Network analysis of preictal iEEG reveals changes in network structure preceding seizure onset.

Seizures likely result from aberrant network activity and synchronization. Changes in brain network connectivity may underlie seizure onset. We used a novel method of rapid network model estimation from intracranial electroencephalography (iEEG) data to characterize pre-ictal changes in network structure prior to seizure onset. We analyzed iEEG data from 20 patients from the iEEG.org database. Using 10 s epochs sliding by 1 s intervals, a multiple input, single output (MISO) state space model was estimated for each output channel and time point with all other channels as inputs, generating sequential directed network graphs of channel connectivity. These networks were assessed using degree and betweenness centrality. Both degree and betweenness increased at seizure onset zone (SOZ) channels 37.0 ± 2.8 s before seizure onset. Degree rose in all channels 8.2 ± 2.2 s prior to seizure onset, with increasing connections between the SOZ and surrounding channels. Interictal networks showed low and stable connectivity. A novel MISO model-based network estimation method identified changes in brain network structure just prior to seizure onset. Increased connectivity was initially isolated within the SOZ and spread to non-SOZ channels before electrographic seizure onset. Such models could help confirm localization of SOZ regions.

Anhedonia and anergia predict mortality in older Australians living in residential aged care.

OBJECTIVES: Depression is common in older adults and is linked to morbidity and mortality. The aim of this study was to investigate whether specific symptoms of depression (dysphoria, anhedonia and anergia) predicted mortality in older Australian Aged Care residents. METHODS: Eighty older adults (M = 83.16 ± 7.14) without cognitive impairment residing in 14 Residential Aged Care facilities located in Melbourne, Australia, completed the 15-item Geriatric Depression Scale-Short Form (GDS-15) and the Standardized Mini Mental State Examination. Residential Aged Care facilities provided the primary end-point of all-cause mortality at follow-up (M = 5.4 years ± 0.1). RESULTS: Univariate Kaplan-Meier survival curves and Cox Proportional Hazards regression analyses were used to evaluate whether symptoms of depression predicted all-cause mortality, with known prognostic factors controlled. The results indicated that anhedonia (Hazard Ratio = 2.931 [95% CI 1.278-6.722], p = .011) and anergia (Hazard Ratio = 2.783 [95% CI 1.065-7.276], p = .037) were associated with almost a threefold increased risk of mortality in older adults living in RAC in adjusted analyses. Dysphoria did not predict mortality. CONCLUSIONS: These findings advance understanding of the mortality risks of anhedonia and anergia in an understudied population. Symptoms of anhedonia and anergia should be targeted for screening in older adults living in Aged Care to increase the detection and potential for referral to treatment for depressive presentation.

Farmer and Public Attitudes Toward Lamb Finishing Systems.

To develop research and policy on the welfare of lambs in intensive finishing systems, it is important to understand public and sheep farmers' attitudes. The aim of this research was to identify and compare farmer and community attitudes relevant to the intensification of lamb finishing. The majority of respondents in the community sample expressed concern about all listed welfare issues, but particularly about feedlotting of lambs and the associated confinement. These attitudes correlated with community views on the importance of welfare issues including social contact and freedom to roam. Farmers expressed much lower levels of concern than did the general public except with regard to the health of lambs, disease control, access to shade, and lack of access to clean water.

Telemedicine Interest for Routine Follow-Up Care Among Neurology Patients in Arkansas.

BACKGROUND: Teleneurology in Arkansas has been used primarily for management of acute stroke with a state-funded hub-and-spoke model allowing physicians at rural hospitals to access vascular neurologists in time to facilitate tissue plasminogen activator administration. Routine neurologic care has been provided only in small pilot studies. We wished to determine patient interest in participating in teleneurology for routine follow-up visits as well as demographic and medical factors associated with interest. MATERIALS AND METHODS: New and established patients of the Neurology Outpatient Clinic at the University of Arkansas for Medical Sciences (UAMS) were surveyed between March 2011 and December 2012 to assess their interest in participating in teleneurology as well as potential factors associated with their interest. RESULTS: Of 1,441 respondents, 52.4% were interested in telemedicine. Of those interested versus uninterested in telemedicine, respectively, 68.9% versus 36.32% traveled more than 1 h to the clinic, 64.7% versus 35.3% had difficulty secondary to neurological conditions, 22.6% versus 6.8% had missed medical appointments due to travel problems, and 43.1% versus 9.4% had travel-imposed financial hardship. CONCLUSIONS: Telemedicine interest for routine follow-up visits was strong among patients at the UAMS Neurology Outpatient Clinic. Factors positively associated with interest included long travel distances, travel expenses, and transportation difficulties. These results suggest that implementing a telemedicine program for follow-up visits would be acceptable to neurology patients for routine ongoing care.

Pilocarpine-induced status epilepticus in mice: A comparison of spectral analysis of electroencephalogram and behavioral grading using the Racine scale.

Pilocarpine-induced status epilepticus (SE) is a widely used seizure model in mice, and the Racine scale has been used to index seizure intensity. The goal of this study was to analyze electroencephalogram (EEG) quantitatively using fast Fourier transformation (FFT) and statistically evaluate the correlation of electrographic seizures with convulsive behaviors. Simultaneous EEG and video recordings in male mice in a mixed genetic background were conducted and pilocarpine was administered intraperitoneally to induce seizures. The videos were graded using the Racine scale and the root-mean-square (RMS) power analysis of EEG was performed with Sirenia Seizure Pro software. We found that the RMS power was very weakly correlated with convulsive behavior induced by pilocarpine. Convulsive behaviors appeared long before electrographic seizures and showed a strong negative correlation with theta frequency activity and a moderate positive correlation with gamma frequency activity. Racine scores showed moderate correlations with RMS power across multiple frequency bands during the transition from first electrographic seizure to SE. However, there was no correlation between Racine scores and RMS power during the SE phase except a weak correlation with RMS power in the theta frequency. Our analysis reveals limitations of the Racine scale as a primary index of seizure intensity in status epilepticus, and demonstrates a need for quantitative analysis of EEG for an accurate assessment of seizure onset and severity.

Ictal asystole in epilepsy patients undergoing inpatient video-EEG monitoring.

Ictal asystole (IA) is uncommonly diagnosed and has been implicated as a potential cause of sudden unexpected death in epilepsy. Sudden unexpected death in epilepsy is an increasingly recognizable condition and is more likely to occur in patients with medically intractable epilepsy and those suffering from convulsive epilepsy. We report 2 cases of recent onset of prolonged syncope and unrevealing cardiac work up. The inpatient video-EEG monitoring recorded left temporal ictal discharges followed by IA. Although the role of cardiac pacing is controversial in these patients, both patients had favorable outcome following cardiac pacemaker insertion. This report demonstrates the variability in IA pathophysiology and clinical manifestations. It also advocates that cardiac pacing might have a role in the management of IA.

Molecular mechanisms of antiseizure drug activity at GABAA receptors.

The GABAA receptor (GABAAR) is a major target of antiseizure drugs (ASDs). A variety of agents that act at GABAARs s are used to terminate or prevent seizures. Many act at distinct receptor sites determined by the subunit composition of the holoreceptor. For the benzodiazepines, barbiturates, and loreclezole, actions at the GABAAR are the primary or only known mechanism of antiseizure action. For topiramate, felbamate, retigabine, losigamone and stiripentol, GABAAR modulation is one of several possible antiseizure mechanisms. Allopregnanolone, a progesterone metabolite that enhances GABAAR function, led to the development of ganaxolone. Other agents modulate GABAergic "tone" by regulating the synthesis, transport or breakdown of GABA. GABAAR efficacy is also affected by the transmembrane chloride gradient, which changes during development and in chronic epilepsy. This may provide an additional target for "GABAergic" ASDs. GABAAR subunit changes occur both acutely during status epilepticus and in chronic epilepsy, which alter both intrinsic GABAAR function and the response to GABAAR-acting ASDs. Manipulation of subunit expression patterns or novel ASDs targeting the altered receptors may provide a novel approach for seizure prevention.

Role of neural stem cell activity in postweaning development of the sexually dimorphic nucleus of the preoptic area in rats.

The sexually dimorphic nucleus of the preoptic area (SDN-POA) has received increased attention due to its apparent sensitivity to estrogen-like compounds found in food and food containers. The mechanisms that regulate SDN-POA volume remain unclear as is the extent of postweaning development of the SDN-POA. Here we demonstrate that the female Sprague-Dawley SDN-POA volume increased from weaning to adulthood, although this increase was not statistically significant as it was in males. The number of cells positive for Ki67, a marker of cell proliferation, in both the SDN-POA and the hypothalamus was significantly higher at weaning than at adulthood in male rats. In contrast, the number of Ki67-positive cells was significantly higher in the hypothalamus but not in the SDN-POA (p>0.05) at weaning than at adulthood in female rats. A subset of the Ki67-positive cells in the SDN-POA displayed the morphology of dividing cells. Nestin-immunoreactivity delineated a potential macroscopic neural stem cell niche in the rostral end of the 3rd ventricle. In conclusion, stem cells may partially account for the sexually dimorphic postweaning development of the SDN-POA.

The 'real world' utility of a web-based bipolar disorder screening measure.

OBJECTIVE: To determine whether those completing a self-report bipolar self-test measure and identified as having a likely bipolar disorder judged the self-test as useful and had a subsequent superior illness course. METHOD: We invited those completing the web-based Mood Swings Questionnaire (or MSQ) to provide contact details and contribute to a 3-month study evaluating their responses to being identified as having a likely bipolar disorder, any subsequent action taken and the impact of such actions on their illness trajectory. RESULTS: We analysed data received from 665 participants screening 'positive' on the MSQ and completing baseline and 3-month follow-up data. High rates of satisfaction with the MSQ were quantified, with respondents viewing the measure as informative, validating and/or motivating. Of those receiving a confirmed bipolar diagnosis, such clarification occurred on average 12 years after their first depressive episode. Most implemented self-management strategies irrespective of whether seeking formal diagnostic clarification or not. Participants improved on depressive, quality of life and overall functioning measures over the study period, but with results indicating (via analysis of three sample subsets differing by the degree of 'actions taken') that those who took assertive action and had the diagnosis confirmed had the most superior outcome. CONCLUSION: This is the first study to formally evaluate the clinical impact of a self-report bipolar disorder screening measure. High acceptance and superior outcomes quantified for those acting assertively in response to such a new diagnosis argue for its 'real world' utility.

Ischemia-induced increase in microvascular phosphodiesterase 4D expression in rat hippocampus associated with blood brain barrier permeability: effect of age.

Phosphodiesterase 4D (PDE4D) is one of 16 PDEs expressed in cerebral microvessels, and may be involved in regulating blood-brain barrier (BBB) permeability. To assess the possible role of PDE4D in stroke-related injury in young versus aged rats, we measured microvascular PDE4D expression, parenchymal albumin immunoreactivity, and changes in the inside bore of the brain microvasculature. Ischemia caused severe hippocampal CA1 damage, associated with significant increases in vascular PDE4D and parenchymal albumin immunoreactivities. This effect was greater in the younger animals, which also had a greater increase in PDE4D expression. Ischemia significantly decreased tissue density in the perimicrovascular space in both young and aged animals. In addition, internal bore circumference and cross-sectional area of the hippocampal microvessels increased dramatically following ischemia. Increased PDE4D expression following cerebral ischemia may play a role in changing BBB permeability, which could secondarily affect ischemic outcome.

Hypoxia enhances high-voltage-activated calcium currents in rat primary cortical neurons via calcineurin.

Hypoxia regulates neuronal ion channels, sometimes resulting in seizures. We evaluated the effects of brief sustained hypoxia (1% O(2), 4h) on voltage-gated calcium channels (VGCCs) in cultured rat primary cortical neurons. High-voltage activated (HVA) Ca(2+) currents were acquired immediately after hypoxic exposure or after 48h recovery in 95% air/5% CO(2). Maximal Ca(2+) current density increased 1.5-fold immediately after hypoxia, but reverted to baseline after 48h normoxia. This enhancement was primarily due to an increase in L-type VGCC activity, since nimodipine-insensitive residual Ca(2+) currents were unchanged. The half-maximal potentials of activation and steady-state inactivation were unchanged. The calcineurin inhibitors FK-506 (in the recording pipette) or cyclosporine A (during hypoxia) prevented the post-hypoxic increase in HVA Ca(2+) currents, while rapamycin and okadaic acid did not. L-type VGCCs were the source of Ca(2+) for calcineurin activation, as nimodipine during hypoxia prevented post-hypoxic enhancement. Hypoxia transiently potentiated L-type VGCC currents via calcineurin, suggesting a positive feedback loop to amplify neuronal calcium signaling that may contribute to seizure generation.

Heteromeric canonical transient receptor potential 1 and 4 channels play a critical role in epileptiform burst firing and seizure-induced neurodegeneration.

Canonical transient receptor potential channels (TRPCs) are receptor-operated cation channels that are activated in response to phospholipase C signaling. Although TRPC1 is ubiquitously expressed in the brain, TRPC4 expression is the most restrictive, with the highest expression level limited to the lateral septum. The subunit composition of neuronal TRPC channels remains uncertain because of conflicting data from recombinant expression systems. Here we report that the large depolarizing plateau potential that underlies the epileptiform burst firing induced by metabotropic glutamate receptor agonists in lateral septal neurons was completely abolished in TRPC1/4 double-knockout mice, and was abolished in 74% of lateral septal neurons in TRPC1 knockout mice. Furthermore, neuronal cell death in the lateral septum and the cornu ammonis 1 region of hippocampus after pilocarpine-induced severe seizures was significantly ameliorated in TRPC1/4 double-knockout mice. Our data suggest that both TRPC1 and TRPC4 are essential for an intrinsic membrane conductance mediating the plateau potential in lateral septal neurons, possibly as heteromeric channels. Moreover, excitotoxic neuronal cell death, an underlying process for many neurological diseases, is not mediated merely by ionotropic glutamate receptors but also by heteromeric TRPC channels activated by metabotropic glutamate receptors. TRPC channels could be an unsuspected but critical molecular target for clinical intervention for excitotoxicity.

Isotopic evidence for the provenance and turnover of organic carbon by soil microorganisms in the Antarctic dry valleys.

The extremely cold and arid Antarctic dry valleys are one of the most environmentally harsh terrestrial ecosystems supporting organisms in which the biogeochemical transformations of carbon are exclusively driven by microorganisms. The natural abundance of (13)C and (15)N in source organic materials and soils have been examined to obtain evidence for the provenance of the soil organic matter and the C loss as CO(2) during extended incubation (approximately 1200 days at 10 degrees C under moist conditions) has been used to determine the potential decay of soil organic C. The organic matter in soils remote from sources of liquid water or where lacustrine productivity was low had isotope signatures characteristic of endolithic (lichen) sources, whereas at more sheltered and productive sites, the organic matter in the soils that was a mixture mainly lacustrine detritus and moss-derived organic matter. Soil organic C declined by up to 42% during extended incubation under laboratory conditions (equivalent to 50-73 years in the field on a thermal time basis), indicating relatively fast turnover, consistent with previous studies indicating mean residence times for soil organic C in dry valley soils in the range 52-123 years and also with recent inputs of relatively labile source materials.

Post-hypoxic changes in rat cortical neuron GABA A receptor function require L-type voltage-gated calcium channel activation.

Hypoxia modifies GABA(A) receptor (GABA(A)R) function and can cause seizures, encephalopathy or myoclonus. To characterize the effects of hypoxia on neuronal GABA(A)Rs, we subjected rat cortical neurons to 1% O2 for 2, 4 or 8h, followed by recovery times of 0-96h, and used whole-cell and perforated patch-clamp recording to assess GABA(A)R currents and pharmacology. Hypoxic exposure for 4h caused downregulation of maximal GABA current immediately following hypoxia and after 48h recovery without changing the EC50 for GABA. Two- and eight-hour hypoxic exposures had inconsistent effects on GABA(A)R currents. Maximal diazepam potentiation was increased immediately following 4h hypoxia, while potentiation by zolpidem was increased after 48h recovery. Pentobarbital enhancement and zinc inhibition of GABA currents were unchanged. Hypoxia also caused a depolarizing shift in the reversal potential of GABA-induced Cl(-) currents after 24h recovery. The L-type voltage-gated calcium channel (L-VGCC) blocker, nitrendipine, during hypoxia or control treatment prevented the reduction in GABA(A)R currents, and increased control currents over baseline. Nitrendipine also prevented the increase in zolpidem potentiation 48h after hypoxia, and blocked the depolarizing shift in Cl(-) reversal potential 24h after hypoxia. The effects of hypoxia on maximal GABA(A)R currents, zolpidem pharmacology and Cl(-) reversal potential thus require depolarization-induced calcium entry via L-VGCCs, and constitutive L-VGCC activity appears to reduce maximal GABA(A)R currents in control neurons via a calcium-dependent process. Calcium-dependent modulation of GABA(A)R currents via L-VGCCs may be a fundamental regulatory mechanism for GABA receptor function.

Chronic benzodiazepine administration potentiates high voltage-activated calcium currents in hippocampal CA1 neurons.

Signs of physical dependence as a consequence of long-term drug use and a moderate abuse liability limit benzodiazepine clinical usefulness. Growing evidence suggests a role for voltage-gated calcium channel (VGCC) regulation in mediating a range of chronic drug effects from drug withdrawal phenomena to dependence on a variety of drugs of abuse. High voltage-activated (HVA) calcium currents were measured in whole-cell recordings from acutely isolated hippocampal CA1 neurons after a 1-week flurazepam (FZP) treatment that results in withdrawal-anxiety. An approximately 1.8-fold increase in Ca(2+) current density was detected immediately after and up to 2 days but not 3 or 4 days after drug withdrawal. Current density was unchanged after acute desalkyl-FZP treatment. A significant negative shift of the half-maximal potential of activation of HVA currents was also observed but steady-state inactivation remained unchanged. FZP and diazepam showed use- and concentration-dependent inhibition of Ca(2+) currents in hippocampal cultured cells following depolarizing trains (FZP, IC(50) = 1.8 microM; diazepam, IC(50) = 36 microM), pointing to an additional mechanism by which benzodiazepines modulate HVA Ca(2+) channels. Systemic preinjection of nimodipine (10 mg/kg), an L-type (L)-VGCC antagonist, prevented the benzodiazepine-induced increase in alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid receptor (AMPAR)-mediated miniature excitatory postsynaptic current in CA1 neurons 2 days after FZP withdrawal, suggesting that AMPAR potentiation, previously linked to withdrawal-anxiety may require enhanced L-VGCC-mediated Ca(2+) influx. Taken together with prior work, these findings suggest that enhanced Ca(2+) entry through HVA Ca(2+) channels may contribute to hippocampal AMPAR plasticity and serve as a potential mechanism underlying benzodiazepine physical dependence.

Benzodiazepine withdrawal-induced glutamatergic plasticity involves up-regulation of GluR1-containing alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors in Hippocampal CA1 neurons.

Modification of glutamatergic synaptic function, a mechanism central to neuronal plasticity, may also mediate long-term drug effects, including dependence and addiction. Benzodiazepine withdrawal results in increased glutamatergic strength, but whether alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors (AMPARs) are functionally and structurally remodeled during benzodiazepine withdrawal is uncertain. Whole-cell recordings of rat hippocampal CA1 neurons, either acutely dissociated or in hippocampal slices, revealed that AMPAR function was enhanced up to 50% during flurazepam (FZP) withdrawal, without changes in whole-cell channel kinetic properties. Agonist-elicited AMPA currents showed a negative shift in rectification in the presence of spermine, suggesting augmented membrane incorporation of glutamate receptor (GluR) 2-lacking AMPARs. As GluR1-containing AMPARs are critical for activity-dependent alterations in excitatory strength, we sought to determine whether changes in GluR1 subunit distribution in CA1 neurons occurred during benzodiazepine withdrawal. Confocal image analysis revealed that FZP withdrawal promoted GluR1 subunit incorporation into somatic and proximal dendritic membranes of CA1 neurons without GluR2 subunit alterations. Findings of immunoblot studies were consistent with immunofluorescent studies indicating increased GluR1, but not GluR2, subunit protein levels in cytosolic, crude membrane and postsynaptic density-enriched fractions from CA1 minislices. As with long-term potentiation (LTP), the FZP-withdrawal-induced GluR1 incorporation into CA1 neuron membranes may require the GluR1-trafficking protein, synapse-associated protein 97, which was also elevated in membrane-associated fractions. Together, our findings provide evidence that during FZP withdrawal, increased membrane incorporation of GluR1-containing AMPARs and associated up-regulation of AMPAR functions in hippocampal CA1 pyramidal neurons share fundamental similarities with the mechanisms underlying LTP. This implies that glutamatergic neuronal remodeling observed in LTP also subserves physiological adaptations to drug withdrawal.