Cognitive Changes after Saline or Plasmalyte Infusion in Healthy Volunteers

2013 ◽  
Vol 119 (3) ◽  
pp. 569-575 ◽  
Author(s):  
David A. Story ◽  
Lucy Lees ◽  
Laurence Weinberg ◽  
Soon-Yee Teoh ◽  
Katherine J. Lee ◽  
...  
Keyword(s):  
Reaction Time ◽  
Incidental Finding ◽  
Plasma Chemistry ◽  
Cognitive Changes ◽  
Time Index ◽  
Blinded Study ◽  
Ringer’S Lactate ◽  
Plasma Chloride ◽  
Adult Volunteers ◽  
Mean Reaction Time

Abstract Background: In an incidental finding, during a study of plasma chemistry after crystalloid infusion, participants reported subjective cognitive changes, particularly slower thinking, after saline but not Hartmann’s (Ringer’s lactate) solution. The authors tested the hypothesis that saline infusion would produce greater adverse cognitive changes than Plasmalyte infusion. Methods: The authors conducted a randomized, cross-over, multiple blinded study of healthy adult volunteers. On separate days, participants received 30 ml/kg over 1 h of either 0.9% saline or Plasmalyte with the order randomly allocated. Plasma chemistry was tested on venous samples. As part of a battery of cognitive tests our primary endpoint was the reaction time index after infusion. Results: The authors studied 25 participants. Plasma chloride was greater after saline than after Plasmalyte: mean difference 5.4 mM (95% CI, 4.1–6.6 mM; P < 0.001). Saline was also associated with greater metabolic acidosis: base-excess 2.5 mM more negative (95% CI, 1.9–3.0 mM more negative; P < 0.001). There was no evidence of a difference in the reaction time index between the two interventions: mean reaction time index 394 ms (SD, 72) after saline versus 385 ms (SD, 55) after Plasmalyte. Difference: saline 9 ms slower (95% CI, 30 ms slower to 12 ms faster; P = 0.39). There were minimal differences in the other cognitive and mood tests. Conclusions: Despite expected differences in plasma chemistry, the authors found that measures of cognition did not differ after infusions of Plasmalyte or saline.

scholarly journals Effect of shift work on fatigue and sleep in neonatal registrars

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245428
Author(s):  
Ajay P. Anvekar ◽  
Elizabeth A. Nathan ◽  
Dorota A. Doherty ◽  
Sanjay K. Patole
Keyword(s):  
Reaction Time ◽  
Vigilance Task ◽  
Sleep Diary ◽  
Secondary Outcome ◽  
Subjective Sleepiness ◽  
Working Day ◽  
Psychomotor Vigilance ◽  
Night Shifts ◽  
Mean Reaction Time

Objective We aimed to study fatigue and sleep in registrars working 12-hour rotating shifts in our tertiary neonatal intensive unit. Methods and participants This study involved neonatal registrar’s working day (08:00–21:00) and night (20:30–08:30) shifts. Participants maintained a sleep diary, answered a self-reported sleepiness questionnaire assessing subjective sleepiness, and performed a 10-minute psychomotor vigilance task (PVT) at the start and end of each shift. Primary outcomes: (1) Fatigue at the (i) “start vs end” of day and night shifts, (ii) end of the “day vs night” shifts, and (iii) end of “first vs last shift” in block of day and night shifts. (2) Duration and quality of sleep before the “day vs night” shifts. Mean reaction time (RTM), relative coefficient of variation (RTCV), and lapses (reaction time > 500ms) were used as measures of fatigue on PVT. Secondary outcome: Subjective sleepiness (self-reported sleepiness questionnaire) at the ‘start vs end” of day and night shifts. Results Fifteen registrars completed the study. Acuity was comparable for all shifts. (1) Psychomotor responses were impaired at the end vs start of day shifts [RTM (p = 0.014), lapses (p = 0.001)], end vs start of night shifts [RTM (p = 0.007), RTCV (p = 0.003), lapses (p<0.001)] and end of night vs day shifts [RTM (p = 0.007), RTCV (p = 0.046), lapses (p = 0.001)]. Only lapses were significantly increased at the end of the last (p = 0.013) vs first shift (p = 0.009) in a block of day and night shifts. (2) Duration of sleep before the night (p = 0.019) and consecutive night shifts was decreased significantly (p = 0.034). Subjective sleepiness worsened after day (p = 0.014) and night shifts (p<0.001). Conclusion Fatigue worsened after the 12-hour day and night shifts with a greater change after night shifts. Lapses increased after block of day and night shifts. Sleep was decreased before night shifts. Our findings need to be confirmed in larger studies.

Reaction Time and Time Course of Neuronal Responses in MT and MST at Different Stimulus Contrasts

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 157-157 ◽  
Author(s):  
A Thiele ◽  
K-P Hoffmann
Keyword(s):  
Reaction Time ◽  
Single Cell ◽  
Single Cells ◽  
Direction Selectivity ◽  
Contrast Level ◽  
Population Activity ◽  
Temporal Area ◽  
Population Mean ◽  
The Mean ◽  
Mean Reaction Time

Direction-selective neurons from the middle temporal area (MT) and the middle superior temporal area (MST) were recorded while a monkey performed a direction discrimination task. Stimuli consisted of evenly spaced bars moving in one of the four cardinal directions. Monkey's reaction time, single-cell latency, and direction selectivity were calculated when stimuli of 53%, 24%, and 4% contrast were presented, and the monkey indicated a correct decision. Mean reaction time was 359±77 ms at 53% contrast, 391±107 ms at 24% contrast, and 582±374 ms at 4% contrast. Most neurons exhibiting direction selective responses at 53% contrast was also active at 24% contrast (MT, 99%; MST, 88%). The number of neurons still exhibiting stimulus-related activity at 4% contrast dramatically decreased (MT to 28%; MST to 41%). Shortest latencies were found at high contrast level (53% contrast; MT, 29 ms; population mean, 76±40 ms; MST, 35 ms; population mean, 77±27 ms). Single cell and population latency increased at lower contrast (4% contrast: MT minimum, 86 ms; population mean, 180±76 ms; MST minimum, 97 ms; population mean, 205±56 ms). This indicates that the mean increase in latency at the single-cell level only partially reflects the increase in reaction time (mean reaction time increased by 223 ms, while mean single-cell latency increased by ∼100 ms in MT and MST). We therefore calculated the normalised population response at different contrast levels. The maximal population activity was always found at the highest contrast level and this was set to 1. In MT it took 75 – 80 ms from stimulus onset until half maximal activity (0.5) was reached at 53% contrast. To reach 0.5 took 85 – 90 ms at 24% contrast and 205 – 210 ms at 4% contrast. For MST the respective values were 85 ms (53% contrast), 90 ms (24% contrast) and 255 ms (4%) contrast. Thus the time to reach half the maximal population activity much better reflects the reaction time than the mean of the latencies calculated from single cells.

Effect of Visual Complexity in Identification of Tachistoscopic Images

1994 ◽  
Vol 78 (3) ◽  
pp. 971-978 ◽  
Author(s):  
Robert Geheb ◽  
Keith E. Whitfield ◽  
Linda Brannon
Keyword(s):  
Reaction Time ◽  
Left Hemisphere ◽  
Right Hemisphere ◽  
Visual Complexity ◽  
Reaction Times ◽  
Right Cerebral Hemisphere ◽  
The Mean ◽  
The Times ◽  
The Right ◽  
Mean Reaction Time

The present study of gender differences in hemispheric processing involved identification of tachistoscopically presented images of varying complexity. A computerized tachistoscopic program was administered to 24 men and 34 women. Time to identify contour and detailed pictures presented to the left or right cerebral hemisphere was recorded. Mean reaction time for contour pictures was significantly faster than for detailed pictures, and mean reaction time to the right hemisphere was significantly faster than that to the left hemisphere. The mean reaction time for men to identify pictures exposed to the left hemisphere was significantly slower than that for exposure to the right hemisphere for women. The mean reaction time for both men and women to identify contour pictures exposed to the right hemisphere was significantly faster than the mean time to identify detailed pictures presented to the left hemisphere. The interaction of gender, hemisphere, and complexity was also significant in that mean reaction times for men to identify detailed pictures presented to the left hemisphere were slower than the times for women to identify contour pictures presented to the right hemisphere. The results are discussed in relation to theories about hemispheres, gender, and differences in picture features.

Divided attention in a reaction time index of traffic sign perception

Ergonomics ◽  
1981 ◽  
Vol 24 (2) ◽  
pp. 111-124 ◽  
Author(s):  
Frank J. Testin ◽  
Robert E. Dewar1
Keyword(s):  
Reaction Time ◽  
Divided Attention ◽  
Traffic Sign ◽  
Time Index

Effect of mean reaction time on saccadic responses to two-step stimuli with horizontal and vertical components

1975 ◽  
Vol 15 (8-9) ◽  
pp. 1021-1025 ◽  
Author(s):  
S.G. Lisberger ◽  
A.F. Fuchs ◽  
W.M. King ◽  
L.C. Evinger
Keyword(s):  
Reaction Time ◽  
Saccadic Responses ◽  
Mean Reaction Time

Intermittent Hypoxic Exposure Improves Mean Reaction Time (MRT) Upon Rapid Ascent to High Altitude

2008 ◽  
Vol 40 (Supplement) ◽  
pp. S171
Author(s):  
Julie Barnes ◽  
Reina Chamberlain ◽  
Trevor Stanley ◽  
Tiffanie Tsui ◽  
Ashley Artese ◽  
...  
Keyword(s):  
Reaction Time ◽  
High Altitude ◽  
Hypoxic Exposure ◽  
Rapid Ascent ◽  
Mean Reaction Time

Emphasizing Nonword Decisions in Word-Decision Performance

2008 ◽  
Vol 103 (1) ◽  
pp. 97-101
Author(s):  
C. Darren Piercey
Keyword(s):  
Reaction Time ◽  
Lexical Decision ◽  
Reaction Times ◽  
Instruction Condition ◽  
Decision Performance ◽  
The Difference ◽  
Speed And Accuracy ◽  
Mean Reaction Time

A robust finding in the lexical decision literature is that decisions to words are made more quickly and accurately than decisions to nonwords. When instructions are presented to participants prior to an experiment, an emphasis is usually placed on identifying words. This study assessed whether instructing participants to emphasize nonword decisions would affect the performance of the speed and accuracy of identification. A total of 98 individuals took part, 49 in a Word Instruction condition and 49 in a Nonword Instruction condition. Analysis indicated changes in emphasis on words versus nonwords decreased the difference in mean reaction time between word and nonword decisions. An interesting finding is that the manipulation of instructions affected reaction times to words but not to nonwords. The analysis of accuracy yielded no significant comparisons. Further research is required to assess the importance of the finding that the manipulation of instructions affects only word decisions.

Startle Reflex Habituation in Children with Cerebral Palsy

1979 ◽  
Vol 48 (3_suppl) ◽  
pp. 1135-1139 ◽  
Author(s):  
Joel Goldberg ◽  
David E. Anderson ◽  
Stephen Wilder
Keyword(s):  
Cerebral Palsy ◽  
Reaction Time ◽  
Auditory Stimulus ◽  
Visual Stimulus ◽  
Stimulus Presentation ◽  
Startle Reflex ◽  
Startle Stimulus ◽  
Normal Children ◽  
Children With Cerebral Palsy ◽  
Mean Reaction Time

Two groups of children (9 with cerebral palsy and 10 normals, matched for sex and age) participated in a study of the startle reflex. Each child was instructed to press a button as soon as possible after the onset of a visual stimulus on a box on the table at which they were seated. During some of the trials, a sudden and intense auditory stimulus (85 dB) was presented concomitantly with the onset of the visual stimulus, and effects on reaction time recorded. Mean reaction time of normal children was significantly faster than that of the group with cerebral palsy. The magnitude of disruption associated with the first startle stimulus presentation was significantly greater for cerebral palsied children. The course between groups of habituation to the startle stimuli was not significantly different. Data support the hypothesis that startle reflexes of children with cerebral palsy are more marked than are those of normal children.

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