Prefrontal Medial Lobe Research Articles

Higher C-peptide levels are associated with regional cortical thinning in 1093 cognitively normal subjects.

Recent studies have demonstrated an association between increased insulin secretion and cognitive impairment. However, there is no previous study that directly evaluates the association between increased insulin secretion and cortical thickness to our knowledge. Therefore, our aim was to evaluate the effect of hyperinsulinemia, as measured by C-peptide level, on cortical thickness in a large sample of cognitively normal individuals. Cortical thickness was measured in 1093 patients who visited the Samsung Medical Health Promotion Center and underwent brain magnetic resonance imaging (MRI) and a blood test to measure C-peptide concentration. Automated surface-based analyses of the MRI data were used to measure cortical thickness. C-peptide levels were divided into quartiles for comparison. Patients in the first to third quartiles were used as the reference category. Patients in the highest quartile group (Q4) of C-peptide levels showed cortical thinning, predominantly in both medial temporal lobes, the right inferior temporal gyrus, both medial prefrontal lobes and the right superior parietal lobule, compared with the lower quartile groups (Q1-Q3) after controlling for age, gender, body mass index, history of hypertension, hyperlipidemia, previous stroke, cardiovascular disease and fasting glucose level. A higher C-peptide level is associated with regional cortical thinning, even in cognitively normal individuals.

Altered brain functional connectivity in hemodialysis patients with end-stage renal disease: a resting-state functional MR imaging study.

The changes of whole brain functional connectivity in hemodialysis (HD) patients with end-stage renal disease (ESRD) are still unclear, which may be associated with multiple factors, such as elevated neurotoxins, anemia, and side effects of hemodialysis. Resting-state functional magnetic resonance imaging (rs-fMRI) data of 71 patients (43 males, 28 females; mean age, 33.4 ± 9.4 years) and 43 age- and gender-matched healthy volunteers (29 males, 14 females; mean age, 30.6 ± 8.8 years) were acquired. Neuropsychological tests including number connection test type A (NCT-A), digit symbol test (DST), line-tracing test (LTT), serial-dotting test (SDT), self-rating depression scale (SDS) and self-rating anxiety scale (SAS) were used to evaluate cognitive and psychiatric conditions in all subjects. Blood biochemistry tests including serum creatinine levels, blood urea, hematocrit, and Ca(2+) level were taken in HD patients. Forty-two connections significantly different between HD patients with ESRD and controls were found (all P < 0.05, Bonferroni corrected) and identified as connectivities of interests (COIs), among which 39 connections (92.9%) were markedly decreased in patients. Of the 39 weaker connections, 24 were related to the frontal lobe regions. Widespread weakening of cortical and subcortical network connectivity in ESRD patients was more directly related with neuropsychological impairments and anemia rather than serum creatinine level, blood urea and dialysis duration. In particular, impairments in the medial prefrontal lobe could play an important role in mediating psychological dysfunctions.

Study of diffusion tensor imaging in subcortical ischemic vascular cognitive impairment

Objective Using diffusion tensor imaging (DTI) to explore the microstructure changes of white matter in subcortical ischemic vascular cognitive impairment (SIVCI) and its correlation with cognitive function. Methods Forty-nine patients with subcortical ischemic cerebrovascular diseases were collected. By using Clinical Dementia Rating Scale (CDR), they were classified into 10 cases of vascular dementia (VaD group), 20 cases of vascular cognitive impairment-no dementia (VCIND group) and 19 cases of normal cognitive function (control group). Conventional MRI and DTI were performed in all cases. Based on the DTI data, voxel-based analysis was used to assess the whole brain region. Correlation analysis was applied to illustrate the relationship between DTI parameters and cognitive scale in VaD patients. Results Compared with the control group, fractional anisotropy (FA) values of patients in VaD group decreased in medial prefrontal cortex, anterior cingulate cortex, corpus callosum stem, bilateral parietal lobes, right temporal lobe and bilateral orbitofrontal lobes ( P = 0.000, for all), and FA values of patients in VCIND group decreased in right inferior frontal gyrus, right hippocampus and bilateral precuneus ( P = 0.000, for all). Compared with VCIND group, FA values of patients in VaD group decreased in medial prefrontal cortex, anterior cingulate, corpus callosum, bilateral parietal lobes and right temporal lobe ( P = 0.000, for all). Compared with the control group, mean diffusivity (MD) values in VaD group increased in medial prefrontal cortex, corpus callosum, bilateral parietal lobes, bilateral temporal lobes and anterior cingulate ( P = 0.000, for all), while in VCIND group increased in bilateral precuneus and right hippocampus ( P = 0.000, for all). Compared with VCIND group, MD values in VaD group increased in right medial prefrontal cortex, anterior cingulate cortex, corpus callosum stem, bilateral parietal lobes and bilateral temporal lobes ( P = 0.000, for all). The correlation analysis showed that the FA value of medial prefrontal lobe in VaD group was negatively correlated with the time to finish Trail Making Test A (TMT-A; r = - 0.782, P = 0.007), and MD value of bilateral inferior frontal gyrus was positively correlated with the time to complete TMT-A ( r = 0.877, P = 0.001). Conclusions DTI was more sensitive on the white matter microstructure change of SIVCI patients than conventional MRI. It can reflect patient's early cognitive functional changes. Microstructrual change in medial prefrontal white matter is an important factor which may influence the executive functions of patients with SIVCI. doi: 10.3969/j.issn.1672-6731.2014.04.009

Isn't it ironic? Neural correlates of irony comprehension in schizophrenia.

Ironic remarks are frequent in everyday language and represent an important form of social cognition. Increasing evidence indicates a deficit in comprehension in schizophrenia. Several models for defective comprehension have been proposed, including possible roles of the medial prefrontal lobe, default mode network, inferior frontal gyri, mirror neurons, right cerebral hemisphere and a possible mediating role of schizotypal personality traits. We investigated the neural correlates of irony comprehension in schizophrenia by using event-related functional magnetic resonance imaging (fMRI). In a prosody-free reading paradigm, 15 female patients with schizophrenia and 15 healthy female controls silently read ironic and literal text vignettes during fMRI. Each text vignette ended in either an ironic (n = 22) or literal (n = 22) statement. Ironic and literal text vignettes were matched for word frequency, length, grammatical complexity, and syntax. After fMRI, the subjects performed an off-line test to detect error rate. In this test, the subjects indicated by button press whether the target sentence has ironic, literal, or meaningless content. Schizotypal personality traits were assessed using the German version of the schizotypal personality questionnaire (SPQ). Patients with schizophrenia made significantly more errors than did the controls (correct answers, 85.3% vs. 96.3%) on a behavioural level. Patients showed attenuated blood oxygen level-dependent (BOLD) response during irony comprehension mainly in right hemisphere temporal regions (ironic>literal contrast) and in posterior medial prefrontal and left anterior insula regions (for ironic>visual baseline, but not for literal>visual baseline). In patients with schizophrenia, the parahippocampal gyrus showed increased activation. Across all subjects, BOLD response in the medial prefrontal area was negatively correlated with the SPQ score. These results highlight the role of the posterior medial prefrontal and right temporal regions in defective irony comprehension in schizophrenia and the mediating role of schizotypal personality traits.

Commonality and Specificity of Acupuncture Action at Three Acupoints as Evidenced by fMRI

Previous work from our team and others has shown that manual acupuncture at LI4 (hegu), ST36 (zusanli), and LV3 (taichong) deactivates a limbic-paralimbic-neocortical brain network, and at the same time activates somatosensory regions of the brain. The objective of the present study was to explore the specificity and commonality of the brain response to manual acupuncture at LI4, ST36, and LV3, acupoints that are located on different meridians and are used to treat pain disorders. We used functional magnetic resonance imaging (fMRI) to monitor the brain responses to acupuncture at three different acupoints; we examined 46 healthy subjects who, according to their psychophysical responses, experienced deqi sensation during acupuncture. Brain responses to stimulation at each of the acupoints were displayed in conjunction with one another to show the spatial distribution. We found clusters of deactivation in the medial prefrontal, medial parietal and medial temporal lobes showing significant convergence of two or all three of the acupoints. The largest regions showing common responses to all three acupoints were the right subgenual BA25, right subgenual cingulate, right isthmus of the cingulum bundle, and right BA31. We also noted differences in major sections of the medial prefrontal and medial temporal lobes, with LI4 predominating in the pregenual cingulate and hippocampal formation, ST36 predominating in the subgenual cingulate, and LV3 predominating in the posterior hippocampus and posterior cingulate. The results suggest that although these acupoints are commonly used for anti-pain and modulatory effects, they may mobilize the same intrinsic global networks, with substantial overlap of common brain regions to mediate their actions. Our findings showing preferential response of certain limbic-paralimbic structures suggests acupoints may also exhibit relative specificity.

Functional anatomy of autobiographical memory recall deficits in depression

BackgroundMajor depressive disorder (MDD) is associated with deficits in recalling specific autobiographical memories (AMs). Extensive research has examined the functional anatomical correlates of AM in healthy humans, but no studies have examined the neurophysiological underpinnings of AM deficits in MDD. The goal of the present study was to examine the differences in the hemodynamic response between patients with MDD and controls while they engage in AM recall.MethodParticipants (12 unmedicated MDD patients; 14 controls) underwent functional magnetic resonance imaging (fMRI) scanning while recalling AMs in response to positive, negative and neutral cue words. The hemodynamic response during memory recall versus performing subtraction problems was compared between MDD patients and controls. Additionally, a parametric linear analysis examined which regions correlated with increasing arousal ratings.ResultsBehavioral results showed that relative to controls, the patients with MDD had fewer specific (p=0.013), positive (p=0.030), highly arousing (p=0.036) and recent (p=0.020) AMs, and more categorical (p<0.001) AMs. The blood oxygen level-dependent (BOLD) response in the parahippocampus and hippocampus was higher for memory recall versus subtraction in controls and lower in those with MDD. Activity in the anterior insula was lower for specific AM recall versus subtraction, with the magnitude of the decrement greater in MDD patients. Activity in the anterior cingulate cortex was positively correlated with arousal ratings in controls but not in patients with MDD.ConclusionsWe replicated previous findings of fewer specific and more categorical AMs in patients with MDD versus controls. We found differential activity in medial temporal and prefrontal lobe structures involved in AM retrieval between MDD patients and controls as they engaged in AM recall. These neurophysiological deficits may underlie AM recall impairments seen in MDD.

Localization of cerebral functional deficits in treatment-naive, first-episode schizophrenia using resting-state fMRI

BackgroundSpontaneous low-frequency fluctuations (LFF) in the blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal have been shown to reflect cerebral spontaneous neural activity, and the present study attempts to explore the functional changes in the regional brain in patients with schizophrenia using the amplitude of the BOLD signals. MethodsA total of 66 treatment-naïve, first-episode schizophrenia (FES) patients and 66 normal age- and sex-matched controls were recruited. Resting-state fMRIs were obtained using a gradient-echo echo-planar imaging sequence. The amplitude of LFF (ALFF) was calculated using REST software. Voxel-based analysis of the ALFF maps between control and patient groups was performed with twos-sample t-tests using SPM2. ResultsCompared to the controls, the FES group showed significantly decreased ALFF in the medial prefrontal lobe (MPFC) and significant increases in the ALFF in the left and right putamen. Significant positive correlations were observed between ALFF values in the bilateral putamen in both the patient and control groups. ConclusionsAlterations of the ALFF in the MPFC and putamen in FES observed in the present study suggest that the functional abnormalities of those areas are at an early stage of the disease.

Acupuncture mobilizes the brain's default mode and its anti-correlated network in healthy subjects

Previous work has shown that acupuncture stimulation evokes deactivation of a limbic–paralimbic–neocortical network (LPNN) as well as activation of somatosensory brain regions. This study explores the activity and functional connectivity of these regions during acupuncture vs. tactile stimulation and vs. acupuncture associated with inadvertent sharp pain. Acupuncture during 201 scans and tactile stimulation during 74 scans for comparison at acupoints LI4, ST36 and LV3 was monitored with fMRI and psychophysical response in 48 healthy subjects. Clusters of deactivated regions in the medial prefrontal, medial parietal and medial temporal lobes as well as activated regions in the sensorimotor and a few paralimbic structures can be identified during acupuncture by general linear model analysis and seed-based cross correlation analysis. Importantly, these clusters showed virtual identity with the default mode network and the anti-correlated task-positive network in response to stimulation. In addition, the amygdala and hypothalamus, structures not routinely reported in the default mode literature, were frequently involved in acupuncture. When acupuncture induced sharp pain, the deactivation was attenuated or became activated instead. Tactile stimulation induced greater activation of the somatosensory regions but less extensive deactivation of the LPNN. These results indicate that the deactivation of the LPNN during acupuncture cannot be completely explained by the demand of attention that is commonly proposed in the default mode literature. Our results suggest that acupuncture mobilizes the anti-correlated functional networks of the brain to mediate its actions, and that the effect is dependent on the psychophysical response.

Shared and disorder‐specific prefrontal abnormalities in boys with pure attention‐deficit/hyperactivity disorder compared to boys with pure CD during interference inhibition and attention allocation

Inhibitory and attention deficits have been suggested to be shared problems of disruptive behaviour disorders. Patients with attention deficit hyperactivity disorder (ADHD) and patients with conduct disorder (CD) show deficits in tasks of attention allocation and interference inhibition. However, functional magnetic resonance imaging (fMRI) of inhibitory and attention control has only been investigated in patients with ADHD, including comorbidity with CD, finding fronto-striatal and temporo-parietal dysfunction. This study investigates differences and commonalities in functional neural networks mediating interference inhibition and attention allocation between medication-naïve children and adolescents with pure CD and those with pure ADHD. Event-related fMRI was used to compare brain activation of 13 boys with non-comorbid CD, 20 boys with non-comorbid ADHD and 20 healthy comparison boys during a Simon task that measures interference inhibition and controls for attention allocation, thus tapping into interference inhibition and selective attention networks. During interference inhibition, both patient groups shared reduced activation compared to controls in right superior temporal lobe and in predominantly right precuneus. During the oddball condition, both patient groups showed reduced activation compared to healthy control children in right medial prefrontal lobe. However, only ADHD patients showed a disorder-specific under-activation compared to the other two groups in an extensive activation cluster in left inferior prefrontal cortex. This study shows shared dysfunction in both patients groups in right hemispheric temporal and parietal brain regions during interference inhibition and in right dorsolateral prefrontal cortex during attention allocation. Ventrolateral prefrontal dysfunction, however, was specific to ADHD and not observed in patients with CD in the context of attention allocation. The findings suggest that the typically reduced functional activation in patients with ADHD in ventrolateral prefrontal cortex may be specific to the disorder, at least when compared to patients with CD.

Abnormal spatiotemporal processing of emotional facial expressions in childhood autism: dipole source analysis of event‐related potentials

Previous studies of face processing in autism suggest abnormalities in anatomical development, functioning and connectivity/coordination of distributed brain systems involved in social cognition, but the spatial sequence and time course of rapid (sub-second) neural responses to emotional facial expressions have not been examined in detail. Source analysis of high-density event-related potentials (ERPs) is an optimal means to examine both the precise temporal profile and spatial location of early electrical brain activity in response to emotionally salient stimuli. Therefore, we recorded 128-channel ERPs from high-functioning males with autism (aged 6-10 years), and age-, sex- and IQ-matched typically developing controls during explicit and implicit processing of emotion from pictures showing happy, angry, fearful, sad and neutral facial expressions. Children with autism showed normal patterns of behavioural and ERP (P1, N170 and P2) responses. However, dipole source analysis revealed that ERP responses relating to face detection (visual cortex) and configural processing of faces (fusiform gyrus), as well as mental state decoding (medial prefrontal lobe), were significantly weaker and/or slower in autism compared with controls during both explicit and implicit emotion-processing tasks. Slower- and larger-amplitude ERP source activity in the parietal somatosensory cortices possibly reflected more effortful compensatory analytical strategies used by the autism group to process facial gender and emotion. Such aberrant neurophysiological processing of facial emotion observed in children with autism within the first 300 ms of stimulus presentation suggests abnormal cortical specialization within social brain networks, which would likely disrupt the development of normal social-cognitive skills.

Change of cerebral metabolism rate of glucose of cerebral white matter in Alzheimer's disease: a study with statistical parametric mapping software

To study the change of cerebral metabolism rate of glucose (CMRglc) of cerebral white matter in Alzheimer's Disease. Positron emission tomography (PET) was performed on 13 AD patients, 6 with behavioral and psychological symptoms of dementia (BPSD) and 7 without BPSD, and 10 healthy controls. The regional cerebral metabolism of glucose (rCMRglc) of some brain regions and nuclei were detected. (1) The rCMRglc of the cerebral white matter decreased extensively in the AD patients, especially in the right frontal lobe, superior gyrus of the left frontal lobe (P = 0.001). (2) The rCMRglc of subcortical white matter of the left medial prefrontal lobe and the left cuneus of occipital lobe increased in the AD patients. (3) The levels of rCMRglc of the subcortical white matter of both side middle occipital lobe, left cuneus of occipital lobe, right inferior parietal lobule, left fusiform gyrus of temporal lobe and the left medial prefrontal lobe were all significantly higher in the AD patients with BPSD than in those without BPSD (P = 0.001). While the levels of rCMRglc of the subcortical white matter of both side paracentral lobule, right superior and middle frontal lobe, and left superior temporal lobe were all significantly lower in the AD patients with BPSD than in those without BPSD (all P = 0.001). There is diffuse abnormal rCMRglc in the cerebral white matter in the AD patients: the rCMRglc decreases in the frontal-temporal-occipital association area, and the rCMRglc of the medial prefrontal lobe and cuneus of occipital lobe increases. BPSD is correlated with the abnormal metabolism of related cerebral regions.

Measurement of GABA and contaminants in gray and white matter in human brain in vivo

A preliminary study of discrimination between GABA and macromolecules (MMs) in human brain by proton double quantum filtering (DQF) at 3.0 T in vivo is presented. GABA-tuned and MM-tuned DQ filters were designed with dual-band 180 degrees radiofrequency (RF) pulses that were tuned for selective refocusing of GABA (3.0 and 1.9 ppm) and putative MM resonances (3.0 and 1.7 ppm), respectively. GABA and putative MM signals were extracted from a combined analysis of the filtered mixture signals and the calculated editing yields. Unexpectedly, the GABA and putative MM signals exhibited a similar doublet linewidth at the optimized TE = 82 ms. Furthermore, substantial MM-tuned DQF signal remained at TE = 148 ms, indicating the presence of a component other than MM. With water segmentation data, the GABA-tuned and MM-tuned DQF measures from the medial prefrontal and left frontal lobes were combined to give the concentrations of GABA and the additional component as 1.1 +/- 0.1 and 0.8 +/- 0.1 mM (mean +/- SD, N=3) for gray matter (GM) and 0.4 +/- 0.1 and 0.7+/-0.1 mM (N=3) for white matter (WM), respectively.

Neuroimaging and emerging psychotic disorders: The Melbourne ultra-high risk studies

Although the underlying neurobiology of emerging psychotic disorders is not well understood, evidence from structural imaging and other studies support the notion that schizophrenia arises as a consequence of both an ‘early neurodevelopmental’ disturbance, as well as ‘late neurodevelopmental’ changes occurring during the initial stages of a psychotic illness, including around the time of transition to illness. In line with this, our longitudinal MRI findings in individuals at ultra-high risk for developing a psychotic illness show that there are excessive neuroanatomical changes in those who convert to psychosis. These aberrant changes are observed most prominently in medial temporal and prefrontal lobe regions. In a further series of longitudinal studies in first-episode psychosis, we have identified changes in prefrontal regions that indicate an accelerated loss of grey matter in patients compared to healthy control subjects. We suggest that the available evidence is consistent with the presence of subtle regionally and temporally specific neurobiological changes through the course of psychosis (Pantelis et al., ), including: (1) evidence for early (pre- and peri-natal) neurodevelopmental anomalies, (2) evidence for progressive grey matter loss involving medial temporal and orbital prefrontal regions around the time of transition to illness, and (3) evidence of late (post-pubertal) neurodevelopmental changes soon after the onset of psychosis, involving an acceleration of normal brain maturational processes, associated with significant loss of grey matter in dorsal prefrontal regions. The pathological processes underlying such changes remain unclear and may reflect anomalies in genetic and/or other endogenous mechanisms responsible for brain maturation, the adverse effects of intense or prolonged stress, or other environmental factors. These findings suggest that early markers of impending illness may prove difficult to define, and that brain changes in psychosis may better be conceptualized as anomalous trajectories of brain development. Further, active changes during transition to illness may present the potential to intervene and ameliorate these changes with potential benefit clinically.

Deficit of social cognition in subjects with surgically treated frontal lobe lesions and in subjects affected by schizophrenia.

The ability of humans to predict and explain other people’s behaviour by attributing independent mental states such as desires and beliefs to them, is considered to be due to our ability to construct a “Theory of Mind”. Recently, several neuroimaging studies have implicated the medial frontal lobes as playing a critical role in a dedicated “mentalizing” or “Theory of Mind” network in the human brain. In this study we compare the performance of patients with right and left medial prefrontal lobe lesions in theory of mind and in social cognition tasks, with the performance of people with schizophrenia.We report a similar social cognitive profile between patients with prefrontal lobe lesions and schizophrenic subjects in terms of understanding of false beliefs, in understanding social situations and in using tactical strategies. These findings are relevant for the functional anatomy of “Theory of Mind”.

Differential cerebral activation during observation of expressive gestures and motor acts

We compared brain activation involved in the observation of isolated right hand movements (e.g. twisting a lid), body-referred movements (e.g. brushing teeth) and expressive gestures (e.g. threatening) in 20 healthy subjects by using functional magnetic resonance imaging (fMRI). Perception-related areas in the occipital and inferior temporal lobe but also the mirror neuron system in the lateral frontal (ventral premotor cortex and BA 44) and superior parietal lobe were active during all three conditions. Observation of body-referred compared to common hand actions induced increased activity in the bilateral posterior superior temporal sulcus (STS), the left temporo-parietal lobe and left BA 45. Expressive gestures involved additional areas related to social perception (bilateral STS, temporal poles, medial prefrontal lobe), emotional processing (bilateral amygdala, bilateral ventrolateral prefrontal cortex (VLPFC), speech and language processing (Broca's and Wernicke's areas) and the pre-supplementary motor area (pre-SMA). In comparison to body-referred actions, expressive gestures evoked additional activity only in the left VLPFC (BA 47). The valence-ratings for expressive gestures correlated significantly with activation intensity in the VLPFC during expressive gesture observation. Valence-ratings for negative expressive gestures correlated with right STS-activity. Our data suggest that both, the VLPFC and the STS are coding for differential emotional valence during the observation of expressive gestures.

Sleep-dependent motor memory plasticity in the human brain

Growing evidence indicates a role for sleep in off-line memory processing, specifically in post-training consolidation. In humans, sleep has been shown to trigger overnight learning on a motor-sequence memory task, while equivalent waking periods produce no such improvement. But while the behavioral characteristics of sleep-dependent motor learning become increasingly well characterized, the underlying neural basis remains unknown. Here we present functional magnetic resonance imaging data demonstrating a change in the representation of a motor memory after a night of sleep. Subjects trained on a motor-skill memory and 12 hours later, after either sleep or wake, were retested during functional magnetic resonance imaging. Following sleep relative to wake, regions of increased activation were expressed in the right primary motor cortex, medial prefrontal lobe, hippocampus and left cerebellum; changes that can support faster motor output and more precise mapping of key-press movements. In contrast, signal decreases were identified in parietal cortices, the left insular cortex, temporal pole and fronto-polar region, reflecting a reduced need for conscious spatial monitoring and a decreased emotional task burden. This evidence of an overnight, systems-level change in the representation of a motor memory holds important implications for acquiring real-life skills and in clinical rehabilitation following brain trauma, such as stroke.

Medial temporal and prefrontal lobe activation during verbal encoding following glucose ingestion in schizophrenia: A pilot fMRI study

Verbal declarative memory is one of the most reliably impaired cognitive functions in schizophrenia. Important issues are whether the problem is reversible, and which brain regions underlie improvement. We showed previously that glucose administration improved declarative memory in patients with schizophrenia, and sought in this pilot study to identify whether glucose affects the location or degree of activation of brain regions involved in a verbal encoding task. Seven clinically stable and medicated patients with schizophrenia or schizoaffective disorder, who showed deficits on a clinical test of memory, participated in the study. Subjects served as their own controls in a double-blind, crossover protocol that consisted of two sessions about a week apart. In each session, subjects ingested a beverage flavored with lemonade that contained 50 g of glucose on one occasion, and saccharin on the other. Blood glucose was measured before and 15, 50, and 75 min after ingestion. After ingesting the beverage, they performed a verbal encoding task while undergoing brain functional magnetic resonance imaging. The results showed significantly greater activation of the left parahippocampus during novel sentence encoding in the glucose condition, compared to the saccharin condition, despite no change in memory performance. A trend towards greater activation of the left dorsolateral prefrontal cortex ( p < .07) was also evident in the glucose condition. These pilot findings emphasize the sensitivity of both the medial temporal and prefrontal regions to effects of glucose administration during encoding, and are consistent with the hypothesis that these regions also participate in declarative memory improvements following glucose administration.

Ethical and clinical implications of liver transplantation in patients on methadone maintenance therapy

Child abuse exerts a deleterious impact on a broad array of mental health outcomes. However, the neurobiological mechanisms that mediate this association remain poorly characterized. Here, we use a longitudinal design to prospectively identify neural mediators of the association between child abuse and psychiatric disorders in a community sample of adolescents.Structural magnetic resonance imaging (MRI) data and assessments of mental health were acquired for 51 adolescents (aged 13-20; M=16.96; SD=1.51), 19 of whom were exposed to physical or sexual abuse. Participants were assessed for abuse exposure (time 1), participated in MRI scanning and a diagnostic structured interview (time 2), and 2 years later were followed-up to assess psychopathology (time 3). We examined associations between child abuse and neural structure, and identified whether abuse-related differences in neural structure prospectively predicted psychiatric symptoms.Abuse was associated with reduced cortical thickness in medial and lateral prefrontal and temporal lobe regions. Thickness of the left and right parahippocampal gyrus predicted antisocial behavior symptoms, and thickness of the middle temporal gyrus predicted symptoms of generalized anxiety disorder. Thickness of the left parahippocampal gyrus mediated the longitudinal association of abuse with antisocial behavior.Child abuse is associated with widespread disruptions in cortical structure, and these disruptions are selectively associated with increased vulnerability to internalizing and externalizing psychopathology. Identifying predictive biomarkers of vulnerability following childhood maltreatment may uncover neurodevelopmental mechanisms linking environmental experience with the onset of psychopathology.

Neural Activity Relating to Generation and Representation of Galvanic Skin Conductance Responses: A Functional Magnetic Resonance Imaging Study

Central feedback of peripheral states of arousal influences motivational behavior and decision making. The sympathetic skin conductance response (SCR) is one index of autonomic arousal. The precise functional neuroanatomy underlying generation and representation of SCR during motivational behavior is undetermined, although it is impaired by discrete brain lesions to ventromedial prefrontal cortex, anterior cingulate, and parietal lobe. We used functional magnetic resonance imaging to study brain activity associated with spontaneous fluctuations in amplitude of SCR, and activity corresponding to generation and afferent representation of discrete SCR events. Regions that covaried with increased SCR included right orbitofrontal cortex, right anterior insula, left lingual gyrus, right fusiform gyrus, and left cerebellum. At a less stringent level of significance, predicted areas in bilateral medial prefrontal cortex and right inferior parietal lobule covaried with SCR. Generation of discrete SCR events was associated with significant activity in left medial prefrontal cortex, bilateral extrastriate visual cortices, and cerebellum. Activity in right medial prefrontal cortex related to afferent representation of SCR events. Activity in bilateral medial prefrontal lobe, right orbitofrontal cortex, and bilateral extrastriate visual cortices was common to both generation and afferent representation of discrete SCR events identified in a conjunction analysis. Our results suggest that areas implicated in emotion and attention are differentially involved in generation and representation of peripheral SCR responses. We propose that this functional arrangement enables integration of adaptive bodily responses with ongoing emotional and attentional states of the organism.