Shifting Attention in a Rapid Visual Search Paradigm

1994 ◽  
Vol 79 (1) ◽  
pp. 315-335 ◽  
Author(s):  
Shulan Hsieh ◽  
Alan Allport
Keyword(s):  
Time Course ◽  
Stimulus Presentation ◽  
Semantic Space ◽  
Attention Shift ◽  
Direct Function ◽  
Monitoring Task ◽  
Attentional System ◽  
Semantic Shift ◽  
The Difference ◽  
Criterion Shifts

A method is introduced for studying shifts of attention in semantic space, testing 56 subjects in four experiments on a semantic monitoring task based on rapid, serial, visually presented (RSVP) word-sequences. Following a cue to shift attention, accuracy of semantic monitoring drops abruptly to a low level, then gradually recovers to reach preshift levels over successive stimuli in the RSVP sequence. Using this method, we compared two kinds of criterion-shifts, one requiring a set-reversal (‘reversal shifts’), the other involving a shift between orthogonally defined categories (‘orthogonal shifts’); no differences were found. We have also examined the difference in a shift between two different processing domains (semantic vs typographic) compared with a shift of criterion within the same processing domain. The results showed no differences for within- vs between-domain shifts. Finally, we studied the time-course of a semantic attention shift. Execution of a semantic shift did not follow an internally controlled time-course but was a direct function of the rate of stimulus presentation. No evidence was found for the operation of a ‘supervisory attentional system’ independent of external stimulus triggering.

Destruction of Actin Filaments by Osmium Tetroxide

1977 ◽  
Vol 35 ◽  
pp. 466-467
Author(s):  
P. Maupin-Szamier ◽  
T. D. Pollard
Keyword(s):  
Actin Filaments ◽  
Time Course ◽  
Osmium Tetroxide ◽  
Rabbit Muscle ◽  
Muscle Actin ◽  
Sodium Phosphate Buffer ◽  
Transmission Electron ◽  
The Difference ◽  
Rates Of Decay ◽  
Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

Sensation of dyspnea during hypercapnia, exercise, and voluntary hyperventilation

1990 ◽  
Vol 68 (5) ◽  
pp. 2100-2106 ◽  
Author(s):  
T. Chonan ◽  
M. B. Mulholland ◽  
J. Leitner ◽  
M. D. Altose ◽  
N. S. Cherniack
Keyword(s):  
Visual Analog Scale ◽  
Line Intensity ◽  
Time Course ◽  
Normal Subjects ◽  
Cycle Ergometer ◽  
Base Line ◽  
Analog Scale ◽  
Voluntary Hyperventilation ◽  
The Difference ◽  
End Tidal

To determine whether the intensity of dyspnea at a given level of respiratory motor output depends on the nature of the stimulus to ventilation, we compared the sensation of difficulty in breathing during progressive hypercapnia (HC) induced by rebreathing, during incremental exercise (E) on a cycle ergometer, and during isocapnic voluntary hyperventilation (IVH) in 16 normal subjects. The sensation of difficulty in breathing was rated at 30-s intervals by use of a visual analog scale. There were no differences in the level of ventilation or the base-line intensity of dyspnea before any of the interventions. The intensity of dyspnea grew linearly with increases in ventilation during HC [r = 0.98 +/- 0.02 (SD)], E (0.95 +/- 0.03), and IVH (0.95 +/- 0.06). The change in intensity of dyspnea produced by a given change in ventilation was significantly greater during HC [0.27 +/- 0.04 (SE)] than during E (0.12 +/- 0.02, P less than 0.01) and during HC (0.30 +/- 0.04) than during IVH (0.16 +/- 0.03, P less than 0.01). The difference in intensity of dyspnea between HC and E or HC and IVH increased as the difference in end-tidal PCO2 widened, even though the time course of the increase in ventilation was similar. No significant differences were measured in the intensity of dyspnea that occurred with changes in ventilation between E and IVH. These results indicate that under nearisocapnic conditions the sensation of dyspnea produced by a given level of ventilation seems not to depend on the method used to produce that level of ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of medial temporal lobe activity in epilepsy patients with hippocampal sclerosis during verbal working memory

2009 ◽  
Vol 15 (4) ◽  
pp. 536-546 ◽  
Author(s):  
PABLO CAMPO ◽  
FERNANDO MAESTÚ ◽  
IRENE GARCÍA-MORALES ◽  
ANTONIO GIL-NAGEL ◽  
BRYAN STRANGE ◽  
...  
Keyword(s):  
Working Memory ◽  
Episodic Memory ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Time Course ◽  
Hippocampal Sclerosis ◽  
Stimulus Presentation ◽  
Verbal Working Memory ◽  
Compelling Evidence ◽  
Electrophysiological Studies

AbstractIt has been traditionally assumed that medial temporal lobe (MTL) is not required for working memory (WM). However, animal lesion and electrophysiological studies and human neuropsychological and neuroimaging studies have provided increasing evidences of a critical involvement of MTL in WM. Based on previous findings, the central aim of this study was to investigate the contribution of the MTL to verbal WM encoding. Here, we used magnetoencephalography (MEG) to compare the patterns of MTL activation of 9 epilepsy patients suffering from left hippocampal sclerosis with those of 10 healthy matched controls while they performed a verbal WM task. MEG recordings allow detailed tracking of the time course of MTL activation. We observed impaired WM performance associated with changes in the dynamics of MTL activity in epilepsy patients. Specifically, whereas patients showed decreased activity in damaged MTL, activity in the contralateral MTL was enhanced, an effect that became significant in the 600- to 700-ms interval after stimulus presentation. These findings strongly support the crucial contribution of MTL to verbal WM encoding and provide compelling evidence for the proposal that MTL contributes to both episodic memory and WM. Whether this pattern is signaling reorganization or a normal use of a damaged structure is discussed. (JINS, 2009, 15, 536–546.)

scholarly journals Comparisons of the effects of tamoxifen, toremifene and raloxifene on enzyme induction and gene expression in the ovariectomised rat uterus

2001 ◽  
Vol 170 (3) ◽  
pp. 555-564 ◽  
Author(s):  
AR Green ◽  
EL Parrott ◽  
M Butterworth ◽  
PS Jones ◽  
P Greaves ◽  
...  
Keyword(s):  
Gene Expression ◽  
Time Course ◽  
Rt Pcr ◽  
Biphasic Response ◽  
Down Regulation ◽  
Rat Uterus ◽  
Carcinogenic Effects ◽  
The Difference ◽  
Er Alpha ◽  
Ovariectomised Rats

This study compares the actions of oestradiol, tamoxifen, toremifene and raloxifene on enzyme and gene expression in uterine tissues of ovariectomised rats over 72 h. The time-course for the induction of ornithine decarboxylase by the compounds showed a rapid biphasic response, while for creatine kinase brain type (BB) there was a continued increase over 72 h. The efficacy of induction showed that, with both markers, oestradiol gave the highest induction level, followed by tamoxifen or toremifene and then raloxifene. RT-PCR demonstrated that all compounds decreased oestrogen receptor (ER) alpha, ERbeta and ERbeta2 gene expression, 8-24 h after the first dose, suggesting that down-regulation of ER is not the primary cause of the difference in efficacy between these compounds. Using cDNA arrays, expression of 512 genes was examined in the uteri of oestradiol- or tamoxifen-treated rats. Both compounds resulted in the up-regulation of heat-shock protein 27, telomerase-associated protein 1 and secretin. However, most surprising was the marked down-regulation of Wilms' tumour and retinoblastoma genes. We speculate that this may result in a loss of regulation of the transition from the G1 to the S phase in the cell cycle and may make cells more vulnerable to the carcinogenic effects of tamoxifen in this tissue.

TGFbeta1 induces a cell-cycle-dependent increase in motility of epithelial cells

1999 ◽  
Vol 112 (4) ◽  
pp. 447-454 ◽  
Author(s):  
D. Zicha ◽  
E. Genot ◽  
G.A. Dunn ◽  
I.M. Kramer
Keyword(s):  
Cell Cycle ◽  
Mass Distribution ◽  
Transforming Growth Factor Beta ◽  
Time Course ◽  
Transforming Growth Factor ◽  
Interference Microscopy ◽  
Response To Treatment ◽  
Gradual Onset ◽  
The Difference ◽  
Cycle Dependent

We have previously shown that addition of type 1 transforming growth factor-beta (TGFbeta1) to an exponentially growing population of mink lung CCl64 cells increases their average intermitotic time from 14.4 to 20.3 hours, predominantly by extending G1 from 7.5 to 13.5 hours. Here we have used the DRIMAPS system (digitally recorded interference microscopy with automatic phase-shifting) for obtaining data on cellular mass distribution, cell motility and morphology. We found no significant change in the cells' rate of mass increase following TGFbeta1 treatment, which implies that the treated cells attained a higher mass during their extended cell cycle and this was confirmed by direct measurement of cell size. However, the cells showed a dramatic motile response to treatment: TGFbeta1-treated cells had a significantly higher time-averaged speed of 36.2 microm hour-1 compared to 14.5 microm hour-1 for the control cells. The time course of the response was gradual, reaching a maximum mean speed of 52.6 microm hour-1 after 15 hours exposure. We found that the gradual onset of the response was probably not due to a slow accumulation of a secondary factor but because cells were dividing throughout the experiment and most of the response to TGFbeta1 occurred only after the first cell division in its presence. Thus, taking only those cells that had not yet divided, the time-averaged speed of treated cells (26.1 micrometer hour-1) was only moderately higher than that of untreated cells (14.9 micrometer hour-1) whereas, for those cells that had divided, the difference in speed between treated cells (45.1 micrometer hour-1) and untreated cells (14.1 microm hour-1) was much greater. Increased speed was a consequence of enhanced protrusion and retraction of the cell margin coupled with an increase in cell polarity. TGFbeta1 also increased the mean spreading of the cells, measured as area-to-mass ratio, from 3.2 to 4.4 micrometer2 pg-1, and the intracellular mass distribution became more asymmetric. The observations indicate that a G2 signal may be necessary to reach maximal motility in the presence of TGFbeta1.

Cell volume and metabolic dependence of NEM-activated K+-Cl- flux in human red blood cells

1985 ◽  
Vol 249 (1) ◽  
pp. C124-C128 ◽  
Author(s):  
P. K. Lauf ◽  
C. M. Perkins ◽  
N. C. Adragna
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Blood Cells ◽  
Time Course ◽  
Transport Activity ◽  
Human Red Blood Cells ◽  
Atp Breakdown ◽  
The Difference ◽  
Metabolic Dependence ◽  
K Transport

The effects of incubation in anisosmotic media and of metabolic depletion on ouabain-resistant (OR) Cl--dependent K+ influxes stimulated by N-ethylmaleimide (NEM) were studied in human red blood cells using Rb+ as K+ analogue. The NEM-stimulated but not the basal Rb+-Cl- influx measured in phosphate-buffered anisosmotic media was found to be cell volume dependent. When cellular ATP, [ATP]c, was lowered to less than 0.10 of its initial level by exposure to nonmetabolizable 2-deoxy-D-glucose, the NEM-stimulated but not the basal Cl--dependent Rb+ influxes were abolished. Metabolically depleted red blood cells subsequently repleted by incubation in glucose plus inosine regained the NEM-inducible Rb+ (K+) transport activity. The difference in the time course of ATP breakdown and Rb+ influx inhibition suggests that energization of the NEM-stimulated Rb+ flux by metabolism may involve factors additional to ATP.

Dissociating early and late visual processing via the Ebbinghaus illusion

2016 ◽  
Vol 33 ◽  
Author(s):  
FILIPP SCHMIDT ◽  
ANDREAS WEBER ◽  
ANKE HABERKAMP
Keyword(s):  
Visual Processing ◽  
High Frequency ◽  
Time Course ◽  
Temporal Dynamics ◽  
Low Frequency ◽  
Response Speed ◽  
Ebbinghaus Illusion ◽  
Priming Effects ◽  
Parvocellular Pathway ◽  
The Difference

AbstractVisual perception is not instantaneous; the perceptual representation of our environment builds up over time. This can strongly affect our responses to visual stimuli. Here, we study the temporal dynamics of visual processing by analyzing the time course of priming effects induced by the well-known Ebbinghaus illusion. In slower responses, Ebbinghaus primes produce effects in accordance with their perceptual appearance. However, in fast responses, these effects are reversed. We argue that this dissociation originates from the difference between early feedforward-mediated gist of the scene processing and later feedback-mediated more elaborate processing. Indeed, our findings are well explained by the differences between low-frequency representations mediated by the fast magnocellular pathway and high-frequency representations mediated by the slower parvocellular pathway. Our results demonstrate the potentially dramatic effect of response speed on the perception of visual illusions specifically and on our actions in response to objects in our visual environment generally.

Platelet Aggregability Measured by SFP Method in Cerebral Thrombosis and Haemorrhage

1975 ◽  
Author(s):  
I. Kobayashi ◽  
H. Yamazaki
Keyword(s):  
Essential Hypertension ◽  
Cerebral Hemorrhage ◽  
Time Course ◽  
Acute Stage ◽  
Cerebral Thrombosis ◽  
Recovery Stage ◽  
Platelet Aggregability ◽  
Significant Difference ◽  
The Difference ◽  
Death Cases

Platelet aggregability of 50 aged healthy people (64.0 ±9.4 yrs., Mean ±SD), 93 essential hypertension (65.6±8.5 yrs.), 166 recovery stage of cerebral thrombosis over 2 months from the onset (62.4 ± 11.8 yrs.) and 74 recovery stage of cerebral hemorrhage (57.4 ±10.0 yrs.) was measured using screen filtration pressure (SFP, Swank, 1961) method. SFP by 3 μM ADP of healthy, hypertension, recovery stage of cerebral hemorrhage and thrombosis were 148.7±53.5, 176.2± 74.4, 189.8±58.3 and 206.3±58.9 mmHg respectively. The differences of the SFP between the healthy and the diseased groups were statistically significant (P < 0.01-0.05). Meanwhile SFP of 9 cerebral thrombosis (66.8±9.5 yrs.) and 18 hemorrhage (66.4 ±10.6 yrs.) was measured during their time course of the diseases from the onset to 180 days. SFP in acute stage of thrombosis showed an increase and it decreased gradually during the time course. On the contrary SFP in acute stage of hemorrhage showed a decrease and it increased gradually. A statistically significant difference was observed between both the groups within 30 days from the onset (P < 0.01 ). SFP in acute stage of hemorrhage showed 95.2 ±17.7 in 9 survival and 1Ö4.0±Ö6.2 mmHg in 9 death cases within 10 days from the onset. The difference of the SFP between survival and death was statistically significant (P < 0.01).

scholarly journals Oxygen cost and oxygen uptake dynamics and recovery with 1 min of exercise in children and adults

1991 ◽  
Vol 71 (3) ◽  
pp. 993-998 ◽  
Author(s):  
S. Zanconato ◽  
D. M. Cooper ◽  
Y. Armon
Keyword(s):  
Time Course ◽  
Significant Degree ◽  
Cycle Ergometer ◽  
Work Intensity ◽  
O2 Uptake ◽  
Ergometer Exercise ◽  
Adults And Children ◽  
The Difference ◽  
Recovery Dynamics ◽  
Best Fit

To test the hypothesis that O2 uptake (VO2) dynamics are different in adults and children, we examined the response to and recovery from short bursts of exercise in 10 children (7–11 yr) and 13 adults (26–42 yr). Each subject performed 1 min of cycle ergometer exercise at 50% of the anaerobic threshold (AT), 80% AT, and 50% of the difference between the AT and the maximal O2 uptake (VO2max) and 100 and 125% VO2max. Gas exchange was measured breath by breath. The cumulative O2 cost [the integral of VO2 (over baseline) through exercise and 10 min of recovery (ml O2/J)] was independent of work intensity in both children and adults. In above-AT exercise, O2 cost was significantly higher in children [0.25 +/- 0.05 (SD) ml/J] than in adults (0.18 +/- 0.02 ml/J, P less than 0.01). Recovery dynamics of VO2 in above-AT exercise [measured as the time constant (tau VO2) of the best-fit single exponential] were independent of work intensity in children and adults. Recovery tau VO2 was the same in both groups except at 125% VO2max, where tau VO2 was significantly smaller in children (35.5 +/- 5.9 s) than in adults (46.3 +/- 4 s, P less than 0.001). VO2 responses (i.e., time course, kinetics) to short bursts of exercise are, surprisingly, largely independent of work rate (power output) in both adults and children. In children, certain features of the VO2 response to high-intensity exercise are, to a small but significant degree, different from those in adults, indicating an underlying process of physiological maturation.

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