Visual pattern recognition in the cerebral hemispheres : the role of spatial filtering

The differences between the left and right cerebral hemispheres in terms of visual pattern recognition were examined in the context of the spatial filtering model of visual perception. On the basis of a wide range of evidence, it was hypothesized that the right hemisphere is superior in the processing of low spatial frequency and/or high contrast information, and that this superiority may underlie its predominant role in "gestalt" perception. The left hemisphere, on the other hand, was hypothesized to be more highly involved in an analysis of high frequency and/or low contrast information contained in the visual environment. The spatial filtering capabilities of the two hemispheres were assessed by presenting square-wave gratings to the left and right visual fields, which project almost exclusively to the primary visual cortical areas of the contralateral hemispheres. Twenty-four right-handed adult male subjects were required to discriminate two different orientations of each of six gratings varying in fundamental spatial frequency and level of contrast

The Effects of Sleep Deprivation on Flight Performance, Instrument Scanning, and Physiological Arousal in United States Air Force Pilots

The effects of 34 hr of continuous wakefulness on flight performance, instrument scanning, subjective fatigue and EEG activity were measured. Ten fixed-wing pilots flew a series of 10 simulator profiles, and root-mean-square error was calculated for various flight parameters. Ocular scanning patterns were obtained by means of infrared tracking. The results showed that flying errors peaked after about 24-28 hr of continuous wakefulness, in line with peaks in subjective- and EEG-measured fatigue. Instrument scanning was very consistent across pilots but was mostly unaffected by the sleep deprivation

The relationship between vestibular function and topographical memory in older adults

Research during the past two decades has demonstrated an important role of the vestibular system in topographical orientation and memory and the network of neural structures associated with them. Almost all of the supporting data have come from animal or human clinical studies, however. The purpose of the present study was to investigate the link between vestibular function and topographical memory in normal elderly humans. Twenty-five participants aged 70 to 85 years who scored from mildly impaired to normal on the Montreal Cognitive Assessment (MoCA) received three topographical memory tests: the Camden Topographical Recognition Memory Test (CTMRT), a computerized topographical mental rotation test (TMRT), and a virtual pond maze (VPM). They also received six vestibular or oculomotor tests: optokinetic nystagmus (OKN), visual pursuit (VP), actively generated vestibulo-ocular reflex (VOR), the sensory orientation test (SOT) for posture, and two measures of rotational memory (error in degrees, or RM°, and correct directional recognition, or RM→). The only significant bivariate correlations were among the three vestibular measures primarily assessing horizontal canal function (VOR, RM°, and RM→). A multiple regression analysis showed significant relationships between vestibular and demographic predictors and both the TMRT (R = 0.78) and VPM (R = 0.66) measures. The significant relationship between the vestibular and topographical memory measures supports the theory that vestibular loss may contribute to topographical memory impairment in the elderly