Visual word form processing deficits driven by severity of reading impairments in children with developmental dyslexia.

The visual word form area (VWFA) in the left ventral occipito-temporal (vOT) cortex is key to fluent reading in children and adults. Diminished VWFA activation during print processing tasks is a common finding in subjects with severe reading problems. Here, we report fMRI data from a multicentre study with 140 children in primary school (7.9-12.2 years; 55 children with dyslexia, 73 typical readers, 12 intermediate readers). All performed a semantic task on visually presented words and a matched control task on symbol strings. With this large group of children, including the entire spectrum from severely impaired to highly fluent readers, we aimed to clarify the association of reading fluency and left vOT activation during visual word processing. The results of this study confirm reduced word-sensitive activation within the left vOT in children with dyslexia. Interestingly, the association of reading skills and left vOT activation was especially strong and spatially extended in children with dyslexia. Thus, deficits in basic visual word form processing increase with the severity of reading disability but seem only weakly associated with fluency within the typical reading range suggesting a linear dependence of reading scores with VFWA activation only in the poorest readers.

High resolution anatomical and quantitative MRI of the entire human occipital lobe ex vivo at 9.4T.

Several magnetic resonance imaging (MRI) contrasts are sensitive to myelin content in gray matter in vivo which has ignited ambitions of MRI-based in vivo cortical histology. Ultra-high field (UHF) MRI, at fields of 7T and beyond, is crucial to provide the resolution and contrast needed to sample contrasts over the depth of the cortex and get closer to layer resolved imaging. Ex vivo MRI of human post mortem samples is an important stepping stone to investigate MRI contrast in the cortex, validate it against histology techniques applied in situ to the same tissue, and investigate the resolutions needed to translate ex vivo findings to in vivo UHF MRI. Here, we investigate key technology to extend such UHF studies to large human brain samples while maintaining high resolution, which allows investigation of the layered architecture of several cortical areas over their entire 3D extent and their complete borders where architecture changes. A 16 channel cylindrical phased array radiofrequency (RF) receive coil was constructed to image a large post mortem occipital lobe sample (~80×80×80mm3) in a wide-bore 9.4T human scanner with the aim of achieving high-resolution anatomical and quantitative MR images. Compared with a human head coil at 9.4T, the maximum Signal-to-Noise ratio (SNR) was increased by a factor of about five in the peripheral cortex. Although the transmit profile with a circularly polarized transmit mode at 9.4T is relatively inhomogeneous over the large sample, this challenge was successfully resolved with parallel transmit using the kT-points method. Using this setup, we achieved 60µm anatomical images for the entire occipital lobe showing increased spatial definition of cortical details compared to lower resolutions. In addition, we were able to achieve sufficient control over SNR, B0 and B1 homogeneity and multi-contrast sampling to perform quantitative T2* mapping over the same volume at 200µm. Markov Chain Monte Carlo sampling provided maximum posterior estimates of quantitative T2* and their uncertainty, allowing delineation of the stria of Gennari over the entire length and width of the calcarine sulcus. We discuss how custom RF receive coil arrays built to specific large post mortem sample sizes can provide a platform for UHF cortical layer-specific quantitative MRI over large fields of view.

Robust and fast nonlinear optimization of diffusion MRI microstructure models.

Advances in biophysical multi-compartment modeling for diffusion MRI (dMRI) have gained popularity because of greater specificity than DTI in relating the dMRI signal to underlying cellular microstructure. A large range of these diffusion microstructure models have been developed and each of the popular models comes with its own, often different, optimization algorithm, noise model and initialization strategy to estimate its parameter maps. Since data fit, accuracy and precision is hard to verify, this creates additional challenges to comparability and generalization of results from diffusion microstructure models. In addition, non-linear optimization is computationally expensive leading to very long run times, which can be prohibitive in large group or population studies. In this technical note we investigate the performance of several optimization algorithms and initialization strategies over a few of the most popular diffusion microstructure models, including NODDI and CHARMED. We evaluate whether a single well performing optimization approach exists that could be applied to many models and would equate both run time and fit aspects. All models, algorithms and strategies were implemented on the Graphics Processing Unit (GPU) to remove run time constraints, with which we achieve whole brain dataset fits in seconds to minutes. We then evaluated fit, accuracy, precision and run time for different models of differing complexity against three common optimization algorithms and three parameter initialization strategies. Variability of the achieved quality of fit in actual data was evaluated on ten subjects of each of two population studies with a different acquisition protocol. We find that optimization algorithms and multi-step optimization approaches have a considerable influence on performance and stability over subjects and over acquisition protocols. The gradient-free Powell conjugate-direction algorithm was found to outperform other common algorithms in terms of run time, fit, accuracy and precision. Parameter initialization approaches were found to be relevant especially for more complex models, such as those involving several fiber orientations per voxel. For these, a fitting cascade initializing or fixing parameter values in a later optimization step from simpler models in an earlier optimization step further improved run time, fit, accuracy and precision compared to a single step fit. This establishes and makes available standards by which robust fit and accuracy can be achieved in shorter run times. This is especially relevant for the use of diffusion microstructure modeling in large group or population studies and in combining microstructure parameter maps with tractography results.

Curved Beam Computed Tomography based Structural Rigidity Analysis of Bones with Simulated Lytic Defect: A Comparative Study with Finite Element Analysis.

In this paper, a CT based structural rigidity analysis (CTRA) method that incorporates bone intrinsic local curvature is introduced to assess the compressive failure load of human femur with simulated lytic defects. The proposed CTRA is based on a three dimensional curved beam theory to obtain critical stresses within the human femur model. To test the proposed method, ten human cadaveric femurs with and without simulated defects were mechanically tested under axial compression to failure. Quantitative computed tomography images were acquired from the samples, and CTRA and finite element analysis were performed to obtain the failure load as well as rigidities in both straight and curved cross sections. Experimental results were compared to the results obtained from FEA and CTRA. The failure loads predicated by curved beam CTRA and FEA are in agreement with experimental results. The results also show that the proposed method is an efficient and reliable method to find both the location and magnitude of failure load. Moreover, the results show that the proposed curved CTRA outperforms the regular straight beam CTRA, which ignores the bone intrinsic curvature and can be used as a useful tool in clinical practices.

[Lipoid Pneumonia Associated with Lipid-Containing Nasal Sprays and Nose Drops]. / Lipidpneumonie durch Lipid-haltige Nasensprays und -tropfen.

BACKGROUND: Regularly updating the German pharmacopoeia on contemporary preparations DAC/NRF, chapter "Nasal Applications" and the recommendations on "Nasal Oils" as well as "Nasal Ointments and Emulsions", the issue of the risk of lipoid pneumonia associated with the use of plant oils and when compared to mineral oils arose. MATERIAL AND METHODS: We searched different databases: the "Grosse Deutsche Arzneimittelspezialitäten-Taxe" containing all products available in German pharmacies, the Cochrane Library, the pharmacovigilance-database of the BfArM, and Medline to evaluate the benefit/risk-ratio of plant oils in nasal drops and sprays. RESULTS: In German pharmacies, a number of both, mineral oil-containing drugs for nasal application and plant oil-containing medical devices are available. The risk of lipoid pneumonia described for mineral oil-containing nasal products can not entirely be transferred to plant oil-containing products. However, evidence from the literature suggests a risk for lipoid pneumonia, which needs to be considered given the non-proven efficacy of such medical devices in the majority of proposed indications. To minimize risks, recommendations are made for patient groups that should not use lipid-containing nasal products. CONCLUSIONS: Acknowledging the potential lethal outcome of lipoid pneumonia, a demanding diagnosis, and absence of a specific therapy, lipid-containing nasal products should be used only with great caution. Based on the current knowledge, the statements regarding the risk of lipoid pneumonia for lipid-containing nasal products in the DAC/NRF should not be modified.

Greater effects of high- compared with moderate-intensity interval training on cardio-metabolic variables, blood leptin concentration and ratings of perceived exertion in obese adolescent females.

This study examined the effects of high- vs. moderate-intensity interval training on cardiovascular fitness, leptin levels and ratings of perceived exertion (RPE) in obese female adolescents. Forty-seven participants were randomly assigned to one of three groups receiving either a 1:1 ratio of 15 s of effort comprising moderate-intensity interval training (MIIT at 80% maximal aerobic speed: MAS) or high-intensity interval training (HIIT at 100% MAS), with matched 15 s recovery at 50% MAS, thrice weekly, or a no-training control group. The HIIT and MIIT groups showed improved (p < 0.05) body mass (BM), BMI Z-score, and percentage of body fat (%BF). Only the HIIT group showed decreased waist circumference (WC) (p = 0.017). The effect of exercise on maximal oxygen uptake (VO2max) was significant (p = 0.019, ES = 0.48 and p = 0.010, ES = 0.57, HIIT and MIIT, respectively). The decrease of rate-pressure product (RPP) (p < 0.05, ES = 0.53 and ES = 0.46, HIIT and MIIT, respectively) followed the positive changes in resting heart rate and blood pressures. Blood glucose, insulin level and the homeostasis model assessment index for insulin decreased (p < 0.05) in both training groups. Significant decreases occurred in blood leptin (p = 0.021, ES = 0.67 and p = 0.011, ES = 0.73) and in RPE (p = 0.001, ES = 0.76 and p = 0.017, ES = 0.57) in HIIT and MIIT, respectively. In the post-intervention period, blood leptin was strongly associated with %BF (p < 0.001) and VO2max (p < 0.01) in the HIIT and MIIT groups, respectively, while RPE was strongly associated with BM (p < 0.01) in the HIIT group. The results suggest that high-intensity interval training may produce more positive effects on health determinants in comparison with the same training mode at a moderate intensity.

The effect of fasting during Ramadan on parameters of the haematological and steroidal modules of the athletes biological passport - a pilot study.

This study investigated the effect of Ramadan on the haematological and steroid module of the Athletes Biological Passport (ABP) of the World Anti-Doping Agency (WADA). Nine healthy physically active subjects were tested in the morning and afternoon for two days before and three days during Ramadan. Sample collection and all analyses were performed according to WADA technical documents. Although there were significant changes in the haemoglobin concentration during Ramadan, especially during the first fasting week, none of the subjects in this study exceeded the individually calculated thresholds of the ABP. No significant effects on testosterone/epitestosterone (T/E) ratio were observed but only the afternoon specific gravity (SG) of the urine was elevated. Thus, when urinary steroid concentrations are required, SG corrections need to be performed. The haematological and the steroid module of the ABP can be reliably applied during Ramadan as the observed changes are only marginal.

Cognitive correlates of frontoparietal network connectivity 'at rest' in individuals with differential risk for psychotic disorder.

Altered frontoparietal network functional connectivity (FPN-fc) has been associated with neurocognitive dysfunction in individuals with (risk for) psychotic disorder. Cannabis use is associated with cognitive and FPN-fc alterations in healthy individuals, but it is not known whether cannabis exposure moderates the FPN-fc-cognition association. We studied FPN-fc in relation to psychosis risk, as well as the moderating effects of psychosis risk and cannabis use on the association between FPN-fc and (social) cognition. This was done by collecting resting-state fMRI scans and (social) cognitive test results from 63 patients with psychotic disorder, 73 unaffected siblings and 59 controls. Dorsolateral prefrontal cortex (DLPFC) seed-based correlation analyses were used to estimate FPN-fc group differences. Additionally, group×FPN-fc and cannabis×FPN-fc interactions in models of cognition were assessed with regression models. Results showed that DLPFC-fc with the left precuneus, right inferior parietal lobule, right middle temporal gyrus (MTG), inferior frontal gyrus (IFG) regions and right insula was decreased in patients compared to controls. Siblings had reduced DLPFC-fc with the right MTG, left middle frontal gyrus, right superior frontal gyrus, IFG regions, and right insula compared to controls, with an intermediate position between patients and controls for DLPFC-IFG/MTG and insula-fc. There were no significant FPN-fc×group or FPN-fc×cannabis interactions in models of cognition. Reduced DLPFC-insula-fc was associated with worse social cognition in the total sample. In conclusion, besides patient- and sibling-specific FPN-fc alterations, there was evidence for trait-related alterations. FPN-fc-cognition associations were not conditional on familial liability or cannabis use. Lower FPN-fc was associated with lower emotion processing in the total group.

Detection of pyrrolizidine alkaloids in German licensed herbal medicinal teas.

BACKGROUND: Because of the hepatotoxic, mutagenic, and cancerogenic effects of pyrrolizidine alkaloids (PAs) the German Federal Institute for Risk Assessment (BfR) recommends not to exceed a daily PA intake of 0.007 µg/kg body weight (0.42 µg/60 kg adult). In a recent study conducted by the BfR, up to 5647 µg PA/kg dried herbal material were detected in tea products marketed as food. PURPOSE: The present study aimed at elucidating whether medicinal teas licensed or registered as medicinal products contain PAs as well. STUDY DESIGN: One hundred sixty-nine different commercially available medicinal teas, i.e. 19 nettle (Urtica dioica L.), 12 fennel (Foeniculum vulgare Mill.), 14 chamomile (Matricaria recutita L.), 11 melissa (Melissa officinalis L.) and 4 peppermint (Mentha piperita L.) teas as well as 109 tea mixtures were analyzed for the presence of 23 commercially available PAs. METHOD: LC/MS was used for the determination of the PAs RESULTS: In general, the total PA contents ranging 0-5668 µg/kg. Thirty percent of the tested single-ingredient tea products and 56.9% of the tested medicinal tea mixtures were found to contain PA concentrations above the limit of quantification (LOQ) of 10 µg/kg. In 11 medicinal teas PA contents >300 µg/kg dry herb were determined thus exceeding the recommended limit for PA intake by BfR. In addition three products of the investigated tea mixtures revealed extremely high PA contents of 4227, 5137, and 5668 µg/kg. Generally, single-ingredient tea products contained much less or even no detectable amounts of PAs when compared to the tea mixtures. PAs in the range between 13 and 1080 µg/kg were also detected in five analyzed aqueous herbal infusions of the medicinal tea mixture products with the highest PA content. Two out of the five investigated herbal infusions exceeded the recommended BfR limit for PA intake. CONCLUSION: This study demonstrates clearly that also medicinal teas licensed as medicinal products may partly contain high amounts of PAs exceeding current recommendations. For that reason manufacturers are advised to carry out more rigorous quality control tests devoted to the detection of PAs. This is very important to minimize PAs in medicinal teas accounting for possible additional exposure of the consumer to PAs from other food sources (e.g. honey).

Altered mesocorticolimbic functional connectivity in psychotic disorder: an analysis of proxy genetic and environmental effects.

BACKGROUND: Altered dopaminergic neurotransmission in the mesocorticolimbic (MCL) system may mediate psychotic symptoms. In addition, pharmacological dopaminergic manipulation may coincide with altered functional connectivity (fc) 'in rest'. We set out to test whether MCL-fc is conditional on (familial risk for) psychotic disorder and/or interactions with environmental exposures. METHOD: Resting-state functional magnetic resonance imaging data were obtained from 63 patients with psychotic disorder, 73 non-psychotic siblings of patients with psychotic disorder and 59 healthy controls. With the nucleus accumbens (NAcc) as seed region, fc within the MCL system was estimated. Regression analyses adjusting for a priori hypothesized confounders were used to assess group differences in MCL connectivity as well as gene (group) × environmental exposure interactions (G × E) (i.e., to cannabis, developmental trauma and urbanicity). RESULTS: Compared with controls, patients and siblings had decreased fc between the right NAcc seed and the right orbitofrontal cortex (OFC) as well as the left middle cingulate cortex (MCC). Siblings showed decreased connectivity between the NAcc seed and lentiform nucleus compared with patients and controls. In addition, patients had decreased left NAcc connectivity compared with siblings in the left middle frontal gyrus. There was no evidence for a significant interaction between group and the three environmental exposures in the model of MCL-fc. CONCLUSIONS: Reduced NAcc-OFC/MCC connectivity was seen in patients and siblings, suggesting that altered OFC connectivity and MCC connectivity are vulnerability markers for psychotic disorder. Differential exposure to environmental risk factors did not make an impact on the association between familial risk and MCL connectivity.

MR Imaging with T2*- mapping for improved acetabular cartilage assessment in FAI-a case report with arthroscopic correlation.

UNLABELLED: Articular cartilage assessment in femoroacetabular impingement (FAI) is challenging. Recent studies on T2* relaxation time mapping suggest the technique may be useful in diagnosing cartilage damage. The purpose of this case report is to describe how quantitative T2*-mapping may improve cartilage assessment of the acetabulum in patients with FAI. MR arthrography was performed at 3 Tesla (T) using intra-articular Gadolinium and a T2* mapping protocol. Data from the acetabular cartilage was separated from femoral head cartilage data and then superimposed on a flattened, map projection representation of the patient's acetabulum. The areas of unhealthy cartilage observed at the time of arthroscopy - including debonding and delamination - were seen preoperatively at the same anatomic locations as areas of decreased T2* values. T2* mapping values provided a non-invasive assessment of the acetabular articular cartilage. A flattened acetabular map projection allowed for anatomic visualization of areas of unhealthy cartilage. LEVEL OF EVIDENCE: Level IV.

Pattern classification of valence in depression.

Neuroimaging biomarkers of depression have potential to aid diagnosis, identify individuals at risk and predict treatment response or course of illness. Nevertheless none have been identified so far, potentially because no single brain parameter captures the complexity of the pathophysiology of depression. Multi-voxel pattern analysis (MVPA) may overcome this issue as it can identify patterns of voxels that are spatially distributed across the brain. Here we present the results of an MVPA to investigate the neuronal patterns underlying passive viewing of positive, negative and neutral pictures in depressed patients. A linear support vector machine (SVM) was trained to discriminate different valence conditions based on the functional magnetic resonance imaging (fMRI) data of nine unipolar depressed patients. A similar dataset obtained in nine healthy individuals was included to conduct a group classification analysis via linear discriminant analysis (LDA). Accuracy scores of 86% or higher were obtained for each valence contrast via patterns that included limbic areas such as the amygdala and frontal areas such as the ventrolateral prefrontal cortex. The LDA identified two areas (the dorsomedial prefrontal cortex and caudate nucleus) that allowed group classification with 72.2% accuracy. Our preliminary findings suggest that MVPA can identify stable valence patterns, with more sensitivity than univariate analysis, in depressed participants and that it may be possible to discriminate between healthy and depressed individuals based on differences in the brain's response to emotional cues.

Real-time fMRI neurofeedback: progress and challenges.

In February of 2012, the first international conference on real time functional magnetic resonance imaging (rtfMRI) neurofeedback was held at the Swiss Federal Institute of Technology Zurich (ETHZ), Switzerland. This review summarizes progress in the field, introduces current debates, elucidates open questions, and offers viewpoints derived from the conference. The review offers perspectives on study design, scientific and clinical applications, rtfMRI learning mechanisms and future outlook.

Upregulation of emotion areas through neurofeedback with a focus on positive mood.

Real-time functional magnetic resonance imaging can be used to feed back signal changes from the brain to participants such that they can train to modulate activation levels in specific brain areas. Here we present the first study combining up-regulation of brain areas for positive emotions with psychometric measures to assess the effect of successful self-regulation on subsequent mood. We localized brain areas associated with positive emotions through presentation of standardized pictures with positive valence. Participants up-regulated activation levels in their target area during specific periods, alternating with rest. Participants attained reliable self-control of the target area by the last of three seven-minute runs. This training effect was supported by an extensive network outside the targeted brain region, including higher sensory areas, paralimbic and orbitofrontal cortex. Self-control of emotion areas was not accompanied by clear changes in self-reported emotions; trend-level improvements on depression scores were counteracted by increases on measures of fatigue, resulting in no overall mood improvement. It is possible that benefits of self-control of emotion networks may only appear in people who display abnormal emotional homeostasis. The use of only a single, short, training session, overlap between positive and negative emotion networks and aversive reactions to the scanning environment may have prevented the detection of subtle changes in mood.

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.

Neurofeedback: A promising tool for the self-regulation of emotion networks.

Real-time functional magnetic resonance imaging (fMRI) affords the opportunity to explore the feasibility of self-regulation of functional brain networks through neurofeedback. We localised emotion networks individually in thirteen participants using fMRI and trained them to upregulate target areas, including the insula and amygdala. Participants achieved a high degree of control of these networks after a brief training period. We observed activation increases during periods of upregulation of emotion networks in the precuneus and medial prefrontal cortex and, with increasing training success, in the ventral striatum. These findings demonstrate the feasibility of fMRI-based neurofeedback of emotion networks and suggest a possible development into a therapeutic tool.

Tease or threat? Judging social interactions from bodily expressions.

We casually observe many interactions that do not really concern us. Yet sometimes we need to be able to rapidly appraise whether an interaction between two people represents a real threat for one of them rather than an innocent tease. Using functional magnetic resonance imaging, we investigated whether small differences in the body language of two interacting people are picked up by the brain even if observers are performing an unrelated task. Fourteen participants were scanned while watching 3-s movies (192 trials and 96 scrambles) showing a male person either threatening or teasing a female one. In one task condition, observers categorized the interaction as threatening or teasing, and in the other, they monitored randomly appearing dots and categorized the color. Our results clearly show that right amygdala responds more to threatening than to teasing situations irrespective of the observers' task. When observers' attention is not explicitly directed to the situation, this heightened amygdala activation goes together with increased activity in body sensitive regions in fusiform gyrus, extrastriate body area-human motion complex and superior temporal sulcus and is associated with a better behavioral performance of the participants during threatening situations. In addition, regions involved in action observation (inferior frontal gyrus, temporoparietal junction, and inferior parietal lobe) and preparation (premotor, putamen) show increased activation for threat videos. Also regions involved in processing moral violations (temporoparietal junction, hypothalamus) reacted selectively to the threatening interactions. Taken together, our results show which brain regions react selectively to witnessing a threatening interaction even if the situation is not attended because the observers perform an unrelated task.

Neural correlates of shape and surface reflectance information in individual faces.

Faces are recognized by means of both shape and surface reflectance information. However, it is unclear how these two types of diagnostic information are represented in the human brain. To clarify this issue, we tested 14 participants in an event-related functional magnetic resonance adaptation paradigm, with four conditions created by using a 3D morphable model: (1) repetition of the same adapting face; (2) variation in shape only; (3) variation in surface reflectance only; (4) variation in both shape and surface reflectance. Change in face shape alone was the dominant driving force of the adaptation release in functionally defined face-sensitive areas in the right hemisphere (fusiform face area [FFA], occipital face area [OFA]). In contrast, homologous areas of the left hemisphere showed comparable adaptation release to changes in face shape and surface reflectance. When both changes in shape and reflectance were combined, there was no further increased release from adaptation in face-sensitive areas. Overall, these observations indicate that the two main sources of information in individual faces, shape and reflectance, contribute to individual face sensitivity found in the cortical face network. Moreover, the sensitivity to shape cues is more dominant in the right hemisphere, possibly reflecting a privileged mode of global (holistic) face processing.

Inverse mapping the neuronal substrates of face categorizations.

Face perception is a complex process involving a network of brain structures, dynamically processing information to enable judgments about a face to be made (e.g., familiarity, identity, and expression). Here we introduce an analysis methodology that makes it possible to directly study this information processing in the brain from spatially and temporally resolved magnetoencephalographic signals. We apply our methodology to the study of 2 face categorization tasks, gender and expressiveness, and track the processing of 3 key visual features that underlie behavioral performance, over time and throughout the cortex. We find information processing correlates beginning from 90 ms following stimulus onset, where features are processed in isolation in occipital extrastriate regions. Over time, processing of successively more features and feature combinations takes place in occipitotemporal regions, with maximal information processing of visual information coinciding with the well-established face-selective M170 component at 170 ms. Later still, around 250-400 ms, cortical activity responds significantly more to task-specific features and their complex combinations. These results indicate a complex process of visual information processing during face perception with face parts processed in isolation at very early stages, and task-specific processing of combinations of features taking place within 300 ms. Crucially, our approach specifically establishes which information in the visual stimulus the brain signal is responding to and how this varies with time, cortical location, and task demands to establish a more precise tracking of information processing mechanisms in the cortex during face perception.