Spontaneous recovery of visually-triggered saccades after focal lesions of the frontal and parietal eye fields: A combined longitudinal oculomotor and fMRI study

To analyze oculomotor recovery in a patient with ischemic lesions restricted to the left frontal eye field (FEF) and the left parietal eye field (PEF).

Trunk sway in mildly disabled multiple sclerosis patients with and without balance impairment

Multiple sclerosis (MS) causes a broad range of neurological symptoms. Most common is poor balance control. However, knowledge of deficient balance control in mildly affected MS patients who are complaining of balance impairment but have normal clinical balance tests (CBT) is limited. This knowledge might provide insights into the normal and pathophysiological mechanisms underlying stance and gait. We analysed differences in trunk sway between mildly disabled MS patients with and without subjective balance impairment (SBI), all with normal CBT. The sway was measured for a battery of stance and gait balance tests (static and dynamic posturography) and compared to that of age- and sex-matched healthy subjects. Eight of 21 patients (38%) with an Expanded Disability Status Scale of 1.0-3.0 complained of SBI during daily activities. For standing on both legs with eyes closed on a normal and on a foam surface, patients in the no SBI group showed significant differences in the range of trunk roll (lateral) sway angle and velocity, compared to normal persons. Patients in the SBI group had significantly greater lateral sway than the no SBI group, and sway was also greater than normal in the pitch (anterior-posterior) direction. Sway for one-legged stance on foam was also greater in the SBI group compared to the no SBI and normal groups. We found a specific laterally directed impairment of balance in all patients, consistent with a deficit in proprioceptive processing, which was greater in the SBI group than in the no SBI group. This finding most likely explains the subjective symptoms of imbalance in patients with MS with normal CBT.

The assessment of cognition in visually impaired older adults

Background: visual and cognitive impairments are common in later life. Yet there are very few cognitive screening tests for the visually impaired. Objective: to screen for cognitive impairment in the visually impaired. Methods: case-control study including 150 elderly participants with visual impairment (n = 74) and a control group without visual impairment (n = 76) using vision-independent cognitive tests and cognitive screening tests (MMSE and clock drawing tests (CDT)) which are in part vision dependent. Results: the scoring of the two groups did not differ in the vision-independent cognitive tests. Visually impaired patients performed poorer than controls in the vision-dependent items of the MMSE (T = 7.3; df: 148; P < 0.001) and in CDT (T = 3.1; df: 145; P = 0.003). No group difference was found when vision-independent items were added to MMSE and CDT. The test score gain by the use of vision-independent items correlated with the severity of visual impairment (P < 0.002). Conclusion: visually impaired patients benefit from cognitive tests, which do not rely on vision. The more visually impaired the greater the benefit.

Whole-body motion discrimination in the visually impaired

Visually impaired people show superior abilities in various perception tasks such as auditory attention, auditory temporal resolution, auditory spatial tuning, and odor discrimination. However, with the use of psychophysical methods, auditory and olfactory detection thresholds typically do not differ between visually impaired and sighted participants. Using a motion platform we investigated thresholds of passive whole-body motion discrimination in nine visually impaired participants and nine age-matched sighted controls. Participants were rotated in yaw, tilted in roll, and translated along the y-axis at two different frequencies (0.3 Hz and 2 Hz). An adaptive 3-down 1-up staircase procedure was used along with a two-alternative direction (leftward vs. rightward) discrimination task. Superior performance of visually impaired participants was found in the 0.3 Hz roll tilt condition. No differences between the visually impaired and controls were observed in all other types of motion. The superior performance in the 0.3 Hz roll tilt condition could reflect differences in the integration of extra-vestibular cues and increased sensitivity towards changes in the direction of the gravito-inertial force. In the absence of visual information, roll tilts entail a more pronounced risk of falling, and this could eventually account for the group difference. It is argued that differences in experimental procedures (i.e. detection vs. discrimination of stimuli) explain the discrepant findings across perceptual tasks comparing blind and sighted participants.

Consciousness and choking in visually-guided actions

Choking under pressure describes the phenomenon of people performing well below their expected standard under circumstances where optimal performance is crucial. One of the prevailing explanations for choking is that pressure increases the conscious attention to the underlying processes of the performer's task execution, thereby disrupting what would normally be a relatively automatic process. However, research on choking has focused mainly on the influence of pressure on motor performance, typically overlooking how it might alter the way that vision is controlled when performing these motor actions. In this article we ask whether the visual component of expert motor-skill execution is susceptible to choking much like the motor component is thought to be. To do so, we draw heavily on empirical findings from studies of sporting expertise, in particular focussing on the role of gaze in three types of visually-guided actions: interceptive actions, aiming tasks, and anticipatory skill. For each of these skills we evaluate the nature of the expert advantage, discuss the role of consciousness in their control, examine the potential impact of pressure on task performance, and consider interventions designed to reduce the likelihood of choking when performing these tasks

Self-motion direction discrimination in the visually impaired

Despite the close interrelation between vestibular and visual processing (e.g., vestibulo-ocular reflex), surprisingly little is known about vestibular function in visually impaired people. In this study, we investigated thresholds of passive whole-body motion discrimination (leftward vs. rightward) in nine visually impaired participants and nine age-matched sighted controls. Participants were rotated in yaw, tilted in roll, and translated along the interaural axis at two different frequencies (0.33 and 2 Hz) by means of a motion platform. Superior performance of visually impaired participants was found in the 0.33 Hz roll tilt condition. No differences were observed in the other motion conditions. Roll tilts stimulate the semicircular canals and otoliths simultaneously. The results could thus reflect a specific improvement in canal–otolith integration in the visually impaired and are consistent with the compensatory hypothesis, which implies that the visually impaired are able to compensate the absence of visual input.