-
Takeshi Matsuo,
Keisuke Kawasaki,
Takahiro Osada,
Hirohito Sawahata,
Takafumi Suzuki,
Masahiro Shibata,
Naohisa Miyakawa,
Kiyoshi Nakahara, Atsuhiko Iijima,
Noboru Sato,
Kensuke Kawai,
Nobuhito Saito,
Isao Hasegawa
[show abstract]
[hide abstract]
ABSTRACT: Electrocorticography (ECoG), multichannel brain-surface recording and stimulation with probe electrode arrays, has become a potent methodology not only for clinical neurosurgery but also for basic neuroscience using animal models. The highly evolved primate's brain has deep cerebral sulci, and both gyral and intrasulcal cortical regions have been implicated in important functional processes. However, direct experimental access is typically limited to gyral regions, since placing probes into sulci is difficult without damaging the surrounding tissues. Here we describe a novel methodology for intrasulcal ECoG in macaque monkeys. We designed and fabricated ultra-thin flexible probes for macaques with micro-electro-mechanical systems technology. We developed minimally invasive operative protocols to implant the probes by introducing cutting-edge devices for human neurosurgery. To evaluate the feasibility of intrasulcal ECoG, we conducted electrophysiological recording and stimulation experiments. First, we inserted parts of the Parylene-C-based probe into the superior temporal sulcus to compare visually evoked ECoG responses from the ventral bank of the sulcus with those from the surface of the inferior temporal cortex. Analyses of power spectral density and signal-to-noise ratio revealed that the quality of the ECoG signal was comparable inside and outside of the sulcus. Histological examination revealed no obvious physical damage in the implanted areas. Second, we placed a modified silicone ECoG probe into the central sulcus and also on the surface of the precentral gyrus for stimulation. Thresholds for muscle twitching were significantly lower during intrasulcal stimulation compared to gyral stimulation. These results demonstrate the feasibility of intrasulcal ECoG in macaques. The novel methodology proposed here opens up a new frontier in neuroscience research, enabling the direct measurement and manipulation of electrical activity in the whole brain.
Frontiers in Systems Neuroscience 01/2011; 5:34.
-
[show abstract]
[hide abstract]
ABSTRACT: Recently available coronal fast magnetic resonance imaging (MRI) has very high spatial resolution with good contrast between the optic nerves and cerebrospinal fluid (CSF). The aim of this study was to evaluate the diagnostic value of coronal fast imaging in optic nerve diseases. Thirty-five patients with various Neuro-ophthalmic conditions including 9 with optic neuritis, 6 with optic atrophy, 5 with glaucoma, 4 with segmental optic nerve hypoplasia and 11 with other optic neuropathies including orbital apex syndrome were evaluated with the three-dimensional fast imaging employing steady-state acquisition (FIESTA) sequence in addition to standard MRI protocols. The optic nerve complexes were evaluated on coronal images of the orbits. Detailed demonstration of the optic nerve complex—the optic nerve, the perineural CSF space and dural sheath—could be readily obtained with FIESTA sequence. The acute phase of both optic neuritis and perineuritis showed enlargement of the perineural CSF space; the optic nerve was swollen in optic neuritis but not in perineuritis. Cases of optic atrophy and glaucoma showed perineural CSF space enlargement with normal optic sheath circumference and a thinner optic nerve, while optic nerve hypoplasia showed a smaller dural sheath circumference without perineural CSF space enlargement. In the cases of orbital apex syndrome optic nerve compression by the extraocular muscles was clearly shown. Coronal FIESTA imaging of the orbit is capable of delineating detailed structural changes in the optic nerve complex and is of diagnostic value for the differentiation of optic nerve diseases.
04/2010; 34(2):88-95.
-
[show abstract]
[hide abstract]
ABSTRACT: Relative afferent pupillary defects (RAPDs) in amblyopia have been reported, and it is widely accepted that amblyopes can have an RAPD. We investigated whether or not this could be confirmed by the use of binocular pupillography. We examined twelve patients (6 males and 6 females, aged 7-57 years) with unilateral amblyopia associated with anisometropia and/or strabismus, using binocular infrared video pupillography (Newopto, Kawasaki, Japan). Eight normal subjects were also tested in the same manner. Two patients' data had to be excluded because of poor recording quality. Only one patient with moderate anisometropic amblyopia was found to have reduced contraction amplitude in the amblyopic eye, and one patient with a borderline pupillary defect. The other amblyopes, some of whom showed even denser amblyopia, did not have a pupillary defect. This study has confirmed that only a small proportion of amblyopes have a reduced pupillary contraction amplitude in the affected eye, as established by pupillographic recordings, and even these amblyopes are not necessarily associated with dense amblyopia.
Clinical ophthalmology (Auckland, N.Z.) 01/2009; 2(4):781-6.
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate visually-induced motion sickness, we integrated subjective and objective responses in terms of autonomic nervous regulation. Twenty-seven subjects viewed a 2-min-long first-person-view video section five times (total 10 min) continuously. Measured biosignals, the RR interval, respiration, and blood pressure, were used to estimate the indices related to autonomic nervous activity (ANA). Then we determined the trigger points and some sensation sections based on the time-varying behavior of ANA-related indices. We found that there was a suitable combination of biosignals to present the symptoms of visually-induced motion sickness. Based on the suitable combination, integrating trigger points and subjective scores allowed us to represent the time-distribution of subjective responses during visual exposure, and helps us to understand what types of camera motions will cause visually-induced motion sickness.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2008; 2008:4597-600.
-
[show abstract]
[hide abstract]
ABSTRACT: Taking advantage of developed image technology, it is expected that image presentation would be utilized to promote health in the field of medical care and public health. To accumulate knowledge on biomedical effects induced by image presentation, an essential prerequisite for these purposes, studies on autonomic responses in more than one physiological system would be necessary. In this study, changes in parameters of the pupillary light reflex and cardiovascular reflex evoked by motion pictures were examined, which would be utilized to evaluate the effects of images, and to avoid side effects.
Three stereoscopic video movies with different properties were field-sequentially rear-projected through two LCD projectors on an 80-inch screen. Seven healthy young subjects watched movies in a dark room. Pupillary parameters were measured before and after presentation of movies by an infrared pupillometer. ECG and radial blood pressure were continuously monitored. The maximum cross-correlation coefficient between heart rate and blood pressure, rho max, was used as an index to evaluate changes in the cardiovascular reflex.
Parameters of pupillary and cardiovascular reflexes changed differently after subjects watched three different video movies. Amplitudes of the pupillary light reflex, CR, increased when subjects watched two CG movies (movies A and D), while they did not change after watching a movie with the real scenery (movie R). The rho max was significantly larger after presentation of the movie D. Scores of the questionnaire for subjective evaluation of physical condition increased after presentation of all movies, but their relationship with changes in CR and rho max was different in three movies. Possible causes of these biomedical differences are discussed.
The autonomic responses were effective to monitor biomedical effects induced by image presentation. Further accumulation of data on multiple autonomic functions would contribute to develop the tools which evaluate the effects of image presentation to select applicable procedures and to avoid side effects in the medical care and rehabilitation.
Journal of NeuroEngineering and Rehabilitation 02/2007; 4:37. · 3.26 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Application of virtual environment (VE) technology to motor rehabilitation increases the number of possible rehabilitation tasks and/or exercises. However, enhancing a specific sensory stimulus sometimes causes unpleasant sensations or fatigue, which would in turn decrease motivation for continuous rehabilitation. To select appropriate tasks and/or exercises for individuals, evaluation of physical activity during recovery is necessary, particularly the changes in the relationship between autonomic nervous activity (ANA) and sensory stimuli.
We estimated the ANA from the R-R interval time series of electrocardiogram and incoming sensory stimuli that would activate the ANA. For experiments in real exercise, we measured vehicle data and electromyogram signals during cycling exercise. For experiments in virtual exercise, we measured eye movement in relation to image motion vectors while the subject was viewing a mountain-bike video image from a first-person viewpoint.
For the real cycling exercise, the results were categorized into four groups by evaluating muscle fatigue in relation to the ANA. They suggested that fatigue should be evaluated on the basis of not only muscle activity but also autonomic nervous regulation after exercise. For the virtual exercise, the ANA-related conditions revealed a remarkable time distribution of trigger points that would change eye movement and evoke unpleasant sensations.
For expanding the options of motor rehabilitation using VE technology, approaches need to be developed for simultaneously monitoring and separately evaluating the activation of autonomic nervous regulation in relation to neuromuscular and sensory systems with different time scales.
Journal of NeuroEngineering and Rehabilitation 02/2007; 4:38. · 3.26 Impact Factor
-
Virtual Reality, Second International Conference, ICVR 2007, Held as part of HCI International 2007, Beijing, China, July 22-27, 2007, Proceedings; 01/2007
-
[show abstract]
[hide abstract]
ABSTRACT: Recently, some studies have indicated that pupillary function only correlates with state/trait anxiety in healthy subjects. In the present study, we examined whether or not there were relationships between the PLR functions and state/trait anxiety in remitted (the absence of panic attack (PA) symptoms for at least 6 months) PD patients compared to normal control (NC) subjects.
Before and after audiovisual stimulation (AS) that induced mental stress through exposure to video images of high stress experiences, such as driving motor vehicles, the pupillary light reflex (PLR) was measured with an infrared pupillometer in 30 remitted PD patients and 30 age- and gender-matched NC subjects. In order to examine the relationships between the 8 PLR parameters (initial pupillary diameter in darkness, pupillary diameter at maximum constriction, constriction ratio, latency of the reflex, time to reach maximum constriction and time constant of redilation) and state/trait anxiety, we used the State-Trait Anxiety Inventory (STAI) and stepwise multiple regression analysis.
There was no significant group difference in the STAI-T score and STAI-S scores before and after AS. We confirmed the significant relationships between pupillary function and state/trait anxiety in NC subjects, but not in PD patients.
These findings suggest that in contrast to NCs, even remitted PD patients may have dysfunctional PLR regulation with mental loading, such as AS. Moreover, it is possible that the abnormalities of ANS exist extensively in PD, since almost all panic symptoms, including PA, are involved in cardiovascular symptoms, but not pupillary ones.
Journal of Affective Disorders 11/2006; 95(1-3):159-64. · 3.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: CASE REPORT: Few previous reports have documented a relative afferent pupillary defect (RAPD) in the eye contralateral to a dense unilateral cataract. We report pupillographic findings of a 55-year-old man with a mature cataract in the left eye and an RAPD in the right eye, whose RAPD disappeared after cataract surgery in his left eye. Using binocular infrared video pupillography, we recorded the pupillary responses of the two eyes simultaneously during an automated swinging flashlight test before and after the cataract surgery. The average contraction amplitude in both eyes was significantly larger when the unaffected left eye was stimulated before the cataract surgery, but this difference in contraction amplitude disappeared after surgery on the left eye. COMMENTS: An RAPD was shown quantitatively with a pupillographic technique in the eye contralateral to a mature cataract, confirming previous studies that indicate a dense cataract may produce a small but definite RAPD in the contralateral eye. Such an RAPD associated with a dense cataract must be taken into consideration when evaluating patients with unilateral visual loss.
Canadian Journal of Ophthalmology 09/2006; 41(4):469-71. · 1.47 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Asthenopia, or visual fatigue, is a frequent complaint from observers of stereoscopic three-dimensional displays. It has been proposed that asthenopia is a consequence of anomalous oculomotor responses generated by conflict between accommodative and convergence stimuli. The hypothesis was examined by measuring accommodation and convergence continuously with a Shin-Nippon SRW5000 infrared autorefractor and a limbus tracking device. Subjects viewed a high contrast Maltese Cross target at three levels of Gaussian filter target blur under conditions of relatively low- and high-conflict between accommodation and convergence stimuli, the latter inducing the sensation of stereopsis. Under the low-conflict conditions accommodation was stable, but convergence-driven accommodation was dominant when the target was extremely blurred. Under the high-conflict conditions the role of convergence-driven accommodation increased systematically with the degree of target blur. It is proposed that defocus-driven accommodation becomes weak when the target comprises low spatial frequency components. Large accommodative overshoots to step stimuli that are not blurred or only mildly blurred were consistently observed and are attributed to the initial accommodative response being convergence-driven. Whereas the possibility that high-conflict conditions are a cause of asthenopia has been previously reported, this is the first evidence that they specifically affect accommodative responses while viewing stereoscopic displays.
Vision Research 03/2006; 46(4):475-84. · 2.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Our purpose was to investigate the changes in the dynamic property of vergence eye movements caused by changes in the co-existing stationary background in the central visual field.
Disparity-driven target movement was presented virtually by a head-mounted liquid-crystal display. Two targets were used: a bar-shaped target that moved between 2 and 0.5 m along the mid-sagittal line at a speed of 50 cm/s (vergence target) and a background image of a cross-shaped target that stayed at a distance of 2 m (background target). Eight normal subjects participated in the experiments. The subject was asked to follow the vergence target while the configuration of the background target was randomly changed among four conditions in each experiment: the length (experiment 1) or the width (experiment 2) of the horizontal and vertical lines composing the cross of the background target was each randomly changed among four conditions. A limbus tracker was used to measure eye movements.
In experiment 1, there was a negative correlation between the amplitude of the vergence eye movements and the lengths of the lines of the cross in each of five subjects (mean r = 0.018, n = 48 in each subject). Similarly, in experiment 2, there was a negative correlation between the amplitude of the vergence eye movements and the width of the lines of the cross in each of 8 subjects (mean r = -0.12, n = 48 in each subject).
The vergence response to a target object significantly differs depending on the texture of background objects on the visual axis.
Ophthalmologica 02/2006; 220(2):94-100. · 1.42 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: For expanding application of virtual reality, such as rehabilitation engineering, concerns of cybersicknes should be cleared. We have investigated changes in autonomic regulations under real cycling and virtual mountain biking video with the first-person viewpoint. The results showed that the dominant sensory stimuli affected autonomic regulation with different process. The different process will lead to the hints for preventing cybersickness.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2005; 5:4994-7.
-
[show abstract]
[hide abstract]
ABSTRACT: Pupillary responses to light were recorded in three patients with unilateral extensive myelinated nerve fibers and amblyopia by means of binocular infrared video pupillography. All of the patients had an afferent pupillary defect in the eye with myelinated nerve fibers. This finding supports the notion that this type of amblyopia is a severe form of anisometropic amblyopia that is often resistant to treatment.
Journal of Pediatric Ophthalmology & Strabismus 45(5):309-12. · 0.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 映像技術が目覚しく発展する一方で，映像酔い等，生体への影響が懸念されており，原因の解明と評価手法の確立が望まれている．本研究では生体影響の中でも特に映像酔いに注目し，生体情報と映像情報との関係から生体に影響を与えていると予想される特徴を動きベクトルで定量的に評価することを目的とした．まず生体信号から，設定した条件に当てはまる生体影響区間を定め，影響を受けたと想定されるトリガ時刻を定義した．その後，トリガ時刻近傍における映像の動きベクトルの時間周波数構造を調べ，単純類似度による評価を行った．更に，動きベクトルからシミュレーション映像（ランダムドットパターン）を制作し，実写映像との比較を行った．その結果，トリガ時刻での時間周波数構造は特定の成分をもち，0.3〜2.5Hzの周波数帯域に0.5以上の規格化パワーをもつ動きベクトルが生体に影響を与えている可能性が示唆された．
