Unraveling interoceptive processing and action dynamics: Exploring neural and psychological responses to food cues using fMRI.

Behavioral studies reveal that obese vs. lean individuals show attentional bias to food stimuli. Yet research has not investigated this relation using objective brain imaging or tested whether attentional bias to food stimuli predicts future weight gain, which are important aims given the prominence of food cues in the environment. We used functional magnetic resonance imaging (fMRI) to examine attentional bias in 35 adolescent girls ranging from lean to obese using an attention network task involving food and neutral stimuli. BMI correlated positively with speed of behavioral response to both appetizing food stimuli and unappetizing food stimuli, but not to neutral stimuli. BMI correlated positively with activation in brain regions related to attention and food reward, including the anterior insula/frontal operculum, lateral orbitofrontal cortex (OFC), ventrolateral prefrontal cortex (vlPFC), and superior parietal lobe, during initial orientation to food cues. BMI also correlated with greater activation in the anterior insula/frontal operculum during reallocation of attention to appetizing food images and with weaker activation in the medial OFC and ventral pallidum during reallocation of attention to unappetizing food images. Greater lateral OFC activation during initial orientation to appetizing food cues predicted future increases in BMI. Results indicate that overweight is related to greater attentional bias to food cues and that youth who show elevated reward circuitry responsivity during food cue exposure are at increased risk for weight gain.

BackgroundPeople with overweight have stronger reactivity (e.g., subjective craving) to food cues than lean people, and this reactivity is positively associated with food intake. Cue reactivity is a learned response that can be reduced with food cue exposure therapy.ObjectivesIt was hypothesized that participants after food cue exposure therapy would show reduced neural activity in brain regions related to food cue reactivity and increased neural activity in brain regions related to inhibitory-control as compared to participants receiving a control lifestyle intervention.MethodNeural activity of 10 women with overweight (BMI ≥ 27 kg/m2) in response to individually tailored visually presented palatable high-caloric food stimuli was examined before vs. after a cue exposure intervention (n = 5) or a control lifestyle (n = 5) intervention. Data were analyzed case-by-case.ResultsNeural responses to food stimuli were reduced in food-cue-reactivity-related brain regions after the lifestyle intervention in most participants, and generally not after the cue exposure therapy. Moreover, cue exposure did not lead to increased activity in inhibitory-control-related brain regions. However, decreased neural activity after cue exposure was found in most participants in the lateral occipital complex (LOC), which suggests a decreased visual salience of high-caloric food stimuli.ConclusionReceiving a cue exposure therapy did not lead to expected neural responses. As cue exposure relies on inhibitory learning mechanisms, differences in contexts (e.g., environments and food types) between the intervention setting and the scanning sessions may explain the general lack of effect of cue-exposure on neural activity.

Editor's evaluation: Task-evoked metabolic demands of the posteromedial default mode network are shaped by dorsal attention and frontoparietal control networks

Food craving, cortisol and ghrelin responses in modeling highly palatable snack intake in the laboratory

See it, grab it, or STOP! Relationships between trait impulsivity, attentional bias for pictorial food cues and associated response inhibition following in-vivo food cue exposure

Objective To evaluate the activation patterns in the cortexes of expressive aphasics after stroke so as to explore the pathogenic mechanism of expressive aphasia.Methods Blood oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) was the method of choice.It was administered to 9 subjects with expressive aphasia at 1 to 3 months post-stroke onset and to 10 healthy controls.Active areas in the patients' brains were observed using a block-designed picture-naming task,and language function was tested with the China Rehabilitation Research Center's aphasia examination (CRRCAE).The control group received BOLD-fMRI only.SPM8 software was used to process the fMRI data.Results Differences were observed in the mapping of activated areas between the two groups,but many activated areas showed no difference.Significant differences in activation were observed in areas associated with vision,language and cognition,including the bilateral inferior frontal gyrus,the bilateral superior temporal gyrus,the bilateral insula,the bilateral basal ganglia,the left superior frontal gyrus,the left middle frontal gyrus,the left precentral gyrus,the left thalamus,and the left middle temporal gyrus.All the patients had activated cortex regions associated with visual processing in the left and/or right hemisphere,such as the middle frontal gyrus,the middle temporal gyrus,the lingual gyrus and the fusiform gyrus.The activation volumes in the left hemisphere were significantly smaller than those in normal adults.Regions related to language such as the left inferior frontal gyrus (Broca's area),the left middle frontal gyrus,and the right inferior frontal gyrus (the mirror region of Broca's area) were activated in some of them.While the activation frequency,activated volume and activation intensity generally were all less in the patients than in the controls,the activation intensity in the right superior temporal gyrus,the bilateral superior parietal lobule and the left inferior temporal gyrus were stronger.Conclusions Language production may be associated with multiple,interconnected regions.The right hemisphere participates in natural language processing.Aphasia damages both linguistic and cognitive areas,reducing activation in Broca's aphasia.Activation areas in the left hemisphere and the right inferior frontal gyrus decrease significantly,while some regions in the right hemisphere are relatively more activated.The right inferior frontal gyrus may play a different role in language recovery at different periods of aphasia after stroke. Key words: Expressive aphasia; Functional magnetic resonance imaging; Brain activation; Language mechanisms

Food and drug cues activate similar brain regions: A meta-analysis of functional MRI studies

Food cue exposure and body image satisfaction: The moderating role of BMI and dietary restraint

Neural reactivity to food cues may play a central role in overeating and excess weight gain. Functional magnetic resonance imaging (fMRI) studies have implicated regions of the reward network in dysfunctional food cue-reactivity, but neural interactions underlying observed patterns of signal change remain poorly understood. Fifty overweight and obese participants with self-reported cue-induced food craving viewed food and neutral cues during fMRI scanning. Regions of the reward network with significantly greater food versus neutral cue-reactivity were used to specify plausible models of task-related neural interactions underlying the observed blood oxygenation level-dependent (BOLD) signal, and a bi-hemispheric winning model was identified in a dynamic causal modeling (DCM) framework. Neuro-behavioral correlations are investigated with group factor analysis (GFA) and Pearson’s correlation tests. The ventral tegmental area (VTA), amygdalae, and orbitofrontal cortices (OFC) showed significant food cue-reactivity. DCM suggests these activations are produced by largely reciprocal dynamic signaling between these regions, with food cues causing regional disinhibition and an apparent shifting of activity to the right amygdala. Intrinsic self-inhibition in the VTA and right amygdala is negatively correlated with measures of food craving and hunger and right-amygdalar disinhibition by food cues is associated with the intensity of cue-induced food craving, but no robust cross-unit latent factors were identified between the neural group and behavioral or demographic variable groups. Our results suggest a rich array of dynamic signals drive reward network cue-reactivity, with the amygdalae mediating much of the dynamic signaling between the VTA and OFCs. Neuro-behavioral correlations suggest particularly crucial roles for the VTA, right amygdala, and the right OFC-amygdala connection but the more robust GFA identified no cross-unit factors, so these correlations should be interpreted with caution. This investigation provides novel insights into dynamic circuit mechanisms with etiologic relevance to obesity, suggesting pathways in biomarker development and intervention.

Objective Aδ and C fiber nociceptors can be excited when people received contact heat stimulation(CHS) and this excitation may be reflected by functional magnetic resonance imaging(fMRI). The aim of this study was to observe the different fMRI characteristics in CHS with distinct temperatures in healthy people and to explore the pain related functional network. Depending on the fMRI results, we can evaluate the values of CHS-fMRI during the research of brain functional connectivity. Methods Twenty-two healthy volunteers were recruited to this study. During the acquisition of fMRI, the right dorsal forearm received two different CHS in 41 and 51 degree respectively( 41 ℃CHS-fMRI group and 51 ℃CHS-fMRI group), and two series of fMRI data were obtained for each subject. The brain activation was obtained by using one sample t test for the 41 ℃CHS-fMRI group and 51 ℃CHS-fMRI group separately. The difference between 41 ℃CHS-fMRI group and 51 ℃CHS-fMRI group was analyzed by paired-sample t-test. Result These activated brain areas in 41 ℃CHS-fMRI group included bilateral superior temporal gyrus (STG),contralateral transverse temporal gyrus, contralateral amygdala, bilateral insula, bilateral inferior frontal gyrus(IFG), contralateral hippocampus, bilateral putamen, contralateral supramarginal, ipsilateral postcentral, ipsilateral inferior parietal lobule, ipsilateral middle temporal gyrus(MTG), bilateral cerebelum, bilateral middle cingulate cortex and bilateral posterior cingulate cortex.These activated brain areas in 51 ℃CHS-fMRI group included bilateral STG, bilateral amygdala, contralateral hippocampus, bilateral thalamus, contralateral putamen, bilateral insula, bilateral IFG, bilateral cerebellum, contralateral postcentral, contralateral superior parietal lobule, bilateral MTG, bilateral precuneus, and contralateral cuneus.Compared with 41 ℃CHS-fMRI group, the 51 ℃CHS-fMRI group showed higher brain activation in bilateral cerebellum(right:4.455, left: 3.891), ipsilateral precuneus(4.150), contralateral insula(3.530), contralateral IFG(3.530), and contralateral postcentral (3.530; t=2.83，P<0.01). Conclusions There are common brain activated areas and specific areas for each group, which suggested that existence of two central pathways activated by Aδ and C fiber which have different effects in perception of pain and have their brain network responsively. It may become one of the ideal pain stimulation methods with CHS-fMRI, which warrant worth further research. Key words: Hyperalgesia; Heat; Magnetic resonance imaging; Brain; Nerve fibers, unmyelinated; Nerve fibers, myelinated

Expectancy violation, reduction of food cue reactivity and less eating in the absence of hunger after one food cue exposure session for overweight and obese women

Disinhibited restrained eaters are particularly susceptible to dietary lapses and are at increased risk for the onset of eating disorders. To elucidate the neural mechanisms underlying this vulnerability, the present study examined interactions between the reward and inhibition systems during food cue exposure. Sixty female restrained eaters (aged 17-26 years) completed a task-based fMRI paradigm involving food and neutral cues under satiety. Participants were grouped by disinhibition level based on the Dutch Eating Behavior Questionnaire. Psychophysiological interaction (PPI) and dynamic causal modeling (DCM) were used to assess task-modulated functional and effective connectivity. Disinhibited eating was behaviorally assessed via the eating in the absence of hunger (EAH) paradigm. Disinhibited restrained eaters showed weaker functional connectivity between reward (e.g., putamen, globus pallidus [GP]) and inhibition (e.g., inferior frontal gyrus [IFG]) regions, as well as reduced excitatory modulation from reward to inhibition regions (GP → inferior parietal lobule [IPL]). This diminished effective connectivity significantly predicted greater caloric intake during the EAH task. The study revealed a convergence of reduced functional and effective connectivity between the reward and inhibition systems in disinhibited restrained eaters. Both the synchrony and directional influence between these systems were weakened during food cue exposure. Notably, diminished excitatory modulation along the GP → IPL pathway significantly predicted greater caloric intake, suggesting this pathway may serve as a neural marker of vulnerability to disinhibited eating and dietary lapses.

Objective To explore the characteristics of the brain regional homogeneity (ReHo)alterations in patients with low back pain disorders using resting-state functianal magnetic resonance imaging (fMRI).Methods Resting-sate fMRI 3.0T scans were separately performed on 15 age-and gender-matched healthy subjects at rest as baseline and during pain of the back muscle (intramuscular injection of 3 g/L hypertonic saline).The ReHo maps were analyzed with paired t-test to compare the changes between the pain and healthy status.Results As compared with the health subjects,the subjects with low back pain showed significantly increased ReHo levels in the bilateral medial prefrontal cortex (mPFC),left inferior frontal gyrus,right middle frontal gyrus,cerebellum posterior lobe-cerebellar tonsil,right pons,fight insula,right caudate,right precuneus,fight parahippocampa gyrus and posterior cingulate gyrus,and decreased ReHo levels in the right superior temporal gyrus,left middle temporal gyrus,left precentral gyrus,left postcentral gyrus,left parahippocampa gyrus,left fusiform gyrus,left anterior cingulate,left superior parietal lobule,right inferior parietal lobule (P＜0.005,cluster threshold ≥10).Consulsion People with low back pain show abnormal spontaneous activity in certain brain regions. Key words: Pain; Resting-state; Functional magnetic resonance imaging; Regional homogeneity

*Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A.; †University Hospital Gent, Gent, Belgium; ‡Departments of Diagnostic Radiology and Neurosurgery, Yale University, New Haven, Connecticut; §Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania; Clinical Epilepsy Section, National Institutes of Health, Bethesda, Maryland; ¶Department of Radiology, Mayo Clinic, Rochester, Minnesota; and **Department of Neurology, Medical College of Georgia, Augusta, Georgia, U.S.A.

Objective To explore the significance of language proficiency in bilingual perception in Chinese-English late bilingual subjects with block-design functional magnetic resonance imaging (bfMRI). Methods Thirteen right-handed Chinese Han healthy male late bilinguists who had limited English proficiency were scanned while listening to short sentences in Chinese and English. Based on blood oxygenation level-dependent (BOLD) signal efficacy, functional images were collected using a 1.5-T MRI. Statistical parametric mapping 2 (SPM2) was used to analyze the data of functional images (P 100). Results For Chinese familiar voices, more significant activation was observed in the right superior temporal gyrus than that for English familiar voices. On the contrary, more significant activations for English familiar voices were observed in the left precuneus, middle frontal gyrus and left posterior cingulate cortex compared with that for Chinese familiar voices.For Chinese unfamiliar voices, more significant activations were observed in the right middle temporal gyrus and right medial frontal gyrus than that for English unfamiliar voices. In contrast, more significant activations by English unfamiliar voices were observed in the right inferior frontal gyrus, middle frontal gyrus and left middle temporal gyrus compared with that for Chinese unfamiliar voices. Conclusion Language proficiency may play an important role in different language perception from auditory level. Key words: Language proficiency; Block design; Functional MRI