Oxytocin enhances cognitive control of food craving in women

In developed countries, obesity has become an epidemic resulting in enormous health care costs for society and serious medical complications for individuals. The homeostatic regulation of food intake is critically dependent on top‐down control of reward‐driven food craving. There is accumulating evidence from animal studies that the neuropeptide oxytocin (OXT) is involved in regulating hunger states and eating behavior, but whether OXT also contributes to cognitive control of food craving in humans is still unclear. We conducted a counter‐balanced, double‐blind, within‐subject, pharmacological magnetic resonance imaging experiment involving 31 healthy women who received 24 IU of intranasal OXT or placebo and were scanned twice while they were exposed to pictures of palatable food. The participants were instructed either to imagine the immediate consumption or to cognitively control the urge to eat the food. Our results show a trend that OXT specifically reduced food craving in the cognitive control condition. On the neural level, these findings were paralleled by an increase of activity in the middle and superior frontal gyrus, precuneus, and cingulate cortex under OXT. Interestingly, the behavioral OXT effect correlated with the OXT‐induced changes in the prefrontal cortex and precuneus. Collectively, the present study provides first evidence that OXT plays a key role in the cognitive regulation of food craving in women by strengthening activity in a broad neurocircuitry implicated in top‐down control and self‐referential processing. Hum Brain Mapp 37:4276–4285, 2016. © 2016 Wiley Periodicals, Inc.     

Brain activity in cigarette smokers performing a working memory task: effect of smoking abstinence.

BACKGROUND: When nicotine-dependent human subjects abstain from cigarette smoking, they exhibit deficits in working memory. An understanding of the neural substrates of such impairments may help to understand how nicotine affects cognition. Our aim, therefore, was to identify abnormalities in the circuitry that mediates working memory in nicotine-dependent subjects after they initiate abstinence from smoking. METHODS: We used blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to study eight smokers while they performed a letter version of the N-Back working memory task under satiety (< or = 1.5 hours abstinence) and abstinence (> or = 14 hours abstinence) conditions. RESULTS: Task-related activity in the left dorsal lateral prefrontal cortex (DLPFC) showed a significant interaction between test session (satiety, abstinence) and task load (1-back, 2-back, and 3-back). This interaction reflected the fact that task-related activity in the satiety condition was relatively low during performance of the 1-back task but greater at the more difficult task levels, whereas task-related activity in the abstinence condition was relatively high at the 1-back level and did not increase at the more difficult task levels. CONCLUSIONS: We conclude that neural processing related to working memory in the left DLPFC is less efficient during acute abstinence from smoking than at smoking satiety.     

Neural circuitry underlying voluntary suppression of sadness.

BACKGROUND: The ability to voluntarily self-regulate negative emotion is essential to a healthy psyche. Indeed, a chronic incapacity to suppress negative emotion might be a key factor in the genesis of depression and anxiety. Regarding the neural underpinnings of emotional self-regulation, a recent functional neuroimaging study carried out by our group has revealed that the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex are involved in voluntary suppression of sexual arousal. As few things are known, still, with respect to the neural substrate underlying volitional self-regulation of basic emotions, here we used functional magnetic resonance imaging to identify the neural circuitry associated with the voluntary suppression of sadness. METHODS: Twenty healthy female subjects were scanned during a Sad condition and a Suppression condition. In the Sad condition, subjects were instructed to react normally to sad film excerpts whereas, in the Suppression condition, they were asked to voluntarily suppress any emotional reaction in response to comparable stimuli. RESULTS: Transient sadness was associated with significant loci of activation in the anterior temporal pole and the midbrain, bilaterally, as well as in the left amygdala, left insula, and right ventrolateral prefrontal cortex (VLPFC) (Brodmann area [BA] 47). Correlational analyses carried out between self-report ratings of sadness and regional blood oxygen level dependent (BOLD) signal changes revealed the existence of positive correlations in the right VLPFC (BA 47), bilaterally, as well as in the left insula and the affective division of the left anterior cingulate gyrus (BA 24/32). In the Suppression condition, significant loci of activation were noted in the right DLPFC (BA 9) and the right orbitofrontal cortex (OFC) (BA 11), and positive correlations were found between the self-report ratings of sadness and BOLD signal changes in the right OFC (BA 11) and right DLPFC (BA 9). CONCLUSIONS: These results confirm the key role played by the DLPFC in emotional self-regulation. They also indicate that the right DLPFC and right OFC are components of a neural circuit implicated in voluntary suppression of sadness.     

Neural correlates of visual search in patients with hereditary retinal dystrophies

In patients with central visual field scotomata a large part of visual cortex is not adequately stimulated. We investigated evidence for possible upregulation in cortical responses in 22 patients (8 females, 14 males; mean age 41.5 years, range 12–65 years) with central visual field loss due to hereditary retinal dystrophies (Stargardt's disease, other forms of hereditary macular dystrophies and cone‐rod dystrophy) and compared their results to those of 22 age‐matched controls (11 females, 11 males; mean age, 42.4 years, range, 13–70 years). Using functional magnetic resonance imaging (fMRI) we recorded differences in behavioral and BOLD signal distribution in retinotopic mapping and visual search tasks. Patients with an established preferred retinal locus (PRL) exhibited significantly higher activation in early visual cortex during the visual search task, especially on trials when the target stimuli fell in the vicinity of the PRL. Compared with those with less stable fixation, patients with stable eccentric fixation at the PRL exhibited greater performance levels and more brain activation. Hum Brain Mapp 34:2607–2623, 2013. © 2012 Wiley Periodicals, Inc.     

Neural abnormalities during cognitive generation of affect in treatment-resistant depression.

BACKGROUND: Dysfunctions in brain regions known to be involved in affect and mood states are thought to be implicated in depression and may have a role in determining the type and symptoms of this illness. METHODS: Functional magnetic resonance imaging was used to elucidate neural correlates of cognitive generation of affect, using a previously published paradigm of evoking affect with picture-caption pairs, in patients with unipolar, treatment-resistant depression. RESULTS: Compared with control participants, patients showed relatively decreased response in the anterior cingulate (rostral; right) with both negative and positive picture-caption pairs and in the medial frontal gyrus and hippocampus (all left) with positive picture-caption pairs. They demonstrated increased response in the inferior (right) and middle temporal gyri (left) with negative picture-caption pairs, and in the parahippocampal gyrus (right), inferior frontal gyrus (left), subgenual cingulate (right), striatum (right), and brain stem (left) with positive picture-caption pairs. CONCLUSIONS: Reduced medial/middle prefrontal and hippocampal activity may account for positive affect disturbances and temporal lobe hyperactivity for negative affect disturbances in treatment-resistant depression. The results also corroborate previous observations from resting positron emission tomography studies and further elucidate the association between hypoactive rostral cingulate and nonresponsiveness to treatment in depression.     

Electroencephalography reveals a selective disruption of cognitive control processes in craving cigarette smokers

Addiction to nicotine is extremely challenging to overcome, and the intense craving for the next cigarette often leads to relapse in smokers who wish to quit. To dampen the urges of craving and inhibit unwanted behaviour, smokers must harness cognitive control, which is itself impaired in addiction. It is likely that craving may interact with cognitive control, and the present study sought to test the specificity of such interactions. To this end, data from 24 smokers were gathered using EEG and behavioural measures in a craving session (following a three‐hour nicotine abstention period) and a non‐craving session (having just smoked). In both sessions, participants performed a task probing various facets of cognitive control (response inhibition, task switching and conflict processing). Results showed that craving smokers were less flexible with the implementation of cognitive control, with demands of task switching and incongruency yielding greater deficits under conditions of craving. Importantly, inhibitory control was not affected by craving, suggesting that the interactions of craving and cognitive control are selective. Together, these results provide evidence that smokers already exhibit specific control‐related deficits after brief nicotine deprivation. This disruption of cognitive control while craving may help to explain why abstinence is so difficult to maintain.     

Neural mechanisms of motion perceptual learning in noise

Practice improves our perceptual ability. However, the neural mechanisms underlying this experience‐dependent plasticity in adult brain remain unclear. Here, we studied the long‐term neural correlates of motion perceptual learning. Subjects’ behavioral performance and BOLD signals were tracked before, immediately after, and 2 weeks after practicing a motion direction discrimination task in noise over six daily sessions. Parallel to the specificity and persistency of the behavioral learning effect, we found that training sharpened the cortical tuning in MT, and enhanced the connectivity strength from MT to the intraparietal sulcus (IPS, a motion decision‐making area). In addition, the decoding accuracy for the trained motion direction was improved in IPS 2 weeks after training. The dual changes in the sensory and the high‐level cortical areas suggest that learning refines the neural representation of the trained stimulus and facilitates the information transmission in the decision process. Our findings are consistent with the functional specialization in the visual cortex, and provide empirical evidence to the reweighting theory of perceptual learning at a large spatial scale. Hum Brain Mapp 38:6029–6042, 2017. © 2017 Wiley Periodicals, Inc.     

Changes of brain activity in the neural substrates for theory of mind during childhood and adolescence

Theory of mind (ToM) refers to the ability to attribute independent mental states, such as beliefs, preferences and desires, to the self and others. Neuroimaging studies of normal adults have consistently demonstrated the importance of particular brain regions for ToM, the superior temporal sulcus (STS), temporal pole (TP) and the medial prefrontal cortex (MPFC). However, there are little data showing how ToM develops during childhood and adolescence. Such data are important for understanding the development of social functioning and its disorders. The authors used functional magnetic resonance imaging to study age-related changes in brain activity associated with ToM during childhood and early adolescence (9-16 years). Normally developed children and adolescents demonstrated significant activation in the bilateral STS, the TP adjacent to the amygdala (TP/Amy) and the MPFC. Furthermore, the authors found a positive correlation between age and the degree of activation in the dorsal part of the MPFC; in contrast, a negative correlation was found for the ventral part of the MPFC. The authors also found a positive correlation between the Z coordinate of the peak activation in the MPFC and age. The data indicated that activity in the MPFC associated with ToM shifted from the ventral to the dorsal part of the MPFC during late childhood and adolescence. No age-related changes were found in the STS and the TP/Amy regions. The authors consider that the age-related brain activity observed in the present study may be associated with the maturation of the prefrontal cortex and the associated development of cognitive functions.     

Specificity of regions processing biological motion

Using functional magnetic resonance imaging and point light displays portraying six different human actions, we were able to show that several visual cortical regions, including human MT/V5 complex, posterior inferior temporal gyrus and superior temporal sulcus, are differentially active in the subtraction comparing biological motion to scrambled motion. Comparison of biological motion to three-dimensional rotation (of a human figure), articulated motion and translation suggests that human superior temporal sulcus activity reflects the action portrayed in the biological motion stimuli, whereas posterior inferior temporal gyrus responds to the figure and hMT/V5+ to the complex motion pattern present in biological motion stimuli. These results were confirmed with implied action stimuli.     

Neural representation and clinically relevant moderators of individualised self-criticism in healthy subjects

Many people routinely criticise themselves. While self-criticism is largely unproblematic for most individuals, depressed patients exhibit excessive self-critical thinking, which leads to strong negative affects. We used functional magnetic resonance imaging in healthy subjects (N = 20) to investigate neural correlates and possible psychological moderators of self-critical processing. Stimuli consisted of individually selected adjectives of personally negative content and were contrasted with neutral and negative non-self-referential adjectives. We found that confrontation with self-critical material yielded neural activity in regions involved in emotions (anterior insula/hippocampus–amygdala formation) and in anterior and posterior cortical midline structures, which are associated with self-referential and autobiographical memory processing. Furthermore, contrasts revealed an extended network of bilateral frontal brain areas. We suggest that the co-activation of superior and inferior lateral frontal brain regions reflects the recruitment of a frontal top–down pathway, representing cognitive reappraisal strategies for dealing with evoked negative affects. In addition, activation of right superior frontal areas was positively associated with neuroticism and negatively associated with cognitive reappraisal. Although these findings may not be specific to negative stimuli, they support a role for clinically relevant personality traits in successful regulation of emotion during confrontation with self-critical material.     

Effect of left prefrontal repetitive transcranial magnetic stimulation on food craving.

BACKGROUND: Dysfunction of the prefrontal cortex is implicated in craving for drugs and food. This study explores the effect of prefrontal cortex stimulation on food craving. METHODS: In a randomized double-blind parallel group study, 28 women, who reported frequent cravings for food were exposed to foods that typically elicit strong cravings before and after a single session of real or sham 10-Hz repetitive transcranial magnetic stimulation to the left dorsolateral prefrontal cortex at an intensity of 110% individual motor threshold. RESULTS: Self-reported food craving during exposure to the experimental foods remained stable before and after real stimulation compared with sham stimulation in which cravings increased over the experimental session. Consumption of snack foods within a 5-min period after stimulation did not differ between groups. CONCLUSIONS: Prefrontal stimulation inhibits the development of craving. A longer period of observation is necessary to establish whether there is an effect on food consumption.     

Neural activity in the hippocampus predicts individual visual short‐term memory capacity

Although the hippocampus had been traditionally thought to be exclusively involved in long‐term memory, recent studies raised controversial explanations why hippocampal activity emerged during short‐term memory tasks. For example, it has been argued that long‐term memory processes might contribute to performance within a short‐term memory paradigm when memory capacity has been exceeded. It is still unclear, though, whether neural activity in the hippocampus predicts visual short‐term memory (VSTM) performance. To investigate this question, we measured BOLD activity in 21 healthy adults (age range 19–27 yr, nine males) while they performed a match‐to‐sample task requiring processing of object‐location associations (delay period = 900 ms; set size conditions 1, 2, 4, and 6). Based on individual memory capacity (estimated by Cowan's K‐formula), two performance groups were formed (high and low performers). Within whole brain analyses, we found a robust main effect of “set size” in the posterior parietal cortex (PPC). In line with a “set size × group” interaction in the hippocampus, a subsequent Finite Impulse Response (FIR) analysis revealed divergent hippocampal activation patterns between performance groups: Low performers (mean capacity = 3.63) elicited increased neural activity at set size two, followed by a drop in activity at set sizes four and six, whereas high performers (mean capacity = 5.19) showed an incremental activity increase with larger set size (maximal activation at set size six). Our data demonstrated that performance‐related neural activity in the hippocampus emerged below capacity limit. In conclusion, we suggest that hippocampal activity reflected successful processing of object‐location associations in VSTM. Neural activity in the PPC might have been involved in attentional updating. © 2013 Wiley Periodicals, Inc.     

Neural correlates of social exclusion during adolescence: understanding the distress of peer rejection

Developmental research has demonstrated the harmful effects of peer rejection during adolescence; however, the neural mechanisms responsible for this salience remain unexplored. In this study, 23 adolescents were excluded during a ball-tossing game in which they believed they were playing with two other adolescents during an fMRI scan; in reality, participants played with a preset computer program. Afterwards, participants reported their exclusion-related distress and rejection sensitivity, and parents reported participants’ interpersonal competence. Similar to findings in adults, during social exclusion adolescents displayed insular activity that was positively related to self-reported distress, and right ventrolateral prefrontal activity that was negatively related to self-reported distress. Findings unique to adolescents indicated that activity in the subgenual anterior cingulate cortex (subACC) related to greater distress, and that activity in the ventral striatum related to less distress and appeared to play a role in regulating activity in the subACC and other regions involved in emotional distress. Finally, adolescents with higher rejection sensitivity and interpersonal competence scores displayed greater neural evidence of emotional distress, and adolescents with higher interpersonal competence scores also displayed greater neural evidence of regulation, perhaps suggesting that adolescents who are vigilant regarding peer acceptance may be most sensitive to rejection experiences.     

Abnormal prefrontal cortex function during response inhibition in Turner syndrome: functional magnetic resonance imaging evidence.

BACKGROUND: Turner syndrome (TuS) arises from the partial or complete absence of one X chromosome. Although neuropsychological studies report impaired attentional function and response inhibition in TuS, the neural correlates of these cognitive problems are unknown. METHODS: Eleven female subjects with TuS and 11 individually matched normal control subjects were imaged using functional magnetic resonance imaging while performing a Go/NoGo task. RESULTS: Groups did not differ on accuracy or reaction time; however, the TuS group activated more in the bilateral superior and middle frontal gyri than control subjects. Control subjects did not activate more than the TuS group in any region. CONCLUSION: These findings suggest that female subjects with TuS compensate for executive dysfunction via recruitment of additional prefrontal cortex regions involved in inhibition, attention, and working memory, functions necessary for successful performance of Go/NoGo tasks. Elucidating brain function in TuS will advance our understanding of the influence of X-chromosome genes on neurodevelopment and brain function and contribute to planning future intervention strategies.     

Functional MRI of the visual cortex and visual testing in patients with previous optic neuritis

The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size of the activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated significantly to both the results of the contrast sensitivity test and to the Snellen visual acuity. Our results indicate that fMRI is a useful method for the study of ON, even in cases where the visual acuity is severely impaired. The reduction in activated volume could be explained as a reduced neuronal input; however, the greater asymmetry might point to a cortical reorganization as a consequence of neuronal damage. Future fMRI studies in ON will add to the understanding of the neural adaptive behaviour following ON.     

Functional magnetic resonance imaging evaluation of visual cortex activation in patients with anterior visual pathway lesions

The aim of this study was to examine the secondary visual cortex functional disorder in patients with glaucoma and large pituitary adenoma by functional magnetic resonance imaging, and to determine the correlation between visual field defect and primary visual cortex activation. Results showed that single eye stimulation resulted in bilateral visual cortex activation in patients with glaucoma or large pituitary adenoma. Compared with the normal control group, the extent and intensity of visual cortex activation was decreased after left and right eye stimulation, and functional magnetic resonance imaging revealed a correlation between visual field defects and visual cortex activation in patients with glaucoma and large pituitary adenoma. These functional magnetic resonance imaging data suggest that anterior optic pathway lesions can cause secondary functional disorder of the visual cortex, and that visual defects are correlated with visual cortex activation.     

Neural substrates of context‐ and person‐dependent altruistic punishment

Human altruistic behaviors are heterogeneous across both contexts and people, whereas the neural signatures underlying the heterogeneity remain to be elucidated. To address this issue, we examined the neural signatures underlying the context‐ and person‐dependent altruistic punishment, conjoining event‐related fMRI with both task‐based and resting‐state functional connectivity (RSFC). Acting as an impartial third party, participants decided how to punish norm violators either alone or in the presence of putative others. We found that the presence of others decreased altruistic punishment due to diffusion of responsibility. Those behavioral effects paralleled altered neural responses in the dorsal anterior cingulate cortex (dACC) and putamen. Further, we identified modulation of responsibility diffusion on task‐based functional connectivity of dACC with the brain regions implicated in reward processing (i.e., posterior cingulate cortex and amygdala/orbital frontal cortex). Finally, the RSFC results revealed that (i) increased intrinsic connectivity strengths of the putamen with temporoparietal junction and dorsolateral PFC were associated with attenuated responsibility diffusion in altruistic punishment and (ii) increased putamen‐dorsomedial PFC connectivity strengths were associated with reduced responsibility diffusion in self‐reported responsibility. Taken together, our findings elucidate the context‐ and person‐dependent altruistic behaviors as well as associated neural substrates and thus provide a potential neurocognitive mechanism of heterogeneous human altruistic behaviors. Hum Brain Mapp 38:5535–5550, 2017. © 2017 Wiley Periodicals, Inc.     

Functional Magnetic Resonance Imaging in Acute Unilateral Optic Neuritis

Despite good clinical criteria for diagnosing optic neuritis (ON), only a few techniques can precisely assess its impact on visual brain function. The authors studied whether functional magnetic resonance imaging (fMRI) of visual activation reliably reflects the cerebral consequences of acute unilateral ON, and how fMRI correlates with clinical function and visual evoked potentials (VEPs). Twenty ON patients, before and after steroid treatment, were compared to 20 controls. Each eye was stimulated separately with a checkerboard pattern reversing at 1, 2, 4, and 8 Hz. VEPs were recorded the same day. Initially, affected eye responses differed significantly from those of unaffected counterparts and controls in 12 patients. Post hoc classification by fMRI criteria was correct in approximately 85%. fMRI and VEP response parameters (as well as visual acuity) correlated significantly. The higher stimulation frequencies yielded greater fMRI responses from unaffected eyes, but not from affected eyes, in controls. The fMRI responses were quantifiable in every subject, whereas in 11 ON eyes, no VEPs were obtained during the acute stage. The authors conclude that fMRI is sensitive to the cerebral response alteration during ON and might therefore contribute to evaluating the temporal evolution of the visual functional deficit during recovery or therapy.     

Neural signatures of lexical tone reading

Research on how lexical tone is neuroanatomically represented in the human brain is central to our understanding of cortical regions subserving language. Past studies have exclusively focused on tone perception of the spoken language, and little is known as to the lexical tone processing in reading visual words and its associated brain mechanisms. In this study, we performed two experiments to identify neural substrates in Chinese tone reading. First, we used a tone judgment paradigm to investigate tone processing of visually presented Chinese characters. We found that, relative to baseline, tone perception of printed Chinese characters were mediated by strong brain activation in bilateral frontal regions, left inferior parietal lobule, left posterior middle/medial temporal gyrus, left inferior temporal region, bilateral visual systems, and cerebellum. Surprisingly, no activation was found in superior temporal regions, brain sites well known for speech tone processing. In activation likelihood estimation (ALE) meta‐analysis to combine results of relevant published studies, we attempted to elucidate whether the left temporal cortex activities identified in Experiment one is consistent with those found in previous studies of auditory lexical tone perception. ALE results showed that only the left superior temporal gyrus and putamen were critical in auditory lexical tone processing. These findings suggest that activation in the superior temporal cortex associated with lexical tone perception is modality‐dependent. Hum Brain Mapp, 36:304–312, 2015. © 2014 Wiley Periodicals, Inc .     

Neural substrates of processing path and manner information of a moving event

Languages consistently distinguish the path and the manner of a moving event in different constituents, even if the specific constituents themselves vary across languages. Children also learn to categorize moving events according to their path and manner at different ages. Motivated by these linguistic and developmental observations, we employed fMRI to test the hypothesis that perception of and attention to path and manner of motion is segregated neurally. Moreover, we hypothesize that such segregation respects the "dorsal-where and ventral-what" organizational principle of vision. Consistent with this proposal, we found that attention to the path of a moving event was associated with greater activity within bilateral inferior/superior parietal lobules and the frontal eye-field, while attention to manner was associated with greater activity within bilateral postero-lateral inferior/middle temporal regions. Our data provide evidence that motion perception, traditionally considered as a dorsal "where" visual attribute, further segregates into dorsal path and ventral manner attributes. This neural segregation of the components of motion, which are linguistically tagged, points to a perceptual counterpart of the functional organization of concepts and language.