Topographic movie of ictal high-frequency oscillations on the brain surface using subdural EEG in neocortical epilepsy

PURPOSE: To understand the rapid dynamic changes of ictal intracranial high-frequency oscillations (HFOs) in neocortical epilepsy. METHODS: We integrated multiple band frequency analysis and brain-surface topographic maps of HFOs from ictal subdural EEG (SDEEG) recordings. We used SDEEG to record partial seizures consisting of right-arm jerks with secondary generalization in a 17-year-old right-handed girl. We selected 20-s EEG sections that included preclinical seizure recordings. We averaged the HFO power between 60 and 120 Hz for 25 selected electrodes, made topographic maps from these averaged powers, and superimposed the maps on the brain-surface image. We filmed consecutive HFO maps at a 10-ms frame rate. RESULTS: Before clinical seizure onset, high-power HFOs emerged at the superior portion of the left precentral gyrus, then appeared in the middle of the left postcentral gyrus, and subsequently reverberated between both regions as well as the posterior portion of the left postcentral gyrus. Right-arm extension and facial grimacing started as the HFO power decreased. As generalized tonic-clonic seizures evolved, HFO power increased but remained within the central region. CONCLUSIONS: Topographic movies of intracranial HFOs on the brain surface allow visualization of the dynamic ictal changes in neocortical epilepsy.     

Human Basophils and Cytokines/Chemokines

Basophils comprise the smallest population in human peripheral blood leukocytes. The role of basophils in the pathogenesis of allergic diseases has long been obscure, although their accumulation and activation in tissues have suggested their potential importance. Recent advances in the field of basophil biology have indicated that cytokines and chemokines are the primary regulators of basophil functions. In addition, various functions of these cells seem differently modulated. The evidence strongly supports the notion that basophils exposed to these substances and allergens will behave as unique effector cells that presumably play proinflammatory roles in type I allergic reactions.     

Involvement of NMDA receptor mechanisms in the modulation of serotonin release in the lateral parabrachial nucleus in the rat

Microdialysis was employed to investigate whether N-methyl-d-asparatate (NMDA) glutamate receptor mechanisms are involved in the modulation of serotonin (5-hydoxytryptamine, 5-HT) release in the region of the lateral parabrachial nucleus (LPBN) in freely moving rats. Perfusion of NMDA (10 and 50 microM) through the microdialysis probe significantly enhanced extracellular concentrations of 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the LPBN area. Local perfusion of the NMDA antagonist dizocilpine (MK801, 10 and 50 microM) did not change the basal 5-HT and 5-HIAA levels in the LPBN area. MK801 (10 microM) administered together with NMDA antagonized the stimulant effect of NMDA (10 microM). The intake of 0.3M NaCl and water induced by subcutaneous injections of the diuretic furosemide (FURO, 10 mg/kg) and the angiotensin converting enzyme inhibitor captopril (CAP, 5 mg/kg) produced significant increases in the 5-HT and 5-HIAA concentrations in the LPBN area. The increased levels of 5-HT and 5-HIAA caused by the combined treatment with FURO and CAP were attenuated by perfusion of MK801 (10 microM). These results indicate the participation of NMDA receptors in the control of 5-HT release in the LPBN area.     

Temporal properties of spatial frequency tuning of surround suppression in the primary visual cortex and the lateral geniculate nucleus of the cat

In primary visual cortex (V1) neurons, a stimulus placed in the extraclassical receptive field suppresses the response to a stimulus within the classical receptive field (CRF), a phenomenon referred to as surround suppression. The aim of the present study was to elucidate the mechanisms of surround suppression in V1. Using stationary‐flashed sinusoidal grating as stimuli, we observed temporal changes of surround suppression in V1 and the lateral geniculate nucleus (LGN) and of the response to CRF stimulation in V1. The spatial frequency (SF) tuning of surround suppression in V1 neurons changed over time after the stimulus onset. In the early phase (< 50 ms), the SF tuning was low‐pass, but later became band‐pass that tuned to the optimal SF in response to CRF stimulation. On the other hand, the SF tuning of CRF responses in V1 was band‐pass throughout the response time whereas the SF peak shifted slightly toward high SF. Thus, SF tuning properties of the CRF response dissociated from that of surround suppression in V1 only in the early phase. We also confirmed that the temporal changes of the SF tuning of surround suppression in the LGN occurred in the same direction as surround suppression in V1, but the shift from low‐pass to band‐pass SF tuning started later than that in V1. From these results, we suggest that subcortical mechanisms contribute to early surround suppression in V1, whereas cortical mechanisms contribute to late surround suppression.     

Nationwide survey (incidence,clinical course,prognosis) of Rasmussen’s encephalitis

Purpose: Rasmussen’s encephalitis (RE) is a progressive and catastrophic epileptic disorder caused by chronic localized encephalitis. We performed a nationwide survey of RE to assess the clinical picture, treatment effect, and prognosis of Japanese RE patients. Subjects & methods: The subjects were 27 patients (male:12; female:15) from 13 medical facilities. All of them satisfied the clinical and neuroimaging criteria for RE, including 14 pathologically proven cases. Results: They were divided into the childhood-onset rapidly progressive type (CORP, n = 19), and late-onset slowly progressive type (LOSP, n = 8). The mean age at epilepsy onset was 4 years and 4 months in CORP, and 16 years in LOSP. The mean period between the onset age of epilepsy and development of frequent seizures was 1 year and 4 months in the former, and 3 years and 4 months in the latter. The immunomodulatory treatment including high-dose steroid (n = 14) and high-dose intravenous immunoglobulin therapies (IVIgG, n = 12) achieved more than a 50% reduction in the seizure frequency in 5 (36%) and 4 (33%) patients, respectively. Eight and seven patients underwent focal cortical resection and functional hemispherectomy, leading to significant improvement in 5 of the 8 patients and excellent seizure control in all 7 patients, respectively. Conclusion: Although the high-dose steroid and IVIG therapies may have alleviated the exacerbation of seizures in those with RE, they could not halt the disease progression. Functional hemispherectomy is still the only curative therapy for RE, despite the fact that the early introduction of this procedure remains controversial.