Presurgical Patients Research Articles

Multiplexing of Theta and Alpha Rhythms in the Amygdala-Hippocampal Circuit Supports Pattern Separation of Emotional Information

How do we remember emotional events? While emotion often leads to vivid recollection, the precision of emotional memories can be degraded, especially when discriminating among overlapping experiences in memory (i.e., pattern separation). Communication between the amygdala and the hippocampus has been proposed to support emotional memory, but the exact neural mechanisms remain unclear. Here, we used intracranial recordings in pre-surgical epilepsy patients to show that successful pattern separation of emotional stimuli is associated with theta band (3-7Hz)-coordinated bidirectional interactions between the amygdala and the hippocampus. In contrast, discrimination errors (i.e., failure to discriminate similar stimuli) were associated with alpha band (7-13Hz)-coordinated unidirectional influence from the amygdala to the hippocampus. These findings imply that alpha band synchrony may impair discrimination of similar emotional events via the amygdala-hippocampal directional coupling, which suggests a target for treatments of psychiatric conditions such as post-traumatic stress disorder, in which aversive experiences are often overgeneralized.

Associations between Weight Loss, Food Likes, Dietary Behaviors, and Chemosensory Function in Bariatric Surgery: A Case-Control Analysis in Women.

We tested the hypothesis that successful weight loss post-bariatric surgery would be associated with healthier chemosensory function, food likes, and dietary behaviors than either unsuccessful weight loss or pre-surgery morbid obesity. In a case-control design, pre-surgical women with morbid obesity (n = 49) were compared with those 1-year post-surgery (24 Roux-en-Y Bypass, 24 Sleeve Gastrectomy) and defined by excess or percent weight loss as successful/unsuccessful. For self-reported smell/taste perception, more post-surgery than pre-surgery reported improved/distorted perception, especially if weight loss successful. Measured taste function (perceived quinine and NaCl intensity) was lower among weight loss unsuccessful versus pre-surgery patients, yet a genetic variation in taste probe (propylthiouracil bitterness) matched expected frequencies without significant pre/post-surgery difference. Regarding survey-reported liking, higher diet quality was seen in the weight loss successful (independent of surgery type) versus pre-surgical patients, with differences driven by lower sweet and refined carbohydrate liking. The post versus pre-surgical patients had greater restraint but less hunger and disinhibition. Patients reporting both higher diet quality and lower hunger showed greater % weight loss, independent of surgery type. Thus, successful weight loss 1-year post-bariatric surgery was associated with improved or distorted chemosensation and patterns of liking associated with healthier diets, especially if coupled with less hunger.

Divergent network properties that predict early surgical failure versus late recurrence in temporal lobe epilepsy.

The objectives of this study were to identify functional and structural network properties that are associated with early versus long-term seizure outcomes after mesial temporal lobe epilepsy (mTLE) surgery and to determine how these compare to current clinically used methods for seizure outcome prediction. In this case-control study, 26 presurgical mTLE patients and 44 healthy controls were enrolled to undergo 3-T MRI for functional and structural connectivity mapping across an 8-region network of mTLE seizure propagation, including the hippocampus (left and right), insula (left and right), thalamus (left and right), one midline precuneus, and one midline mid-cingulate. Seizure outcome was assessed annually for up to 3 years. Network properties and current outcome prediction methods related to early and long-term seizure outcome were investigated. A network model was previously identified across 8 patients with seizure-free mTLE. Results confirmed that whole-network propagation connectivity patterns inconsistent with the mTLE model predict early surgical failure. In those patients with networks consistent with the mTLE network, specific bilateral within-network hippocampal to precuneus impairment (rather than unilateral impairment ipsilateral to the seizure focus) was associated with mild seizure recurrence. No currently used clinical variables offered the same ability to predict long-term outcome. It is known that there are important clinical differences between early surgical failure that lead to frequent disabling seizures and late recurrence of less frequent mild seizures. This study demonstrated that divergent network connectivity variability, whole-network versus within-network properties, were uniquely associated with these disparate outcomes.

Concordance and discordance between self-reported and performance-based function among individuals with knee osteoarthritis

Purpose: Physical function can be assessed in osteoarthritis (OA) patients using self-report questionnaires and/or through performance-based measures. A preference for self-report measures is often associated with ease of administration and minimal cost, whereas preference for performance-based measures relates to their objectiveness in assessment. The purpose of this study was to investigate the relationship between self-reported and performance-based function in a clinical population of patients with knee OA and to understand what factors are associated with an individual having concordance or discordance between their self-reported and performance-based scores. Methods: In a cohort of 511 knee OA patients scheduled for joint replacement surgery, self-reported function prior to surgery was assessed with the physical function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (score range 0-68; higher indicates worse function), and performance-based function was assessed with the Timed Up and Go (TUG) (measures, in seconds, the time taken by an individual to stand up from a standard arm chair, walk a distance of 3 meters, turn, walk back to the chair, and sit down; higher indicates worse function). In addition, individuals completed a questionnaire capturing socio-demographic (age, sex, and level of education), health status (BMI and comorbidity count), pain (symptomatic joint count and knee pain intensity), and psychosocial (depressive symptoms and pain catastrophizing) characteristics. WOMAC and log transformed TUG scores were each separated into three groups, (1) below average, (2) average, and (3) above average, where average is a score falling within one standard deviation of the mean. These score groups were then combined to derive three categories of individuals: “concordant” (those who reported similar functional ability on the WOMAC compared to their TUG scores); “underestimators” (those who reported worse functional ability on the WOMAC than their TUG scores would suggest); “overestimators” (those who reported better functional ability on the WOMAC than their TUG scores would suggest). Multinomial logistic regression was used to examine the association between these categories (outcomes: “underestimators” vs. “concordant” and “overestimators” vs. “concordant”) and the noted study variables. Results: The mean age of participants was 65.3 years and 56.4% were women. Overall, 297 (58.1%) were classified as “concordant”, 106 (20.8%) were “underestimators”, and 108 (21.1%) were “overestimators”. From the multinomial logistic regression age, pain intensity, and pain catastrophizing behaviours were found to be significantly associated with whether an individual was “concordant”. Relative to having concordant scores, older individuals were more likely to overestimate and less likely to underestimate their functional ability. For every 5-year increase in age, the odds of being an overestimator of functional ability increased (OR = 1.29, 95%CI: 1.09-1.52) and the odds of being an underestimator of functional ability decreased (OR = 0.83, 95%CI: 0.71-0.98) relative to concordant individuals. Individuals who reported more pain were less likely to overestimate their functional ability and individuals who reported more pain catastrophizing behaviours were more likely to underestimate their functional ability. As pain intensity increased, the odds of being an overestimator of functional ability decreased (OR = 0.86, 95%CI: 0.76-0.98), while greater pain catastrophizing behaviours were associated with an increased odds of being an underestimator of functional ability (OR = 1.03, 95%CI: 1.00-1.05). Conclusions: About 60% of pre-surgical knee OA patients were concordant in their self-reported and performance-based functional ability and the remaining 40% were divided evenly into those who underestimated and overestimated their functional ability. Age, pain, and pain catastrophizing behaviours were all factors associated with whether individuals were concordant/discordant in their scores. Self-reported physical function appears to differentially reflect functional ability depending on certain patient factors. Given the general reliance on self-reported measures in clinical assessments, findings suggest that greater awareness is needed of the emotional response to pain, such as pain catastrophizing, and the likelihood of older individuals to minimize their functional difficulties.

Improving Self-Reported Preoperative Anxiety Through a Preoperative Education Program: A Quality Improvement Project

Preoperative education is an important component of preparing patients for surgery. Preoperative anxiety is one of the most important problems for patients, because it causes emotional and psychiatric problems as well as physical problems. Anxiety has been associated with several pathophysiological responses such as hypertension and dysrhythmias, which can increase perioperative morbidity. Estimates suggest that between 11% and 80% of adult presurgical patients experience heightened levels of anxiety. The purpose of this pilot project was to develop a preoperative education program for thoracic surgery patients and to assess the effectiveness of the program in decreasing patient's self-reported anxiety levels using the validated Patient-Reported Outcomes Measurement Information System (PROMIS) tool. This quality improvement project used a pre- and posttest improvement design to evaluate patient's self-reported anxiety levels at three different timepoints during the preoperative and postoperative period. A total of 15 patients from a thoracic surgery practice participated in the study. The study showed no statistically significant change in patients' self-reported anxiety levels after completion of the preoperative education program (p = .538). Patients reported improvements in parameters such as expectations, pain, and preparedness. Although some studies have found that preoperative patient education decreases anxiety, this study supports others that indicate that anxiety is not affected by or associated with educational preparation prior to thoracic surgery. Though no statistical improvement in anxiety levels was demonstrated in this study, a majority of patients reported improvements in parameters such as expectations, pain, and preparedness. As patient education is largely provided by the nursing profession, this article will help the profession to better understand what is important for patients to know in the preoperative setting. Setting patient expectations has a great impact on the patient's recovery and satisfaction with their surgical experience. As this is a pilot study, the goal is for continued research in the area of decreasing preoperative anxiety and preparing patients for surgery.

Intracranial Recordings and Computational Modeling of Music Reveal the Time Course of Prediction Error Signaling in Frontal and Temporal Cortices.

Prediction is held to be a fundamental process underpinning perception, action, and cognition. To examine the time course of prediction error signaling, we recorded intracranial EEG activity from nine presurgical epileptic patients while they listened to melodies whose information theoretical predictability had been characterized using a computational model. We examined oscillatory activity in the superior temporal gyrus (STG), the middle temporal gyrus (MTG), and the pars orbitalis of the inferior frontal gyrus, lateral cortical areas previously implicated in auditory predictive processing. We also examined activity in anterior cingulate gyrus (ACG), insula, and amygdala to determine whether signatures of prediction error signaling may also be observable in these subcortical areas. Our results demonstrate that the information content (a measure of unexpectedness) of musical notes modulates the amplitude of low-frequency oscillatory activity (theta to beta power) in bilateral STG and right MTG from within 100 and 200 msec of note onset, respectively. Our results also show this cortical activity to be accompanied by low-frequency oscillatory modulation in ACG and insula-areas previously associated with mediating physiological arousal. Finally, we showed that modulation of low-frequency activity is followed by that of high-frequency (gamma) power from approximately 200 msec in the STG, between 300 and 400 msec in the left insula, and between 400 and 500 msec in the ACG. We discuss these results with respect to models of neural processing that emphasize gamma activity as an index of prediction error signaling and highlight the usefulness of musical stimuli in revealing the wide-reaching neural consequences of predictive processing.

Impact of nominal photon energies on normal tissue sparing in knowledge-based radiotherapy treatment planning for rectal cancer patients.

The interactive adjustment of the optimization objectives during the treatment planning process has made it difficult to evaluate the impact of beam quality exclusively in radiotherapy. Without consensus in the published results, the arbitrary selection of photon energies increased the probability of suboptimal plans. This work aims to evaluate the dosimetric impact of various photon energies on the sparing of normal tissues by applying a preconfigured knowledge-based planning (RapidPlan) model to various clinically available photon energies for rectal cancer patients, based on model-generated optimization objectives, which provide a comparison basis with less human interference. A RapidPlan model based on 81 historical VMAT plans for pre-surgical rectal cancer patients using 10MV flattened beam (10X) was used to generate patient-specific objectives for the automated optimization of other 20 patients using 6X, 8X, 10X (reference), 6MV flattening-filter-free (6F) and 10F beams respectively on a TrueBeam accelerator. It was observed that flattened beams produced very comparable target dose coverage yet the conformity index using 6F and 10F were clinically unacceptable (>1.29). Therefore, dose to organs-at-risk (OARs) and normal tissues were only evaluated for flattened beams. RapidPlan-generated objectives for 6X and 8X beams can achieve comparable target dose coverage as that of 10X, yet the dose to normal tissues increased monotonically with decreased energies. Differences were statistically significant except femoral heads. From the radiological perspective of view, higher beam energy is still preferable for deep seated tumors, even if multiple field entries such as VMAT technique can accumulate enough dose to the target using lower energies, as reported in the literature. In conclusion, RapidPlan model configured for flattened beams cannot optimize un-flattened beams before adjusting the target objectives, yet works for flattened beams of other energies. For the investigated 10X, 8X and 6X photons, higher energies provide better normal tissue sparing.

BARIATRIC SURGERY AND BINGE EATING DISORDER: SHOULD SURGEONS CARE ABOUT IT? A LITERATURE REVIEW OF PREVALENCE AND ASSESSMENT TOOLS.

Eating pathologies among bariatric surgery candidates are common and associated with adverse surgical outcomes, including weight regain and low quality of life. However, their assessment is made difficult by the great variety and inconsistent use of standardized measures. The purpose of this review was to synthesize current knowledge on the prevalence of binge eating disorder (BED) in presurgical patients and to make a critical appraisal of assessment tools for BED. A search was conducted on PubMed, Scopus, and Web of Science databases from January 1994 to March 2017. Data were extracted, tabulated and summarized using a narrative approach. A total of 21 observational studies were reviewed for data extraction and analysis. Prevalence of BED in bariatric populations ranged from 2% to 53%. Considerable variation in patient characteristics and in BED assessment measures was evident among the studies. In addition, several methodological weaknesses were recognized in most of the studies. Ten different psychometric instruments were used to assess BED. Clinical interviews were used in only 12 studies, though this is the preferred tool to diagnose BED. Study heterogeneity accounted for the variability of the results from different centers and methodological flaws such as insufficient sample size and selection bias impaired the evidence on the magnitude of BED in surgical settings. For the sake of comparability and generalizability of the findings in future studies, researchers must recruit representative samples of treatment-seeking candidates for bariatric surgery and systematically apply standard instruments for the assessment of BED.

A study of Serum Albumin level and it’s association in cure in chronically ill patients

Background: In cases of a pathological state there might be a low formation of the albumin in liver or high degradation of the albumin. In either of the ways the serum albumin will be lowered. Stress and strain is also known to cause hypoalbuminemia i.e low serum level of albumin. Since albumin is a protein it has to be transcribed rom the genes and studies have shown that TNF - alpha supresses this transcription process. The TNF – alpha is known to increase in any inflammation and thus forms a cascade. In case of hospitalised patients the stress and strain in pre surgical patients and chronically hospitalised patients the serum albumin levels are known to be less than normal. In chronically hospitalised patients the nutritional cause can also be taken into consideration for lower serum albumin levels. Early detection of these low levels of serum albumin levels helps the the physicians to intervene and thus cut off the progression of the disease. A sincere effort has been made in this study to understand the relations of the serum albumin level and its effects on the prognosis of the chronic diseases and outcome of the treatment if the patient is undergoing any. This study is intended to help the physician, surgeon and general practitioners to understand and intervene in the event and thus help the patient to recover earlier and in a better way. Aim of the study: is to estimate the mean serum albumin levels in hospitalised patients, to estimate the mean serum albumin levels in patients undergoing surgery and to correlate the serum albumin levels and the prognosis of the patient. Methods: This study was done in the Department of General Medicine at Kanachur Institute of Medical Sciences, Mangalore. This study was done from Jan 2017 to Dec 2018 The study is a cross – sectional study. The study is also double blinded and randomised. The study is a multi - level study. The sample size included one hundred patients. One hundred patients were identified in the department of Medicine. The patients were either chronically ill who were hospitalised for more than three weeks or who were undergoing treatment. The serum albumin levels were estimated. In chronically hospitalised patients the patients were divided into three groups 1. Serum levels less than 2 gm / Dl 2. Serum levels between 2 g/ dl and 5 gm / Dl 3. Serum levels more than 5 gm / Dl The serum albumin levels were again estimated and the prognosis was checked in the form of pain, worsening of symptoms, positive progression of disease, cure and death. In each group the necessary treatment was given in the form of nutrition supplementation and was observed for the prognosis. The serum albumin levels were again estimated and the prognosis was checked in the form of pain, worsening of symptoms, positive progression of disease, cure and death. Result: In the present study there is a significant difference in the prognosis of the patients when the serum albumin level increases in the serum. The mean serum levels in the three groups were found to be 1.95 gm / Dl, 2.85 gm / Dl and 5.1 gm / Dl. In the third group the cure was complete with treatment, showing the significance of serum albumin levels in the prognosis and outcome of the disease. Conclusion: The disease prognosis was significantly altered when the low serum albumin was altered.

Retrieval of semantic knowledge in language pre-surgical mapping. A MEG study.

Retrieval of semantic knowledge in language pre-surgical mapping. A MEG study.

A Role for Tryptophan-2,3-dioxygenase in CD8 T-cell Suppression and Evidence of Tryptophan Catabolism in Breast Cancer Patient Plasma.

Tryptophan catabolism is an attractive target for reducing tumor progression and improving antitumor immunity in multiple cancers. Tumor infiltration by CD8 T cells correlates with improved prognosis in triple-negative breast cancer (TNBC) and a significant effort is underway to improve CD8 T-cell antitumor activity. In this study, primary human immune cells were isolated from the peripheral blood of patients and used to demonstrate that the tryptophan catabolite kynurenine induces CD8 T-cell death. Furthermore, it is demonstrated that anchorage-independent TNBC utilizes the tryptophan-catabolizing enzyme tryptophan 2,3-dioxygenase (TDO) to inhibit CD8 T-cell viability. Publicly available data revealed that high TDO2, the gene encoding TDO, correlates with poor breast cancer clinical outcomes, including overall survival and distant metastasis-free survival, while expression of the gene encoding the more commonly studied tryptophan-catabolizing enzyme, IDO1 did not. Metabolomic analysis, using quantitative mass spectrometry, of tryptophan and its catabolites, including kynurenine, in the plasma from presurgical breast cancer patients (n = 77) and 40 cancer-free donors (n = 40) indicated a strong correlation between substrate and catabolite in both groups. Interestingly, both tryptophan and kynurenine were lower in the plasma from patients with breast cancer compared with controls, particularly in women with estrogen receptor (ER)-negative and stage III and IV breast cancer. IMPLICATIONS: This study underscores the importance of tryptophan catabolism, particularly in aggressive disease, and suggests that future pharmacologic efforts should focus on developing drugs that target both TDO and IDO1.

Modulation of Item and Source Memory by Auditory Beat Stimulation: A Pilot Study With Intracranial EEG.

Auditory beat stimulation is an upcoming technique for non-invasive brain stimulation. Its influence on mediotemporal regions and memory processes has not yet been thoroughly investigated. A recent study suggests that auditory beats are able to alter intracranial EEG (iEEG) power and phase synchronization. 5 Hz binaural beat stimulation increased temporo-lateral phase synchronization, while 5 Hz monaural beat stimulation decreased mediotemporal synchronization. Based on the relevance of phase synchronization for memory operations, we hypothesized that 5 Hz binaural beat stimulation enhances, while 5 Hz monaural beat stimulation decreases long-term memory performance. We analyzed data from presurgical epilepsy patients with implanted depth electrodes in the hippocampus and rhinal cortex. 5 Hz monaural and binaural beat vs. control stimulation was applied while patients performed an associative learning task involving item and source recognition. We evaluated behavioral effects for item (hits minus false alarms) and source memory (correct minus incorrect) and the impact of auditory beats on iEEG power, rhinal-hippocampal phase synchronization and inter-trial phase locking. A three-way repeated measures ANOVA (encoding/retrieval, item/source, monaural/binaural/control) revealed a main effect of stimulation (p = 0.03) and a linear effect in the expected direction: binaural > control > monaural (p = 0.036). Both monaural and binaural stimulation were associated with increased phase locking of 5 Hz oscillations within rhinal cortex. These phase locking increases, however, corresponded to reverse phase shifts. Our data suggest that binaural vs. monaural 5 Hz stimulation increases vs. decreases long-term memory performance. These behavioral effects appear to be related to reverse phase shifts within rhinal cortex.

2004. Clinical Application of Xpert SA Nasal Complete for Direct Detection of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus in Nasal Swabs in Pediatric Care Setting

Background Staphylococcus aureus (SA) is a major human pathogen, causing a variety of nosocomial and community-acquired infections. Nasal carriers of SA are at increased risk for healthcare associated infections with this organism. Timely detection of SA and Methicillin-resistant Staphylococcus aureus (MRSA) and decolonization of pre-surgical patients carrying SA are of importance in infection prevention. We sought to evaluate the clinical performance of the Xpert SA Nasal Complete assay (Xpert SA) for detection of SA and MRSA in the nasal specimens from pediatric patients.MethodsA total of 504 nasal specimens were collected in the Copan dual swab systems from patients with ages between 0 to 61 years with 91.9% patients ≤21 year-old (n = 463). For each sample, one swab was tested with Xpert SA. The second swab was plated onto Blood agar, Mannitol salt agar and ChromID™ MRSA plate and incubated at 35°C in non-CO2 incubator. The identification of SA and MRSA was compared between Xpert SA and the culture results. Methicillin resistance was determined using conventional methods (susceptibility testing or detection of altered penicillin binding protein).ResultsWhen compared with culture for the identification of SA (n = 481), there was an agreement of 95.0% with sensitivity and specificity being 95.6% and 94.8%, respectively. Among those culture-confirmed and Xpert SA positive samples (n = 131), concordance between Xpert SA and conventional methods for detection of methicillin resistance was 97.0% with sensitivity and specificity being 100% and 96.3%, respectively. Four culture-confirmed methicillin-susceptible SA (MSSA) were identified as MRSA by Xpert SA. Among 504 nasal specimens, 23 (4.6%) samples had invalid or instrument failure results. Nasal swabs collected from pediatric patients (≤21-year-old) had a higher invalid/instrument failure rate (5.0%) than those from adults (0%) (P < 0.001).ConclusionXpert SA Nasal Complete assay provides a rapid and sensitive method to detect and differentiate between MSSA and MRSA colonization. The higher invalid rate in pediatric patients and misidentification of MSSA as MRSA by Xpert SA warrant the confirmation by bacterial culture and conventional susceptibility test.Disclosures A. Leber, Nationwide Children’s Hospital: Research Contractor, Research support.

COMPARATIVE STUDY OF βS-LACTAM DE-LABELING ON THE FREQUENCY OF PERI-OPERATIVE VANCOMYCIN USE

Introduction Vancomycin is the antibiotic of choice in β-lactam allergic adults undergoing surgical antibiotic prophylaxis. Because it is a suboptimal option, in 2015 a pre-operative drug allergy screening program began at the Montreal General Hospital (MGH). It de-labeled 94 % of patients evaluated, reducing vancomycin use to 3 %. To validate the program effectiveness a prospective study comparing the Royal Victoria Hospital (RVH), which lacked de-labeling was undertaken.The aim of the study was to determine the effect of a de-labeling program on vancomycin use. Methods From Jan 1st to Dec 31st 2017 pre-surgical patients suspected of penicillin allergy at both hospitals were studied. Variables captured included; gender, age, time, type, place of surgery, prophylactic antibiotics and number/type of postoperative infections. Results Among 618 RVH patients with suspected β-lactam allergy, 385 received peri-operative antibiotics and 175 got vancomycin (only one had Methicillin Resistant Staphylococcus Aureus (MRSA)). Of the 31 post-operative infectious complications, 20 (65%) occurred in those administered vancomycin. Among the 658 MGH patients with suspected β-lactam allergy 116 had pre-operative allergy assessments of which 98 got antibiotics. Vancomycin was given peri-operatively to 4 patients (none MRSA positive). Cefazolin in 84 and no antibiotics in 18.Only 3 patients (3 %) had post-operative complications but none on vancomycin. Vancomycin prophylaxis was higher at the RVH (175 of 385,45.45%) versus MGH (4 of 98,4.08%), with a difference of 41.37% (95%CI, 34.40%, 48.34 %). Conclusions Lack of β-lactam allergy screening was associated with a significantly higher frequency of vancomycin use and higher rates of post-operative complications.

Hippocampal CA1 gamma power predicts the precision of spatial memory judgments

The hippocampus plays a critical role in spatial memory. However, the exact neural mechanisms underlying high-fidelity spatial memory representations are unknown. We report findings from presurgical epilepsy patients with bilateral hippocampal depth electrodes performing an object-location memory task that provided a broad range of spatial memory precision. During encoding, patients were shown a series of objects along the circumference of an invisible circle. At test, the same objects were shown at the top of the circle (0°), and patients used a dial to move the object to its location shown during encoding. Angular error between the correct location and the indicated location was recorded as a continuous measure of performance. By registering pre- and postimplantation MRI scans, we were able to localize the electrodes to specific hippocampal subfields. We found a correlation between increased gamma power, thought to reflect local excitatory activity, and the precision of spatial memory retrieval in hippocampal CA1 electrodes. Additionally, we found a similar relationship between gamma power and memory precision in the dorsolateral prefrontal cortex and a directional relationship between activity in this region and in the CA1, suggesting that the dorsolateral prefrontal cortex is involved in postretrieval processing. These results indicate that local processing in hippocampal CA1 and dorsolateral prefrontal cortex supports high-fidelity spatial memory representations.

Direct Electrophysiological Evidence for Prefrontal Control of Hippocampal Processing during Voluntary Forgetting

Forgetting does not necessarily reflect failure to encode information but can, to some extent, also be voluntarily controlled. Previous studies have suggested that voluntary forgetting relies on active inhibition of encoding processes in the hippocampus by the dorsolateral prefrontal cortex (DLPFC) [1-4]. During attentional and sensorimotor processing, enhanced DLPFC theta power alongside increased alpha/beta oscillations are a neural signature of an inhibitory top-down mechanism, with theta oscillations reflecting prefrontal control and alpha/beta oscillations occurring in areas targeted by inhibition [5-12]. Here, we used intracranial EEG recordings in presurgical epilepsy patients implanted in DLPFC (n= 13) and hippocampus (n= 15) during an item-method directed forgetting paradigm. We found that voluntary forgetting is associated with increased neural oscillations in the low theta band (3-5Hz) in DLPFC and in a broad theta/alpha/beta (6-18Hz) frequency range in hippocampus. Combining time-lagged correlation analysis, phase synchronization,and Granger causality in 6 patients with electrodes in both DLPFC and hippocampus, we obtained converging evidence for a top-down control of hippocampal activity by the DLPFC. Together, our results provide strong support for a model in which voluntary forgetting relies on enhanced inhibition of the hippocampus by the DLPFC.

Basal forebrain cholinergic system volume is associated with general cognitive ability in the elderly

ObjectiveAt the present, it is unclear whether association of basal forebrain cholinergic system (BFCS) volume with cognitive performance exists in healthy as well as in cognitively impaired elderly subjects. Whereas one small study reported an association of BFCS volume with general cognitive ability ‘g’ in healthy ageing, effects on specific cognitive domains have only been found in subjects with cognitive decline. Here we aim to clarify whether an association of BFCS volume and ‘g’ is present in a larger sample of elderly subjects without obvious symptoms of dementia and whether similar associations can also be observed in specific cognitive domains. Methods282 pre-surgical patients from the BioCog study (aged 72.7 ± 4.9 years with a range of 65–87 years, 110 women) with a median MMSE score of 29 points (range 24–30) were investigated. BFCS and brain volume as well as brain parenchymal fraction were assessed in T1-weighted MR images using SPM12 and a probabilistic map of the BFCS. Neuropsychological assessment comprised the CANTAB cognitive battery and paper-and-pencil based tests. For data analysis, generalised linear models and quantile regression were applied. ResultsSignificant associations of BFCS volume with ‘g’ and several cognitive domains were found, with the strongest association found for ‘g’. BFCS volume explained less variance in cognitive performance than brain volume. The association was not confounded by brain parenchymal fraction. Furthermore, the association of BFCS volume and ‘g’ was similar in high- and low-performers. ConclusionOur results extend previous study findings on BFCS volume associations with cognition in elderly subjects. Despite the observed associations of BFCS volume and cognitive performance, this association seems to reflect a more general association of brain volume and cognition. Accordingly, a specific association of BFCS volume and cognition in non-demented elderly subjects is questionable.

Gender-related patterns of psychiatric disorder clustering among bariatric surgery candidates: A latent class analysis

BackgroundPsychiatric disorders tend to distribute unevenly in women and men with severe obesity. The current research aimed to identify homogeneous clusters of concurrent psychiatric disorders among patients seeking bariatric surgery, by gender. MethodsWe recruited a consecutive sample of 393 candidates with obesity (311 women and 82 men) in a university-based bariatric center. Trained clinicians assessed psychiatric disorders through the Structured Clinical Interview for DSM-IV (SCID). Latent class analysis categorized pre-surgical patients into uniform clusters of co-occurring psychiatric disorders. ResultsFor both genders, the 3-class psychopathological clustering was the best-fitting solution. Among women, the latent classes were: (1) “oligosymptomatic”, wherein 42% of patients showed low probability of psychiatric disorders; (2) “bipolar with comorbidities”, in 33%; and (3) “anxiety/depression”, in 25%. Among men, (1) “bipolar with comorbidities” was found in 47% of patients; (2) “oligosymptomatic”, in 40%; and (3) “anxiety/depression”, in 13%. For both genders, the probability of presenting eating disorders was higher in both “bipolar” and “anxiety/depression” classes. Substance use disorders was prominent among “bipolar” men. In comparison with “oligosymptomatic” class, the likelihood of higher BMI was observed among “bipolar” men and poorer work attainment among men with “anxiety/depression”. LimitationParticipants was cross-sectionally drawn from a single bariatric center. ConclusionsPre-surgical men and women with severe obesity were distributed in three comorbidity profiles and revealed analogous psychopathological patterns. The class of “bipolar disorders” most likely presented comorbidity with eating and substance use disorder. This natural clustering of psychiatric disorders among bariatric patients suggests gender-related therapeutic approaches and surgical outcomes.

O 097 – Predictors of midfoot break in children with cerebral palsy and flatfeet

Degenerative lumbar diseases (DLDs) are characterized by motor functional deficits and postural instability. In this study, we investigated the differences in the trunk muscle responses to postural control between the presurgical DLD patients and healthy individuals while performing the static and perturbed balance tasks.Thirty-five DLD patients (aged 61.1 ± 8.0 years) and thirty-five asymptomatic controls (aged 62.9 ± 3.7 years) participated in this study. All participants stood on a force plate and performed the quiet standing (QS) and in situ weight-lifting (WL) tasks. The participants’ performance in the QS task was tested under the eyes-open, eyes-closed, wide-base, and narrow-base conditions. Center of pressure (CoP) movements and electromyography of the erector spinae (ES) were recorded. The Mann–Whitney U test was applied for statistical analysis.The DLD group showed a significantly greater CoP movements and muscle activations during the QS task. Nevertheless, smaller CoP movements were noted during the WL task in the DLD group. Under the eyes-closed and narrow-base conditions, the DLD group showed even higher muscle activations and CoP movements.The DLD patients demonstrated a poor postural control ability and tended to rely on the visual feedback and wide-base standing posture. A rigid and restricted posture was also adopted during the perturbed WL task. A high level of ES activation was required to maintain their postural steadiness. This study reveals an aberrant pattern of postural control and trunk muscle activations in symptomatic DLD patients which potentially contributes to the development of beneficial rehabilitation programs.

Postural stability and trunk muscle responses to the static and perturbed balance tasks in individuals with and without symptomatic degenerative lumbar disease

BackgroundDegenerative lumbar diseases (DLDs) are characterized by motor functional deficits and postural instability. In this study, we investigated the differences in the trunk muscle responses to postural control between the presurgical DLD patients and healthy individuals while performing the static and perturbed balance tasks. MethodsThirty-five DLD patients (aged 61.1 ± 8.0 years) and thirty-five asymptomatic controls (aged 62.9 ± 3.7 years) participated in this study. All participants stood on a force plate and performed the quiet standing (QS) and in situ weight-lifting (WL) tasks. The participants’ performance in the QS task was tested under the eyes-open, eyes-closed, wide-base, and narrow-base conditions. Center of pressure (CoP) movements and electromyography of the erector spinae (ES) were recorded. The Mann–Whitney U test was applied for statistical analysis. ResultsThe DLD group showed a significantly greater CoP movements and muscle activations during the QS task. Nevertheless, smaller CoP movements were noted during the WL task in the DLD group. Under the eyes-closed and narrow-base conditions, the DLD group showed even higher muscle activations and CoP movements. SignificanceThe DLD patients demonstrated a poor postural control ability and tended to rely on the visual feedback and wide-base standing posture. A rigid and restricted posture was also adopted during the perturbed WL task. A high level of ES activation was required to maintain their postural steadiness. This study reveals an aberrant pattern of postural control and trunk muscle activations in symptomatic DLD patients which potentially contributes to the development of beneficial rehabilitation programs.