Stimulus Sensitivity and Stimulus Intensity Control

1969 ◽  
Vol 28 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Julian Silverman ◽  
Monte Buchsbaum ◽  
Robert Henkin
Keyword(s):  
Stimulus Intensity ◽  
Control Mechanism ◽  
Sensory Threshold ◽  
Response Tendency ◽  
Low Intensity ◽  
Intensity Control ◽  
The Central Nervous System ◽  
And Performance ◽  
Light Flashes ◽  
Opposite Response

Previous research had suggested a relationship between averaged cortical evoked response (AER) characteristics and the perception of stimulus intensity. In this study a systematic relationship was hypothesized between AER characteristics and performance on traditional sensory threshold procedures. Averaged evoked responses to light flashes and performances on a battery of psychophysical tasks were measured in 20 normal volunteers. Ss with one AER pattern were sensitive to low-intensity stimulation; Ss with another AER pattern exhibited the opposite response tendency. These findings were interpreted in terms of a theoretical construct regarding a stimulus-intensity control mechanism in the central nervous system.

scholarly journals Noninvasive neuromodulation and thalamic mapping with low-intensity focused ultrasound

2018 ◽  
Vol 128 (3) ◽  
pp. 875-884 ◽  
Author(s):  
Robert F. Dallapiazza ◽  
Kelsie F. Timbie ◽  
Stephen Holmberg ◽  
Jeremy Gatesman ◽  
M. Beatriz Lopes ◽  
...  
Keyword(s):  
Focused Ultrasound ◽  
Thalamic Nucleus ◽  
Acoustic Energy ◽  
Similar Degree ◽  
Thalamic Nuclei ◽  
Low Intensity ◽  
Tissue Heating ◽  
The Central Nervous System ◽  
Selective Mapping ◽  
Noninvasive Neuromodulation

OBJECTIVEUltrasound can be precisely focused through the intact human skull to target deep regions of the brain for stereotactic ablations. Acoustic energy at much lower intensities is capable of both exciting and inhibiting neural tissues without causing tissue heating or damage. The objective of this study was to demonstrate the effects of low-intensity focused ultrasound (LIFU) for neuromodulation and selective mapping in the thalamus of a large-brain animal.METHODSTen Yorkshire swine (Sus scrofa domesticus) were used in this study. In the first neuromodulation experiment, the lemniscal sensory thalamus was stereotactically targeted with LIFU, and somatosensory evoked potentials (SSEPs) were monitored. In a second mapping experiment, the ventromedial and ventroposterolateral sensory thalamic nuclei were alternately targeted with LIFU, while both trigeminal and tibial evoked SSEPs were recorded. Temperature at the acoustic focus was assessed using MR thermography. At the end of the experiments, all tissues were assessed histologically for damage.RESULTSLIFU targeted to the ventroposterolateral thalamic nucleus suppressed SSEP amplitude to 71.6% ± 11.4% (mean ± SD) compared with baseline recordings. Second, we found a similar degree of inhibition with a high spatial resolution (∼ 2 mm) since adjacent thalamic nuclei could be selectively inhibited. The ventromedial thalamic nucleus could be inhibited without affecting the ventrolateral nucleus. During MR thermography imaging, there was no observed tissue heating during LIFU sonications and no histological evidence of tissue damage.CONCLUSIONSThese results suggest that LIFU can be safely used to modulate neuronal circuits in the central nervous system and that noninvasive brain mapping with focused ultrasound may be feasible in humans.

Characteristics of the Analgesic Effects and Drug Interactions of Intrathecal Carbachol in Rats

1995 ◽  
Vol 83 (4) ◽  
pp. 844-849. ◽  
Author(s):  
Stephen E. Abram ◽  
Therese C. O'Connor
Keyword(s):  
Adverse Effects ◽  
Drug Interactions ◽  
Stimulus Intensity ◽  
Hind Limb ◽  
Intrathecal Morphine ◽  
Radiant Heat ◽  
Limb Weakness ◽  
Analgesic Effects ◽  
Low Intensity ◽  
Significant Difference

Background Intrathecal carbachol produces consistent analgesia in animals without appreciable adverse effects. Little is known about the ability of this drug to provide analgesia as stimulus intensity is increased. Likewise, there are few data regarding interactions between carbachol and other intrathecal analgesics. Methods Using two different noxious radiant heat intensities, one applied to each hind limb, analgesic effects of 1, 3, 10, and 30 micrograms intrathecal carbachol on paw withdrawal latencies were measured. Similar testing was done for intrathecal morphine and clonidine. ED50 fractions (1/2, 1/4, 1/8, 1/16) of drug combinations of carbachol-morphine and carbachol-clonidine were administered, responses to the low intensity stimulus were recorded, and the ED50 of each combination was established and isobolographic analysis of the drug interactions was carried out. Results The 30-micrograms dose of carbachol was associated with transient agitation, salivation, and hind limb weakness. No other adverse effects were noted. The ED50 (95% confidence interval) of intrathecal carbachol was 2.34 micrograms (1.34-4.04) for low intensity stimulation and 12.64 micrograms (4.18-38.25) for high intensity. There was no significant difference between high- and low-intensity ED50 values for intrathecal morphine and clonidine. The analgesic effect of the carbachol-morphine and carbachol-clonidine combinations were significantly greater than the calculated additive effects. The ED50 for the carbachol-morphine combination was 12% of the expected additive value and the ED50 for the carbachol-clonidine combination was 30% of the expected additive value. Conclusions Intrathecal carbachol provides analgesia to noxious thermal stimulation of the hind paw in rats. It is relatively less effective at providing analgesia than intrathecal morphine or clonidine when stimulus intensity is raised. Intrathecal carbachol is synergistic when combined with intrathecal morphine or clonidine.

scholarly journals Does caffeine consumption affect laparoscopic skills in a motion tracking analysis? A prospective, randomized, blinded crossover trial

2021 ◽  
Author(s):  
Felix von Bechtolsheim ◽  
Florian Oehme ◽  
Michael Maruschke ◽  
Sofia Schmidt ◽  
Alfred Schneider ◽  
...  
Keyword(s):  
Motion Analysis ◽  
Motion Tracking ◽  
Crossover Trial ◽  
Potential Interaction ◽  
Caffeine Intake ◽  
Caffeine Consumption ◽  
Laparoscopic Skills ◽  
The Central Nervous System ◽  
And Performance ◽  
Laparoscopic Performance

Abstract Background Coffee can increase vigilance and performance, especially during sleep deprivation. The hypothetical downside of caffeine in the surgical field is the potential interaction with the ergonomics of movement and the central nervous system. The objective of this trial was to investigate the influence of caffeine on laparoscopic performance. Methods Fifty laparoscopic novices participated in this prospective randomized, blinded crossover trial and were trained in a modified FLS curriculum until reaching a predefined proficiency. Subsequently, all participants performed four laparoscopic tasks twice, once after consumption of a placebo and once after a caffeinated (200 mg) beverage. Comparative analysis was performed between the cohorts. Primary endpoint analysis included task time, task errors, OSATS score and a performance analysis with an instrument motion analysis (IMA) system. Results Fifty participants completed the study. Sixty-eight percent of participants drank coffee daily. The time to completion for each task was comparable between the caffeine and placebo cohorts for PEG transfer (119 s vs 121 s; p = 0.73), precise cutting (157 s vs 163 s; p = 0.74), gallbladder resection (190 s vs 173 s; p = 0.6) and surgical knot (171 s vs 189 s; p = 0.68). The instrument motion analysis showed no significant differences between the caffeine and placebo groups in any parameters: instrument volume, path length, idle, velocity, acceleration, and instrument out of view. Additionally, OSATS scores did not differ between groups, regardless of task. Major errors occurred similarly in both groups, except for one error criteria during the circle cutting task, which occurred significantly more often in the caffeine group (34% vs. 16%, p < 0.05). Conclusion The objective IMA and performance scores of laparoscopic skills revealed that caffeine consumption does not enhance or impair the overall laparoscopic performance of surgical novices. The occurrence of major errors is not conclusive but could be negatively influenced in part by caffeine intake.

Bio-Inspired Cell Concentration and Deformability Monitoring Chips

2007 ◽  
Vol 7 (11) ◽  
pp. 4214-4219 ◽  
Author(s):  
Young-Ho Cho ◽  
Sechan Youn ◽  
Dong Woo Lee
Keyword(s):  
Experimental Study ◽  
Control Mechanism ◽  
Cell Concentration ◽  
Biological Cell ◽  
High Integrability ◽  
Digital Signals ◽  
Cell Deformability ◽  
Destruction Mechanism ◽  
Biomedical Systems ◽  
And Performance

The paper presents a couple of biofluidic devices, whose functions are inspired from biological cell concentration and deformability monitoring functions. The cell concentration monitoring chip is inspired from RBC control mechanism in kidney, performing cell concentration monitoring functions. The cell deformability chip, inspired from selective RBC destruction mechanism in spleen, performs mechanical cell deformability monitoring functions. The structures and principles of the bio-inspired chips are presented and compared with those of the biological organs. The unique features and performance characteristics of the bio-inspired chips are analyzed and verified from experimental study. The bio-inspired cell concentration monitoring chips perform flow-rate insensitive concentration measurement, while the bio-inspired cell deformability monitoring chips achieve size-independent cell deformability measurement. Common advantages of the bio-inspired chips include simple structures, digital signals and high integrability, thus making them suitable for use in integrated digital biomedical systems.

Results of omacetaxine plus low-dose cytarabine (LD-araC) in older patients with acute myeloid leukemia (AML).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 7068-7068
Author(s):  
Tapan M. Kadia ◽  
Naval Guastad Daver ◽  
Farhad Ravandi ◽  
Elias Jabbour ◽  
Naveen Pemmaraju ◽  
...  
Keyword(s):  
Older Patients ◽  
Performance Status ◽  
Intensive Chemotherapy ◽  
Eligibility Criteria ◽  
Normal Organ ◽  
Low Intensity ◽  
Resistant Disease ◽  
Poor Tolerance ◽  
And Performance

7068 Background: Older patients with AML have poor tolerance to intensive chemotherapy and poor prognosis. Omacetaxine is active in AML and is part of standard combination chemotherapy in China under the name of homoharringtonine. Methods: The aim of the study was to evaluate the efficacy of low intensity therapy with omacetaxine and LD-ara C in newly diagnosed older patients (>/= 60 years) with AML or myelodysplastic syndrome (MDS). Older patients with AML not fit or who refuse intensive chemotherapy were eligible. Normal organ functions and performance status </= 2 were required. Other eligibility criteria were standard. Induction therapy consisted of omacetaxine 1.25 mg/m2 subcutaneously twice daily for 3 days and ara-C 20 mg subcutaneously twice daily for 7 days. Maintenance therapy was with the same induction schedule, repeated every 4-6 weeks for up to 2 years. Dose adjustments for prolonged myelosupression or severe non-hematologic toxicities were made by reducing the number of days of omacetaxine (-1 day by level) and cytarabine (-1 to 2 days by level). Results: 30 patients have been treated, with a median age of 71 years (range 64-81); 60% were age 70 years or older. AML post MDS in 20%; chromosome 5 and 7 abnormalities were present in 23%. Overall, 9 patients achieved CR (30%), 5 had CRp (17%) and 1 had PR (3%), for an overall response rate of 50%. Induction mortality was noted in 4 (Day 5, 27, 27, and 70 from start of therapy; 13%); resistant disease in 8 (27%); too early in 4 (13%). With the median follow-up time of 10 months the median survival is 9.3 months and the estimated 1-year survival rate 42%. No serious drug related adverse effects were observed with the combination. Conclusions: Low-intensity therapy with omacetaxine + LD-ara C shows promising activity and is safe in older patients with AML not fit for intensive chemotherapy. Clinical trial information: NCT01272245.

Stimulus Intensity Control and the Cortical Evoked Response

1968 ◽  
Vol 30 (1) ◽  
pp. 12-22 ◽  
Author(s):  
MONTE BUCHSBAUM ◽  
JULIAN SILVERMAN
Keyword(s):  
Stimulus Intensity ◽  
Evoked Response ◽  
Intensity Control

scholarly journals Associations between Tactile Sensory Threshold and Postural Performance and Effects of Healthy Aging and Subthreshold Vibrotactile Stimulation on Postural Outcomes in a Simple Dual Task

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Marius Dettmer ◽  
Amir Pourmoghaddam ◽  
Beom-Chan Lee ◽  
Charles S. Layne
Keyword(s):  
Older Adults ◽  
Performance Measures ◽  
Dual Task ◽  
Healthy Aging ◽  
Control Measures ◽  
Future Research ◽  
Sensory Threshold ◽  
Vibrotactile Stimulation ◽  
And Performance ◽  
Postural Performance

Specific activities that require concurrent processing of postural and cognitive tasks may increase the risk for falls in older adults. We investigated whether peripheral receptor sensitivity was associated with postural performance in a dual-task and whether an intervention in form of subthreshold vibration could affect performance. Ten younger (age: 20–35 years) and ten older adults (70–85 years) performed repeated auditory-verbal 1-back tasks while standing quietly on a force platform. Foot sole vibration was randomly added during several trials. Several postural control and performance measures were assessed and statistically analyzed (significance set toα-levels of .05). There were moderate correlations between peripheral sensitivity and several postural performance and control measures (r=.45to .59). Several postural performance measures differed significantly between older and younger adults (p<0.05); addition of vibration did not affect outcome measures. Aging affects healthy older adults’ performance in dual-tasks, and peripheral sensitivity may be a contributor to the observed differences. A vibration intervention may only be useful when there are more severe impairments of the sensorimotor system. Hence, future research regarding the efficacy of sensorimotor interventions in the form of vibrotactile stimulation should focus on older adults whose balance is significantly affected.

Stimulus Intensity Control in Depression: A Study of the Comparative Effect of Doxepin and Amitriptyline on Cortical Evoked Potentials

1980 ◽  
Vol 14 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Jeannette Friedman ◽  
Peter McCallum ◽  
Russell Meares
Keyword(s):  
Evoked Potentials ◽  
Stimulus Intensity ◽  
Comparative Effect ◽  
Cortical Evoked Potentials ◽  
Perceived Intensity ◽  
Intensity Control

The perceived intensity of a stimulus may be magnified during depression. Stimulus intensity control can be studied by means of cortical evoked potentials. In a study of 33 depressives, cortical evoked potentials were greater during depression than on recovery. The effect of doxepin on the amplitudes of evoked potentials of depressives was compared with that of amitriptyline. Doxepin reduced amplitudes. Amitriptyline had a similar, but non-significant effect.

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