Network analysis reveals a role of the hippocampus in absence seizures: The effects of a cannabinoid agonist.

The role of the hippocampus (Hp) in absence epileptic networks and the effect of endocannabinoid system on this network remain enigmatic. Here, using adapted nonlinear Granger causality, we compared the differences in network strength in four intervals (baseline or interictal, preictal, ictal and postictal) in two hours before (Epoch 1) and six hours (epochs 2, 3 and 4) after the administration of three different doses of the endocannabinoid agonist WIN55,212-2 (WIN) or solvent. Local field potentials were recorded for eight hours in 23 WAG/Rij rats in the Frontal (FC), Parietal PC), Occipital Cortex (OC) and in the hippocampus (Hp).

The interaction between pain and cognition: on the roles of task complexity and pain intensity.

Objectives: The interaction between pain and cognition includes a concurrent negative effect of pain on cognitive performance and an analgesic effect of cognitive distraction on pain experience. The purpose of this exploratory study was to investigate the role of pain intensity and task complexity on this interaction.

Methods: Two experiments were conducted in healthy volunteers.

Lateralized EEG mu power during action observation and motor imagery in typically developing children and children with unilateral Cerebral Palsy.

Objective: During motor execution (ME), mu power is diminished over the contralateral hemisphere and increased over the ipsilateral hemisphere, which has been associated with cortical activation of the contralateral motor areas and inhibition of the ipsilateral motor areas respectively. The influence of action observation (AO) and motor imagery (MI) on mu power is less clear, especially in children, and remains to be studied in children with unilateral cerebral palsy (uCP).

Methods: We determined mu power during ME, AO, and MI of 45 typically developing (TD) children and 15 children with uCP over both hemispheres, for each hand.

Immediate versus late effects of vigabatrin on spike and wave discharges.

Vigabatrin increases GABA concentrations by inhibiting GABA transaminase. In previous studies, it was shown that vigabatrin increases the incidence of Spike and Wave Discharges (SWD) in the WAG/Rij rat model for absence epilepsy. Since following a single dose of vigabatrin GABA concentrations are known to be increased for several days, the present study sheds light on how the previously described changes in SWD characteristics develop over a longer time frame.

Altered SWD stopping mechanism in WAG/Rij rats subchronically treated with the cannabinoid agonist R(+)WIN55,212-2.

A single injection of the cannabinoid agonist R(+)WIN55,212-2 (WIN) is known to cause an increase of the mean duration of spontaneously occurring spike-and-wave discharges (SWDs) in rats of the WAG/Rij strain, a genetic model for absence epilepsy. The aim of the present study was to establish whether repeated activation of CB receptors with WIN leads to tolerance in its effect on SWD parameters, spectral density, and behavior over time. Adult male WAG/Rij rats (n = 16) were treated with WIN (6 mg/kg) or vehicle (olive oil).

Placebo analgesia induced by verbal suggestion in the context of experimentally induced fear and anxiety.

The role of state anxiety and state fear in placebo effects is still to be determined. We aimed to investigate the effect of fear of movement-related pain (FMRP) and contextual pain related anxiety (CPRA) on the magnitude of placebo analgesia induced by verbal suggestion. Fifty-six female participants completed a modified voluntary joystick movement paradigm (VJMP) where half participated in a predictable pain condition (PC), in which one of the joystick movements is always followed by pain and the other movement is never followed by pain, and half in an unpredictable pain condition (UC), in which pain was delivered unpredictably.

Neonatal exposure to AY-9944 increases typical spike and wave discharges in WAG/Rij and Wistar rats.

Absence-epileptic seizures appear in the EEG as Spike and Wave Discharges (SWDs). Typical SWDs develop spontaneously in WAG/Rij rats, an inbred Wistar strain. Atypical SWDs however were reported in studies in which the cholesterol synthesis inhibitor AY-9944 was administered to neonatal Wistar rats, causing absence-like seizures later in life.

Effective Connectivity of Beta Oscillations in Endometriosis-Related Chronic Pain During rest and Pain-Related Mental Imagery.

Using the EEG recordings of patients with endometriosis-related chronic pelvic pain, we have examined the effective connectivity within the cortical pain-related network during rest and during pain-related imagery. During rest, an altered connectivity was hypothesized between cortical somatosensory pain areas and regions involved in emotional and cognitive modulation of pain. During pain-related imagery, alterations in prefrontal-temporal connectivity were expected.

Pain catastrophizing is associated with altered EEG effective connectivity during pain‑related mental imagery.

Pain catastrophizing - defined as a tendency to exaggerate the threat value or seriousness of experienced pain ‑ has been shown to be a risk factor for pain chronification. However, the neural basis of pain catastrophizing remains unclear and requires thorough investigation. This study aimed to explore the relationship between pain catastrophizing and effective connectivity of the pain systems in healthy participants.

Pain Processing in a Social Context and the Link with Psychopathic Personality Traits-An Event-Related Potential Study.

Empathy describes the ability to understand another person's feelings. Psychopathy is a disorder that is characterized by a lack of empathy. Therefore, empathy and psychopathy are interesting traits to investigate with respect to experiencing and observing pain.

Influence of transient spatial attention on the P3 component and perception of painful and non-painful electric stimuli in crossed and uncrossed hands positions.

Recent reports show that focusing attention on the location where pain is expected can enhance its perception. Moreover, crossing the hands over the body's midline is known to impair the ability to localise stimuli and decrease tactile and pain sensations in healthy participants. The present study investigated the role of transient spatial attention on the perception of painful and non-painful electrical stimuli in conditions in which a match or a mismatch was induced between skin-based and external frames of reference (uncrossed and crossed hands positions, respectively).

Evidence for a Priori Existence of Attentional Bias Subgroups in Emotional Processing of Aversive Stimuli.

Little is known regarding inter-individual differences in attentional biases for pain-related information; more knowledge is crucial, since these biases have been associated with differences in pain processing as well as in predicting the risk of postoperative pain. The present study investigated EEG correlates of attentional bias patterns for pain-related information, with specific focus on avoidance- and vigilance-like behavior. Forty-one participants performed a dot-probe task, where neutral and pain-related words were used to create neutral, congruent, incongruent, and double (two pain-related words) trials.

Cannabinoid antagonist SLV326 induces convulsive seizures and changes in the interictal EEG in rats.

Cannabinoid CB1 antagonists have been investigated for possible treatment of e.g. obesity-related disorders.

The cannabinoid receptor agonist WIN55.212 reduces consequences of status epilepticus in rats.

An acute brain insult can cause a spectrum of primary and secondary pathologies including increased risk for epilepsy, mortality and neurodegeneration. The endocannabinoid system, involved in protecting the brain against network hyperexcitability and excitotoxicity, is profoundly dysregulated by acute brain insults. We hypothesize that post-insult dysregulation of the endocannabinoid signaling may contribute to deleterious effects of an acute brain injury and potentiation of endocannabinoid transmission soon after an insult may reduce its pathological outcomes.

Changes in corticocortical and corticohippocampal network during absence seizures in WAG/Rij rats revealed with time varying Granger causality.

Purpose: Spike-and-wave discharges (SWDs) recorded in the cortical EEGs of WAG/Rij rats are the hallmark for absence epilepsy in this model. Although this type of epilepsy was long regarded as a form of primary generalized epilepsy, it is now recognized that there is an initiation zone - the perioral region of the somatosensory cortex. However, networks involved in spreading the seizure are not yet fully known.

Depressive rumination and the emotional control circuit: An EEG localization and effective connectivity study.

Ruminations are repetitive thoughts associated with symptoms, causes, and consequences of one's negative feelings. The objective of this study was to explore the neuronal basis of depressive rumination in a non-clinical population within the context of emotional control. Participants scoring high or low on the tendency to ruminate scale took part in the EEG experiment.

The anti-absence effect of mGlu5 receptor amplification with VU0360172 is maintained during and after antiepileptogenesis.

Purpose: Ethosuximide (ETX) is the drug of choice for the treatment of patients with absence seizures - taking into account both its efficacy, tolerability and antiepileptogenic properties. However, 47% of subjects failed in ETX-therapy, and most antiepileptic drugs have cognitive side effects. VU0360172, a positive allosteric modulator (PAM) of mGluR5, has been proposed as a new anti-absence drug.

Unilateral and Bilateral Cortical Resection: Effects on Spike-Wave Discharges in a Genetic Absence Epilepsy Model.

Research Question: Recent discoveries have challenged the traditional view that the thalamus is the primary source driving spike-and-wave discharges (SWDs). At odds, SWDs in genetic absence models have a cortical focal origin in the deep layers of the perioral region of the somatosensory cortex. The present study examines the effect of unilateral and bilateral surgical resection of the assumed focal cortical region on the occurrence of SWDs in anesthetized WAG/Rij rats, a well described and validated genetic absence model.

Long-term disease-modifying effect of the endocannabinoid agonist WIN55,212-2 in a rat model of audiogenic epilepsy.

Background: Modulation of the endocannabinoid (eCB) transmission is a promising approach to treating epilepsy. Animal models can be used to investigate this approach. Krushinsky-Molodkina (KM) rats have, genetically, audiogenic epilepsy.

Altered resting state EEG in chronic pancreatitis patients: toward a marker for chronic pain.

Objectives: Electroencephalography (EEG) may be a promising source of physiological biomarkers accompanying chronic pain. Several studies in patients with chronic neuropathic pain have reported alterations in central pain processing, manifested as slowed EEG rhythmicity and increased EEG power in the brain's resting state. We aimed to investigate novel potential markers of chronic pain in the resting state EEG of patients with chronic pancreatitis.

Altered cortical responsiveness to pain stimuli after high frequency electrical stimulation of the skin in patients with persistent pain after inguinal hernia repair.

Background: High Frequency electrical Stimulation (HFS) of the skin induces enhanced brain responsiveness expressed as enhanced Event-Related Potential (ERP) N1 amplitude to stimuli applied to the surrounding unconditioned skin in healthy volunteers. The aim of the present study was to investigate whether this enhanced ERP N1 amplitude could be a potential marker for altered cortical sensory processing in patients with persistent pain after surgery.

Materials And Methods: Nineteen male patients; 9 with and 10 without persistent pain after inguinal hernia repair received HFS.

Patients with persistent pain after breast cancer treatment show enhanced alpha activity in spontaneous EEG.

Objective: The aim of the present study was to investigate whether patients with persistent pain after breast cancer treatment show an enhanced and slowed dominant alpha activity in their electroencephalogram (EEG) recorded during rest in comparison with patients that also had undergone breast cancer treatment but do not have pain.

Methods: The spontaneous EEG was recorded during rest and before painful stimulation of the calf and analyzed with spectral analysis (Fast Fourier Transformation). Outcome measures, i.