Dynamic competition between large-scale functional networks differentiates fear conditioning and extinction in humans.

The high evolutionary value of learning when to respond to threats or when to inhibit previously learned associations after changing threat contingencies is reflected in dedicated networks in the animal and human brain. Recent evidence further suggests that adaptive learning may be dependent on the dynamic interaction of meta-stable functional brain networks. However, it is still unclear which functional brain networks compete with each other to facilitate associative learning and how changes in threat contingencies affect this competition. The aim of this study was to assess the dynamic competition between large-scale networks related to associative learning in the human brain by combining a repeated differential conditioning and extinction paradigm with independent component analysis of functional magnetic resonance imaging data. The results (i) identify three task-related networks involved in initial and sustained conditioning as well as extinction, and demonstrate that (ii) the two main networks that underlie sustained conditioning and extinction are anti-correlated with each other and (iii) the dynamic competition between these two networks is modulated in response to changes in associative contingencies. These findings provide novel evidence for the view that dynamic competition between large-scale functional networks differentiates fear conditioning from extinction learning in the healthy brain and suggest that dysfunctional network dynamics might contribute to learning-related neuropsychiatric disorders

Salience and default-mode network connectivity during threat and safety processing in older adults.

The appropriate assessment of threat and safety is important for decision-making but might be altered in old age due to neurobiological changes. The literature on threat and safety processing in older adults is sparse and it is unclear how healthy ageing affects the brain's functional networks associated with affective processing. We measured skin conductance responses as an indicator of sympathetic arousal and used functional magnetic resonance imaging and independent component analysis to compare young and older adults' functional connectivity in the default mode (DMN) and salience networks (SN) during a threat conditioning and extinction task. While our results provided evidence for differential threat processing in both groups, they also showed that functional connectivity within the SN - but not the DMN - was weaker during threat processing in older compared to young adults. This reduction of within-network connectivity was accompanied by an age-related decrease in low frequency spectral power in the SN and a reduction in inter-network connectivity between the SN and DMN during threat and safety processing. Similarly, we found that skin conductance responses were generally lower in older compared to young adults. Our results are the first to demonstrate age-related changes in brain activation during aversive conditioning and suggest that the ability to adaptively filter affective information is reduced in older adults

Burning oral and mid-facial pain in ventral pontine infarction

The symptom of burning orofacial pain may help to identify the site of ischaemia in otherwise pure motor strokes resulting from infarction of the ventral pons. A patient with hemiplegia due to ventral pontine infarction, in whom burning oral and mid-facial pain was a prominent initial symptom, is described. Similar pain preceded transient episodes of the ‘locked-in’ state. Awareness of this herald symptom may permit early recognition and careful monitoring of patients at risk of progressing to the ‘locked-in’ state

Idiopathic generalized epilepsy of adolescence: Are the syndromes clinically distinct?

AB Juvenile myoclonic epilepsy, juvenile absence epilepsy, and epilepsy with generalized tonic-clonic seizures (GTCS) on awakening are the three syndromes of idiopathic generalized epilepsy of adolescent onset currently included in the classification of epilepsy syndromes of the International League Against Epilepsy (ILAE). Although they differ in their predominant seizure types, the syndromes share several clinical features, thus giving rise to questions of phenotypic overlap and purity. We studied the clinical features of 101 patients with idiopathic generalized epilepsy beginning in adolescence. A standardized interview was used to elucidate seizure phenomenology, precipitants, frequency, and response to treatment. Groups defined by seizure type were compared and their similarities examined. The group with myoclonic but not absence seizures (21 patients) corresponded to the ILAE syndrome of juvenile myoclonic epilepsy, whereas those with absences but not myoclonus (37 patients) resembled juvenile absence epilepsy. Twenty-six patients shared the features of juvenile myoclonic epilepsy and juvenile absence epilepsy. Epilepsy with GTCS on awakening was not a specific syndromic entity; 10 patients had this seizure type alone. Seven patients were without a syndromic diagnosis. In these patients only GTCS occurred, but neither on awakening nor in the evening period of relaxation. We conclude that whilst syndromes of idiopathic generalized epilepsy of adolescence can be recognized, the current classification does not include all patients. In addition, the boundaries between the syndromes are indistinct, suggesting underlying neurobiological, possibly genetic, relationships

Neuroleptic malignant syndrome complicating levodopa withdrawal

Objective: To describe a case of neuroleptic malignant syndrome (NMS) resulting from withdrawal of low-dose levodopa therapy for mild Parkinson's disease

Cortical hyperexcitability in progressive myoclonus epilepsy: A study with transcranial magnetic stimulation.

In progressive myoclonus epilepsy (PME), responses to afferent input are frequently abnormal. It is unclear whether the abnormality lies at the cortical, subcortical, or segmental level. To obtain evidence for an exaggerated effect on motor cortical excitability, we used peripheral nerve and transcranial magnetic stimulation in controls and subjects with idiopathic generalized epilepsy and PME. Mean threshold intensity was higher in those with idiopathic generalized epilepsy and PME than in controls, probably as a result of anticonvulsant treatment. A long-latency response to peripheral stimulation and an exaggerated facilitatory effect of peripheral stimulation on the motor evoked potential was present in subjects with PME. Latency differences between the late responses in the upper and lower limbs provided evidence against a segmental reflex and implicated rapidly conducting fibers in the spinal cord. Both the late response and the facilitatory effect had onset latencies consistent with a transcortical pathway, suggesting an exaggerated effect of afferent input on motor cortical excitability in PME

Triphasic waves in accidental hypothermia

Triphasic waves occur in a variety of metabolic, toxic and diffuse encephalopathies. We describe an elderly patient in whom triphasic waves accompanied moderately severe accidental hypothermia and disappeared on rewarming

Is intravenous lidocaine clinically effective in acute migraine?

We performed a prospective, randomized, double-blind, placebo-controlled trial of intravenous lidocaine (1 mg/kg) in the treatment of acute migraine. Thirteen subjects were randomly allocated to receive intravenous lidocaine and 12 received intravenous normal saline. Subjects scored the intensity of headache and nausea on separate visual analogue scales before the injection and at 10 and 20 min after injection. At 20 min, the mean pain intensity score was 80% of initial intensity in the lidocaine group and 82% in the placebo group. The difference was not statistically significant; at 20 min, the 95% confidence interval for the difference between the two groups in mean percentage of initial pain score was 2 ± 29%. At the dose studied, intravenous lidocaine has, at best, only a modest effect in acute migraine