The impact of overweight on lipid phenotype in different forms of dyslipidemia: a retrospective cohort study.

PURPOSE: Dyslipidemia plays a pivotal role in increasing cardiovascular risk. In clinical practice the misleading association between altered lipid profile and obesity is common, therefore genetically inherited dyslipidemias may not completely be addressed among patients with overweight. Thus, we aim to investigate the influence of overweight and obesity on the lipid phenotype in a cohort of patients with different forms of dyslipidemia. METHODS: A retrospective analysis was conducted on patients with dyslipidemia from 2015 to 2022. Patients were stratified in familial hypercholesterolemia (FH), familial combined hyperlipidemia (FCHL), non-familial hyperlipidemia or polygenic hypercholesterolemia (PH). Clinical characteristics and lipid profile were evaluated. RESULTS: Of the total of 798 patients, 361 were affected by non-familial hyperlipidemia (45.2%), while FCHL, FH and PH was described in 19.9%, 14.0% and 20.9% of patients, respectively. Overweight prevalence was higher in FCHL and non-familial hyperlipidemia patients than FH and PH patients. Subjects with overweight and obesity were independently associated with lower levels of high-density lipoprotein cholesterol (HDL-C) compared to patients with normal weight (52.4 and 46.0 vs 58.1, respectively; p < 0.0001); levels of triglycerides (TG) and non-HDL-C were higher in patients with overweight and obesity than patients with normal weight (257.3 and 290.9 vs 194.8, and 221.5 and 219.6 vs 210.1, p < 0.0001 and p = 0.01, respectively), while no differences were observed between patients with overweight and obesity. CONCLUSION: While dyslipidemias can be influenced by various factors, an important determinant may lie in genetics, frequently acting as an underlying cause of altered lipid profiles, even in cases of overweight conditions.

A 7T fMRI study investigating the influence of oscillatory phase on syllable representations.

Stimulus categorization is influenced by oscillations in the brain. For example, we have shown that ongoing oscillatory phase biases identification of an ambiguous syllable that can either be perceived as /da/ or /ga/. This suggests that phase is a cue for the brain to determine syllable identity and this cue could be an element of the representation of these syllables. If so, brain activation patterns for /da/ should be more unique when the syllable is presented at the /da/ biasing (i.e. its "preferred") phase. To test this hypothesis we presented non-ambiguous /da/ and /ga/ syllables at either their preferred or non-preferred phase (using sensory entrainment) while measuring 7T fMRI. Using multivariate pattern analysis in auditory regions we show that syllable decoding performance is higher when syllables are presented at their preferred compared to their non-preferred phase. These results suggest that phase information increases the distinctiveness of /da/ and /ga/ brain activation patterns.

Acute stress and food-related reward activation in the brain during food choice during eating in the absence of hunger.

BACKGROUND: Stress results in eating in the absence of hunger, possibly related to food reward perception. HYPOTHESIS: Stress decreases food reward perception. AIM: Determine the effect of acute stress on food choice and food choice reward-related brain activity. SUBJECTS: Nine females (BMI = 21.5 + or - 2.2 kg/m(2), age = 24.3 + or - 3.5 years). PROCEDURE: Fasted subjects came twice to randomly complete either a rest or stress condition. Per session, two functional MRI scans were made, wherein the subjects chose the subsequent meal (food images). The rewarding value of the food was measured as liking and wanting. Food characteristics (for example, crispiness, fullness of taste and so on), energy intake, amount of each macronutrient chosen, plasma cortisol and Visual Analog Scale (VAS) hunger and satiety were measured. RESULTS: Fasted state was confirmed by high hunger (80 + or - 5 mm VAS). Breakfast energy intake (3 + or - 1 MJ) and liking were similar in all conditions. Wanting was lower postprandially (Delta = -0.3 items/category, P<0.01). Breakfast decreased hunger (-42 mm VAS, P<0.01). Postprandially, energy intake (-1.1 MJ), protein intake (-14.7 g) and carbohydrate intake (-32.7 g all P<0.05) were lower. Fat intake was not different (-7.3, P = 0.4). Putamen activity was not lower postprandially. Cortisol levels were increased in the stress condition (Area under the curve of cortisol: DeltaAUC = +2.2 x 10(4) nmol min(-1) l(-1), P<0.05). Satiety was lower after breakfast (-8 mm VAS, P<0.01). Postprandial energy intake, protein intake and carbohydrate intake were relatively higher compared with the rest condition, resulting from more choice for crispiness and fullness of taste (P<0.05). Brain activation was reduced in reward areas: amygdala, hippocampus and cingulate cortex (AUC = -13.33, -1.34, -2.56% blood oxygen level dependent (BOLD) s for choosing breakfast and AUC = -9.31, -1.25, -2.34%BOLD s<0.05 for choosing the second meal). Putamen activation was decreased postprandially (AUC = -1.2%BOLD s, P<0.05). CONCLUSION: Reward signaling and reward sensitivity were significantly lower under stress, coinciding with increased energy intake from food choice for more crispiness and fullness of taste. The changes in putamen activation may reflect specifically decreased reward prediction sensitivity.

Dynamic Time-Locking Mechanism in the Cortical Representation of Spoken Words.

Human speech has a unique capacity to carry and communicate rich meanings. However, it is not known how the highly dynamic and variable perceptual signal is mapped to existing linguistic and semantic representations. In this novel approach, we used the natural acoustic variability of sounds and mapped them to magnetoencephalography (MEG) data using physiologically-inspired machine-learning models. We aimed at determining how well the models, differing in their representation of temporal information, serve to decode and reconstruct spoken words from MEG recordings in 16 healthy volunteers. We discovered that dynamic time-locking of the cortical activation to the unfolding speech input is crucial for the encoding of the acoustic-phonetic features of speech. In contrast, time-locking was not highlighted in cortical processing of non-speech environmental sounds that conveyed the same meanings as the spoken words, including human-made sounds with temporal modulation content similar to speech. The amplitude envelope of the spoken words was particularly well reconstructed based on cortical evoked responses. Our results indicate that speech is encoded cortically with especially high temporal fidelity. This speech tracking by evoked responses may partly reflect the same underlying neural mechanism as the frequently reported entrainment of the cortical oscillations to the amplitude envelope of speech. Furthermore, the phoneme content was reflected in cortical evoked responses simultaneously with the spectrotemporal features, pointing to an instantaneous transformation of the unfolding acoustic features into linguistic representations during speech processing.

Activation of Heschl's gyrus during auditory hallucinations.

Apart from being a common feature of mental illness, auditory hallucinations provide an intriguing model for the study of internally generated sensory perceptions that are attributed to external sources. Until now, the knowledge about the cortical network that supports such hallucinations has been restricted by methodological limitations. Here, we describe an experiment with paranoid schizophrenic patients whose on- and offset of auditory hallucinations could be monitored within one functional magnetic resonance imaging (fMRI) session. We demonstrate an increase of the blood oxygen level-dependent (BOLD) signal in Heschl's gyrus during the patients' hallucinations. Our results provide direct evidence of the involvement of primary auditory areas in auditory verbal hallucinations and establish novel constraints for psychopathological models.

The experimental combination of rTMS and fMRI reveals the functional relevance of parietal cortex for visuospatial functions.

We combined repetitive transcranial magnetic stimulation (rTMS) and functional magnetic resonance imaging (fMRI) to investigate the functional relevance of parietal cortex activation during the performance of visuospatial tasks. fMRI provides information about local transient changes in neuronal activation during behavioural or cognitive tasks. Information on the functional relevance of this activation was obtained by using rTMS to induce temporary regional deactivations. We thereby turned the physiological parameter of brain activity into an independent variable controlled and manipulated by the experimenter and investigated its effect on the performance of the cognitive tasks within a controlled experimental design. We investigated cognitive tasks that were performed on the same visual material but differed in the demand on visuospatial functions. For the visuospatial tasks we found a selective enhancement of fMRI signal in the superior parietal lobule (SPL) and a selective impairment of performance after rTMS to this region in comparison to a control group. We could thus show that the parietal cortex is functionally important for the execution of spatial judgements on visually presented material and that TMS as an experimental tool has the potential to interfere with higher cognitive functions such as visuospatial information processing.

Exploring brain function with magnetic resonance imaging.

Since its invention in the early 1990s, functional magnetic resonance imaging (fMRI) has rapidly assumed a leading role among the techniques used to localize brain activity. The spatial and temporal resolution provided by state-of-the-art MR technology and its non-invasive character, which allows multiple studies of the same subject, are some of the main advantages of fMRI over the other functional neuroimaging modalities that are based on changes in blood flow and cortical metabolism. This paper describes the basic principles and methodology of fMRI and some aspects of its application to functional activation studies. Attention is focused on the physiology of the blood oxygenation level-dependent (BOLD) contrast mechanism and on the acquisition of functional time-series with echo planar imaging (EPI). We also provide an introduction to the current strategies for the correction of signal artefacts and other image processing techniques. In order to convey an idea of the numerous applications of fMRI, we will review some of the recent results in the fields of cognitive and sensorimotor psychology and physiology.

Localisation and characterisation of auditory perception through Functional Magnetic Resonance Imaging.

In the last few years, Functional Magnetic Resonance Imaging (fMRI) has been widely accepted as an effective tool for mapping brain activities in both the neurosensorial and the cognitive field. The present work aims to assess the possibility of using fMRI methods to perform a non-invasive evaluation of the human auditory function. To this end the cortical response to different non speech stimuli (pure tones, pulsed tones) was examined for ten subjects with no audiological impairment. Our findings point out some remarkable differences in both the spatial and the temporal features of the primary auditory cortex response to pulsed tones and to pure tones.

Independent component analysis of interictal fMRI in focal epilepsy: comparison with general linear model-based EEG-correlated fMRI.

The general linear model (GLM) has been used to analyze simultaneous EEG-fMRI to reveal BOLD changes linked to interictal epileptic discharges (IED) identified on scalp EEG. This approach is ineffective when IED are not evident in the EEG. Data-driven fMRI analysis techniques that do not require an EEG derived model may offer a solution in these circumstances. We compared the findings of independent components analysis (ICA) and EEG-based GLM analyses of fMRI data from eight patients with focal epilepsy. Spatial ICA was used to extract independent components (IC) which were automatically classified as either BOLD-related, motion artefacts, EPI-susceptibility artefacts, large blood vessels, noise at high spatial or temporal frequency. The classifier reduced the number of candidate IC by 78%, with an average of 16 BOLD-related IC. Concordance between the ICA and GLM-derived results was assessed based on spatio-temporal criteria. In each patient, one of the IC satisfied the criteria to correspond to IED-based GLM result. The remaining IC were consistent with BOLD patterns of spontaneous brain activity and may include epileptic activity that was not evident on the scalp EEG. In conclusion, ICA of fMRI is capable of revealing areas of epileptic activity in patients with focal epilepsy and may be useful for the analysis of EEG-fMRI data in which abnormalities are not apparent on scalp EEG.

The functional neuroanatomy of target detection: an fMRI study of visual and auditory oddball tasks.

The neuronal response patterns that are required for an adequate behavioural reaction to subjectively relevant changes in the environment are commonly studied by means of oddball paradigms, in which occasional 'target' stimuli have to be detected in a train of frequent 'non-target' stimuli. The detection of such task-relevant stimuli is accompanied by a parietocentral positive component of the event-related potential, the P300. We performed EEG recordings of visual and auditory event-related potentials and functional magnetic resonance imaging (fMRI) when healthy subjects performed an oddball task. Significant increases in fMRI signal for target versus non-target conditions were observed in the supramarginal gyrus, frontal operculum and insular cortex bilaterally, and in further circumscribed parietal and frontal regions. These effects were consistent over various stimulation and response modalities and can be regarded as specific for target detection in both the auditory and the visual modality. These results therefore contribute to the understanding of the target detection network in human cerebral cortex and impose constraints on attempts at localizing the neuronal P300 generator. This is of importance both from a neurobiological perspective and because of the widespread application of the physiological correlates of target detection in clinical P300 studies.

Matching two imagined clocks: the functional anatomy of spatial analysis in the absence of visual stimulation.

Do spatial operations on mental images and those on visually presented material share the same neural substrate? We used the high spatial resolution of functional magnetic resonance imaging to determine whether areas in the parietal lobe that have been implicated in the spatial transformation of visual percepts are also activated during the generation and spatial analysis of imagined objects. Using a behaviourally controlled mental imagery paradigm, which did not involve any visual stimulation, we found robust activation in posterior parietal cortex in both hemispheres. We could thus identify the subset of spatial analysis-related activity that is involved in spatial operations on mental images in the absence of external visual input. This result clarifies the nature of top-down processes in the dorsal stream of the human cerebral cortex and provides evidence for a specific convergence of the pathways of imagery and visual perception within the parietal lobes.

Functional fields in human auditory cortex revealed by time-resolved fMRI without interference of EPI noise.

The gradient switching during fast echoplanar functional magnetic resonance imaging (EPI-fMRI) produces loud noises that may interact with the functional activation of the central auditory system induced by experimental acoustic stimuli. This interaction is unpredictable and is likely to confound the interpretation of functional maps of the auditory cortex. In the present study we used an experimental design which does not require the presentation of stimuli during EPI acquisitions and allows for mapping of the auditory cortex without the interference of scanner noise. The design relies on the physiological delays between the onset, or the end, of stimulation and the corresponding hemodynamic response. Owing to these delays and through a time-resolved acquisition protocol it is possible to analyze the decay of the stimulus-specific signal changes after the cessation of the stimulus itself and before the onset of the EPI-acoustic noise related activation (decay-sampling technique). This experimental design, which might permit a more detailed insight in the auditory cortex, has been applied to the study of the cortical responses to pulsed 1000 Hz sine tones. Distinct activation clusters were detected in the Heschl's gyri and the planum temporale, with an increased extension compared to a conventional block-design paradigm. Furthermore, the comparison of the hemodynamic response of the most anterior and the posterior clusters of activation highlighted differential response patterns to the sound stimulation and to the EPI-noise. These differences, attributable to reciprocal saturation effects unevenly distributed over the superior temporal cortex, provided evidence for functionally distinct auditory fields.