Age-dependent and task-related volume changes in the mushroom bodies of visually guided desert ants,Cataglyphis bicolor

In field environments it is not usually possible to provide robots in advance with valid geometric models of its environment and task element locations. The robot or robot teams need to create and use these models to locate critical task elements by performing appropriate sensor based actions. Here, an information-based iterative algorithm to intelligently plan the robot’s visual exploration strategy is proposed to enable it to efficiently build 3D models of its environment and task elements. The method assumes mobile robot or vehicle with cameras carried by articulated mounts. The algorithm uses the measured scene information to find the next camera position based on expected new information content of that pose. This is achieved by utilizing a metric derived from Shannon’s information theory to determine optimal sensing poses for the agent(s) mapping a highly unstructured environment. Once an appropriate environment model has been built, the quality of the information content in the model is used to determine the constraint-based optimum view for task execution. Experimental demonstrations on a cooperative robot platform performing an assembly task in the field show the effectiveness of this algorithm for single and multiple cooperating robotic systems.

Download Full-text

Iodine fortification may influence the age-related change in thyroid volume: a longitudinal population-based study (DanThyr)

Acta Endocrinologica ◽

10.1530/eje-13-0918 ◽

2014 ◽

Vol 170 (4) ◽

pp. 507-517 ◽

Cited By ~ 11

Author(s):

Anne Krejbjerg ◽

Lena Bjergved ◽

Inge Bülow Pedersen ◽

Allan Carlé ◽

Torben Jørgensen ◽

...

Keyword(s):

Thyroid Volume ◽

Population Based ◽

Iodine Intake ◽

Multivariate Regression Model ◽

Volume Changes ◽

Population Based Study ◽

Age Related ◽

Age Dependent ◽

Volume Decrease

ObjectiveTo assess the individuals' thyroid volume changes after the mandatory nationwide iodine fortification (IF) program in two Danish areas with different iodine intake at baseline (Copenhagen, mild iodine deficiency (ID) and Aalborg, moderate ID).DesignA longitudinal population-based study (DanThyr).MethodsWe examined 2465 adults before (1997) and after (2008) the Danish IF of salt (2000). Ultrasonography was carried out by the same sonographers using the same equipment, after controlling performances. Participants treated for thyroid disease were excluded from analyses.ResultsOverall, median thyroid volume had increased in Copenhagen (11.8–12.2 ml, P=0.001) and decreased in Aalborg, although not significantly (13.3–13.1 ml, P=0.07) during the 11 years of follow-up.In both regions, there was an age-related trend in individual changes in thyroid volume from baseline to follow-up; thyroid volume increased in women <40 years of age and decreased in women >40 years of age.In a multivariate regression model, higher age at entry was a predictor (P<0.05) for thyroid volume decrease >20% during the follow-up period (women aged 40–45 years: odds ratio (OR) 4.3 (95% CI, 2.2–8.2); women aged 60–65 years: 5.8 (2.9–11.6)) and individuals of higher age were also less likely to have an increase in thyroid volume (women aged 40–45 years: OR 0.2 (0.1–0.3); women aged 60–65: OR 0.3 (0.2–0.4)).ConclusionsAge-dependent differences in thyroid volume and enlargement had leveled out after the Danish iodization program. Thus, the previously observed increase in thyroid volume with age may have been caused by ID.

Download Full-text

Phylogeny of three parapatric species of desert ants, Cataglyphis bicolor, C. viatica, and C. savignyi: A comparison of mitochondrial DNA, nuclear DNA, and morphological data

Zoology ◽

10.1016/j.zool.2005.03.005 ◽

2005 ◽

Vol 108 (2) ◽

pp. 169-177 ◽

Cited By ~ 11

Author(s):

Markus Knaden ◽

Alberto Tinaut ◽

Xim Cerda ◽

Sibylle Wehner ◽

Rüdiger Wehner

Keyword(s):

Mitochondrial Dna ◽

Nuclear Dna ◽

Morphological Data ◽

Desert Ants ◽

Cataglyphis Bicolor

Download Full-text

The ontogeny of foragwehaviour in desert ants, Cataglyphis bicolor

Ecological Entomology ◽

10.1111/j.0307-6946.2004.00591.x ◽

2004 ◽

Vol 29 (2) ◽

pp. 240-250 ◽

Cited By ~ 76

Author(s):

Rudiger Wehner ◽

Christoph Meier ◽

Christoph Zollikofer

Keyword(s):

Desert Ants ◽

Cataglyphis Bicolor

Download Full-text

Eye Movements Reveal Spatiotemporal Dynamics of Active Sensing and Planning in Navigation

10.1101/2021.04.26.441482 ◽

2021 ◽

Author(s):

Seren Zhu ◽

Kaushik Lakshminarasimhan ◽

Nastaran Arfaei ◽

Dora Angelaki

Keyword(s):

Eye Movements ◽

Temporal Evolution ◽

Optimal Path ◽

Active Sensing ◽

Visually Guided ◽

Sequential Decision ◽

Environmental Complexity ◽

Path Lengths ◽

Future Path ◽

And Task

AbstractGoal-oriented navigation is widely understood to depend critically upon internal maps. Although this may be the case in many settings, many animals, such as humans, tend to rely on vision when the environment is complex or unfamiliar. The nature of gaze during visually-guided navigation remains unknown. To study this, we tasked humans to navigate to transiently visible goals in virtual mazes of varying complexity, observing that they achieved near-optimal path lengths in all arenas. By analyzing subjects’ eye movements, we gained insights into the principles of active sensing and prospection that would not have been gleaned from observing navigational behavior alone. The spatial distribution of fixations revealed that environmental complexity mediated a striking trade-off in the extent to which attention was directed towards two complimentary aspects of the world model: the reward location and task-relevant transitions. Furthermore, the temporal evolution of gaze revealed rapid, sequential prospection of the future path, evocative of neural ’preplay’. These findings suggest that the spatiotemporal characteristics of eye movements during navigation are significantly shaped by the unique cognitive computations underlying real-world, sequential decision making.

Download Full-text