Linking the Rapid Cascade of Visuo-Attentional Processes to Successful Memory Encoding.

While it is broadly accepted that attention modulates memory, the contribution of specific rapid attentional processes to successful encoding is largely unknown. To investigate this issue, we leveraged the high temporal resolution of electroencephalographic recordings to directly link a cascade of visuo-attentional neural processes to successful encoding: namely (1) the N2pc (peaking ~200 ms), which reflects stimulus-specific attentional orienting and allocation, (2) the sustained posterior-contralateral negativity (post-N2pc), which has been associated with sustained visual processing, (3) the contralateral reduction in oscillatory alpha power (contralateral reduction in alpha > 200 ms), which has also been independently related to attentionally sustained visual processing. Each of these visuo-attentional processes was robustly predictive of successful encoding, and, moreover, each enhanced memory independently of the classic, longer-latency, conceptually related, difference-due-to memory (Dm) effect. Early latency midfrontal theta power also promoted successful encoding, with at least part of this influence being mediated by the later latency Dm effect. These findings markedly expand current knowledge by helping to elucidate the intimate relationship between attentional modulations of perceptual processing and effective encoding for later memory retrieval.

Older adults benefit from more widespread brain network integration during working memory.

Neuroimaging evidence suggests that the aging brain relies on a more distributed set of cortical regions than younger adults in order to maintain successful levels of performance during demanding cognitive tasks. However, it remains unclear how task demands give rise to this age-related expansion in cortical networks. To investigate this issue, functional magnetic resonance imaging was used to measure univariate activity, network connectivity, and cognitive performance in younger and older adults during a working memory (WM) task. Here, individuals performed a WM task in which they held letters online while reordering them alphabetically. WM load was titrated to obtain four individualized difficulty levels with different set sizes. Network integration-defined as the ratio of within-versus between-network connectivity-was linked to individual differences in WM capacity. The study yielded three main findings. First, as task difficulty increased, network integration decreased in younger adults, whereas it increased in older adults. Second, age-related increases in network integration were driven by increases in right hemisphere connectivity to both left and right cortical regions, a finding that helps to reconcile existing theories of compensatory recruitment in aging. Lastly, older adults with higher WM capacity demonstrated higher levels of network integration in the most difficult task condition. These results shed light on the mechanisms of age-related network reorganization by demonstrating that changes in network connectivity may act as an adaptive form of compensation, with older adults recruiting a more distributed cortical network as task demands increase.

Characterization of Surgical Procedures in the Spanish Mohs Surgery Registry (REGESMOHS) for 2013-2015. / Descripción de las intervenciones quirúrgicas recogidas en el registro español de cirugía de Mohs (REGESMOHS) (2013-2015).

INTRODUCTION: The Spanish Mohs Surgery Registry is used to collect data on the use and outcomes of Mohs micrographic surgery (MMS) in Spain. The aim of this study was to describe perioperative and intraoperative data recorded for MMS procedures performed between July 2013 (when the registry started) and January 2016. MATERIAL AND METHODS: Prospective cohort study of data from 18 hospitals. The data collected included type of anesthesia, surgical technique, hospital admission, number of Mohs stages, management of preoperative risk factors, additional treatments, previous treatments, type of tumor, operating time, and complications. RESULTS: Data were available for 1796 operations. The most common tumor treated by MMS was basal cell carcinoma (85.96%), followed by squamous cell carcinoma (6.18%), lentigo maligna (2.81%), and dermatofibrosarcoma protuberans (1.97%). Primary tumors accounted for 66.9% of all tumors operated on; 19.2% of tumors were recurrent and 13.9% were persistent. The most common previous treatment was surgical. MMS was mostly performed under local anesthesia (86.7% of cases) and as an outpatient procedure (71.8%). The frozen section technique was used in 89.5% of cases. One stage was needed to achieve tumor-free margins in 56.45% of patients; 2 stages were required in 32.1% of patients, 3 in 7.1%%, 4 in 2.7%, and 5 or more in 1.8%. The defect was reconstructed by the dermatologist in 98% of patients and the most common technique was flap closure (47.2%). Intraoperative complications were recorded for just 1.62% of patients and the median (interquartile range) duration of surgery was 75 (60-100) minutes. CONCLUSION: The characteristics of the patients and tumors treated by MMS are similar to those reported for similar studies in other geographic areas. Lentigo maligna and dermatofibrosarcoma protuberans accounted for a higher proportion of cases in our series, and repair of the surgical defect by a dermatologist was also more common. Operating times in MMS are not much longer than those reported for other procedures and the rate of intraoperative complications is very low.

The effect of 6-week exercise programme and whole body vibration on strength and quality of life in women with fibromyalgia: a randomised study.

OBJECTIVES: The aim of this study was to investigate the effectiveness of a 6-week traditional exercise programme with supplementary whole-body vibration (WBV) in improving strength and health status in women with fibromyalgia (FM). METHODS: Thirty postmenopausal women with FM (mean (SD) age: 59 (7.90) years) were randomised into one of two groups, one intervention group (GEV n=15), which combined exercise training (two days a week) with three days of WBV (3 sets of 45 s at 20 Hz-3 mm and four sets of unilateral static squats at 20 Hz-2 mm) and another control group (n=15), that performed the same physical activity programme but without vibration training (GEnV). The Fibromyalgia Impact Questionnaire (FIQ) and the global score of the SF-36 were used to assess functional capacity and quality of life. Two additional tests were employed to assess muscle strength. Baseline data and pre-test and post-test data were collected before and after the six-week intervention period. RESULTS: Significant improvements in all outcomes measured were found from baseline in both groups. A 5% improvement from baseline in total FIQ score was observed in the exercise groups (p≤0.05), and was accompanied by reductions in SF36 scores of 9.8% (p<0.001) and 7.9% (p<0.001) in the GEV and GEnV group, respectively. Improvements were also observed in muscle strength in both groups but greater in the GEV group. CONCLUSIONS: The results suggest that women with FMS can gain additional health benefits by engaging in a 6-week traditional exercise programme with supplementary WBV.

Online repetitive transcranial magnetic stimulation during working memory in younger and older adults: A randomized within-subject comparison.

Working memory is the ability to perform mental operations on information that is stored in a flexible, limited capacity buffer. The ability to manipulate information in working memory is central to many aspects of human cognition, but also declines with healthy aging. Given the profound importance of such working memory manipulation abilities, there is a concerted effort towards developing approaches to improve them. The current study tested the capacity to enhance working memory manipulation with online repetitive transcranial magnetic stimulation in healthy young and older adults. Online high frequency (5Hz) repetitive transcranial magnetic stimulation was applied over the left dorsolateral prefrontal cortex to test the hypothesis that active repetitive transcranial magnetic stimulation would lead to significant improvements in memory recall accuracy compared to sham stimulation, and that these effects would be most pronounced in working memory manipulation conditions with the highest cognitive demand in both young and older adults. Repetitive transcranial magnetic stimulation was applied while participants were performing a delayed response alphabetization task with three individually-titrated levels of difficulty. The left dorsolateral prefrontal cortex was identified by combining electric field modeling to individualized functional magnetic resonance imaging activation maps and was targeted during the experiment using stereotactic neuronavigation with real-time robotic guidance, allowing optimal coil placement during the stimulation. As no accuracy differences were found between young and older adults, the results from both groups were collapsed. Subsequent analyses revealed that active stimulation significantly increased accuracy relative to sham stimulation, but only for the hardest condition. These results point towards further investigation of repetitive transcranial magnetic stimulation for memory enhancement focusing on high difficulty conditions as those most likely to exhibit benefits.

Brain regions differentially involved in remembering what and when: a PET study.

Recollecting a past episode involves remembering not only what happened but also when it happened. We used positron emission tomography (PET) to directly contrast the neural correlates of item and temporalorder memory. Subjects studied a list of words and were then scanned while retrieving information about what words were in the list or when they occurred within the list. Item retrieval was related to increased neural activity in medial temporal and basal forebrain regions, whereas temporal-order retrieval was associated with activations in dorsal prefrontal, cuneus/precuneus, and right posterior parietal regions. The dissociation between temporal and frontal lobe regions confirms and extends previous lesion data. The results show that temporal-order retrieval involves a network of frontal and posterior brain regions.

Complementary topology of maintenance and manipulation brain networks in working memory.

Working memory (WM) is assumed to consist of a process that sustains memory representations in an active state (maintenance) and a process that operates on these activated representations (manipulation). We examined evidence for two distinct, concurrent cognitive functions supporting maintenance and manipulation abilities by testing brain activity as participants performed a WM alphabetization task. Maintenance was investigated by varying the number of letters held in WM and manipulation by varying the number of moves required to sort the list alphabetically. We found that both maintenance and manipulation demand had significant effects on behavior that were associated with different cortical regions: maintenance was associated with bilateral prefrontal and left parietal cortex, and manipulation with right parietal activity, a link that is consistent with the role of parietal cortex in symbolic computations. Both structural and functional architecture of these systems suggested that these cognitive functions are supported by two dissociable brain networks. Critically, maintenance and manipulation functional networks became increasingly segregated with increasing demand, an effect that was positively associated with individual WM ability. These results provide evidence that network segregation may act as a protective mechanism to enable successful performance under increasing WM demand.

Study of on-line adaptive discriminant analysis for EEG-based brain computer interfaces.

A study of different on-line adaptive classifiers, using various feature types is presented. Motor imagery brain computer interface (BCI) experiments were carried out with 18 naive able-bodied subjects. Experiments were done with three two-class, cue-based, electroencephalogram (EEG)-based systems. Two continuously adaptive classifiers were tested: adaptive quadratic and linear discriminant analysis. Three feature types were analyzed, adaptive autoregressive parameters, logarithmic band power estimates and the concatenation of both. Results show that all systems are stable and that the concatenation of features with continuously adaptive linear discriminant analysis classifier is the best choice of all. Also, a comparison of the latter with a discontinuously updated linear discriminant analysis, carried out in on-line experiments with six subjects, showed that on-line adaptation performed significantly better than a discontinuous update. Finally a static subject-specific baseline was also provided and used to compare performance measurements of both types of adaptation.

A fully on-line adaptive BCI.

A viable fully on-line adaptive brain computer interface (BCI) is introduced. On-line experiments with nine naive and able-bodied subjects were carried out using a continuously adaptive BCI system. The data were analyzed and the viability of the system was studied. The BCI was based on motor imagery, the feature extraction was performed with an adaptive autoregressive model and the classifier used was an adaptive quadratic discriminant analysis. The classifier was on-line updated by an adaptive estimation of the information matrix (ADIM). The system was also able to provide continuous feedback to the subject. The success of the feedback was studied analyzing the error rate and mutual information of each session and this analysis showed a clear improvement of the subject's control of the BCI from session to session.

Adaptive on-line classification for EEG-based brain computer interfaces with AAR parameters and band power estimates.

We present the result of on-line feedback Brain Computer Interface experiments using adaptive and non-adaptive feature extraction methods with an on-line adaptive classifier based on Quadratic Discriminant Analysis. Experiments were performed with 12 naïve subjects, feedback was provided from the first moment and no training sessions were needed. Experiments run in three different days with each subject. Six of them received feedback with Adaptive Autoregressive parameters and the rest with logarithmic Band Power estimates. The study was done using single trial analysis of each of the sessions and the value of the Error Rate and the Mutual Information of the classification were used to discuss the results. Finally, it was shown that even subjects starting with a low performance were able to control the system in a few hours: and contrary to previous results no differences between AAR and BP estimates were found.

The neural correlates of intentional learning of verbal materials: a PET study in humans.

The purpose of this study was to identify the brain regions invoked when subjects attempt to learn verbal materials for a subsequent memory test. Twelve healthy subjects undertook two different tasks: reading and encoding of word pairs, while they were being scanned using [15O]H2O positron emission tomography (PET). As expected, the encoding pairs were remembered much better (recall 39% vs. 8%; P < 0.001) than reading pairs in a subsequent memory test. The encoding scans, as compared to reading scans, showed activation of the left prefrontal cortex, the anterior cingulate cortex and the left medial temporal cortex. The left prefrontal activations were in two discrete regions: (i) a left anterior and inferior left prefrontal (Brodmann's areas 45, 46) which we attribute to semantic processing; and (ii) a left posterior mid-frontal region (BA 6, 44) which may reflect rote rehearsal. We interpret the data to suggest that when subjects use cognitive strategies of semantic processing and rote-rehearsal to learn words, they invoke discrete regions of the left prefrontal cortex. And this activation of the left prefrontal cortex along with the medial temporal region leads to a neurophysiological memory trace which can be used to guide subsequent memory retrieval.

Event-related potentials of recognizing happy and neutral faces.

In event-related potentials (ERPs) studies, recognition memory is associated with two positivities: one over parietal regions, and one over frontal regions. With nameable neutral stimuli, such as words or common objects, the parietal effect is usually left lateralized, and the frontal effect is usually right lateralized. We investigated the lateralization of these effects for nonnameable emotional stimuli: unfamiliar faces with happy and neutral expressions. The parietal effect was bilateral, suggesting that the left lateralization of this effect in studies using nameable stimuli reflected verbal processing. The frontal effect was left lateralized for happy faces, but right lateralized for neutral faces. This finding is consistent with the valence hypothesis, which posits that processing of pleasant emotions is lateralized to the left hemisphere.

Age-related differences in effective neural connectivity during encoding and recall.

Age-related differences in brain activity may reflect local neural changes in the regions involved or they may reflect a more global transformation of brain function. To investigate this issue, we applied structural equation modeling to the results of a positron emission tomography (PET) study in which young and old adults encoded and recalled word pairs. In the young group there was a shift from positive interactions involving the left prefrontal cortex during encoding to positive interactions involving the right prefrontal cortex during recall, whereas in the old group frontal interactions were mixed during encoding and bilaterally positive during recall. The present results suggest that age-related changes in neural activation are partly due to age-related changes in effective connectivity in the neural network underlying the task.

Anandamide-induced sleep is blocked by SR141716A, a CB1 receptor antagonist and by U73122, a phospholipase C inhibitor.

Anandamide (ANA) alters sleep by increasing the amount of time spent in slow wave sleep 2 (SWS2) and rapid eye movement sleep (REMS) at the expense of wakefulness (W) in rats. In this report, we describe a similar effect of ANA when injected itracerebroventricularly (i.c.v.) or into the peduriculopontine tegmental nucleus (PPTg) and the lack of an effect when ANA is administered into the medial preoptic area (MPOA). Furthermore, the i.c.v. or PPTg administration of SR141716A, a CB1 antagonist, or U73122, a PLC inhibitor, 15 min prior to ANA, readily prevents the ANA induced changes in sleep. The present results suggest that a cannabinoid system in the PPTg may be involved in sleep regulation and that the cannabinoid effect is mediated by the CB1 receptor coupled to a PLC second messenger system.

Functional brain maps of retrieval mode and recovery of episodic information.

Positron emission tomography (PET) was used to identify brain regions associated with two component processes of episodic retrieval; those related to thinking back in subjective time (retrieval mode) and those related to actual recovery of stored information (ecphory). Healthy young subjects recognized words that had been encoded with respect to meaning or the speaker's voice. Regardless of how the information had been encoded, recognition was associated with increased activation in regions in right prefrontal cortex, left anterior cingulate, and cerebellum. These activations reflect retrieval mode. Recognition following meaning encoding was specifically associated with increased activation in left temporal cortex, and recognition following voice encoding involved regions in right orbital frontal and parahippocampal cortex. These activations reflect ecphory of differentially encoded information.

Oleamide modulates memory in rats.

Oleamide is a recently described lipid, obtained from the cerebrospinal fluid of sleep-deprived cats. It has been observed that oleamide possesses several biological effects, such as sleep induction, and immunological suppression as well as serotonin and gamma-aminobutyric acid receptors activation. In addition, oleamide also binds to the cannabinoid receptors. In this study, we have observed that oleamide facilitates memory extinction in a passive avoidance paradigm, reduces core temperature and pain perception, but does not affect significantly locomotion. These results suggest that oleamide modulates memory processes. However, we do not know if oleamide impairs the retrieval of the memory associated to the "not go" behavior, or facilitates the fast re-learning of the "go" behavior. In addition, since these effects are also induced by marijuana and anandamide, it is very likely that oleamide may be affecting the cerebral cannabinoid system to induce its effects.

A dissociation between two implicit conceptual tests supports the distinction between types of conceptual processing.

Subjects studied words in a classification task (to what categories does it belong?) or in a production task (producing associates to the word) and then completed one of two implicit memory tests-category association or free association. The classification study task and the category-association test emphasize categorical relations between concepts, and the production study task and the free-association test draw on associative relations. As predicted by the transfer-appropriate processing principle, priming in the category-association test was larger for words studied under the classification task than for those studied under the production task, whereas the opposite was true in the free-association test. This crossover dissociation is the first obtained between two implicit conceptual tests, and it provides support for the claim that it is necessary to distinguish between different types of conceptual processing.

PET studies of encoding and retrieval: The HERA model.

We review positron emission tomography (PET) studies whose results converge on the hemispheric encoding/retrieval asymmetry (HERA) model of the involvement of prefrontal cortical regions in the processes of human memory. The model holds that the left prefrontal cortex is differentially more involved in retrieval of information from semantic memory, and in simultaneously encoding novel aspects of the retrieved information into episodic memory, than is the right prefrontal cortex. The right prefrontal cortex, on the other hand, is differentially more involved in episodic memory retrieval than is the left prefrontal cortex. This general pattern holds for different kinds of information (e.g., verbal materials, pictures, faces) and a variety of conditions of encoding and retrieval.

Estimating the frequency of nonevents: the role of recollection failure in false recognition.

Participants studied lists of multiply presented converging associates (e.g., bed, dream, pillow, etc.) and were timed as they estimated how often they saw list items, related foils (e.g., blanket), and nonpresented critical items (SLEEP). Average number of repetitions (few [3] vs. many [6]) and repetition variability (fixed vs. variable) were manipulated between subjects. Participants responded more slowly to critical items (3.18 sec) than to list items (2.45 sec) or foils (2.22 sec). In addition, critical-item judgments of frequency (JOFs) were about as large as list-item JOFs, and false recognition (i.e., nonzero JOFs) of critical items was most likely in the few-fixed condition (96%) and least likely in the many-fixed condition (74%). These findings suggest that people can use recollection failure--the absence of an anticipated recollective experience, coupled with strong familiarity--to distinguish critical items from list items and that recollection failure is weighted most heavily when people expect familiar probes to access episodic information.

False memories and semantic lexicon arrangement.

A description of semantic lexicon arrangement is a central goal in examinations of language processing. There are a number of ways in which this description has been cast and a host of different mechanisms in place for providing operational descriptions (e.g., feature sharing, category membership, associations, and co-occurrences). We first review two views of the structure of semantic space and then describe an experiment that attempts to adjudicate between these two views. The use of a false memory paradigm provides us with evidence that supports the notion that the semantic lexicon is arranged more by association than by categories or features.