' anagram-solving strategies may be influenced by allostasis , that is, the estimation and marshalling of neurocognitive resources required to cope with an expected task. Specifically, when a participant adequately prepares for an upcoming problem, then MCC activity is high, enabling solution by resource-intensive analytic processing. Alternatively, when preparation is insufficient for analytic processing, then MCC activity is low and subsequent solving occurs by low-demand insight processing. The current findings and explanatory model differ from those of previous studies that used a CRA task, suggesting the possibility of complex interactions between task-type and procedure-type in determining the nature of prestimulus preparation. Future research examining such interactions may yield results that benefit educators who teach students problem-solving strategies. • People can solve problems using insight or analytic strategies. • Solving strategy selection is influenced by pre-problem brain activity. • Preparatory pre-problem brain activity varies with the type of task. • Analytic solving of anagrams follows mid-cingulate cortex preparatory activity. • Mid-cingulate activity is thought to reflect allostasis, the priming of needed resources. [ABSTRACT FROM AUTHOR]

Early diagnosis of Alzheimer's disease (AD) is becoming an increasingly important healthcare concern. Prior approaches analyzing event-related potentials (ERPs) had varying degrees of success, primarily due to smaller study cohorts, and the inherent difficulty of the problem. A new effort using multiresolution analysis of ERPs is described. Distinctions of this study include analyzing a larger cohort, comparing different wavelets and different frequency bands, using ensemble-based decisions and, most importantly, aiming the earliest possible diagnosis of the disease. Surprising yet promising outcomes indicate that ERPs in response to novel sounds of oddball paradigm may be more reliable as a biomarker than the more commonly used responses to target sounds. [ABSTRACT FROM AUTHOR]

After a person has become stuck on a problem, they sometimes achieve a clear and sudden solution through insight – the so-called Aha! experience. Because of its distinctive experience, the origins and characteristics of insight have received considerable attention historically in psychological research. However, despite considerable progress in characterizing insight, the underlying mechanisms remain mysterious. We argue that research on insight could be greatly advanced by supplementing traditional insight research, which depends on a few complex problems, with paradigms common in other domains of cognitive science. We describe a large set of mini-insight problems to which multiple methods can be applied, together with subjective reports to identify insight problem-solving. Behavioral priming and neuroimaging methods are providing evidence about what, where, and how neural activity occurs during insight. Such evidence constrains theories of component processes, and will help to demystify insight. [Copyright &y& Elsevier]

Objective: Electroencephalographic (EEG) peak alpha frequency (PAF) (measured in Hz) has been correlated to cognitive performance between healthy and clinical individuals, and among healthy individuals. PAF also varies within individuals across developmental stages, among different cognitive tasks, and among physiological states induced by administration of various substances. The present study suggests that, among other things, PAF reflects a trait or state of cognitive preparedness.Methods: Experiment 1 involved 19-channel EEG recordings from 10 individuals with traumatic brain injury (TBI) and 12 healthy matched controls, before, during, and after tasks of visual and auditory attention. Experiment 2 involved EEG recordings from 19 healthy young adults before and after a working memory task (WAIS-R Digit Span), repeated on 2 different days to measure within-individual differences.Results: Experiment 1 showed significantly lower PAF in individuals with TBI, mostly during post-task rest. Experiment 2 showed PAF during pre-task baseline to be significantly correlated with Digit Span performance of the same day but not with Digit Span performance of another day. Moreover, PAF was significantly increased after Digit Span for those participants whose PAF was lower than the sample median before the task, but not for those who had it higher. Finally, both PAF and Digit Span performance were increased during the second day.Conclusions: PAF was shown to detect both trait and state differences in cognitive preparedness, as well as to be affected by cognitive tasks. Traits are better reflected during post-task rest, whereas states are better reflected during initial resting baseline recordings. [Copyright &y& Elsevier]