RESUMO
Viewing a person perform an action activates the observer's motor system. Whether this phenomenon reflects the action's kinematics or its final goal remains a matter of debate. One alternative to this apparent controversy is that the relative influence of goal and kinematics depends on the information available to the observer. Here, we addressed this possibility. For this purpose, we measured corticospinal excitability (CSE) while subjects viewed 3 different grasping actions with 2 goals: a large and a small object. Actions were directed to the large object, the small object, or corrected online in which case the goal switched during the movement. We first determined the kinematics and dynamics of the 3 actions during execution. This information was used in 2 other experiments to measure CSE while observers viewed videos of the same actions. CSE was recorded prior to movement onset and at 3 time points during the observed action. To discern between goal and kinematics, information about the goal was manipulated across experiments. We found that the goal influenced CSE only when its identity was known before movement onset. In contrast, a kinematic modulation of CSE was observed whether or not information regarding the goal was provided.
Assuntos
Objetivos , Percepção de Movimento/fisiologia , Atividade Motora/fisiologia , Adulto , Braço/fisiologia , Fenômenos Biomecânicos , Eletromiografia , Feminino , Humanos , Masculino , Músculo Esquelético/fisiologia , Estimulação Luminosa , Tratos Piramidais/fisiologia , Estimulação Magnética Transcraniana , Gravação em Vídeo , Adulto JovemRESUMO
The honey bee's waggle dance constitutes a remarkable example of an efficient code allowing social exploitation of available feeding sites. In addition to indicating the position (distance, direction) of a food patch, both the occurrence and frequency of the dances depend on the profitability of the exploited resource (sugar concentration, solution flow rate). During the waggle dance, successful foragers generate pulsed thoracic vibrations that putatively serve as a source of different kinds of information for hive bees, who cannot visually decode dances in the darkness of the hive. In the present study, we asked whether these vibrations are a reliable estimator of the excitement of the dancer when food profitability changes in terms of both sugar concentration and solution flow rate. The probability of producing thoracic vibrations as well as several features related to their intensity during the waggle phase (pulse duration, velocity amplitude, duty cycle) increased with both these profitability variables. The number of vibratory pulses, however, was independent of sugar concentration and reward rate exploited. Thus, pulse number could indeed be used by dance followers as reliable information about food source distance, as suggested in previous studies. The variability of the dancer's thoracic vibrations in relation to changes in food profitability suggests their role as an indicator of the recruiter's motivational state. Hence, the vibrations could make an important contribution to forager reactivation and, consequently, to the organisation of collective foraging processes in honey bees.
Assuntos
Comunicação Animal , Abelhas/fisiologia , Alimentos , Mel , Tórax/fisiologia , Vibração , Animais , Carboidratos/análise , Reologia , SoluçõesRESUMO
A recent study showed that the stingless bee Melipona quadrifasciata could learn to discriminate odors in a classical conditioning of proboscis extension response (PER). Here we used this protocol to investigate the ability of these bees to use olfactory information obtained within the colony in an experimental context: the PER paradigm. We compared their success in solving a classical differential conditioning depending on the previous olfactory experiences received inside the nest. We found that M. quadrifasciata bees are capable of transferring the food-odor information acquired in the colony to a differential conditioning in the PER paradigm. Bees attained higher discrimination levels when they had previously encountered the rewarded odor associated to food inside the hive. The increase in the discrimination levels, however, was in some cases unspecific to the odor used indicating a certain degree of generalization. The influence of the food scent offered at a field feeder 24 h before the classical conditioning could also be seen in the discrimination attained by the foragers in the PER setup, detecting the presence of long-term memory. Moreover, the improved performance of recruited bees in the PER paradigm suggests the occurrence of social learning of nectar scents inside the stingless bees' hives.