Auditory verbal hallucinations (AVHs) are among the most common and disabling symptoms of schizophrenia. They involve the superior temporal sulcus (STS), which is associated with language processing; specific STS patterns may reflect vulnerability to auditory hallucinations in schizophrenia. STS sulcal pits are the deepest points of the folds in this region and were investigated here as an anatomical landmark of AVHs. This study included 53 patients diagnosed with schizophrenia and past or present AVHs, as well as 100 healthy control volunteers. All participants underwent a 3-T magnetic resonance imaging T1 brain scan, and sulcal pit differences were compared between the two groups. Compared with controls, patients with AVHs had a significantly different distributions for the number of sulcal pits in the left STS, indicating a less complex morphological pattern. The association of STS sulcal morphology with AVH suggests an early neurodevelopmental process in the pathophysiology of schizophrenia with AVHs.
Nineteen female silver European eels (Anguilla anguilla L.) were tagged with satellite tags and released in the Gulf of Lion in the Mediterranean during the migration seasons 2013 and 2015. Sixteen tags transmitted data: five in the Atlantic Ocean, and eleven in the Mediterranean. Of those, 50% of migrating eels were consumed by marine mammals in each year, all in the Mediterranean. The diving behaviour recorded by the tags after the eels were consumed indicated that the most likely predators were deep diving toothed whales. Measurements of the acoustic target strength of the tag showed a negligible effect on the detectability by whale biosonar. Overall, the observed predation rate was similar to that reported for eels escaping into the Atlantic. However, unlike eels in the Atlantic, which are most vulnerable to predators in the first week of escapement as they traverse the continental shelf and before they reach the refuge of the deep ocean, eels escaping from the Mediterranean were predated in deep water, months after release, likely as a consequence of their migration within a relatively narrow and deep corridor in the Alboran Sea. This emphasises the challenge of accounting for natural mortality in management plans for the long-term recovery of the European eel.
Visual scenes are processed in terms of spatial frequencies. Low spatial frequencies (LSF) carry coarse information, whereas high spatial frequencies (HSF) subsequently carry information about fine details. The present magnetic resonance imaging study investigated how cortical thickness covaried with LSF/HSF processing abilities in ten-year-old children and adults. Participants indicated whether natural scenes that were filtered in either LSF or HSF represented outdoor or indoor scenes, while reaction times (RTs) and accuracy measures were recorded. In adults, faster RTs for LSF and HSF images were consistently associated with a thicker cortex (parahippocampal cortex, middle frontal gyrus, and precentral and insula regions for LSF; parahippocampal cortex and fronto-marginal and supramarginal gyri for HSF). On the other hand, in children, faster RTs for HSF were associated with a thicker cortex (posterior cingulate, supramarginal and calcarine cortical regions), whereas faster RTs for LSF were associated with a thinner cortex (subcallosal and insula regions). Increased cortical thickness in adults and children could correspond to an expansion mechanism linked to visual scene processing efficiency. In contrast, lower cortical thickness associated with LSF efficiency in children could correspond to a pruning mechanism reflecting an ongoing maturational process, in agreement with the view that LSF efficiency continues to be refined during childhood. This differing pattern between children and adults appeared to be particularly significant in anterior regions of the brain, in line with the proposed existence of a postero-anterior gradient of brain development. Taken together, our results highlight the dynamic brain processes that allow children and adults to perceive a visual natural scene in a coherent way.
BACKGROUND:Organophosphate pesticides (OP) are widely used for both agricultural and domestic purposes. Epidemiological studies suggest neurotoxicity in children after exposure to organophosphates pesticides (OP) at low levels but possible mechanism is still unclear. OBJECTIVES:We aimed at investigating the effects of prenatal exposure to OPs on inhibitory control of 10-12 year-old-children assessed by a motor inhibition task during functional magnetic resonance imaging (fMRI). METHODS:Ninety-five children from the PELAGIE cohort (Brittany-France, from 2002) underwent a fMRI examination during which inhibition was assessed by a Go/No-Go task. Task performance was assessed by average response latency, commission rate and composite performance score (PS). Whole brain activation was estimated by modeling the hemodynamic response related to inhibition demand and successful inhibition. OP exposure was assessed by measuring six dialkylphosphate (DAP) metabolites in the urine of women in early pregnancy (<19 WG). Concentrations were summed to obtain overall levels of diethylphosphate (DE), dimethylphosphate (DM) and total non-specific metabolites (DAP), standardized to homogenize sampling conditions and categorized into levels of exposure: low (reference), moderate or high. Regression models were adjusted for potential cofounders considered by restriction and statistical criteria. RESULTS:Moderate levels of DAP were associated with a decreased commission rate (β = -6.65%, p = 0.04), indicating improved performance. Increasing levels of DM and DE were associated with decreased brain activity in the left inferior and bilateral superior frontal regions during successful inhibition. We did not observe any differential activation related to inhibitory demands. DISCUSSION:These results suggest that prenatal OPs may be associated with altered pattern of brain activity in regions related to inhibition among children and need to be confirmed by additional studies.
Some economic transactions require people to trust strangers, whose trustworthiness is unknown. In these circumstances, behavioral studies have shown that adults (but not young adolescents) seem to have some minimal ability to detect the trustworthiness of adult strangers based on their facial features. In this study, we explored the neural correlates of this facial trustworthiness detection. A group of adolescents and adults played a series of economic Trust Games with adult trustees of which we had previously recorded the strategy. Results showed that when adult investors were looking at the picture of a trust-abusing trustee, the left amygdala was relatively more activated than when they were looking at a trust-honoring player. Younger adolescents did not show this pattern and responded with a more pronounced deactivation when facing a trust-abusing trustee. An exploratory whole-brain analysis detected a similar age shift for mentalizing regions of the brain. Our results fit with an emerging model suggesting that the amygdala is implicated in an associative learning process that progressively refines a mapping of faces onto trustworthy behavior and may result in avoiding to be exploited by untrustworthy strangers.
Abstract Background Hallucinations are the most common and debilitating symptom in schizophrenia, affecting more than 70% of patients. The superior temporal sulcus (STS) is involved in the language process notably in the perception of the human voice and several studies show its implication in auditory verbal hallucinations (AVHs). Sulcal patterns in the white matter can reflect an early vulnerability, probably genetic since they set up at a very early stage and are stable over the life course. In contrast, the cortical thickness is dynamic and variable over the development and so can reflect the impact of environmental factors on the maturation of the brain. The aim of this study is therefore to determine whether AVHs are associated with morphological changes of the STS and in particular, whether these changes concern sulcal patterns or cortical thickness reflecting early (genetic) or late (environmental) vulnerability respectively. Methods Seventy-three schizophrenia patients (DSM-IV) with a proneness of AVH (53 AVH+) and without AVH (20 AVH-) and 100 healthy volunteers (HC) had a 3T MRI brain scan. Cortical reconstructions were generated using Freesurfer. Mean cortical thickness was measured over the entire brain in each participant. Number of sulcal pits, which represents the position with the maximum depth in the sulcus, was automatically counted on the white matter surface. Both measures were compared between groups and related to the Auditory Hallucination Rating Scale (AHRS). Results AVH+ patients compared to HC showed a significantly thinner cortical thickness in the left temporal and frontal regions and especially in the STS (p ≤ 0.05 FDR corrected). A negative correlation (r²=0.25) between the cortical thickness in the central part of the left STS and the AHRS score was found (p = 0.01 uncorrected). A different distribution of the number of pits in the left STS is found in AVH+ patients compared to HC (p = 0.05). Discussion The results suggest that AVH+ patients compared to HC have a lower cortical thickness in the left STS, but also have a specific white matter pattern of the left STS. These results support the hypothesis that a particular morphology of the STS related with auditory hallucinations might be due to both early (genetic) and late (environmental) factors.
Since reasoning is often biased by intuitive heuristics, the development of sound reasoning has long been postulated to depend on successful bias monitoring and inhibition. The present fMRI study aimed to identify neural correlates of developmental changes in these processes. A group of adults and young adolescents were presented with ratio-bias problems in which an intuitively cued heuristic response could be incongruent (conflict item) or congruent (no-conflict item) with the correct response. Results showed that successfully avoiding biased responding on conflict items across both age groups was associated with increased activation in Anterior Cingulate Cortex (ACC) and the right Lateral Prefrontal Cortex (LPFC) regions of interest. Critically, the right LPFC activation decreased with age. Biased responding did not result in right LPFC or ACC modulation and failed to show any developmental activation changes. We discuss implications for ongoing debates on the nature of heuristic bias and its development.
BACKGROUND:Pregnant women are ubiquitously exposed to organic solvents, such as glycol ethers. Several studies suggest potential developmental neurotoxicity following exposure to glycol ethers with a lack of clarity of possible brain mechanisms. OBJECTIVES:We investigated the association between urinary levels of glycol ethers of women during early pregnancy and motor inhibition function of their 10- to 12-year-old children by behavioral assessment and brain imaging. METHODS:Exposure to glycol ethers was assessed by measuring six metabolites in urine (<19 weeks of gestation) of 73 pregnant women of the PELAGIE mother-child cohort (France). Maternal urinary levels were classified as low, medium, or high. Children underwent functional magnetic resonance imaging (fMRI) examinations during which motor inhibition function was assessed with a Go/No-Go task. Analyses were performed using linear regression for task performance and generalized linear mixed-effect models for brain activation, FWER-corrected for multiple testing at the spatial cluster level. Confounders were considered by restriction and a priori adjustment. RESULTS:Higher maternal butoxyacetic acid (BAA) urinary concentrations were associated with poorer child performance (β = -1.1; 95% CI: -1.9, -0.2 for high vs low). There was also a trend for ethoxyacetic acid (EAA) towards poorer performance (β = -0.3; 95% CI: -0.7, 0.01). Considering inhibition demand, there were increased activity in occipital regions in association with moderate EAA (left cuneus) and moderate methoxyacetic acid (MAA) (right precuneus). When children succeeded to inhibit, high ethoxyethoxyacetic acid (EEAA) and moderate phenoxyacetic acid (PhAA) levels were associated with differential activity in frontal cortex, involved in inhibition network. DISCUSSION:Prenatal urinary levels of two glycol ether metabolites were associated with poorer Go/No-Go task performance. Differential activations were observed in the brain motor inhibition network in relation with successful inhibition, but not with cognitive demand. Nevertheless, there is no consistence between performance indicators and cerebral activity results. Other studies are highly necessary given the ubiquity of glycol ether exposure.
Long-latency auditory event potentials (LLAEPs) involving local and global auditory processes have been investigated to examine the impact of low-frequency (LF) and high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) on the cortical excitability of the temporal cortex. We hypothesized that both stimulation frequencies have the same modulation effect, in accordance with clinical data showing a reduction in auditory verbal hallucinations (AVHs) after LF and HF temporal rTMS in patients with schizophrenia. With 30 right-handed healthy volunteer participants enrolled in a crossover trial, we analyzed LLAEPs before and after LF- and HF-rTMS of the left temporal cortex. While we observed no changes in latencies, we did observe a similar inhibitory action of both rTMS frequencies on LLAEP amplitudes. Analysis of surface potential maps and cortical generators revealed some differences regarding auditory processes: HF-rTMS produced earlier, more diffuse, and more right-lateralized effects than LF-rTMS. Beyond a local impact, rTMS exerted a remote modulation influence on the frontal cortex that might be involved in attentional processes. This association could explain the therapeutic effect of temporal HF-rTMS on AVH.
Background/Aim: Epidemiological studies reported that prenatal solvent exposure was associated with adverse neurobehavioral outcomes that suggest impaired motor inhibition function. Using functional Magnetic Resonance Imaging (fMRI) among children aged 10-12 years old, we aimed at investigating the effect of prenatal exposure to solvents on the activation of cerebral regions involved in the motor inhibition function. Methods: Fifty-three children from the PELAGIE mother-child cohort (France, from 2002) underwent a 10-minutes fMRI go/no-go task using an event-related design. : Children were asked to press a button as quickly as possible in response to a green smiley ('go') but not press the button when seeing a red smiley ('no-go': inhibition event). Solvent exposure was assessed at the beginning of pregnancy (<19 WG) by measuring three glycol ether metabolites in maternal urine and defined as 'unexposed' (1st tercile) or 'exposed' (2nd and 3rd tercile) for each solvent. Go and no-go cerebral activations at individual and group levels were assessed using SPM. T-test with p-value corrected for multiple testing was used to estimate difference of brain activations between differentially exposed children. Confounders as tobacco smoke and alcohol consumption at the beginning of pregnancy were taken into account by restriction. Results: 'No-go' cerebral activations were larger in middle and inferior frontal regions of the right hemisphere among children unexposed to methoxyacetic acid as compared to exposed ones. No differential activations were found with ethoxyacetic acid and phenoxyacetic acid. Conclusions: The present study suggests association between prenatal solvent exposure and larger activations in cerebral regions involved in motor inhibition function at the age of 10-12 years old. Analysis will be extended to a bigger sample (on-going urinary measurements) to confirm and refine these results.
Adolescents have been shown to be more likely to engage in risky behaviors in daily life. Many studies have indicated that adolescents could make advantageous choices when they receive explicit information but could fail to choose advantageously when they are not informed about risks. The current study aimed to examine the influence of explicit risk information (i.e., when risk information is directly available) versus implicit risk information (i.e., when risk information has to be learned from feedback) on risk-taking engagement, in order to clarify whether the enhanced risk-taking observed in decision making under ambiguity in adolescents results from either a greater exploration of ambiguous situations (i.e., a higher ambiguity tolerance) or a specific difficulty associated with learning based on previous choices' outcomes. Adolescents and young adults completed a new adaptation of the Balloon Analogue Risk Task. They were required to accumulate as many points as possible by inflating balloons associated with variable break points and avoiding explosions. This adaptation involved a manipulation of the information level with two conditions, an informed condition and a noninformed condition, in which the participants had to learn the matching of colors with balloons' resistances based on feedback. The results demonstrated that providing explicit risk information allows adolescents to be as efficient as adults at the end of the game. In contrast, adolescents failed to adjust risk-taking to the balloon resistance in the noninformed condition. These findings critically suggest that this failure reflects a specific impairment of feedback-based learning ability but not a global excess of risk-taking during adolescence. Copyright (c) 2017 John Wiley & Sons, Ltd.
ABSTRACTReading relies on a left‐lateralized network of brain areas that include the pre‐lexical processing regions of the ventral stream. Specifically, a region in the left lateral occipitotemporal sulcus (OTS) is consistently more activated for visual presentations of words than for other categories of stimuli. This region undergoes dramatic changes at the functional and structural levels when children learn to read, but little is known about the effects of early cerebral constraints on reading skills. Using anatomical magnetic resonance imaging, we investigated whether the sulcal pattern of the lateral OTS—a stable brain feature—was associated with oral reading skills. The sulcal pattern of the left but not the right lateral OTS was associated with the number of words correctly read in 3 min. This study is the first to evidence that reading is affected by early cerebral constraints, such as the sulcal morphology of the left lateral OTS.
Repetitive transcranial magnetic stimulation (rTMS) shows a high inter-subjects variability in the efficacy of the treatment of resistant auditory verbal hallucinations (AVH) in schizophrenia, but causal factors of this variability are not known. Focal anatomical alterations of the left temporal cortex that is targeted in the rTMS treatment are well demonstrated, and could be one cause of this variability, but they are not taken into account in the treatment procedure.
Children’s number conservation is often biased by misleading intuitions but the precise nature of these conservation errors is not clear. A key question is whether children detect that their erroneous conservation judgment is unwarranted. The present study reanalyzed available fMRI data to test the implication of the anterior cingulate cortex (ACC) in this detection process. We extracted mean BOLD (Blood Oxygen Level Dependent) signal values in an independently defined ACC region of interest (ROI) during presentation of classic and control number conservation problems. In classic trials, an intuitively cued visuospatial response conflicted with the correct conservation response, whereas this conflict was not present in the control trials. Results showed that ACC activation increased when solving the classic conservation problems. Critically, this increase did not differ between participants who solved the classic problems correctly (i.e., so-called conservers) and incorrectly (i.e., so-called non-conservers). Additional control analyses of inferior and lateral prefrontal ROIs showed that the group of conservers did show stronger activation in the right inferior frontal gyrus and right lateral middle frontal gyrus. In line with recent behavioral findings, these data lend credence to the hypothesis that even non-conserving children detect the biased nature of their judgment. The key difference between conservers and non-conservers seems to lie in a differential recruitment of inferior and lateral prefrontal regions associated with inhibitory control.
Effects of low and high frequency rTMS were studied in healthy volunteers on the neural generators of P50, N1 and P2 auditory evoked potentials (AEP). A secondary subgroup analysis by individual level of sensory gating was also performed; low suppressors subjects (LS) are considered as a translational model of the neurophysiological impairments observed in schizophrenia.
The acquisition of number conservation is a critical step in children's numerical and mathematical development. Classic developmental studies have established that children's number conservation is often biased by misleading intuitions. However, the precise nature of these conservation errors is not clear. A key question is whether conservation errors result from a failure to inhibit the misleading intuitions or from a failure to detect that these intuitions are erroneous in the first place. The present paper focuses on this fundamental conservation error or conflict sensitivity issue. We review behavioral and neuroimaging work that suggests that non-conserving preschoolers detect that their response is questionable and are less ignorant about conservation than their well-documented errors might have previously suggested.
BACKGROUND:Repetitive transcranial magnetic stimulation (rTMS) shows high inter-subject variability in its efficacy for treating resistant auditory verbal hallucinations in schizophrenia. Currently, the response of an individual patient to rTMS treatment cannot be predicted. It is possible that cortical anatomical characteristics could affect the therapeutic response.OBJECTIVE:We hypothesized that rTMS efficacy is related to anatomical variations underlying the stimulation target in the left temporal cortex. We investigated two regions of interest (ROIs) that have been implicated in rTMS: the left temporal cortex, where the stimulation is delivered, and the primary hand motor cortex, where the stimulation strength is determined by the resting motor threshold (rMT).METHODS:Fifteen patients with schizophrenia (DSM IV) underwent rTMS and magnetic resonance imaging. The scalp-to-cortex distance (SCD) and the grey matter density (GMD) were measured in both ROIs. Linear regression models were used to investigate the relationships between these measures and the clinical efficacy of rTMS.RESULTS:Treatment efficacy was highly predicted by the temporal SCD and the GMD in the temporal and primary hand motor cortex regions. In contrast, the rMT was not predicted by the primary hand motor cortex SCD or GMD.CONCLUSION:These results suggest that rTMS treatment efficacy could be related to the depth of the temporal target. The data raise the question of whether rMT is the best measure for assessing the stimulation intensity in treating patients with schizophrenia.
Few studies have examined the impact of repetitive transcranial magnetic stimulation (rTMS) on the cortical excitability of nonmotor cortices; current treatments often target the temporal or prefrontal cortex. We used auditory evoked potentials recorded in 24 healthy subjects to evaluate the neuromodulatory effects of low- and high-frequency rTMS in the temporal lobe. Both auditory evoked potential P50 amplitude, a marker of cortical excitability, and P50 ratio, a marker of sensory gating known to be impaired in patients with auditory verbal hallucinations, were compared before and after rTMS. We observed a similar effect after both stimulation frequencies, with a decrease in P50 amplitude and no significant effect on P50 ratio. Low- and high-frequency rTMS applied to the temporal lobe seemed to exert the same cortical neuromodulation effect, while auditory sensory gating may not be modulated by temporal rTMS.
Even if objectively presented with similar visual stimuli, children younger than 6 years of age exhibit a strong attraction to local visual information (e.g., the trees), whereas children older than 6 years of age, similar to adults, exhibit a visual bias toward global information (e.g., the forest). Here, we studied the cortical thickness changes that underlie this bias shift from local to global visual information. Two groups, matched for age, gender, and handedness, were formed from a total of 30 children who were 6 years old, and both groups performed a traditional global/local visual task. The first group presented a local visual bias, and the other group presented a global visual bias. The results indicated that, compared with the local visual bias group, children with a global visual bias exhibited (1) decreased cortical thickness in the bilateral occipital regions and (2) increased cortical thickness in the left frontoparietal regions. These findings constitute the first structural study that supports the view that both synaptic pruning (i.e., decreased cortical thickness) and expansion mechanisms (i.e., increased cortical thickness) cooccur to allow healthy children to develop a global perception of the visual world.