Endpoint accuracy in saccades interrupted by stimulation in the omnipause region in monkey

Electrical stimulation of the omnipause neuron region (OPN) at saccade onset results in interrupted saccades (IS)- eye movements which pause in midflight, resume after a brief period, and end near the target location. Details on the endpoint accuracy of IS do not exist, except for a brief report by Becker et al. (1981). Their analysis emphasized the accuracy of IS relative to the visual target which remained on during the interrupted period. We instead quantified the metric properties of IS relative to nonstimulated saccades during a target flash paradigm. Our results show that IS tend to be slightly hypermetric relative to the nonstimulated saccades to the same target location. The amount of overshoot is not correlated with target eccentricity. Detailed analyses also indicate that the standard deviations of the endpoint in IS are not significantly larger than those for nonstimulated saccades, although there was a much larger variability produced in eye position during the interruption. Both these latter observations support the notion that saccades are controlled by an internal negative feedback system. Also, the size of the remaining motor error during the interrupted period is one factor influencing when an IS resumes, but the variability in this measure is large particularly for smaller motor errors. Recent results have suggested that the resettable neural integrator involved in the feedback loop may be reset after each saccade through an exponential decay process. To probe the properties of the neural integrator, we varied the duration of interruption between the initial and resumed saccades and sought a systematic overshoot in the final eye position with increasing interruption period and variable initial saccade size. Our results showed the neural integrator does not decay during the pause period of interrupted saccades.

Effects of intracavity dispersion on the starting dynamics of continuous-wave passively mode-locked Ti:sapphire/DDI lasers

Through analysis of transient autocorrelation traces, we show that intracavity dispersion significantly affects the number of initially oscillating modes as well as the buildup of passive mode locking in picosecond and femtosecond lasers.

Starting dynamics of a cw passively mode-locked picosecond Ti:sapphire/DDI laser

We show that, for a cw passively mode-locked picosecond Ti:sapphire/DDI laser, the first autocorrelation trace with negligible cw background occurs at a delay time of 20 mu;s, or 1600 round trips from the first relaxationoscillation peak. The trace suggests that the pulse consists of a primary pulse as short as 4.4 ps and of small secondary pulses that form a much wider pedestal of the trace, each containing approximately 50% of the photon energy. Nearly transform-limited approximately 5-ps-wide Gaussian pulses were observed at a delay time of 40 mu;s. After 45 mu;s, the optical spectrum broadened considerably, and the time-bandwidth product increased to 4 in the steady state (after 60 micros).

[Pulmonary cryptococcosis: analyses of 17 cases in VGH-Taipei]

Seventeen patients with pulmonary cryptococcosis collected at VGH-Taipei from 1967 to 1991 were analysed. Their ages ranged from 16 to 70 years with a mean of 45.2. Twelve were men and five were female. The chief characteristic symptoms and signs were cough (58.8%), fever (29.4%) and dyspnea (23.5%). Nearly one third of cases were asymptomatic and presented with abnormal chest roentgenogram. The chest roentgenogram included single nodule or mass (41.2%), multiple nodules (35.3%), pneumonic patch or consolidation (23.5%). In addition, 5 cases (29.4%) and 4 cases (23.5%) were combined with cavitary formation and pleural effusion respectively. Only two cases had associated immunologic deficiency. No patient was found to have history of breeding pigeon. Five cases didn't receive any treatment but were followed from 6 months to 5 years. The remaining 12 cases underwent medical treatment, surgical resection or a combination of both. Prognosis was good in all except one patient who died of multiple myeloma.

Congenital tracheal stenosis: report of three cases

Three infants of congenital tracheal stenosis were experienced in our hospital from 1987 to 1990. They were free from perinatal insult with the onset of symptoms at less than three months of age. Their clinical course deteriorated progressively and all died of respiratory failure in spite of the use of respirator and intensive care. One case received tracheoplasty 2 days before he died. This rare disease entity confronts neonatologist and pediatric surgeon with very high mortality. Only certain types of this disease may be corrected by advanced reconstructive surgery. Congenital tracheal stenosis is usually diagnosed by bronchoscopy, bronchography, xerography or computed tomography. The clinical characteristics and therapeutic management of our cases are discussed and literatures reviewed.