Jutta Billino

Differential aging of motion processing mechanisms: Evidence against general perceptual decline

While the percentage of older people in our society is steadily increasing, knowledge about perceptual changes during healthy aging is still limited. We investigated age effects on visual motion perception in order to differentiate between general decline and specific vulnerabilities. A total of 119 subjects ranging in age from 20 to 82 years participated in our study. Perceptual thresholds for different types of motion information, including translational motion, expanding radial flow, and biological motion, were determined. Results revealed a substantial increase of thresholds for translational motion with age. Biological motion perception was only moderately affected by age. For both motion types, threshold elevation seemed to develop gradually with age. In contrast, we found stable radial flow analysis across lifespan. There was no evidence that age effects were dependent on gender. Results demonstrate that visual capabilities are not equally prone to age-related decline. Surprisingly, higher motion complexity might not be necessarily associated with more pronounced perceptual constraints. We suggest that differential age effects on the perception of specific motion types might indicate that specialized neuronal processing mechanisms differ in their vulnerability to physiological changes during aging.

Effects of arousing emotional scenes on the distribution of visuospatial attention: changes with aging and early subcortical vascular dementia

BACKGROUND The modulation of attention by emotionally arousing stimuli is highly important for each individuals social function. Disturbances of emotional processing are a supportive feature for the diagnosis of subcortical vascular dementia (SVD). We address here whether these disturbances might be useful as an early disease marker. METHODS In order to examine the modulation of visual attention by emotionally arousing stimuli of different valence, 12 elderly patients with early SVD, 12 age-comparable healthy adults and 12 young healthy subjects were studied while looking at pairs of pictures from the International Affective Picture Battery that were either neutral-neutral, neutral-positive or neutral-negative in terms of emotional content. Eye movements were recorded with an infrared eye-tracking system. The direction of the first saccade and the dwell time during the 10 s of presentation were measured and compared among groups with parametric tests. RESULTS All subjects showed a modulation of initial attentional orienting as well as a higher percentage of dwell time towards the pictures containing emotional material. Patients with SVD and old controls did not differ in either experimental measure. Young patients showed a stronger bias towards emotionally negative material than both groups of older individuals. CONCLUSIONS Modulation of visuospatial attention is preserved in early SVD. This might have implications for therapeutic interventional approaches. A weakened sustained attention towards negative but not positive emotional pictures in the elderly is in accordance with the socioemotional selectivity theory, describing a relative selection of positive stimuli with aging.

Motion processing at low light levels: Differential effects on the perception of specific motion types

While many aspects of human vision at low light levels have been studied in great detail, motion perception has rarely been investigated so far. Here we address differential effects of light level on the perception of coherent motion, heading from radial flow, and biological motion. We determined detection thresholds under photopic, mesopic, and scotopic conditions. Results indicate that the perception of specific motion types differs in vulnerability to changes in light level. Thresholds for coherent motion and heading from radial flow increased monotonically from photopic to mesopic and scotopic light levels. We suppose that observed deficits are due to temporal pooling under rod-dominated vision. In contrast, detection thresholds for biological motion, which is distinguished by temporal dynamics and a specific spatial distribution of nearby signals, were exclusively elevated under mesopic conditions. Thresholds under scotopic conditions matched those under photopic conditions. Selective constraints under mesopic conditions might be explained by a detrimental interaction of rod and cone vision as well as by activity of different rod pathways. Findings suggest that very early retinal signal processing can have complex effects on the perception of different motion types, which is generally considered to rely on cortical areas.

Age effects on the perception of motion illusions.

Anomalous motion illusions represent a popular class of illusions and several studies have made an effort to explain their perception. However, understanding is still inconsistent. Age-related differences in susceptibility to illusory motion may contribute to further clarification of the underlying processing mechanisms. We investigated the effect of age on the perception of four different anomalous motion illusions. The Enigma illusion, the Rotating-Snakes illusion, the Pinna illusion, and the Rotating-Tilted-Lines illusion were tested on a total of one hundred and thirty-nine participants covering an age range from 3 to 82 years. In comparison with young adults, children showed a lower likelihood of perceiving motion in all illusions with the exception of the Rotating-Tilted-Lines illusion. For adult subjects, we found significant age effects in the Rotating-Snakes illusion and the Rotating-Tilted-Lines illusion: occurrence of the illusory effect decreased with age. The other two illusions turned out to be unaffected by aging. Finally, inter-correlations between different motion illusions revealed that only the Pinna illusion and the Rotating-Tilted-Lines illusion correlated significantly with each other. The results confirm that anomalous motion illusions should not be considered as a homogeneous group. Possible links between perceptual data and neurophysiological changes related to age are discussed. Perceptual differences due to age provide the opportunity to improve our understanding of illusory motion and point to specific underlying mechanisms.

Visual Search in Patients with Subcortical Vascular Dementia: Short Fixations but Long Reaction Times

Visual search is a cognitive function of high ecological relevance. It involves rapid alternations between allocating and shifting attention. In patients with Alzheimer’s disease, the duration of fixations during visual search increases already in the early stage of the illness. Subcortical vascular dementia (SVD), a newly defined subgroup of vascular dementia, has not yet been examined in this respect. SVD affects patients with a history of lacunar infarctions and/or transient ischemic attacks, focal neurological signs and evidence of subcortical white matter lesions as well as lacunes in the deep grey matter. Here, we report our findings from tracking eye movements during a visual search task with different array sizes in 9 patients with SVD and compare the number and duration of eye fixations they made with the values obtained in 9 healthy elderly control subjects. While patients with SVD were significantly slower in the tasks with longer center to target distances (mean reaction time), the number and duration of fixations they made did not differ from those in controls. Impairment of visual search in patients with SVD seems to be an effect of general cognitive slowing in more demanding arrays of visual search rather than a specific deficit in parameters of eye fixation.

SENTENCES WRITTEN DURING THE MINI‐MENTAL STATE EXAMINATION: CONTENT AND DIAGNOSTIC VALUE IN COGNITIVELY HEALTHY ELDERLY PEOPLE AND PATIENTS WITH DEMENTIA

Financial Disclosure: None of the authors had any financial conflicts. Author Contributions: Tatsuya Suzuki contributed toward study concept and design, acquisition of subjects and/ or data, analysis and interpretation of the data, and preparation of manuscript. Shoko Futami, Yoshimasa Igari, Noriaki Matsumura, Kentaro Watanabe, Hiroshi Nakano, Kenzo Oba, Yuichi Murata, Hitoshi Koibuchi, and Yoshiaki Kigawa all equally contributed to the acquisition of subjects, data, or both and to analysis and interpretation of the data. Sponsor’s Role: None.

Challenges to normal neural functioning provide insights into separability of motion processing mechanisms

There is a long history of attempts to disentangle different visual processing mechanisms for physically different motion cues. However, underlying neural correlates and separability of networks are still under debate. We aimed to refine the current understanding by studying differential vulnerabilities when normal neural functioning is challenged. We investigated effects of ageing and extrastriate brain lesions on detection thresholds for motion defined by either luminance- or contrast modulations, known as first- and second-order motion. Both approaches focus on extrastriate processing changes and combine distributed as well as more focal constraints. Our ageing sample comprised 102 subjects covering an age range from 20 to 82 years. Threshold signal-to-noise ratios for detection approximately doubled across the age range for both motion types. Results suggest that ageing affects perception of both motion types to an equivalent degree and thus support overlapping processing resources. Underlying neural substrates were further qualified by testing perceptual performance of 18 patients with focal cortical brain lesions. We determined selective first-order motion deficits in three patients, selective second-order motion deficits in only one patient, and deficits for both motion types in three patients. Lesion analysis yielded support for common functional substrates in higher cortical regions. Functionally specific substrates remained ambiguous, but tended to cover earlier visual areas. We conclude that observed vulnerabilities of first- and second-order motion perception provide limited evidence for functional specialization at early extrastriate stages, but emphasize shared processing pathways at higher cortical levels.

Robust Underestimation of Speed During Driving: A Field Study

Traffic reports consistently identify speeding as a substantial source of accidents. Adequate driving speeds require reliable speed estimation; however, there is still a lack of understanding how speed perception is biased during driving. Therefore, we ran three experiments measuring speed estimation under controlled driving and lighting conditions. In the first experiment, participants had to produce target speeds as drivers or had to judge driven speed as passengers. Measurements were performed at daylight and at night. In the second experiment, participants were required to produce target speeds at dusk, under rapidly changing lighting conditions. In the third experiment, we let two cars approach and pass each other. Drivers were instructed to produce target speeds as well as to judge the speed of the oncoming vehicle. Here measurements were performed at daylight and at night, with full or dipped headlights. We found that passengers underestimated driven speed by about 20% and drivers went over the instructed speed by roughly the same amount. Interestingly, the underestimation of speed extended to oncoming cars. All of these effects were independent of lighting conditions. The consistent underestimation of speed could lead to potentially fatal situations where drivers go faster than intended and judge oncoming traffic to approach slower than it actually is.

Effects of Subcortical Vascular Ischemic Dementia and Aging on Negative and Neutral Word List Learning

Background: Subcortical ischemic vascular dementia (SIVD) represents an important subgroup of vascular dementia. Besides characteristic cognitive deficits, particular emotional problems support the diagnosis. Emotional disturbances in SIVD are not well understood. Method: We studied the performance of SIVD patients, healthy young control persons and old control persons in an emotional word list learning task. Results: SIVD patients showed lower memory performance than both control groups for neutral as well as for negative words. However, we found a significant emotional memory advantage for negative words in all 3 diagnostic groups. Conclusion: SIVD patients are able to profit from emotional information in order to enhance their memory performance.

Healthy aging is associated with decreased risk-taking in motor decision-making.

Healthy aging is associated with changes in both cognitive abilities, including decision-making, and motor control. Previous research has shown that young healthy observers are close to optimal when they perform a motor equivalent of economic decision-making tasks that are known to produce suboptimal decision patterns. We tested both younger (age 20–29) and older (age 60–79) adults in such a task, which involved rapid manual aiming and monetary rewards and punishments contingent on hitting different areas on a touch screen. Older adults were as close to optimal as younger adults at the task, but differed from the younger adults in their strategy. Older adults appeared to be relatively less risk-seeking, as evidenced by the fact that they adjusted their aiming strategy to a larger extent to avoid the penalty area. A model-based interpretation of the results suggested that the change in aiming strategy between younger and older adults was mainly driven by the fact that the first weighted monetary gains more than losses, rather than by a mis-estimation of one’s motor variability. The results parallel the general finding that older adults tend to be less risk-seeking than younger adults in economic decision-making and complement the observation that children are even more risk-seeking than younger adults in a similar motor decision-making paradigm.