Novel mutation in EIF2B gene in a case of adult-onset leukoencephalopathy with vanishing white matter.
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Adult↗
Biomedical subjects
Hiroshi Shibasaki
Publications and source records attributed to Hiroshi Shibasaki.
Functional connectivity in human cortical motor system: a cortico-cortical evoked potential study.
In order to understand the complex functional organization of the motor system, it is essential to know the anatomical and functional connectivity among individual motor areas. Clinically, knowledge of these cortico-cortical connections is important to understand the rapid spread of epileptic discharges through the network underlying ictal motor manifestation. In humans, however, knowledge of neuronal in vivo connectivity has been limited. We recently reported a new method, 'cortico-cortical evoked potential (CCEP)', to electrically track the cortico-cortical connections by stimulating a part of the brain through subdural electrodes and recording the cortical evoked potentials that emanate from a distant region of the cortex via neuronal projections. We applied the CCEP methodology to investigate in vivo cortico-cortical connections between the lateral motor cortex [LMCx; sensorimotor (SM) and lateral premotor areas] and the medial motor cortex [MMCx; supplementary motor area proper (SMA), pre-SMA and foot SM]. Seven patients with intractable partial epilepsy were studied. These patients had chronic implantation of subdural electrodes covering part of the lateral and medial frontal areas. As a part of the routine pre-surgical evaluation, comprehensive cortical mapping was performed by electrical stimulation of the subdural electrodes, and the precise localization of the subdural electrodes was defined by MRI co-registration. Single-pulse electrical stimuli were delivered to MMCx (7 patients) and LMCx (4), and CCEPs time-locked to the stimuli were recorded by averaging electrocorticograms from LMCx and MMCx, respectively. Short-latency CCEPs were observed when stimulating MMCx and recording from LMCx (mean latency: 21.6 ms, range: 9-47 ms) and vice versa when stimulating LMCx and recording from MMCx (mean latency: 29.4 ms, range: 11-57 ms). In terms of the location of these stimulus sites and CCEP responses along the rostrocaudal axis, regression analysis revealed a consistent correlation between the sites of stimulation and maximum CCEP for stimulation of both MMCx and LMCx. Functionally, stimulation of the positive motor areas in MMCx elicited CCEPs at the somatotopically homologous regions in LMCx (71%). The same findings were observed in MMCx (82%) upon stimulation of LMCx. In four subjects in whom bi-directional connectivity was investigated by stimulating both MMCx and LMCx, reciprocality was observed in the majority of connections (78-94%). In conclusion, the present study demonstrated a human motor cortico-cortical network connecting (i) anatomically homologous areas of LMCx and MMCx along the rostrocaudal cognitive-motor gradient; and (ii) somatotopically homologous regions in LMCx and MMCx in a reciprocal manner.
Adolescent↗
Transient functional suppression and facilitation of Japanese ideogram writing induced by repetitive transcranial magnetic stimulation of posterior inferior temporal cortex.
The Japanese writing system is unique in that it is composed of two different orthographies: kanji (morphograms) and kana (syllabograms). The retrieval of the visual orthographic representations of Japanese kanji is crucial to the process of writing in Japanese. We used low-frequency repetitive transcranial magnetic stimulation (rTMS) to clarify the functional relevance of the left and right posterior inferior temporal cortex (PITC) to this process in native Japanese speakers. The experimental paradigms included the mental recall of kanji, kana-to-kanji transcription, semantic judgment, oral reading, and copying of kana and kanji. The first two tasks require the visualization of the kanji image of the word. We applied 0.9 Hz rTMS (600 total pulses) over individually determined left or right PITC to suppress cortical activity and measured subsequent task performance. In the mental recall of kanji and kana-to-kanji transcription, rTMS over the left PITC prolonged reaction times (RTs), whereas rTMS over the right PITC reduced RTs. In the other tasks, which do not involve the mental visualization of kanji, rTMS over the left or right PITC had no effect on performance. These results suggest that the left PITC is crucial for the retrieval of the visual graphic representation of kanji. Furthermore, the right PITC may work to suppress the dominant left PITC in the neural network for kanji writing, which involves visual word recognition.
Adult↗
Low-frequency electric cortical stimulation decreases interictal and ictal activity in human epilepsy.
We previously reported that low-frequency electric cortical stimulation (LFECS) directly applied to the epileptic focus by means of subdural electrodes decreased the number of interictal epileptiform discharges in patients with intractable partial epilepsy. In the present study, LFECS was applied to the epileptic foci directly in four patients with medically intractable partial epilepsy through subdural electrodes and evaluated its effect on the number of interictal epileptiform discharges as well as simple partial seizures. We used alternating electric current of 0.3 ms duration presented at 0.9 Hz frequency for 250 s. LFECS did not induce seizures in any of the four patients. In one patient, the number of interictal epileptiform discharge decreased significantly by LFECS, which is in conformity with our previous report. In addition, LFECS applied to the seizure onset zone decreased the frequency of simple partial seizures in one patient. These results suggest that LFECS has an inhibitory effect not only on the interictal but also the ictal activities in patients with intractable partial epilepsy. Further study is required to determine the inhibitory effect of LFECS more in details.
Adolescent↗
Rapid recovery from coma with multifocal PLEDs in a patient with severe dementia and transient hypoxemia.
We report a patient with severe dementia who acutely developed transient coma following possible acute anoxic encephalopathy, and presented multifocal periodic lateralized epileptiform discharges (PLEDs) on EEG, who had a good recovery from the acute state. Two EEGs were recorded from this patient. In the first EEG taken immediately after admission, multifocal PLEDs were prominent, and the background activity consisted of low voltage, continuous and irregular theta activity (4-6 Hz). The patient recovered from coma (GCS-3) to the conscious state (GCS-15) within 14 hours and was not associated with newly developed focal or global neurological deficits except for stable severe dementia which had developed in the previous several years. Another EEG taken 5 days later showed disappearance of multifocal PLEDs. Transient appearance of multifocal PLEDs might represent at least the transient, vulnerability associated with underlying dementia in this particular patient. We concluded that multifocal PLEDs do not always indicate a poor outcome in patients with possible acute anoxic encephalopathy, and rapid diagnosis and appropriate treatment should be done even if the initial EEG shows multifocal PLEDs.
Aged, 80 and over↗
Ipsilateral facial sensory and motor responses to basal fronto-temporal cortical stimulation: evidence suggesting direct activation of cranial nerves.
To clarify the generator mechanism of sensory and motor facial responses ipsilateral to electrical stimulation of the inferior fronto-temporal cortex in epilepsy patients. Out of 30 patients who have been evaluated with chronically implanted subdural electrodes for medically intractable partial seizure or brain tumor involving the basal frontal or temporal cortex, 4 patients (age ranging 24-57 years) showed sensory and motor responses in the ipsilateral face to high frequency electrical cortical stimulation of the inferior fronto-temporal cortex. We investigated motor evoked potentials (MEPs) in the facial muscle by single pulse stimulation in 2 out of 4 patients. Three patients showed both sensory symptoms and muscle contraction in the ipsilateral lower face when the orbitofrontal or basal temporal cortex was stimulated with 50 Hz electric current. One patient had only sensory symptoms in the lower face when ipsilateral basal temporal area was stimulated. MEPs at the left orbicularis oris muscle were constantly elicited with the onset latency of 7 ms throughout the stimulus rate of 2-30 Hz in 1 patient out of 2 patients was tested. In another patient, MEP onset latency was 3.0 ms with 11 Hz stimulation. With electrical stimulation of the basal fronto-temporal cortex, the ipsilateral facial twitch might occur through either the direct activation of the facial nerve by the current spread in the middle cranial fossa or through the mechanism similar to blink reflex.
Adult↗
What is the Bereitschaftspotential?
Since discovery of the slow negative electroencephalographic (EEG) activity preceding self-initiated movement by Kornhuber and Deecke [Kornhuber HH, Deecke L. Hirnpotentialänderungen bei Willkurbewegungen und passiven Bewegungen des Menschen: Bereitschaftspotential und reafferente Potentiale. Pflugers Archiv 1965;284:1-17], various source localization techniques in normal subjects and epicortical recording in epilepsy patients have disclosed the generator mechanisms of each identifiable component of movement-related cortical potentials (MRCPs) to some extent. The initial slow segment of BP, called 'early BP' in this article, begins about 2 s before the movement onset in the pre-supplementary motor area (pre-SMA) with no site-specificity and in the SMA proper according to the somatotopic organization, and shortly thereafter in the lateral premotor cortex bilaterally with relatively clear somatotopy. About 400 ms before the movement onset, the steeper negative slope, called 'late BP' in this article (also referred to as NS'), occurs in the contralateral primary motor cortex (M1) and lateral premotor cortex with precise somatotopy. These two phases of BP are differentially influenced by various factors, especially by complexity of the movement which enhances only the late BP. Event-related desynchronization (ERD) of beta frequency EEG band before self-initiated movements shows a different temporospatial pattern from that of the BP, suggesting different neuronal mechanisms for the two. BP has been applied for investigating pathophysiology of various movement disorders. Volitional motor inhibition or muscle relaxation is preceded by BP quite similar to that preceding voluntary muscle contraction. Since BP of typical waveforms and temporospatial pattern does not occur before organic involuntary movements, BP is used for detecting the participation of the 'voluntary motor system' in the generation of apparently involuntary movements in patients with psychogenic movement disorders. In view of Libet et al.'s report [Libet B, Gleason CA, Wright EW, Pearl DK. Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act. Brain 1983;106:623-642] that the awareness of intention to move occurred much later than the onset of BP, the early BP might reflect, physiologically, slowly increasing cortical excitability and, behaviorally, subconscious readiness for the forthcoming movement. Whether the late BP reflects conscious preparation for intended movement or not remains to be clarified.
Beta Rhythm↗
Generators and temporal succession of giant somatosensory evoked potentials in cortical reflex myoclonus: epicortical recording from sensorimotor cortex.
OBJECTIVE: To clarify the generator mechanism of giant somatosensory evoked potentials (giant SEPs) and the hyperexcitability of primary somatosensory and motor cortices (SI and MI). METHODS: In a patient with intractable focal seizures manifesting cortical reflex myoclonus of the left foot, giant SEPs to left tibial nerve stimulation were epicortically recorded as a part of presurgical evaluation with subdural electrodes. RESULTS: In the single pulse SEPs, enlarged P1-N1 components were observed at the foot area of the SI and MI (86.5-258.8 microV, respectively), and the peak latencies were always shorter at SI than at MI by 6 ms. Similar findings were obtained for peroneal and sural nerve stimulation. In the paired pulse SEPs, the second response was less suppressed, as compared to other interstimulus intervals (ISIs), with ISIs of 40 and 200 ms both at SI and MI. CONCLUSIONS: In this particular patient, cortical hyperexcitability to somatosensory stimuli seems to originate from SI but subsequently both SI and MI are responsible for the generation of giant SEPs and cortical reflex myoclonus. SIGNIFICANCE: Somatosensory and primary motor cortices both generated enhanced early cortical components of SEPs, most likely by enhancing the latter by the former.
Adult↗
Effects of continuous masking noise on tone-evoked magnetic fields in humans.
Two different types of steep loudness growth have been reported in detail in psychoacoustical studies but have rarely been evaluated by objective methods in humans. One occurs in inner-ear hearing-impaired patients and is known as loudness recruitment. Another similar phenomenon is observed in healthy subjects with concurrent presence of background noise. Concerning the first type, our previous study using magnetoencephalography (MEG) showed that enhancement of the dipole moment of N100m with increase in stimulus intensity was greater in patients than in normal individuals. However, it is unclear whether the enhancement of activity in auditory cortex will also be detected with background noise in healthy subjects. To elucidate the effects of continuous background noise on tone-evoked cortical activity, we measured auditory-evoked magnetic fields (AEFs) from 7 normal-hearing subjects in two different conditions, with and without 55 dB SPL continuous masking white noise (noise/quiet conditions). The stimuli were 200 ms 1-kHz tones delivered monaurally and randomly at 4 different intensities (40-70 dB SPL) with constant 1-s interstimulus intervals. The N100m increased in amplitude and decreased in latency as a function of stimulus intensity in both noise and quiet conditions. The dipole moment of N100m was significantly smaller in the noise than in the quiet condition, showing that continuous background noise suppresses the strength of tone-evoked cortical responses. The mechanisms underlying these two psychoacoustically similar phenomena of rapid loudness growth thus differ.
Acoustic Stimulation↗
Bereitschaftspotentials recorded from the lateral part of the superior frontal gyrus in humans.
To demonstrate the Bereitschaftspotentials (BPs) over the high lateral convexity in the superior frontal gyrus, movement-related cortical potentials with respect to the middle finger extension were recorded in seven patients with refractory epilepsy who underwent subdural implantation of platinum electrode grids and/or strips covering the high lateral frontal convexity. In two out of the seven patients, BPs were recorded from the electrodes placed on the superior frontal gyrus in the vicinity of the border between the medial and lateral frontal lobes, which were distinct from those recorded from the primary sensorimotor cortex. The results suggest the possible contribution of either the lateral dorsal non-primary motor area or the SMA to the generation of the BPs.
Contingent Negative Variation↗
Clinical outcome of patients with SREDA (subclinical rhythmic EEG discharge of adults).
OBJECTIVE: To clarify the clinical significance of subclinical rhythmic EEG discharge of adults' (SREDA) by analyzing characteristics of SREDA and the outcome of patients based on retrospective analysis of EEG data base. METHODS: EEGs were recorded soon after the onset of patient's initial symptoms and repeatedly recorded at various intervals of 2-3 months in all 4 patients. Neurological findings, MRI and SPECT were also investigated. SUBJECTS: Out of 340 consecutive inpatient population who had EEGs, 4 patients (1.2%) showed SREDA. They had a diagnosis of syncope, transient global amnesia, generalized tonic-clonic seizure and right temporal lobe epilepsy for each. RESULTS: There was no consistent abnormality in the brain MRI, CT or SPECT among the 4 patients. The acute and transient symptoms disappeared and did not recur within the follow-up period of 28 months in any patient. In 2 patients SREDA disappeared in the follow-up EEG taken 7-14 days after the first EEG showing SREDA. In the other 2 patients, the follow-up EEGs taken 5 days after the first EEG with SREDA when clinical symptoms disappeared showed less frequent occurrence of SREDA. CONCLUSION: Being different from the previous reports suggesting the relation with cardiogenic insults or persistent ischemic abnormality, SREDA can occur in patients with various acute brain dysfunctions followed by a favorable clinical outcome.
Adolescent↗
The role of biological system other than auditory air-conduction in the emergence of the hypersonic effect.
Although human beings cannot perceive elastic vibrations in the frequency range above 20 kHz, nonstationary sounds containing a wealth of inaudible high-frequency components (HFC) above the human audible range activate deep-lying brain structures, including the brainstem and thalamus and evoke various physiological, psychological, and behavioral responses. In the previous reports, we have called these phenomena collectively "the hypersonic effect." It remains unclear, however, if vibratory stimuli above the audible range are transduced and perceived solely via the conventional air-conducting auditory system or if other mechanisms also contribute to mediate transduction and perception. In the present study, we have examined the emergence of the hypersonic effect when inaudible HFC and audible low-frequency components (LFC) were presented selectively to the ears, the entrance of an air-conducting auditory system, or to the body surface including the head which might contain some unknown vibratory sensing mechanisms. We used two independent measurements based on differing principles; one physiological (alpha 2 frequency of spontaneous electroencephalogram [alpha-EEG]) and the other behavioral (the comfortable listening level [CLL]). Only when the listener's entire body surface was exposed to HFC, but not when HFC was presented exclusively to the air-conducting auditory system, did both the alpha-EEG and the CLL significantly increase compared to the presentation of LFC alone, that is to say, there was an evident emergence of the hypersonic effect. The present findings suggest that the conventional air-conducting auditory system alone does not bring about the hypersonic effect. We may need to consider the possible involvement of a biological system distinct from the conventional air-conducting auditory nervous system in sensing and transducing high-frequency elastic vibration above the human audible range.
Adult↗
Narcolepsy without cataplexy: 2 subtypes based on CSF hypocretin-1/orexin-A findings.
STUDY OBJECTIVES: Cerebrospinal fluid (CSF) hypocretin-1 levels and their relationship with the clinical characteristics of narcolepsy without cataplexy have not been well elucidated. Our aim was to examine whether clinical characteristics vary with CSF hypocretin-1 levels among narcoleptic patients without cataplexy. DESIGN: Clinical features, variables on the multiple sleep latency test, and results of HLA typing were correlated with CSF hypocretin-1 levels. SETTING: University-based sleep laboratories and a sleep disorders center. PATIENTS: Seventeen patients (5 male, 12 female) who fulfilled the diagnostic criteria of narcolepsy without cataplexy according to the International Classification of Sleep Disorders. INERVENTIONS: Patients underwent lumbar puncture for CSF sampling. MEASUREMENTS AND RESULTS: Five patients showed a markedly decreased CSF hypocretin-1 level, whereas the remaining 12 patients showed almost normal levels. The mean rapid eye movement (REM) latency was significantly shorter and the age at onset was significantly earlier in the low CSF hypocretin-1 group compared with the normal CSF hypocretin-1 group. HLA-DR2 was positive in all of the patients with low CSF hypocretin-1, whereas only 33.3% of patients with normal CSF hypocretin-1 were DR2 positive. CONCLUSIONS: Some narcoleptic patients without cataplexy have low CSF hypocretin-1 levels. In patients who have narcolepsy without cataplexy, short mean REM latency, younger age at onset, and HLA-DR2 are associated with CSF hypocretin-1 deficiency. Markedly decreased CSF hypocretin-1 levels could be a significant marker for identifying subgroups of narcolepsy patients without cataplexy.
Adolescent↗
"Burst and slow complexes" in nonconvulsive epileptic status.
Generalized 1Hz, burst-and-slow-wave complexes were observed in a comatosed patient with acute disseminated encephalomyelitis (ADEM) when she showed extremely intractable, generalized convulsions and fragmented myoclonus in the whole body. Two types of short-latency SEPs were obtained separately during the burst and slow phase of the EEG (SEP-burst and SEP-slow, respectively), which showed a two fold greater amplitude of N20 in the former than in the latter. This suggests enhanced responsiveness to the peripheral stimuli during the burst phase as compared with the slow phase. CSF and serum were positive for autoantibodies to NMDA receptors. The "burst and slow complexes" reported here are considered to be an atypical EEG pattern of a generalized epileptic phenomenon.
Adult↗
[Case presenting both clinical features of progressive supranuclear palsy and amyotrophic lateral sclerosis].
A 70-year-old Japanese male farmer, born and living in Kyoto prefecture, developed gait disturbance, with tendency to fall at age 68, and muscle atrophy and weakness of the right shoulder and arm a year and half later. All symptoms have been progressive ever since. The patient manifested marked dementia, parkinsonism associated with limitation of ocular movements in all directions with slow saccade, loss of startle reflex, asymmetric muscle atrophy and weakness in shoulder girdles and upper limbs with hyperreflexia, and positive Babinski reflexes. The needle electromyogram showed evidence of active denervation. Brain MRI showed cortical atrophy in the frontal and temporal lobes, and midbrain tegmentum. Cerebral blood flow image on SPECT suggested hypoperfusion in the frontal, temporal and parietal cortices and basal ganglia bilaterally. Thus, it is most likely that the present case suffered from clinical features of amyotrophic lateral sclerosis (ALS) and progressive supranuclear palsy at the same time. Relation to the ALS/Parkinsonism/Dementia complex reported from Kii peninsula and Guam was discussed.
Aged↗
Neural underpinning of postural responses to visual field motion.
Numerous results emerging from current research strongly implicate the effect of Visual Field Motion on the organization of postural responses. However, this is the first empirical study exploring the neural substrates underlying the subjects' response to Visual Field Motion. Two separate experiments were conducted to investigate the subject responses to Visual Field Motion. In the first experiment, the standing subjects were exposed to Visual Field Motion in the VR environment. In the second experiment, the recumbent subjects viewed the same Visual Field Motion while in a MRI scanner. A virtual reality (VR) prototype of the moving room paradigm [Lee, D.N., Aronson, E., 1974. Visual proprioceptive control of standing in human infants. Perception & Psychophysics 15, 529-532] was developed to simulate various optic flow patterns in a controlled VR environment. Postural responses (center of pressure, body kinematics, vection, egomotion) and brain activation patterns (fMRI signals) were examined. The subjects experienced egomotion and have reported vection in both experiments only when certain attributes of Visual Field Motion were introduced. This was accompanied by significant activation of specific brain structures, including prefrontal, parietal cortices and bilateral cerebellum. We propose the existence of functional interactions between modality specific areas of the brain involved in postural responses to Visual Field Motion (VFM).
Adult↗
Evidence for a wide distribution of negative motor areas in the perirolandic cortex.
OBJECTIVE: The perirolandic regions were studied by extensive electrical stimulation to clarify the topography and somatotopic distribution of negative motor areas (NMAs) and examine the clinical significance of these areas. METHODS: We evaluated the cortical function elicited by electrical stimulation in 30 patients with tumors or intractable epilepsy. The somatotopic distribution of NMAs was examined by localizing these regions using Talairach's bicommissural reference system. NMAs within the lesions of two patients were removed under local anesthesia. RESULTS: We obtained negative motor responses following the stimulation of 30 electrodes in 15 patients. On the lateral brain surface, the majority of NMAs for the upper extremities were distributed broadly throughout the premotor cortex, while NMAs for the tongue were only found in the inferior frontal gyrus of the dominant hemisphere. During removal of the NMAs within the lesions of two patients, we documented transient hand clumsiness in one patient. CONCLUSIONS: NMAs were widely distributed throughout the perirolandic area, as well as the previously reported regions in the inferior frontal gyrus. These areas likely function in the control of skilled movements; dysfunction of such movements transiently follows resection of these regions, but is subsequently well compensated for after surgery. SIGNIFICANCE: The localization and consequences of resection of NMAs suggests their clinical significance in motor control.
Adolescent↗
Cortical mechanisms of unilateral voluntary motor inhibition in humans.
While motor control is very often a goal-oriented event, little is known about the mechanisms underlying the termination of motor performance. To investigate what type of cortical activation underlies the muscle relaxation required to terminate the act, we performed single- and double-pulse transcranial magnetic stimulation (TMS) studies during voluntary muscle relaxation in nine normal volunteers. Subjects maintained a weak isometric contraction of the right first dorsal interosseous muscle (FDI), and either increased the level of contraction (Contraction), terminated the contraction (Relaxation), or maintained it (No-go) depending on a visual cue. Motor evoked potentials (MEP) and the silent period (SP) were recorded from the FDI during motor activity. To measure intra-cortical inhibition (ICI), we also performed double-pulse TMS, applying subthreshold conditioning stimuli at interstimulus intervals of 2 ms. When single-pulse TMS was given just prior to muscle relaxation (-21 to -70 ms), the MEP was reduced while the SP was unchanged. Intra-cortical inhibition was smaller just prior to the muscle relaxation. Unilateral voluntary muscle relaxation may not be associated with activation of the intracortical inhibitory system, but rather with the possible excitation of the corticospinal system, which can inhibit motoneurons disynaptically. These findings suggest that multiple inhibitory mechanisms act in diverse ways to achieve motor inhibition.
Adult↗