The influence of the SARS-CoV-2 lockdown on patients with inflammatory rheumatic diseases on their adherence to immunomodulatory medication: a cross sectional study over 3 months in Germany.

OBJECTIVES: To evaluate the influence of the SARS-CoV-2 pandemic on the adherence of patients with inflammatory rheumatic diseases (IRD) to their immunomodulatory medication during the three-month lockdown in Germany. METHODS: From 16th March until 15th June 2020, IRD patients from private practices and rheumatology departments were asked to answer a questionnaire addressing their behaviour with respect to their immunomodulating therapy. Eight private practices and nine rheumatology departments that included rheumatology primary care centres and university hospitals participated. A total of 4252 questionnaires were collected and evaluated. RESULTS: The majority of patients (54%) were diagnosed with RA, followed by psoriatic arthritis (14%), ankylosing spondylitis (10%), connective tissue diseases (12%) and vasculitides (6%). Most of the patients (84%) reported to continue their immunomodulatory therapy. Termination of therapy was reported by only 3% of the patients. The results were independent from the type of IRD, the respective immunomodulatory therapy and by whom the patients were treated (private practices vs rheumatology departments). Younger patients (<60 years) reported just as often as older patients to discontinue their therapy. CONCLUSION: The data show that most of the patients continued their therapy in spite of the pandemic. A significant change in behaviour with regard to their immunomodulatory therapy was not observed during the three months of observation. The results support the idea that the immediate release of recommendations of the German Society of Rheumatology were well received, supporting the well-established physician-patient relationship in times of a crisis.

[A cross sectional study on patients with inflammatory rheumatic diseases in terms of their compliance to their immunsuppressive medication during COVID-19 pandemic]. / Einstellung von Patienten mit entzündlich-rheumatischen Erkrankungen zur immunsuppressiven Therapie im Rahmen der COVID-19 Pandemie ­ eine Situationsanalyse.

The current COVID-19 pandemic inherits an unprecedented challenge for the treating rheumatologists. On the one hand, antirheumatic drugs can increase the risk of infection and potentially deteriorate the course of an infection. On the other hand, an active inflammatory rheumatic disease can also increase the risk for an infection. In the recommendations of the German Society for Rheumatology (www.dgrh.de), it is recommended that our patients continue the antirheumatic therapy to maintain remission or low state of activity despite the pandemic. In this study, patients with inflammatory rheumatic disease were asked in the first weeks of the pandemic on their opinion of their immunomodulating therapy. The result shows that over 90% of the patients followed the recommendation of the rheumatologist to continue the antirheumatic therapy, and only a small percentage of the patients terminated the therapy on their own. This result was independent of the individual anti-rheumatic therapy. Taken together, the results of this study illustrate not only the trustful patient-physician partnership in a threatening situation but also the high impact of state-of-the art recommendations by the respective scientific society.

[The rich diversity of Whipple's disease]. / Facettenreichtum des Morbus Whipple.

Whipple's disease (WD) is a rare, chronic multiorgan disease which can caused by Tropheryma whipplei, a ubiquitous gram positive bacterium. Detection of T. whipplei is mostly performed histologically using periodic acid-Schiff (PAS) staining in affected tissues to visualize characteristic PAS-positive macrophages and by the polymerase chain reaction (PCR). Clinically, WD is often characterized by gastrointestinal symptoms (diarrhea, colic-like abdominal pain and weight loss). Arthritis is a common presentation of WS, often leading to a misdiagnosis of seronegative rheumatoid arthritis and as a consequence to immunosuppressive therapy. The clinical presentation of WD is highly polymorphic affecting different organ systems (e. g. cardiac or neurological manifestation) and making an appropriate clinical diagnosis and even the diagnostic process itself difficult. This article reports on three cases presenting with completely different leading symptoms (initially misdiagnosed as seronegative rheumatoid arthritis, spondyloarthritis and adult onset of Still's disease, respectively) that illustrate the rich diversity of WD. The cases were chosen to draw attention to the fact that although WD is mainly associated with the field of gastroenterology and gastrointestinal (GI) involvement is common, it may appear without GI symptoms. In cases of a clinical suspicion of WD, diagnostic efforts should be made to detect the bacterium in the affected organ. The German S2k guidelines on GI infections and WD published in January 2015 summarized the current state of the art for WD. The currently recommended primary treatment is antibiotics that can infiltrate the cerebrospinal fluid, e. g. ceftriaxone, followed by cotrimoxazole, which should be maintained over several months.

Attention and normalization circuits in macaque V1.

Attention affects neuronal processing and improves behavioural performance. In extrastriate visual cortex these effects have been explained by normalization models, which assume that attention influences the circuit that mediates surround suppression. While normalization models have been able to explain attentional effects, their validity has rarely been tested against alternative models. Here we investigate how attention and surround/mask stimuli affect neuronal firing rates and orientation tuning in macaque V1. Surround/mask stimuli provide an estimate to what extent V1 neurons are affected by normalization, which was compared against effects of spatial top down attention. For some attention/surround effect comparisons, the strength of attentional modulation was correlated with the strength of surround modulation, suggesting that attention and surround/mask stimulation (i.e. normalization) might use a common mechanism. To explore this in detail, we fitted multiplicative and additive models of attention to our data. In one class of models, attention contributed to normalization mechanisms, whereas in a different class of models it did not. Model selection based on Akaike's and on Bayesian information criteria demonstrated that in most cells the effects of attention were best described by models where attention did not contribute to normalization mechanisms. This demonstrates that attentional influences on neuronal responses in primary visual cortex often bypass normalization mechanisms.

Nuclear imaging to support anti-inflammatory drug discovery and development.

Nuclear medicine contributes important tools to support antiinflammatory drug discovery and development in many ways. The support provided is manifold: new molecular entities (NME, either small molecules or biologics) labeled with radioisotopes can be applied in animal models and humans to measure biodistribution, target engagement, and pharmacokinetics. In addition, nuclear imaging techniques can be used to select or enrich the patient populations in clinical trials, to assess disease activity, target status and distribution and to quantify response to therapeutic interventions. In the first part of this review we will outline how nuclear imaging techniques can be applied to support informed decision making in drug development. In the second part, we will briefly highlight the use of nuclear imaging of inflammation in drug development in selected diseases, specifically rheumatoid arthritis (RA), inflammatory bowel diseases (IBD), atherosclerosis (ATS) and as an emerging topic cancer.

Acetylcholine contributes through muscarinic receptors to attentional modulation in V1.

Attention exerts a strong influence over neuronal processing in cortical areas. It selectively increases firing rates and affects tuning properties, including changing receptive field locations and sizes. Although these effects are well studied, their cellular mechanisms are poorly understood. To study the cellular mechanisms, we combined iontophoretic pharmacological analysis of cholinergic receptors with single cell recordings in V1 while rhesus macaque monkeys (Macaca mulatta) performed a task that demanded top-down spatial attention. Attending to the receptive field of the V1 neuron under study caused an increase in firing rates. Here we show that this attentional modulation was enhanced by low doses of acetylcholine. Furthermore, applying the muscarinic antagonist scopolamine reduced attentional modulation, whereas the nicotinic antagonist mecamylamine had no systematic effect. These results demonstrate that muscarinic cholinergic mechanisms play a central part in mediating the effects of attention in V1.

Development of a novel fluorine-18 labeled deuterated fluororasagiline ([(18)F]fluororasagiline-D2) radioligand for PET studies of monoamino oxidase B (MAO-B).

The objective of this study was to synthesize and evaluate a novel fluorine-18 labeled deuterium substituted analogue of rasagiline (9, [(18)F]fluororasagiline-D2) as a potential PET radioligand for studies of monoamine oxidase B (MAO-B). The precursor compound (6) and reference standard (7) were synthesized in multi-step syntheses. Radiolabeling of 9 was accomplished by a two-step synthesis, compromising a nucleophilic substitution followed by hydrolysis of the sulfamidate group. The incorporation radiochemical yield from fluorine-18 fluoride was higher than 30%, the radiochemical purity was >99% and the specific radioactivity was >160GBq/µmol at the time of administration. In vitro compound 7 inhibited the MAO-B activity with an IC50 of 173.0±13.6nM. The MAO-A activity was inhibited with an IC50 of 9.9±1.1µM. The fluorine-18 version 9 was characterized in the cynomolgus monkey brain where a high brain uptake was found (275% SUV at 4min). There was a higher uptake in the striatum and thalamus compared to the cortex and cerebellum. A pronounced blocking effect (50% decrease) was observed in the specific brain regions after administration of l-deprenyl (0.5mg/kg) 30min prior to the administration of 9. Radiometabolite studies demonstrated 40% of unchanged radioligand at 90min post injection. An efficient radiolabeling of 9 was successfully established and in the monkey brain 9 binds to MAO-B rich regions and its binding is blocked by the selective MAO-B compound l-deprenyl. The radioligand 9 is a potential candidate for human PET studies.

Synthesis and biological evaluation of novel propargyl amines as potential fluorine-18 labeled radioligands for detection of MAO-B activity.

The aim of this project was to synthesize and evaluate three novel fluorine-18 labeled derivatives of propargyl amine as potential PET radioligands to visualize monoamine oxidase B (MAO-B) activity. The three fluorinated derivatives of propargyl amine ((S)-1-fluoro-N,4-dimethyl-N-(prop-2-ynyl)-pent-4-en-2-amine (5), (S)-N-(1-fluoro-3-(furan-2-yl)propan-2-yl)-N-methylprop-2-yn-1-amine (10) and (S)-1-fluoro-N,4-dimethyl-N-(prop-2-ynyl)pentan-2-amine (15)) were synthesized in multi-step organic syntheses. IC(50) values for inhibition were determined for compounds 5, 10 and 15 in order to determine their specificity for binding to MAO-B. Compound 5 inhibited MAO-B with an IC(50) of 664 ± 48.08 nM. No further investigation was carried out with this compound. Compound 10 inhibited MAO-B with an IC(50) of 208.5 ± 13.44 nM and compound 15 featured an IC(50) of 131.5 ± 0.71 nM for its MAO-B inhibitory activity. None of the compounds inhibited MAO-A activity (IC(50) > 2 µM). The fluorine-18 labeled analogues of the two higher binding affinity compounds (10 and 15) (S)-N-(1-[(18)F]fluoro-3-(furan-2-yl)propan-2-yl)-N-methylprop-2-yn-1-amine (16) and (S)-1-[(18)F]fluoro-N,4-dimethyl-N-(prop-2-ynyl)pentan-2-amine (18) were both prepared from the corresponding precursors 9A, 9B and 14A, 14B by a one-step fluorine-18 nucleophilic substitution reaction. Autoradiography experiments on human postmortem brain tissue sections were performed with 16 and 18. Only compound 18 demonstrated a high selectivity for MAO-B over MAO-A and was, therefore, chosen for further examination by PET in a cynomolgus monkey. The initial uptake of 18 in the monkey brain was 250% SUV at 4 min post injection. The highest uptake of radioactivity was observed in the striatum and thalamus, regions with high MAO-B activity, whereas lower levels of radioactivity were detected in the cortex and cerebellum. The percentage of unchanged radioligand 18 was 30% in plasma at 90min post injection. In conclusion, compound 18 is a selective inhibitor of MAO-B in vitro and demonstrated a MAO-B specific binding pattern in vivo by PET in monkey. It can, therefore, be considered as a candidate for further investigation in human by PET.

Effect of feature-selective attention on neuronal responses in macaque area MT.

Attention influences visual processing in striate and extrastriate cortex, which has been extensively studied for spatial-, object-, and feature-based attention. Most studies exploring neural signatures of feature-based attention have trained animals to attend to an object identified by a certain feature and ignore objects/displays identified by a different feature. Little is known about the effects of feature-selective attention, where subjects attend to one stimulus feature domain (e.g., color) of an object while features from different domains (e.g., direction of motion) of the same object are ignored. To study this type of feature-selective attention in area MT in the middle temporal sulcus, we trained macaque monkeys to either attend to and report the direction of motion of a moving sine wave grating (a feature for which MT neurons display strong selectivity) or attend to and report its color (a feature for which MT neurons have very limited selectivity). We hypothesized that neurons would upregulate their firing rate during attend-direction conditions compared with attend-color conditions. We found that feature-selective attention significantly affected 22% of MT neurons. Contrary to our hypothesis, these neurons did not necessarily increase firing rate when animals attended to direction of motion but fell into one of two classes. In one class, attention to color increased the gain of stimulus-induced responses compared with attend-direction conditions. The other class displayed the opposite effects. Feature-selective activity modulations occurred earlier in neurons modulated by attention to color compared with neurons modulated by attention to motion direction. Thus feature-selective attention influences neuronal processing in macaque area MT but often exhibited a mismatch between the preferred stimulus dimension (direction of motion) and the preferred attention dimension (attention to color).

Tetrahydrobiopterin (BH4) in PKU: effect on dietary treatment, metabolic control, and quality of life.

BACKGROUND: Tetrahydrobiopterin (BH(4))-sensitive phenylketonuria (PKU) can be treated with sapropterin dihydrochloride. We studied metabolic control and health-related quality of life (HRQoL) in PKU patients treated with BH(4). SUBJECTS AND METHODS: Based on the review of neonatal BH(4) test results and mutation analysis in 41 PKU patients, 19 were identified as potentially BH(4)-sensitive (9 females, 10 males, age 4-18 years). We analyzed phenylalanine (phe) concentrations in dried blood samples, nutrition protocols, and HRQoL questionnaires (KINDL(®)) beginning from 1 year before, during the first 42 days, and after 3 months of BH(4) therapy. RESULTS: Eight BH(4)-sensitive patients increased their phe tolerance (629 ± 476 vs. 2131 ± 1084 mg, p = 0.006) while maintaining good metabolic control (phe concentration in dried blood 283 ± 145 vs. 304 ± 136 µM, p = 1.0). Six of them were able to stop dietary protein restriction entirely. BH(4)-sensitive patients had average HRQoL scores that were comparable to age-matched healthy children. There was no improvement in HRQoL scores after replacing classic dietary treatment with BH(4) supply, although personal reports given by the patients and their parents suggest that available questionnaires are inappropriate to detect aspects relevant to inborn metabolic disorders. DISCUSSION: BH(4) can allow PKU patients to increase their phe consumption significantly or even stop dietary protein restrictions. Unexpectedly, this does not improve HRQoL as assessed with KINDL(®), partly due to high scores even before BH(4) therapy. Specific questionnaires should be developed for inborn metabolic disorders.

Synthesis and evaluation of [¹8F]fluororasagiline, a novel positron emission tomography (PET) radioligand for monoamine oxidase B (MAO-B).

The aim of this study was to synthesize and evaluate a novel fluorine-18 labeled analogue of rasagiline (6) as a PET radioligand for monoamine oxidase B (MAO-B). The corresponding non-radioactive fluorine-19 ligand, (1S,2S)-2-fluoro-N-(prop-2-yn-1-yl)indan-1-amine (4), was characterized in in vitro assays. The precursor compound (3aS,8aR)-3-(prop-2-yn-1-yl)-3,3a,8,8a-tetrahydroindeno[1,2-d][1,2,3]oxathiazole 2,2-dioxide (3) and reference standard 4 were synthesized in multi-step syntheses. Recombinant human MAO-B and MAO-A enzyme preparations were used in order to determine IC(50) values for compound 4 by use of an enzymatic assay employing kynuramine as substrate. Radiolabeling was accomplished by a two-step synthesis, compromising a nucleophilic substitution followed by hydrolysis of the sulphamidate group. Human whole hemisphere autoradiography (ARG) was performed with [(18)F]fluororasagiline. Blocking experiments with pirlindole (MAO-A), L-deprenyl and rasagiline (MAO-B) were conducted to demonstrate the specificity of the binding. A positron emission tomography (PET) study was carried out in a cynomolgus monkey where time activity curves for whole brain and regions with high and low MAO-B activity were recorded. Radiometabolites were measured in monkey plasma using gradient HPLC. Compound 4 inhibited MAO-B with an IC(50) of 27 nM and MAO-A with an IC(50) of 2.3 µM. Radiolabeling of precursor 3 and subsequent hydrolysis of the protecting group towards (1S,2S)-2-[(18)F]fluoro-N-(prop-2-yn-1-yl)indan-1-amine (6) was successfully accomplished with an radiochemical yield of 40-70%, a radiochemical purity higher than 99% and a specific radioactivity higher than 200GBq/µmol. ARG demonstrated selective binding for [(18)F]fluororasagiline (6) to MAO-B containing brain regions, for example, striatum. The initial uptake in the monkey brain was 250% SUV at 4 min post injection. The highest amounts of radioactivity were observed in the striatum and thalamus as expected whereas in the cortex and cerebellum lower levels were observed. Metabolite studies demonstrated 30% unchanged radioligand at 90 min post injection. Our investigations demonstrated that the new ligand [(18)F]fluororasagiline (6) binds specifically to MAO-B in vitro and has a MAO-B specific binding pattern in vivo. Thus, it could serve as a novel potential candidate for human PET studies.

Stimulus-induced dissociation of neuronal firing rates and local field potential gamma power and its relationship to the resonance blood oxygen level-dependent signal in macaque primary visual cortex.

The functional magnetic resonance imaging (fMRI) blood oxygenation level-dependent (BOLD) signal is regularly used to assign neuronal activity to cognitive function. Recent analyses have shown that the local field potential (LFP) gamma power is a better predictor of the fMRI BOLD signal than spiking activity. However, LFP gamma power and spiking activity are usually correlated, clouding the analysis of the neural basis of the BOLD signal. We show that changes in LFP gamma power and spiking activity in the primary visual cortex (V1) of the awake primate can be dissociated by using grating and plaid pattern stimuli, which differentially engage surround suppression and cross-orientation inhibition/facilitation within and between cortical columns. Grating presentation yielded substantial V1 LFP gamma frequency oscillations and significant multi-unit activity. Plaid pattern presentation significantly reduced the LFP gamma power while increasing population multi-unit activity. The fMRI BOLD activity followed the LFP gamma power changes, not the multi-unit activity. Inference of neuronal activity from the fMRI BOLD signal thus requires detailed a priori knowledge of how different stimuli or tasks activate the cortical network.

Potent leukocidal action of Escherichia coli hemolysin mediated by permeabilization of target cell membranes.

The contribution of Escherichia coli hemolysin (ECH) to bacterial virulence has been considered mainly in context with its hemolytic properties. We here report that this prevalent bacterial cytolysin is the most potent leukocidin known to date. Very low concentrations (approximately 1 ng/ml) of ECH evoke membrane permeability defects in PMN (2-10 x 10(6) cells/ml) leading to an efflux of cellular ATP and influx of propidium iodide. The attacked cells do not appear to repair the membrane lesions. Human serum albumin, high density and low density lipoprotein, and IgG together protect erythrocytes and platelets against attack by even high doses (5-25 micrograms/ml) of ECH. In contrast, PMN are still permeabilized by ECH at low doses (50-250 ng/ml) in the presence of these plasma inactivators. Thus, PMN become preferred targets for attack by ECH in human blood and protein-rich body fluids. Kinetic studies demonstrate that membrane permeabilization is a rapid process, ATP-release commencing within seconds after application of toxin to leukocytes. It is estimated that membrane permeabilization ensues upon binding of approximately 300 molecules ECH/PMN. This process is paralleled by granule exocytosis, and by loss of phagocytic killing capacity of the cells. The recognition that ECH directly counteracts a major immune defence mechanism of the human organism through its attack on granulocytes under physiological conditions sheds new light on its possible role and potential importance as a virulence factor of E. coli.

[Otogenic meningitis and bilateral spontaneous dehiscences of the lateral skull base. Two case reports]. / Otogene Meningitis bei bilateralen knöchernen Dehiszenzen der Laterobasis. Zwei Fallberichte.

Meningitis in the case of spontaneous dehiscences of the lateral skull base is rare. We report on two patients with otogenic meningitis. High-resolution CT (HR-CT) showed bilateral dehiscences at the lateral skull base in both cases. Infection along the skull base was assumed. In the first case sufficient repair was achieved using a multilayered technique, while in the second case conservative treatment on an intensive care unit was successful. Conservative therapy can prove successful in exceptional cases.

[Mucosal remodeling in chronic rhinosinusitis without nasal polyposis - an ultrastructural evaluation]. / Ultrastrukturelle Untersuchungen bei chronischer Rhinosinusitis ohne Polypen.

OBJECTIVE: Because of recurrent scarring of the ostiomeatal complex after paranasal sinus surgery the therapy of chronic rhinosinusitis without nasal polyps (CRSsNP) seems to be difficult. The aim of this study was to evaluate ultrastructural changes of nasal mucosa in patients with CRSsNP. MATERIAL AND METHODS: In case of revision sinus surgery we took specimens of altered mucosa from 21 patients. All subjects suffered from recurrent CRSsNP. Twelve patients without signs of chronic rhinosinusitis dealed as control group. To prepare for electron microscopy the samples were immersed in 3% phosphate-buffered glutaraldehyde and refixed in 1% osmium acid. After dehydration and heat polymerization ultrathin cuts were prepared. After double-contrasting ultrastructures were evaluated by transmission electron microscopy. RESULTS: Typical changes evaluated by electron microscopy were loss of cilia, an increase of microvilli, collagen fibres, fibrocytes, fibroblasts and myofibroblasts as well as perivascular alterations and endothelial changes. CONCLUSION: The study revealed the presence of evident ultrastructural changes in the mucosa of patients with chronic rhinosinusitis without nasal polyps. Mucosal remodeling seems to be not reversible by conservative treatment.

[Smoking behaviour after laryngectomy]. / Rauchverhalten nach Laryngektomie.

BACKGROUND: Tobacco smoking is an important risk factor for laryngeal cancer. Aim of this study was to investigate the prevalence of smoking and to identify factors that can promote tobacco abstinence. PATIENTS AND METHODS: In a multi-centre cross-sectional study, 187 patients after laryngectomy were surveyed regarding their smoking behaviour. Instruments used were the questionnaire "Quality of Life after Laryngectomy" (Ackerstaff & Hilgers) and the "Questionnaire of Health Behaviour" ("Fragebogen zur Erfassung des Gesundheitsverhaltens", Dlugosch & Krieger). RESULTS: Life time prevalence of tobacco smoking was 89%, whereas current prevalence was only 6%. None of the laryngectomies believed tobacco consumption to be safe. 24% thought that their tumour was caused mainly by smoking, although the current prevalence of smoking was not related to that number. 74% of all ex-smokers had stopped smoking at the time of the laryngectomy. CONCLUSIONS: Only a small fraction of laryngectomized patients do smoke several years after the operation. Anti-tobacco interventions should therefore be focused on high risk persons, not on the entire patient population.

Neural correlates of chromatic motion perception.

A variety of psychophysical and neurophysiological studies suggest that chromatic motion perception in the primate brain may be performed outside the classical motion processing pathway. We addressed this provocative proposal directly by assessing the sensitivity of neurons in motion area MT to moving colored stimuli while simultaneously determining perceptual sensitivity in nonhuman primate observers. The results of these studies demonstrate a strong correspondence between neuronal and perceptual measures. Our findings testify that area MT is indeed a principal component of the neuronal substrate for color-based motion processing.

Neural correlates of contrast detection at threshold.

Human psychophysical studies have demonstrated that, for stimuli near the threshold of visibility, detection of motion in one direction is unaffected by the superimposition of motion in the opposite direction. To investigate the neural basis for this perceptual phenomenon, we recorded from directionally selective neurons in macaque visual area MT (middle temporal visual area). Contrast thresholds obtained for single gratings moving in a neuron's preferred direction were compared with those obtained for motion presented simultaneously in the neuron's preferred and antipreferred directions. A simple model based on probability summation between neurons tuned to opposite directions could sufficiently account for contrast thresholds revealed psychophysically, suggesting that area MT is likely to provide the neural basis for contrast detection of stimuli modulated in time.

Comparison of spatial integration and surround suppression characteristics in spiking activity and the local field potential in macaque V1.

Neurons in primary visual cortex exhibit well documented centre-surround receptive field organization, whereby the centre is dominated by excitatory influences and the surround is generally dominated by inhibitory influences. These effects have largely been established by measuring the output of neurons, i.e. their spiking activity. How excitation and inhibition are reflected in the local field potential (LFP) is little understood. As this can bear on the interpretation of human fMRI BOLD data and on our understanding of the mechanisms of local field potential oscillations, we measured spatial integration and centre-surround properties in single- and multiunit recordings of V1 in the awake fixating macaque monkey, and compared these to spectral power in different frequency bands of simultaneously recorded LFPs. We quantified centre-surround organization by determining the size of the summation and suppression area in spiking activity as well as in different frequency bands of the LFP, with the main focus on the gamma band. Gratings extending beyond the summation area usually inhibited spiking activity while the LFP gamma-band activity increased monotonically for all grating sizes. This increase was maximal for stimuli infringing upon the near classical receptive field surround, where suppression started to dominate spiking activity. Thus, suppressive influences in primary cortex can be inferred from spiking activity, but they also seem to affect specific features of gamma-band LFP activity.

Attention and contrast differently affect contextual integration in an orientation discrimination task.

Attention is often regarded as a mechanism by which attended objects become perceptually more salient, akin to increasing their contrast. We demonstrate that attention is better described as a mechanism by which task relevant information impacts on ongoing processing, while excluding task irrelevant information. We asked subjects to judge the orientation of a target relative to a reference, in a single and dual task setting. The target orientation percept was systematically influenced by the presentation of prior spatio-temporal context. We found that the sign of the context influence depended on target contrast, but its strength depended on the level of attention devoted to the task. Thus the effects of attention and contrast were fundamentally different; contrast influenced the sign of contextual interactions, while attention suppressed these interactions irrespective of their sign.