Multivariate pattern classification of brain white matter connectivity predicts classic trigeminal neuralgia.

Trigeminal neuralgia (TN) is a severe form of chronic facial neuropathic pain. Increasing interest in the neuroimaging of pain has highlighted changes in the root entry zone in TN, but also group-level central nervous system gray and white matter (WM) abnormalities. Group differences in neuroimaging data are frequently evaluated with univariate statistics; however, this approach is limited because it is based on single, or clusters of, voxels.

Affective Circuitry Alterations in Patients with Trigeminal Neuralgia.

Trigeminal neuralgia (TN) is a severe chronic neuropathic facial pain disorder. Affect-related behavioral and structural brain changes have been noted across chronic pain disorders, but have not been well-studied in TN. We examined the potential impact of TN (37 patients: 23 with right-sided TN, 14 with left-sided TN), compared to age- and sex-matched healthy controls, on three major white matter tracts responsible for carrying affect-related signals-i.

Negative childhood experiences alter a prefrontal-insular-motor cortical network in healthy adults: A preliminary multimodal rsfMRI-fMRI-MRS-dMRI study.

Research in humans and animals has shown that negative childhood experiences (NCE) can have long-term effects on the structure and function of the brain. Alterations have been noted in grey and white matter, in the brain's resting state, on the glutamatergic system, and on neural and behavioural responses to aversive stimuli. These effects can be linked to psychiatric disorder such as depression and anxiety disorders that are influenced by excessive exposure to early life stressors.

Subcallosal Cingulate Connectivity in Anorexia Nervosa Patients Differs From Healthy Controls: A Multi-tensor Tractography Study.

Background: Anorexia nervosa is characterized by extreme low body weight and alterations in affective processing. The subcallosal cingulate regulates affect through wide-spread white matter connections and is implicated in the pathophysiology of anorexia nervosa.

Objectives: We examined whether those with treatment refractory anorexia nervosa undergoing deep brain stimulation (DBS) of the subcallosal white matter (SCC) show: (1) altered anatomical SCC connectivity compared to healthy controls, (2) white matter microstructural changes, and (3) microstructural changes associated with clinically-measured affect.

A Neuroimaging Strategy for the Three-Dimensional in vivo Anatomical Visualization and Characterization of Insular Gyri.

Background: Interest in the anatomy of the insula is driven by its multifunctionality and the need for accurate visualization for surgical purposes. Few in vivo studies of human insular anatomy have been conducted due to methodological and anatomical challenges.

Objective: We used brain cortical morphometry tools to accurately reconstruct insular topology and permit a detailed visualization of its gyri in 3 dimensions.

Age-related changes in diffusion tensor imaging metrics of fornix subregions in healthy humans.

Objective: White matter diffusivity measures of the fornix change with aging, which likely relates to changes in memory and cognition in older adults. Subregional variations in forniceal diffusivity may exist, given its heterogeneous anatomy and connectivity; however, these have not been closely examined in vivo. We examined diffusivity parameters (fractional anisotropy, FA; radial diffusivity, RD; axial diffusivity, AD) in forniceal subregions of healthy subjects and correlated them with age and hippocampal volume.

A comparison of neural responses to appetitive and aversive stimuli in humans and other mammals.

Distinguishing potentially harmful or beneficial stimuli is necessary for the self-preservation and well-being of all organisms. This assessment requires the ongoing valuation of environmental stimuli. Despite much work on the processing of aversive- and appetitive-related brain signals, it is not clear to what degree these two processes interact across the brain.

Brain γ-aminobutyric acid: a neglected role in impulsivity.

The investigation of impulsivity as a core marker of several major neuropsychiatric disorders has been greatly influenced by the therapeutic efficacy of drugs that block the reuptake of dopamine and noradrenaline in the brain. As a result, research into the neural mechanisms of impulsivity has focused on the catecholamine systems as the loci responsible for the expression of impulsive behaviour and the primary mechanism of action of clinically effective drugs for attention-deficit hyperactivity disorder (ADHD). However, abnormalities in the catecholamine systems alone are unlikely to account for the full diversity and complexity of impulsivity subtypes, nor can they fully explain co-morbid brain disorders such as drug addiction.

GABA in the insula - a predictor of the neural response to interoceptive awareness.

The insula has been identified as a key region involved in interoceptive awareness. Whilst imaging studies have investigated the neural activation patterns in this region involved in intero- and exteroceptive awareness, the underlying biochemical mechanisms still remain unclear. In order to investigate these, a well-established fMRI task targeting interoceptive awareness (heartbeat counting) and exteroceptive awareness (tone counting) was combined with magnetic resonance spectroscopy (MRS).

Glutamate concentration in the medial prefrontal cortex predicts resting-state cortical-subcortical functional connectivity in humans.

Communication between cortical and subcortical regions is integral to a wide range of psychological processes and has been implicated in a number of psychiatric conditions. Studies in animals have provided insight into the biochemical and connectivity processes underlying such communication. However, to date no experiments that link these factors in humans in vivo have been carried out.

GABAA receptors predict aversion-related brain responses: an fMRI-PET investigation in healthy humans.

The perception of aversive stimuli is essential for human survival and depends largely on environmental context. Although aversive brain processing has been shown to involve the sensorimotor cortex, the neural and biochemical mechanisms underlying the interaction between two independent aversive cues are unclear. Based on previous work indicating ventromedial prefrontal cortex (vmPFC) involvement in the mediation of context-dependent emotional effects, we hypothesized a central role for the vmPFC in modulating sensorimotor cortex activity using a GABAergic mechanism during an aversive-aversive stimulus interaction.

GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation.

Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations.

External awareness and GABA--a multimodal imaging study combining fMRI and [18F]flumazenil-PET.

Awareness is an essential feature of the human mind that can be directed internally, that is, toward our self, or externally, that is, toward the environment. The combination of internal and external information is crucial to constitute our sense of self. Although the underlying neuronal networks, the so-called intrinsic and extrinsic systems, have been well-defined, the associated biochemical mechanisms still remain unclear.

Common brain activations for painful and non-painful aversive stimuli.

Background: Identification of potentially harmful stimuli is necessary for the well-being and self-preservation of all organisms. However, the neural substrates involved in the processing of aversive stimuli are not well understood. For instance, painful and non-painful aversive stimuli are largely thought to activate different neural networks.

Identifying a network of brain regions involved in aversion-related processing: a cross-species translational investigation.

The ability to detect and respond appropriately to aversive stimuli is essential for all organisms, from fruit flies to humans. This suggests the existence of a core neural network which mediates aversion-related processing. Human imaging studies on aversion have highlighted the involvement of various cortical regions, such as the prefrontal cortex, while animal studies have focused largely on subcortical regions like the periaqueductal gray and hypothalamus.

5-HT receptors and reward-related behaviour: a review.

The brain's serotonin (5-HT) system is key in the regulation of reward-related behaviours, from eating and drinking to sexual activity. The complexity of studying this system is due, in part, to the fact that 5-HT acts at many receptor subtypes throughout the brain. The recent development of drugs with greater selectivity for individual receptor subtypes has allowed for rapid advancements in our understanding of this system.

Is our self nothing but reward?

Neuroscience has increasingly explored the neural mechanisms underlying our sense of self. Recent studies have demonstrated the recruitment of regions like the ventral tegmental area, ventromedial prefrontal cortex, and the ventral striatum to self-specific stimuli-regions typically associated with reward-related processing. This raises the question of whether there is a relationship between self and reward and, if so, how these different fields can be linked.

The role of nucleus accumbens shell GABA receptors on ventral tegmental area intracranial self-stimulation and a potential role for the 5-HT(2C) receptor.

Brain γ-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT)(2C) receptors are implicated in the neuronal regulation of reward- and aversion-related behaviour. Within the mesocorticolimbic pathways of the brain, relationships between GABA containing neurons and 5-HT(2C) receptor activity may be important in this context. The primary aim of this study was to investigate the role of NAc shell GABA receptors on ventral tegmental area intracranial self-stimulation (ICSS) and to examine the systemic effects of GABAergic ligands in this context.

The brain and its resting state activity--experimental and methodological implications.

Despite all the recent progress in neuroscience, we still do not understand the basic principles according to which the brain functions. This may be due, at least in part, to our lack of knowledge how the brain's intrinsic activity, the brain's input, impacts stimulus-induced changes in the brain. We here discuss the neuronal, experimental and methodological relevance of the brain's resting state activity for future studies.

Is subcortical-cortical midline activity in depression mediated by glutamate and GABA? A cross-species translational approach.

Major depressive disorder has recently been characterized by abnormal resting state hyperactivity in anterior midline regions. The neurochemical mechanisms underlying resting state hyperactivity remain unclear. Since animal studies provide an opportunity to investigate subcortical regions and neurochemical mechanisms in more detail, we used a cross-species translational approach comparing a meta-analysis of human data to animal data on the functional anatomy and neurochemical modulation of resting state activity in depression.

Effects of systemic 5-HT(1B) receptor compounds on ventral tegmental area intracranial self-stimulation thresholds in rats.

Serotonin 1B (5-HT(1B)) receptors may play a role in regulating motivation and reward-related behaviours. To date, no studies have investigated the effects of the highly selective 5-HT(1B) receptor agonist CP 94253, on the reward model of ventral tegmental area intracranial self-stimulation. The current study investigated the hypothesis that 5-HT(1B) receptors play an inhibitory role in ventral tegmental area ICSS.

Effects of systemic and intra-nucleus accumbens 5-HT2C receptor compounds on ventral tegmental area self-stimulation thresholds in rats.

Rationale: Serotonin 2C (5-HT(2C)) receptors may play a role in regulating motivation and reward-related behaviours. To date, no studies have investigated the possible role of 5-HT(2C) receptors in ventral tegmental area (VTA) intracranial self-stimulation (ICSS).

Objectives: The current study investigated the hypotheses that 5-HT(2C) receptors play an inhibitory role in VTA ICSS, and that 5-HT(2C) receptors within the nucleus accumbens (NAc) shell may be involved.