Seiichiro Mine

Parietal cortex neurons of the monkey related to the visual guidance of hand movement

SummaryA class of neurons specifically related to hand movements was studied in the posterior parietal cortex while the monkeys manipulated different types of objects. We examined the neuronal activity during manipulation of objects by the hand in the light and in the dark. Fiftyfive neurons were active during manipulation in the dark and were classified as “hand-movement-related” neurons. Of these, 38/55 (69%) cells were also influenced by the visual stimulus. Most of the hand-movement-related neurons were selective in the type of objects manipulated. Moreover, some of these cells were selective in the axis of orientation of the object. These results suggest that the hand-movement-related neurons of the parietal cortex are concerned with the visual guidance of the hand movement, especially in matching the pattern of movement with the spatial characteristics of the object to be manipulated.

Functional properties of rotation-sensitive neurons in the posterior parietal association cortex of the monkey

We studied the functional properties of rotation-sensitive (RS) neurons of the posterior parietal association cortex in detail. We classified 58 neurons as RS neurons on the basis of statistical analysis, to indicate that their responses to rotary movement were significantly greater (P<0.01) than those to linear movement of the same stimulus. We calculated rotation index, 1 — (L/R), in 82 cells, where L/R is the ratio of net response to linear movement to that to rotary movement. All the RS neurons had rotation index greater than or equal to 0.3. The recording site of these RS neurons was localized in the posterolateral part of area PG (area 7a of Vogt), on the anterior bank of the caudal superior temporal sulcus (STS), in the region partly overlapping the medial superior temporal (MST) area. We compared the response of RS neurons to rotation with that to shearing movement as well as to linear movement. In the majority of RS neurons the ratio of shearing response to rotation response (S/R) was smaller than the ratio of linear response to rotation response (L/R), indicating that the response to rotation was not due to a simple combination of linear movements in the opposite direction. Most of the RS neurons responded to the rotary movement of a single spot as well as that of a slit, although the response was smaller (average 70%) for the former. Most of the RS neurons had large receptive fields (60–180° in diameter) and their responses were independent of the position within the receptive field. The responses of most RS neurons increased monotonically with the increase in angular velocity and were also dependent on the size of the stimulus, although the rate of increase was small when the length was more than 10°. The majority of RS neurons (37/58) responded better to rotation in depth than to that in the frontoparallel plane. Some of them (12/37) responded to diagonal rotation rather than to sagittal or horizontal rotation. We found that some depth RS neurons showed reversal in the preferred direction when we used a trapezoidal window-like plate as the rotating stimulus in the monocular viewing condition, just as occurs in the case of the Ames window illusion. The response of some RS neurons (5/7) was enhanced by tracking eye movement. The enhanced responses were observed during rotary tracking but not during linear tracking. Other RS neurons (n = 2) showed maximum response to the rotation of the monkey chair in the light, as a result of convergence of visual and vestibular signals. We concluded that the continuous change of direction of movement was the most important cue for RS neurons to respond selectively to rotary movement in contrast to linear translational movement, and that these neurons were likely to discriminate the direction and orientation of the plane of rotation of the object in space.

Outcome of Traumatic Optic Neuropathy. Comparison Between Surgical and Nonsurgical Treatment

Summary 34 patients with indirect traumatic optic neuropathy were studied to identify factors affecting outcome and surgical indications. 12 cases (13 eyes = group A) underwent surgery and 24 patients (24 eyes = group B) were managed without surgery. Age, optic canal fracture, visual acuity before treatment (initial visual acuity) and days until surgery (only group A) were employed as variables. Visual acuity improved significantly more in patients with initial visual acuity, hand movement (HM) or better than in those with initial visual acuity for light perception (LP) only or worse. When initial visual acuity was HM or better, vision improved significantly more in patients with surgery than in those without surgery (p=0.0003) by Mann-Whitney U test). Days until surgery were correlated with visual improvement in patients with visual acuity HM or better. Age and optic canal fracture did not affect visual improvement or influence the decision for or against surgery.

Evaluation of outcome and QOL in patients with craniofacial resection for malignant tumors involving the anterior skull base.

Abstract The purpose of this study was to retrospectively evaluate the effectiveness of anterior craniofacial resection in the treatment of nasal and paranasal malignant tumors involving anterior skull base. Between 1992 and 1998, 13 patients with nasal or paranasal malignant tumors underwent this surgical procedure. The site and time of metastasis or recurrence, and survival outcome were retrospectively surveyed. Current status of long-surviving patients and their subjective assessment of the surgical treatment were also evaluated through questionnaires. Median follow-up period was 52 months. Nine patients (69%) were alive with no evidence of disease. Of these patients, eight had survived for more than three years. Recurrence or metastasis occurred in four patients (31%). The mean time interval between surgery and recurrence or metastasis was 11 months. According to the results of questionnaires to long-surviving patients, 89% patients had some complaints. In particular, complaints of unsightly appearance were manifested by all these patients. When the patients themselves evaluated their current conditions resulting from this surgical treatment, 63% were dissatisfied. These results suggest that this surgical treatment is valid for selected patients in regard to survival outcome. When the effectiveness of this treatment is evaluated, however, psychological and functional issues should not be taken lightly. [Neurol Res 2000; 22: 545-550]

Risk factors for poor outcome of untreated arteriovenous malformation.

This study was conducted to determine risk factors for poor outcome in the natural history of arteriovenous malformation (AVM). We statistically analysed the correlation between clinical or angiographical findings and clinical outcomes for 55 cases of untreated AVM. Subsequent haemorrhage from AVMs was the only significant risk factor for poor outcome (P< 0.0001). The odds ratio was 44.56 with a 95% confidence interval (CI) from 4.80 to 413.90. Risk factors for subsequent haemorrhage from AVMs were also determined. The size (P = 0.0483) and location (P = 0.0147) of an AVM were significant risk factors for subsequent haemorrhage. The odds ratios were 3.97 with a 95% CI from 1.18 to 13.33 and 3.89 with a 95% CI from 1.10 to 13.72, respectively. AVMs of more than 60 mm, and deep or infratentorial AVMs had more chance of subsequent haemorrhage, and hence of a poor outcome. We propose using an aggressive multidisciplinary approach to treating these AVMs.

Different patterns of dipole source localization in gelastic seizure with or without a sense of mirth

Dipole source localization corresponding to interictal spikes were estimated using EEG dipole tracing with a realistic three-shell head model in three patients with cryptogenic gelastic epilepsy. The dipole sources in two patients, whose gelastic seizures were accompanied by a subjective feeling of mirth, were estimated in the right or left medio-basal temporal regions. In the other patient, with gelastic seizures without a sense of mirth, the dipole sources were localized in the right frontal region corresponding to the anterior cingulate. The results suggest that the neural activities in hippocampal regions are involved with the generation of gelastic seizures with a sense of mirth and those in the cingulate might be associated with the motor act of laughter.

Involvement of highly polysialylated neural cell adhesion molecule (PSA-NCAM)-positive granule cells in the amygdaloid-kindling-induced sprouting of a hippocampal mossy fiber trajectory.

The mossy fiber system in the hippocampus of amygdaloid-kindled rats was examined by using highly polysialylated neural cell adhesion molecule (PSA-NCAM) as a marker for immunohistochemical detection of immature dentate granule cells and mossy fibers in combination with bromodeoxyuridine (BrdU) labeling of newly generated granule cells. Statistically significant increases in BrdU-labeled cells and PSA-NCAM-positive cells occurred in the dentate gyrus following kindling. The increase in PSA-NCAM-immunoreactive neurites was confined to the entire stratum lucidum of CA3. Immunoelectron-microscopic examination also revealed that PSA-NCAM-positive immature synaptic terminals of the sprouting mossy fibers increased in the stratum lucidum of CA3 in the kindled rats. The increase in the numbers of PSA-NCAM-positive granule cells correlated well with the increase in the immunopositive neurites and synaptic terminals on the mossy fiber trajectory. The increase in these PSA-NCAM-immunopositive structures is thought to reflect the enhancement of sprouting and synaptogenesis of mossy fibers by a subset of granule cells newly generated during amygdaloid-kindling and suggests that the reorganization of the mossy fiber system on the normal trajectory at least in part contributes to the acquisition and maintenance of an epileptogenic state.

Dipole source localization of ictal epileptiform activity.

DIPOLE source localization of ictal epileptiform activity recorded by scalp EEG was performed in patients prior to surgical treatment. The dipole tracing method combined with the scalp—skull—brain head model was used to locate epileptogenic foci. A digital EEG system was used for data collection. The accuracy of dipole source localization was evaluated by comparing the focus location with that obtained by chronic subdural electrocorticography. In a case of frontal lobe epilepsy with epileptogenic focus in the frontoparietal convexity, the results of dipole source localization agreed well with those obtained with chronic subdural electrocorticography. In a case of lateral temporal lobe epilepsy, the results of dipole source localization were consistent with those obtained with chronic subdural electrocorticography, but a small localization error was observed. The clinical usefulness of and suggestions for improving this method are discussed.

Fascicular arrangement within the oculomotor nerve MRI analysis of a midbrain infarct

The fascicular arrangement of the oculomotor nerve within the midbrain is not adequately elucidated in humans. We treated a patient with a partial oculomotor palsy who had impaired adduction and supraduction on the left side, which were attributed to an ipsilateral lacunar infarct. CT and MRI revealed a discrete lesion in the centre of the midbrain tegmentum in the rostrocaudal plane. This case suggests that the oculomotor fibres for extraocular movement are located in the middle of the the midbrain, and supports the fascicular proximity of the superior and medial rectus muscles. The fascicular arrangement of the midbrain oculomotor nerve is speculated to be pupillary component, extraocular movement and eyelid elevation in that rostrocaudal order, based on the previous reports of neuro-ophthalmological impairment and MRI findings, which are analogous to the nuclear arrangement proposed by Warwick.

Eosinophilia of the cerebrospinal fluid in a case of shunt infection: case report

A very rare case of eosinophilic granulocytosis of the cerebrospinal fluid (CSF eosinophilia) due to drug allergy caused by the intraventricular administration of gentamicin sulfate is presented with a review of the pertinent literature. An unusual clinical course and clinicoimmunological examination are also described.