scholarly journals Moderate acute alcohol intoxication has minimal effect on surround suppression measured with a motion direction discrimination task

2015 ◽  
Vol 15 (1) ◽  
pp. 5-5 ◽  
Author(s):  
J. C. A. Read ◽  
R. Georgiou ◽  
C. Brash ◽  
P. Yazdani ◽  
R. Whittaker ◽  
...  
Keyword(s):  
Discrimination Task ◽  
Alcohol Intoxication ◽  
Acute Alcohol Intoxication ◽  
Minimal Effect ◽  
Surround Suppression ◽  
Motion Direction ◽  
Direction Discrimination

scholarly journals Electrophysiological aftereffects of high-frequency transcranial random noise stimulation (hf-tRNS): an EEG investigation

2021 ◽  
Author(s):  
Filippo Ghin ◽  
Louise O’Hare ◽  
Andrea Pavan
Keyword(s):  
High Frequency ◽  
Discrimination Task ◽  
Temporal Dynamics ◽  
Random Noise ◽  
Decomposition Analysis ◽  
Oscillatory Activity ◽  
Motion Direction ◽  
Time Frequency ◽  
Direction Discrimination ◽  
Transcranial Random Noise Stimulation

AbstractThere is evidence that high-frequency transcranial random noise stimulation (hf-tRNS) is effective in improving behavioural performance in several visual tasks. However, so far there has been limited research into the spatial and temporal characteristics of hf-tRNS-induced facilitatory effects. In the present study, electroencephalogram (EEG) was used to investigate the spatial and temporal dynamics of cortical activity modulated by offline hf-tRNS on performance on a motion direction discrimination task. We used EEG to measure the amplitude of motion-related VEPs over the parieto-occipital cortex, as well as oscillatory power spectral density (PSD) at rest. A time–frequency decomposition analysis was also performed to investigate the shift in event-related spectral perturbation (ERSP) in response to the motion stimuli between the pre- and post-stimulation period. The results showed that the accuracy of the motion direction discrimination task was not modulated by offline hf-tRNS. Although the motion task was able to elicit motion-dependent VEP components (P1, N2, and P2), none of them showed any significant change between pre- and post-stimulation. We also found a time-dependent increase of the PSD in alpha and beta bands regardless of the stimulation protocol. Finally, time–frequency analysis showed a modulation of ERSP power in the hf-tRNS condition for gamma activity when compared to pre-stimulation periods and Sham stimulation. Overall, these results show that offline hf-tRNS may induce moderate aftereffects in brain oscillatory activity.

The Effect of Temporal Phase on the Perception of Apparent Motion

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 68-68
Author(s):  
H S Hock ◽  
K Kogan ◽  
N Lodes
Keyword(s):  
Apparent Motion ◽  
Motion Detection ◽  
Discrimination Task ◽  
Luminance Contrast ◽  
Background Luminance ◽  
Motion Direction ◽  
Direction Discrimination ◽  
Temporal Phase ◽  
The Difference ◽  
Perceived Speed

In classical apparent motion, a spot of light is presented in alternation such that the waveforms describing the varying luminance at each of two locations are 180° out of phase. However, when the luminance variation at each location is approximately sinusoidal, and the perceiver's task is to discriminate motion direction, the optimum temporal phase is 90° (van Santen and Sperling, 1984 Journal of the Optical Society of America A1 451 – 473). The results reported in this study suggest that the optimality of the 90° temporal phase may be specific to the direction-discrimination task. Our experiments were based on a new procedure for measuring classical apparent motion thresholds (Hock, Kogan, and Espinoza, 1996, paper presented at ARVO). Two horizontally displaced dots are presented simultaneously against a darker background. The luminance ( L1) of one dot is always greater than that of the other ( L2), and the luminance values for the dots are exchanged on successive frames. Whether motion or stationarity is perceived depends on the background-relative luminance contrast (BRLC): ( L1- L2) divided by the difference between the average [( L1+ L2)/2] and background luminance. We found in the current study that motion thresholds depend on the temporal phase of the luminance variation at each location (rather than temporal asynchrony); the greater the phase difference (from 41° to 180°) the less the BRLC required for motion perception. At suprathreshold BRLC values, the perceived speed of apparent motion decreases with increased differences in temporal phase. The results are discussed in terms of Reichardt-type motion detection models.

Age Related Changes to Perceptual Surround Suppression of Moving Stimuli

2012 ◽  
Vol 25 (5) ◽  
pp. 409-424 ◽  
Author(s):  
Renee Karas ◽  
Allison M. McKendrick
Keyword(s):  
Discrimination Task ◽  
Perceptual Task ◽  
Surround Suppression ◽  
Motion Direction ◽  
Perception Task ◽  
Inhibitory Function ◽  
Age Related ◽  
Indirect Measures ◽  
Clinical Disorders ◽  
Contrast Perception

Perceptual analogues of centre–surround suppression have been applied as indirect measures of cortical inhibitory function in several clinical disorders. Two tasks have been used: a centre–surround contrast perception task and a motion direction discrimination task, where the stimulus size and contrast is varied to measure surround suppression effects. The tasks are markedly different, yet previous literature implies that both measures indirectly assess inhibitory function and that results will be complementary. This is not the case for age-related effects on surround suppression, however, as previous reports using the different measures are conflicting. Here we use a low-spatial frequency, drifting grating version of the centre–surround contrast perception task, and compare results to those obtained with the motion direction task in a single group of older observers. Older adults demonstrate significantly increased perceptual surround suppression of contrast for drifting, high contrast stimuli. Using the motion discrimination task, older observers showed similar amounts of surround suppression for the largest stimulus. This study confirms that visual surround suppression is altered by ageing. The complexity of neuronal systems involved in centre–surround interactions makes it unlikely that a single perceptual task will be sufficient to describe the effects of clinical disorders on surround suppression.

scholarly journals Effector-dependent response deterioration by stochastic transformations reveals mixed reference frames for decisions

2017 ◽  
Author(s):  
T. Scott Murdison ◽  
Dominic Standage ◽  
Philippe Lefèvre ◽  
Gunnar Blohm
Keyword(s):  
Decision Making ◽  
Discrimination Task ◽  
Reference Frames ◽  
Button Press ◽  
Perceptual Decision Making ◽  
Motion Direction ◽  
Perceptual Decision ◽  
Direction Discrimination ◽  
Electrophysiological Recordings ◽  
Sensorimotor Transformations

AbstractRecent psychophysical and modeling studies have revealed that sensorimotor reference frame transformations (RFTs) add variability to motor output by decreasing the fidelity of sensory signals. How RFT stochasticity affects the sensory input underlying perceptual decisions, if at all, is unknown. To investigate this, we asked participants to perform a simple two-alternative motion direction discrimination task under varying conditions of head roll and/or stimulus rotation while responding either with a saccade or button press, allowing us to attribute behavioral effects to eye-, head- and shoulder-centered reference frames. We observed a rotation-induced, increase in reaction time and decrease in accuracy, indicating a degradation of motion evidence commensurate with a decrease in motion strength. Inter-participant differences in performance were best explained by a continuum of eye-head-shoulder representations of accumulated decision evidence, with eye- and shoulder-centered preferences during saccades and button presses, respectively. We argue that perceptual decision making and stochastic RFTs are inseparable, consistent with electrophysiological recordings in neural areas thought to be encoding sensorimotor signals for perceptual decisions. Furthermore, transformational stochasticity appears to be a generalized phenomenon, applicable throughout the perceptual and motor systems. We show for the first time that, by simply rolling one’s head, perceptual decision making is impaired in a way that is captured by stochastic RFTs.Significance statementWhen exploring our environment, we typically maintain upright head orientations, often even despite increased energy expenditure. One possible explanation for this apparently suboptimal behavior might come from the finding that sensorimotor transformations, required for generating geometrically-correct behavior, add signal- dependent variability (stochasticity) to perception and action. Here, we explore the functional interaction of stochastic transformations and perceptual decisions by rolling the head and/or stimulus during a motion direction discrimination task. We find that, during visuomotor rotations, perceptual decisions are significantly impaired in both speed and accuracy in a way that is captured by stochastic transformations. Thus, our findings suggest that keeping one’s head aligned with gravity is in fact ideal for making perceptual judgments about our environment.

THE INFLUENCE OF VITAMIN C ON EOSINOPHIL RESPONSE TO ACUTE ALCOHOL INTOXICATION IN RATS

1960 ◽  
Vol XXXV (IV) ◽  
pp. 585-593 ◽  
Author(s):  
T. P. J. Vanha-Perttula
Keyword(s):  
Vitamin C ◽  
Ethyl Alcohol ◽  
Intraperitoneal Injection ◽  
Alcohol Intoxication ◽  
Albino Rats ◽  
Acute Alcohol Intoxication ◽  
Alcohol Administration ◽  
Initial Values

ABSTRACT The effect of ethyl alcohol on the circulating eosinophil cells has been studied in female albino rats. An intoxicating dose of alcohol caused a marked depletion of circulating eosinophils which was most clearly evident four hours after the administration of the alcohol. The initial values were not reached before 24 hours had elapsed. Intraperitoneal injection of vitamin C 12 hours prior to the alcohol administration very effectively prevented this eosinopenic reaction. The mechanism of regulation of the eosinophil cells in the circulation has been discussed in the light of previous results and of those obtained in this study.

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