Adaptation Aftereffects in the Perception of Crabs and Lobsters as Examples of Complex Natural Objects

Neural correlates of dual-task walking in people with central neurological disorders: a systematic review

BACKGROUND

People with central neurological disorders experience difficulties with dual-task walking due to disease-related impairments. The objective of this review was to provide a comprehensive examination of the neural correlates (structural/functional brain changes) of dual-task walking in people with Parkinson's disease (PD), multiple sclerosis (MS), stroke, and Alzheimer's disease (AD).

METHODS

A systematic review of the literature was conducted, following PRISMA guidelines, on Medline, Embase, and Scopus. Included studies examined the relationship between structural and functional brain imaging and dual-task walking performance in people with PD, MS, stroke, and AD. Articles that met the inclusion criteria had baseline characteristics, study design, and behavioral and brain outcomes extracted. Twenty-three studies were included in this review.

RESULTS

Most structural imaging studies (75%) found an association between decreased brain integrity and poor dual-task performance. Specific brain regions that showed this association include the striatum regions and hippocampus in PD and supplementary motor area in MS. Functional imaging studies reported an association between increased prefrontal activity and maintained (compensatory recruitment) or decreased dual-task walking performance in PD and stroke. A subset (n = 2) of the stroke papers found no significant correlations. Increased supplementary motor area activity was associated with decreased performance in MS and stroke. No studies on AD were identified.

CONCLUSION

In people with PD, MS, and stroke, several neural correlates of dual-task walking have been identified, however, the direction of the association between neural and performance outcomes varied across the studies. The type of cognitive task used and presentation modality (e.g., visual) may have contributed to these mixed findings.

The emotional adaptation aftereffect discriminates between individuals with high and low levels of depressive symptoms

The adaptation aftereffect plays a critical role in human development and survival. Existing studies have found that, compared with general individuals, individuals with learning disability, autism and dyslexia show a smaller amount of non-affective-based cognitive adaptation aftereffect. Nevertheless, it is unclear whether individuals with depression or depression tendency show similar phenomenon in the adaptation aftereffect, and whether such depression tendency occurs in the non-affective-based cognitive or emotional adaptation aftereffect. To address this question, the present study conducted two experiments. Experiments 1A and 1B used the emotional facial expression adaptation paradigm to examine whether Chinese participants showed the emotional adaptation aftereffect and whether the emotional adaptation aftereffect was influenced by physical features of faces, respectively. Experiment 2 recruited two groups of participants, with high and low depression, respectively, to examine whether they showed differences in the emotional or cognitive adaptation aftereffect. Results showed that Chinese participants showed the typical emotional adaptation aftereffect, which was not influenced by physical features of faces. More importantly, compared to the low-depression group, the high-depression group showed a smaller emotional adaptation aftereffect, but the two groups showed a similar cognitive adaptation aftereffect. These results suggest that level of depressive symptoms is associated with the emotional adaptation aftereffect.

Eocarcinus praecursor Withers, 1932 (Malacostraca, Decapoda, Meiura) is a stem group brachyuran

Beginning with the description by Withers in 1932, Eocarcinus praecursor from the Jurassic has long been considered the oldest representative of the Brachyura. In 2010 Feldmann and Schweitzer re-investigated the specimens of E. praecursor and expressed doubts about the brachyuran nature of this species. Among other characters, the suspected existence of small chelae in the 2nd or 3rd pereopods led them to the conclusion that E. praecursor must be removed from the Brachyura and rather be seen as a representative of the Anomala. However, Anomala also do not possess chelae on the 2nd and 3rd pereopods. This contradiction and other aspects initiated a new investigation of E. praecursor. It can be shown that neither the 2nd nor the 3rd pereopods of E. praecursor are chelate. Furthermore, there are no other derived characters shared with anomalans. By contrast, there are a number of apomorphies shared with Brachyura such as the shape and articulation of the large chelae and the attachment points of the last two pereopods. However, not all apomorphies of the crown group are present yet. Thus, E. praecursor is a stem group representative, which allows statements about individual steps in the evolution of the set of characters of the crown group Brachyura.

D’Arcy W. Thompson’s Cartesian transformations: a critical evaluation

The images of D’Arcy Wentworth Thompson’s book “On Growth and Form” got an iconic status and became influential for biometrics and other mathematical approaches to organismic form. In particular, this is true for those of the chapter on the theory of transformation, which even has an impact on art and humanities. Based on his approach, Thompson formulated far-reaching conclusions with a partly anti-Darwinian stance. Here, we use the example of Thompson’s transformation of crab carapaces to test to what degree the transformation of grids, landmarks, and shapes result in congruent images. For comparison, we applied the same series of tests to digitized carapaces of real crabs. Both approaches show similar results. Only the simple transformations show a reasonable form of congruence. In particular, the transformations to majoid spider crabs reveal a complicated transformation of grids with partly crossing lines. By contrast, the carapace of the lithodid species is relatively easily created despite the fact that it is no brachyuran, but evolved a spider crab-like shape convergently from a hermit crab ancestor.