- Email: [email protected]
46. The effect of sleep inertia after a nap during extended wakefulness on the error-monitoring ability
Society Proceedings / Clinical Neurophysiology 121 (2010) e19–e34
(EMG) showed denervation potentials in the left gastrocnemius, while the potentials in the long head of left biceps femoris were normal. Four months later, he developed left drop foot; NCS revealed low amplitudes in left peroneal CMAP by peroneal nerve stimulation and left sural nerve sensory action potential (SNAP). The left gluteus medius was not weak but showed denervation potentials in EMG. Presently, he showed marked muscle atrophy, sensory loss and occasional neuralgia in the left L5 and S1 segments. CMAPs and SNAPs were all absent in the left leg in NCS. Cerebrospinal fluid (CSF) analysis showed 7.0 cells/ll and elevated protein level. MRI revealed swelling in left L4–S2 nerve roots. A biopsy specimen of the left sural nerve demonstrated marked loss of myelinated and unmyelinated fibers. A left S1 nerve root biopsy specimen demonstrated T-lymphocyte infiltration within the roots and ganglia and root sheath thickening. CSF lymphocyte analysis later revealed IgH rearrangement and atypism, suggesting a diagnosis of neurolymphomatosis. doi:10.1016/j.clinph.2010.02.123
43. Assessment of cerebral ischemia using near infrared optical topography with inhalation of oxygen—Akira Ebihara, Takehiko Konno, Yuichi Tanaka, Eiju Watanabe (Jichi Medical University, Tochigi, Japan) Background: The drawbacks in assessing cerebral ischemia using conventional methods such as SPECT or angiography are invasiveness and inability to repeat measurements. We describe the use of near infrared optical topography (OT) to overcome these disadvantages. Methods: Twenty-five normal volunteers and 33 patients with cerebral ischemia were enrolled in this study on a 48-channel OT system covering the bilateral fronto-temporal areas. The subject inhaled pure oxygen for 2 min and fingertip SpO2 was monitored. All of the patients with ischemia underwent IMP-SPECT. Results: The concentration of oxy-hemoglobin determined by OT and the time course of SpO2 in normal volunteers increased in a trapezoidal pattern in accordance with oxygen inhalation, whereas the increase in oxy-hemoglobin was delayed and/or the peak was lower in ischemic areas. These findings suggested that transmission of the systemic SpO2 was delayed and/or reduced in areas of ischemia. Statistical assessment of the data using principal component analysis showed that the weight of the principal component in the ischemic regions was reduced, findings that agreed with those of IMP-SPECT. Conclusions: Our results suggested that regional attenuation of the oxy-hemoglobin wave reflects the status of cerebral ischemia, which can be non-invasively assessed using OT. doi:10.1016/j.clinph.2010.02.124
44. Evaluation of the results of motor evoked potentials monitoring during craniotomy—Ryuichi Abe, Masahiko Kawaguchi, Hironobu Hayashi, Yasushi Motoyama, Hiroyuki Nakase, Tsunenori Takatani, Tatsuko Imai, Hitoshi Furuya (Nara Medical University, Nara, Japan) We reviewed the results of motor evoked potentials (MEP) monitoring in 38 patients undergoing craniotomy at Nara Medical University, Nara, Japan. MEPs in response to transcranial stimulation (TcMEP) and direct cortical stimulation (dMEP) with train of five pulses were elicited and compound muscle action potentials were recorded from abductor pollicis brevis muscles. Anesthesia was
e29
maintained with sevoflurane (13 cases) or propofol (25 cases) based-regime. Continuous administration of neuromuscular blockade was performed in 22 cases. TcMEP monitoring was successful in 38 cases (100%), whereas dMEP monitoring was successful in 33 cases (86.8%). Reduction of dMEP amplitudes occurred in 3 cases (7.9%). Of these, dMEP reduction was recovered during surgery in 2 cases and sustained in 1 case with postoperative motor deficit. In a case in which MEPs could be monitored by only TcMEP, postoperative motor deficit developed regardless of no intraoperative changes in TcMEP (false negative result). These results suggest that, although application of TcMEP can increase success rate of MEP monitoring, it may reduce the reliability of MEP monitoring in patients undergoing craniotomy. doi:10.1016/j.clinph.2010.02.125
45. Effect of partial sleep deprivation on eye-blink parameters during Oxford sleep resistance test—Takashi Abe, Syoichi Asaoka, Yoko Komada, Aya Matsuzaki, Tomohide Nonomura, Taeko Sasai, Akira Usui, Akinori Ueno, Yuichi Inoue (Neuropsychiatric Research Institute, Tokyo, Japan) The aim of this study was to determine the effect of partial sleep deprivation (PSD) on eye-blink parameters during Oxford sleep resistance test (OSLER test). Ten healthy volunteers (M:F = 8:2, mean age: 23.4 ± 3.9 years old) participated in this study. All participants underwent the OSLER test at 10:00 a.m. after 8-h nocturnal sleep and after PSD allowing 4-h sleep. Eye-blinks during OSLER test were recorded using electrooculogram. Eye-blink parameters used for this study were duration, amplitude, velocity, and amplitude-velocity ratio (AVR: reciprocal of relative velocity; Johns and Tucker, 2005) for closing phase and reopening phase in each eye-blink. The value of AVR for reopening phase after PSD was significantly greater than that after nocturnal sleep. In addition, cut-off value of the each eyeblink parameter detecting sleepiness was determined as the average +2 SD of each value obtained during initial 3 min in OSLER test after nocturnal sleep. We found that durations for closing and reopening phase after PSD condition exceeded cut-off value was earlier than that in 8-h sleep condition. These findings suggest that PSD significantly affect some of eye-blink parameters during OSLER test and furthermore, eye-blink parameters can be useful indices for detecting sleepiness. doi:10.1016/j.clinph.2010.02.126
46. The effect of sleep inertia after a nap during extended wakefulness on the error-monitoring ability—Shoichi Asaoka, Yuichi Inoue, Kazuhiko Fukuda (Tokyo Medical University, Tokyo, Japan) We explored the effects of a 1-h nap on error-monitoring ability during a period of extended wakefulness, using two event-related potentials, i.e., error negativity/error-related negativity (Ne/ERN) and error positivity (Pe). Twenty-two young adults were participated in this study. Half of them took a 1-h nap, and the other had a 1-h awake-rest at 01:00–02:00. Participants performed a stimulusresponse compatibility task (the arrow-orientation task) before (21:00), immediately after (02:00), and 1-h after (03:00) the nap or awake-rest period. The results showed that behavioral performances and amplitude of Pe declined at midnight (i.e., 02:00 and/ or 03:00) in both groups. The participants in the awake-rest condition showed more non-responses (omissions) and fewer correct
e30
Society Proceedings / Clinical Neurophysiology 121 (2010) e19–e34
responses than those in the nap condition during the test period started at 03:00. However, concerning to Ne/ERN and Pe, there were no significant differences between the two conditions. These results suggest that the 1-h nap might prevent the decline in the behavioral performances during nighttime but it had no effect on the error monitoring ability. doi:10.1016/j.clinph.2010.02.127
Results: Stimulation of seizure onset zone induced significant increase of power in 12–16 Hz band and decrease in 22–30 Hz band, whereas stimulation of non-epileptogenic area induced significant decrease in 10–30 Hz band in the surrounding cortices (p < 0.01). Conclusions: In this patient, high frequency electric cortical stimulation of seizure onset zone and of non-epileptogenic area induced the distinct pattern of changes in power spectra in the surrounding cortices. doi:10.1016/j.clinph.2010.02.129
47. Postural control to unpredictable unilateral perturbation during stance—Masaki Hyodo, Mayumi Saito, Junichi Ushiba, Yutaka Tomita, Yoshihisa Masakado (Tokai University School of Medicine, Kanagawa, Japan) There are many reports of postural control to bilateral leg perturbations during stance. However, it remains unknown how balance was recovered when unilateral leg was perturbed during stance. We therefore investigated what and how muscles were activated by unilateral leg perturbations during stance. Ten young and healthy volunteers participated. EMG responses were recorded in both legs and trunk after uni- and bilateral leg perturbations directed forward or backward during stance on a treadmill with split belts. Backward perturbations were followed by EMG response in order of gastrocnemius (GC), hamstrings (Ham), paraspinal (Par). In unilateral perturbations, GC onset time of perturbed leg was earlier than non perturbed leg. In contrast Ham onset time of perturbed leg was later than non perturbed leg. Forward perturbations were followed by EMG response in order of Tibialis anterior (TA), Quadriceps femoris (Quad), Rectus abdominis (Abd). In unilateral perturbations, TA onset time of perturbed leg was earlier than non perturbed leg, but Quad onset time were approximately at the same time. This result suggests that non perturbed leg’s thigh muscles play an important part in postural control to unilateral leg perturbation. This study considered EMG activity and no kinematic analysis was performed. Further investigation is expected. doi:10.1016/j.clinph.2010.02.128
49. Morphological characteristics of MEG and EEG epileptiform discharge: Comparison of duration and number of peaks—Yohei Yokoyama, Riki Matsumoto, Morito Inouchi, Masao Matsuhashi, Nobuhiro Mikuni, Akio Ikeda, Takashi Nagamine, Hidenao Fukuyama, Susumu Miyamoto, Nobuo Hashimoto (Kyoto University, Kyoto, Japan) The purpose of this study is to compare the morphological characteristics between electroencephalography (EEG) and magnetoencephalography (MEG) epileptiform discharges. The subjects were seven patients with intractable epilepsy who showed frequent epileptiform discharges both on EEG and MEG. MEG (with 204 ch planar type gradiometers (GRA) and 102 ch magnetometers (MAG)) and EEG (standard 10-20) were recorded simultaneously. We selected the largest waves in EEG, GRA and MAG channels of each epileptiform discharge and compared their duration and number of peaks. The averaged duration of EEG, GRA, and MAG epileptiform discharge were 123, 102, and 104 ms, respectively, and the duration of EEG epileptiform discharges was significantly longer than that of MEG. Number of peaks of EEG epileptiform discharge was significantly less than that of MEG. 72% of EEG epileptiform discharges were monophasic, while 49% and 50% of GRA and MAG epileptiform discharges were polyphasic. This study suggests that MEG detects more polyphasic nature of epileptiform discharges than EEG does and each single epileptic wave has shorter duration in MEG than EEG. These morphological difference may reflect properties of MEG that can detect more localized and tangentially (mainly from sulci) oriented activities. doi:10.1016/j.clinph.2010.02.130
48. Change in cortical fast activities after high frequency electric cortical stimulation in a patient with cortical dysplasia and intractable epilepsy—Masako Kinoshita, Takahiro Mitsueda-Ono, Takefumi Hitomi, Junya Taki, Keiko Usui, Masao Matsuhashi, Riki Matsumoto, Nobuhiro Mikuni, Hidenao Fukuyama, Ryosuke Takahashi, Akio Ikeda (Utano National Hospital, Kyoto, Japan)
50. Change-related response in the human somatosensory cortex: An MEG study—Koya Yamashiro, Koji Inui, Naofumi Otsuru, Tomokazu Urakawa, Ryusuke Kakigi (National Institute for Physiological Sciences, Okazaki, Japan)
Objective: To analyze the stimulus-induced change in fast cortical activities of surrounding cortices after high frequency electric cortical stimulation in a patient with cortical dysplasia and intractable epilepsy. Methods: A 31-year-old patient with intractable partial epilepsy who underwent invasive presurgical evaluations using chronic subdural grids with inter-electrode distance of 1 cm and had a pathological diagnosis of focal cortical dysplasia type IIb was analyzed. Cortical functional mapping was performed for clinical purpose by using electric cortical stimulation (50 Hz, bipolar, alternating square pulse of 0.3 ms duration, 1–15 mA, within 5 s). For two stimulated sites (one in seizure onset zone, the other in non-epileptogenic area), stimulus-induced change in the surrounding cortices (24 electrodes in total) was evaluated by comparing ECoG power spectra between each 5 min of before and after stimulation.
Our recent study showed that both the onset and offset of somatosensory stimulation elicited a very similar magnetic component peaking at around 100 ms, ON-100m and OFF-100m, suggesting common generating mechanisms. In the present study, we recorded cortical activation in response to the onset and offset of a train of electrical pulses using magnetencephalography (MEG) while the subjects watched a silent movie to clarify the physiological significance of the somatosensory 100 m component. Four inter-trial intervals (ITIs) (0.5, 1.5, 3 and 6 s) were used for each of the two somatosensory events (ON and OFF). Results showed that (i) the two somatosensory events elicited 100 m with a similar topography and similar temporal profile, (ii) the amplitude of 100 m as a function of the duration of the steady state preceding the change (ITI) was similar among the two events, that is, the amplitude was linearly correlated with the logarithm of the ITI, and (iii) there was
(EMG) showed denervation potentials in the left gastrocnemius, while the potentials in the long head of left biceps femoris were normal. Four months later, he developed left drop foot; NCS revealed low amplitudes in left peroneal CMAP by peroneal nerve stimulation and left sural nerve sensory action potential (SNAP). The left gluteus medius was not weak but showed denervation potentials in EMG. Presently, he showed marked muscle atrophy, sensory loss and occasional neuralgia in the left L5 and S1 segments. CMAPs and SNAPs were all absent in the left leg in NCS. Cerebrospinal fluid (CSF) analysis showed 7.0 cells/ll and elevated protein level. MRI revealed swelling in left L4–S2 nerve roots. A biopsy specimen of the left sural nerve demonstrated marked loss of myelinated and unmyelinated fibers. A left S1 nerve root biopsy specimen demonstrated T-lymphocyte infiltration within the roots and ganglia and root sheath thickening. CSF lymphocyte analysis later revealed IgH rearrangement and atypism, suggesting a diagnosis of neurolymphomatosis. doi:10.1016/j.clinph.2010.02.123
43. Assessment of cerebral ischemia using near infrared optical topography with inhalation of oxygen—Akira Ebihara, Takehiko Konno, Yuichi Tanaka, Eiju Watanabe (Jichi Medical University, Tochigi, Japan) Background: The drawbacks in assessing cerebral ischemia using conventional methods such as SPECT or angiography are invasiveness and inability to repeat measurements. We describe the use of near infrared optical topography (OT) to overcome these disadvantages. Methods: Twenty-five normal volunteers and 33 patients with cerebral ischemia were enrolled in this study on a 48-channel OT system covering the bilateral fronto-temporal areas. The subject inhaled pure oxygen for 2 min and fingertip SpO2 was monitored. All of the patients with ischemia underwent IMP-SPECT. Results: The concentration of oxy-hemoglobin determined by OT and the time course of SpO2 in normal volunteers increased in a trapezoidal pattern in accordance with oxygen inhalation, whereas the increase in oxy-hemoglobin was delayed and/or the peak was lower in ischemic areas. These findings suggested that transmission of the systemic SpO2 was delayed and/or reduced in areas of ischemia. Statistical assessment of the data using principal component analysis showed that the weight of the principal component in the ischemic regions was reduced, findings that agreed with those of IMP-SPECT. Conclusions: Our results suggested that regional attenuation of the oxy-hemoglobin wave reflects the status of cerebral ischemia, which can be non-invasively assessed using OT. doi:10.1016/j.clinph.2010.02.124
44. Evaluation of the results of motor evoked potentials monitoring during craniotomy—Ryuichi Abe, Masahiko Kawaguchi, Hironobu Hayashi, Yasushi Motoyama, Hiroyuki Nakase, Tsunenori Takatani, Tatsuko Imai, Hitoshi Furuya (Nara Medical University, Nara, Japan) We reviewed the results of motor evoked potentials (MEP) monitoring in 38 patients undergoing craniotomy at Nara Medical University, Nara, Japan. MEPs in response to transcranial stimulation (TcMEP) and direct cortical stimulation (dMEP) with train of five pulses were elicited and compound muscle action potentials were recorded from abductor pollicis brevis muscles. Anesthesia was
e29
maintained with sevoflurane (13 cases) or propofol (25 cases) based-regime. Continuous administration of neuromuscular blockade was performed in 22 cases. TcMEP monitoring was successful in 38 cases (100%), whereas dMEP monitoring was successful in 33 cases (86.8%). Reduction of dMEP amplitudes occurred in 3 cases (7.9%). Of these, dMEP reduction was recovered during surgery in 2 cases and sustained in 1 case with postoperative motor deficit. In a case in which MEPs could be monitored by only TcMEP, postoperative motor deficit developed regardless of no intraoperative changes in TcMEP (false negative result). These results suggest that, although application of TcMEP can increase success rate of MEP monitoring, it may reduce the reliability of MEP monitoring in patients undergoing craniotomy. doi:10.1016/j.clinph.2010.02.125
45. Effect of partial sleep deprivation on eye-blink parameters during Oxford sleep resistance test—Takashi Abe, Syoichi Asaoka, Yoko Komada, Aya Matsuzaki, Tomohide Nonomura, Taeko Sasai, Akira Usui, Akinori Ueno, Yuichi Inoue (Neuropsychiatric Research Institute, Tokyo, Japan) The aim of this study was to determine the effect of partial sleep deprivation (PSD) on eye-blink parameters during Oxford sleep resistance test (OSLER test). Ten healthy volunteers (M:F = 8:2, mean age: 23.4 ± 3.9 years old) participated in this study. All participants underwent the OSLER test at 10:00 a.m. after 8-h nocturnal sleep and after PSD allowing 4-h sleep. Eye-blinks during OSLER test were recorded using electrooculogram. Eye-blink parameters used for this study were duration, amplitude, velocity, and amplitude-velocity ratio (AVR: reciprocal of relative velocity; Johns and Tucker, 2005) for closing phase and reopening phase in each eye-blink. The value of AVR for reopening phase after PSD was significantly greater than that after nocturnal sleep. In addition, cut-off value of the each eyeblink parameter detecting sleepiness was determined as the average +2 SD of each value obtained during initial 3 min in OSLER test after nocturnal sleep. We found that durations for closing and reopening phase after PSD condition exceeded cut-off value was earlier than that in 8-h sleep condition. These findings suggest that PSD significantly affect some of eye-blink parameters during OSLER test and furthermore, eye-blink parameters can be useful indices for detecting sleepiness. doi:10.1016/j.clinph.2010.02.126
46. The effect of sleep inertia after a nap during extended wakefulness on the error-monitoring ability—Shoichi Asaoka, Yuichi Inoue, Kazuhiko Fukuda (Tokyo Medical University, Tokyo, Japan) We explored the effects of a 1-h nap on error-monitoring ability during a period of extended wakefulness, using two event-related potentials, i.e., error negativity/error-related negativity (Ne/ERN) and error positivity (Pe). Twenty-two young adults were participated in this study. Half of them took a 1-h nap, and the other had a 1-h awake-rest at 01:00–02:00. Participants performed a stimulusresponse compatibility task (the arrow-orientation task) before (21:00), immediately after (02:00), and 1-h after (03:00) the nap or awake-rest period. The results showed that behavioral performances and amplitude of Pe declined at midnight (i.e., 02:00 and/ or 03:00) in both groups. The participants in the awake-rest condition showed more non-responses (omissions) and fewer correct
e30
Society Proceedings / Clinical Neurophysiology 121 (2010) e19–e34
responses than those in the nap condition during the test period started at 03:00. However, concerning to Ne/ERN and Pe, there were no significant differences between the two conditions. These results suggest that the 1-h nap might prevent the decline in the behavioral performances during nighttime but it had no effect on the error monitoring ability. doi:10.1016/j.clinph.2010.02.127
Results: Stimulation of seizure onset zone induced significant increase of power in 12–16 Hz band and decrease in 22–30 Hz band, whereas stimulation of non-epileptogenic area induced significant decrease in 10–30 Hz band in the surrounding cortices (p < 0.01). Conclusions: In this patient, high frequency electric cortical stimulation of seizure onset zone and of non-epileptogenic area induced the distinct pattern of changes in power spectra in the surrounding cortices. doi:10.1016/j.clinph.2010.02.129
47. Postural control to unpredictable unilateral perturbation during stance—Masaki Hyodo, Mayumi Saito, Junichi Ushiba, Yutaka Tomita, Yoshihisa Masakado (Tokai University School of Medicine, Kanagawa, Japan) There are many reports of postural control to bilateral leg perturbations during stance. However, it remains unknown how balance was recovered when unilateral leg was perturbed during stance. We therefore investigated what and how muscles were activated by unilateral leg perturbations during stance. Ten young and healthy volunteers participated. EMG responses were recorded in both legs and trunk after uni- and bilateral leg perturbations directed forward or backward during stance on a treadmill with split belts. Backward perturbations were followed by EMG response in order of gastrocnemius (GC), hamstrings (Ham), paraspinal (Par). In unilateral perturbations, GC onset time of perturbed leg was earlier than non perturbed leg. In contrast Ham onset time of perturbed leg was later than non perturbed leg. Forward perturbations were followed by EMG response in order of Tibialis anterior (TA), Quadriceps femoris (Quad), Rectus abdominis (Abd). In unilateral perturbations, TA onset time of perturbed leg was earlier than non perturbed leg, but Quad onset time were approximately at the same time. This result suggests that non perturbed leg’s thigh muscles play an important part in postural control to unilateral leg perturbation. This study considered EMG activity and no kinematic analysis was performed. Further investigation is expected. doi:10.1016/j.clinph.2010.02.128
49. Morphological characteristics of MEG and EEG epileptiform discharge: Comparison of duration and number of peaks—Yohei Yokoyama, Riki Matsumoto, Morito Inouchi, Masao Matsuhashi, Nobuhiro Mikuni, Akio Ikeda, Takashi Nagamine, Hidenao Fukuyama, Susumu Miyamoto, Nobuo Hashimoto (Kyoto University, Kyoto, Japan) The purpose of this study is to compare the morphological characteristics between electroencephalography (EEG) and magnetoencephalography (MEG) epileptiform discharges. The subjects were seven patients with intractable epilepsy who showed frequent epileptiform discharges both on EEG and MEG. MEG (with 204 ch planar type gradiometers (GRA) and 102 ch magnetometers (MAG)) and EEG (standard 10-20) were recorded simultaneously. We selected the largest waves in EEG, GRA and MAG channels of each epileptiform discharge and compared their duration and number of peaks. The averaged duration of EEG, GRA, and MAG epileptiform discharge were 123, 102, and 104 ms, respectively, and the duration of EEG epileptiform discharges was significantly longer than that of MEG. Number of peaks of EEG epileptiform discharge was significantly less than that of MEG. 72% of EEG epileptiform discharges were monophasic, while 49% and 50% of GRA and MAG epileptiform discharges were polyphasic. This study suggests that MEG detects more polyphasic nature of epileptiform discharges than EEG does and each single epileptic wave has shorter duration in MEG than EEG. These morphological difference may reflect properties of MEG that can detect more localized and tangentially (mainly from sulci) oriented activities. doi:10.1016/j.clinph.2010.02.130
48. Change in cortical fast activities after high frequency electric cortical stimulation in a patient with cortical dysplasia and intractable epilepsy—Masako Kinoshita, Takahiro Mitsueda-Ono, Takefumi Hitomi, Junya Taki, Keiko Usui, Masao Matsuhashi, Riki Matsumoto, Nobuhiro Mikuni, Hidenao Fukuyama, Ryosuke Takahashi, Akio Ikeda (Utano National Hospital, Kyoto, Japan)
50. Change-related response in the human somatosensory cortex: An MEG study—Koya Yamashiro, Koji Inui, Naofumi Otsuru, Tomokazu Urakawa, Ryusuke Kakigi (National Institute for Physiological Sciences, Okazaki, Japan)
Objective: To analyze the stimulus-induced change in fast cortical activities of surrounding cortices after high frequency electric cortical stimulation in a patient with cortical dysplasia and intractable epilepsy. Methods: A 31-year-old patient with intractable partial epilepsy who underwent invasive presurgical evaluations using chronic subdural grids with inter-electrode distance of 1 cm and had a pathological diagnosis of focal cortical dysplasia type IIb was analyzed. Cortical functional mapping was performed for clinical purpose by using electric cortical stimulation (50 Hz, bipolar, alternating square pulse of 0.3 ms duration, 1–15 mA, within 5 s). For two stimulated sites (one in seizure onset zone, the other in non-epileptogenic area), stimulus-induced change in the surrounding cortices (24 electrodes in total) was evaluated by comparing ECoG power spectra between each 5 min of before and after stimulation.
Our recent study showed that both the onset and offset of somatosensory stimulation elicited a very similar magnetic component peaking at around 100 ms, ON-100m and OFF-100m, suggesting common generating mechanisms. In the present study, we recorded cortical activation in response to the onset and offset of a train of electrical pulses using magnetencephalography (MEG) while the subjects watched a silent movie to clarify the physiological significance of the somatosensory 100 m component. Four inter-trial intervals (ITIs) (0.5, 1.5, 3 and 6 s) were used for each of the two somatosensory events (ON and OFF). Results showed that (i) the two somatosensory events elicited 100 m with a similar topography and similar temporal profile, (ii) the amplitude of 100 m as a function of the duration of the steady state preceding the change (ITI) was similar among the two events, that is, the amplitude was linearly correlated with the logarithm of the ITI, and (iii) there was