Habituation Of Mealworm Pupae, Tenebio-Molitor Coleoptera-Tenebrionidae

In holometabolous insects, information acquired at the larval stage can persist through the intervening pupal stage and influence adult behavior (Thorpe and Jones 1937, Thorpe 1939, Borell du Vernay 1942, Borsellino et al. 1970, Somberg et al. 1970, Dethier and Goldrich 1971, Alloway 1972). To account for this relatively permanent storage of information, one must assume that those neural elements which hold this information endure through metamorphosis. The question remains: Can new information be acquired and can behavior be modified during the extensive neural reorganization that accompanies metamorphosis (Edwards 1969, Satija and Luthra 1969)? The present study indicates that a simple kind of behavior modification, namely habituation, can occur at the pupal stage during the transformation from larva to adult in Tenebrio molitor L

Age-related decline of peripheral visual processing: the role of eye movements

Earlier work suggests that the area of space from which useful visual information can be extracted (useful field of view, UFoV) shrinks in old age. We investigated whether this shrinkage, documented previously with a visual search task, extends to a bimanual tracking task. Young and elderly subjects executed two concurrent tracking tasks with their right and left arms. The separation between tracking displays varied from 3 to 35 cm. Subjects were asked to fixate straight ahead (condition FIX) or were free to move their eyes (condition FREE). Eye position was registered. In FREE, young subjects tracked equally well at all display separations. Elderly subjects produced higher tracking errors, and the difference between age groups increased with display separation. Eye movements were comparable across age groups. In FIX, elderly and young subjects tracked less well at large display separations. Seniors again produced higher tracking errors in FIX, but the difference between age groups did not increase reliably with display separation. However, older subjects produced a substantial number of illicit saccades, and when the effect of those saccades was factored out, the difference between young and older subjects’ tracking did increase significantly with display separation in FIX. We conclude that the age-related shrinkage of UFoV, previously documented with a visual search task, is observable with a manual tracking task as well. Older subjects seem to partly compensate their deficit by illicit saccades. Since the deficit is similar in both conditions, it may be located downstream from the convergence of retinal and oculomotor signals

Dual-task costs while walking increase in old age for some, but not for other tasks: an experimental study of healthy young and elderly persons

<p>Abstract</p> <p>Background</p> <p>It has been suggested in the past that the ability to walk while concurrently engaging in a second task deteriorates in old age, and that this deficit is related to the high incidence of falls in the elderly. However, previous studies provided inconsistent findings about the existence of such an age-related dual-task deficit (ARD). In an effort to explain this inconsistency, we explored whether ARD while walking emerges for some, but not for other types of task.</p> <p>Methods</p> <p>Healthy young and elderly subjects were tested under five different combinations of a walking and a non-walking task. The results were analysed jointly with those of a previous study from our lab, such that a total of 13 task combinations were evaluated. For each task combination and subject, we calculated the mean dual-task costs across both constituent tasks, and quantified ARD as the difference between those costs in elderly and in young subjects.</p> <p>Results</p> <p>An analysis of covariance yielded no significant effects of obstacle presence and overall task difficulty on ARD, but a highly significant effect of visual demand: non-walking tasks which required ongoing visual observation led to ARD of more than 8%, while those without such requirements led to near-zero ARD. We therefore concluded that the visual demand of the non-walking task is critical for the emergence of ARD while walking.</p> <p>Conclusion</p> <p>Combinations of walking and concurrent visual observation, which are common in everyday life, may contribute towards disturbed gait and falls during daily activities in old age. Prevention and rehabilitation programs for seniors should therefore include training of such combinations.</p