Biology subjects

Helene, A. F.

Publications and source records attributed to Helene, A. F..

3 recordsLinked to original sources

bioRxiv2024

Spatio-temporal learning in a mass-recruiting leaf-cutting ant (Acromyrmex subterraneus)

The ability to anticipate periodically available resources is observed in several animals and improves performance in obtaining resources and adaptability. Spatio-temporal learning occurs when they associate the correct time and location of future events. We evaluate whether leaf-cutting ants Acromyrmex subterraneus can anticipate the presence of sucrose and examine potential anticipatory effects. Five colonies were used in an experimental setup where, from a central tray, two trails in opposite directions gave access to either the sucrose or to nothing. For 21 consecutive days sucrose was offered at the same place and the same time. Cameras recorded the flow of individuals at 4 different phases: before feeding (10h00-11h00), pre-feeding (11h30-12h00), feeding (12h00-13h00) and after feeding (14h00-15h00). On the 22nd day sugar was not supplied. On the 21st day the ants were marked and the next day, observed. Our results shows that: (1) the ants responded positively to the stimulus presented by forming the foraging trail to collect sucrose; (2) before feeding there was no significant difference in ant flow between the trails, but after feeding, the ant flow was consistently higher on trail that led to sucrose, which we called a keep going behavior; (3) there was a progressive spatio-temporal learning, given that ants began to appear earlier in pre-feeding throghout the weeks; (4) on the 22nd day, the ants presented themselves 10 minutes in advance and remained in the correct place; (5) the marked ants indicated that even without any resource the empty place continued to be explored. The colonies were able to learn where and when to look for food. Due to the adjustment of the ants to the stimuli of the environment it was possible to prepare for the collection of sucrose and the success in foraging for the colony. Summary statementLeaf-cutting ants are capable of spatio-temporal learning and this process has relevance on mass foraging recruitment and overall social organization of the colony.

animal behavior and cognition↗

bioRxiv2020

Integrative Responses of Leaf-Cutting Ants to Temperature Rises

Thermal variation has complex effects on organisms and they deal with it by combining behavioral and physiological thermal tolerance. However, we still do not understand well how these two types of traits relate to body condition (e.g. size, hydration) and environmental variables (e.g. relative humidity), some of which are typical aspects of thermal tolerance experiments (warming rates, start temperature). We explored these interactions using a set of experiments that sequentially measure behavioral (Voluntary Thermal Maxima) and physiological thermal tolerance (Critical Thermal Maxima) for individuals of Atta sexdens rubropilosa (Forel, 1908). We found non-linear effects of body size on behavioral thermal tolerance and refuted the traditional hypothesis that body size increases ants physiological thermal tolerance. Hydration state and humidity had complex effects on behavioral and physiological tolerance. However, both tolerance measures increased with heating rates and start temperature. Our work helps understanding how an ectotherm integrates stimuli affecting its thermal tolerance to decide which temperatures to avoid. We discuss implications for the ecology of ants, their labor division, and for their susceptibility to climate warming and drought. Summary StatementHere we show how internal (body size, hydration level) and external factors (heating rate, relative humidity) affect leaf-cutting ants behavioral and physiological responses to temperature rises.

physiology↗

bioRxiv2018

Goalkeeper game: a new assessment instrument in neurology showed higher predictive power than moca for gait performance in people with parkinson’s disease

ObjectiveTo investigate the use of the Goalkeeper Game (GG) to assess gait automaticity decline under dual task conditions in people with Parkinsons disease (PPD) and compare its predictive power with the one of the MoCA test.\n\nMaterials and Methods74 PPD (H&Y stages: 23 in stage 1; 31 in stage 2; 20 in stage 3), without dementia (MoCA cut-off 23), tested in ON period with dopaminergic medication were submitted to single individual cognitive/motor evaluation sessions. The tests applied were: MoCA, GG, dynamic gait index (DGI) task and timed up and go test (TUG) under single and dual-task (DT) conditions. GG test resulted in 9 measures extracted via a statistical model. The predictive power of the GG measures and the MoCA score with respect to gait performance, as assessed by DGI and DT-TUG, were compared.\n\nResultsThe predictive models based on GG measures and MoCA score obtained, respectively, sensitivities of 65% and 56% for DGI scores and 59% and 57% for DT-TUG cost at a 50% specificity. GG application proved to be feasible and aroused more motivation in PPDs than MoCa.\n\nConclusionGG, a friendly and ludic game, was able to reach a good power of gait performance prediction in people at initial and intermediate stages of PD evolution.

neuroscience↗