Publications by authors named "Martin Giurfa"

Honeybees see the world through photoreceptors in their compound eyes and ocelli, which express four opsins: UVOP (UV-sensitive), BLOP (blue-sensitive), and LOP1/LOP2 (both green-sensitive). Here, we provide the first comparative mapping of opsin RNA across the three bee castes: workers, drones, and queens. In all castes, was exclusive to the compound eyes, while was confined to the ocelli, which also contained photoreceptors.

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Neuropeptides are crucial molecules in the nervous system, regulating various biological processes. Neuropeptide F (NPF) and its shorter form, short neuropeptide F (sNPF), serve functions in invertebrates analogous to those of neuropeptide Y (NPY) in vertebrates, modulating growth, reproduction, nociception, circadian rhythms and feeding behaviours. In the honeybee, a social insect that adjusts foraging strategies based on colony needs, sNPF is a key regulator of foraging-related behaviours, including food intake, sucrose sensitivity, olfactory perception and visual memory formation.

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Animals use learning and memory to recognise cues that predict rewards or punishments, allowing flexible decision-making. When facing new stimuli, they often generalise - responding similarly to different but related cues - enabling adaptive behaviour despite natural variation. Pheromones, chemical signals central to social interactions, are known to affect learning and memory, but their role in generalisation is unknown.

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Research on associative learning typically focuses on behavioral and neural changes in response to learned stimuli. In Pavlovian conditioning, changes in responsiveness to conditioned stimuli are crucial for demonstrating learning. A less explored, but equally important, question is whether learning can induce changes not only in the processing of conditioned stimuli but also in the processing of unconditioned stimuli.

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Transitive inference, the ability to establish hierarchical relationships between stimuli, is typically tested by training with premise pairs (e.g., A + B-, B + C-, C + D-, D + E-), which establishes a stimulus hierarchy (A > B > C > D > E).

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In honey bees, appetitive motivation is primarily driven by the needs of the colony rather than individual needs. The regulation of appetitive behavior is achieved through the coordinated action of neuropeptides, hormones and biogenic amines, which integrate multiple signals to ensure appropriate appetitive responses. Dopamine signalling underpins a food-related wanting system that is sensitive to aversive experiences.

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Neonicotinoids represent over a quarter of the global pesticide market. Research on their environmental impact has revealed their adverse effect on the cognitive functions of pollinators, in particular of bees. Cognitive impairments, mostly revealed by behavioural studies, are the phenotypic expression of an alteration in the underlying neural circuits, a matter deserving greater attention.

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Odour processing exhibits multiple parallels between vertebrate and invertebrate olfactory systems. Insects, in particular, have emerged as relevant models for olfactory studies because of the tractability of their olfactory circuits. Here, we used fast calcium imaging to track the activity of projection neurons in the honey bee antennal lobe (AL) during olfactory stimulation at high temporal resolution.

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Invasive plants represent a significant global challenge as they compete with native plants for limited resources such as space, nutrients and pollinators. Here, we focused on four invasive species that are widely spread in the French Pyrenees, , , and , and analyzed their visual advertisement signals with respect to those displayed by their surrounding native species using a perceptual approach based on the neural mechanisms of bee vision given that bees are regular pollinators of these plants. We collected 543 spectral reflections from the 4 invasive species, and 66 native species and estimated achromatic and chromatic similarities to the bee eye.

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A new study on insect social learning shows that crickets learn to prefer a rewarded odorant by observing the choice of a conspecific and without experiencing the reward themselves. The mere perception of the conspecific activates octopaminergic reward neurons in the brain of the observer, thus facilitating odorant learning.

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In a technical comment, Barron . () criticized the work of Huang . () putting the accent on the quantification of dopamine levels via high-performance liquid chromatography (HPLC), yet also including data interpretation through alternative hypotheses aimed at invalidating the original ones proposed by Huang .

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Long-term memory (LTM) can be induced by repeated spaced training trials. Using the weak inhibitory avoidance (wIA) task, we showed that one wIA session does not lead to a 24-h LTM, whereas two identical wIA sessions spaced by 15 min to 6 h induce a 24-h LTM. This LTM promotion depends both on hippocampal protein synthesis and the activity of several kinases.

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A dopaminergic wanting system drives foraging in honey bees. A new study shows that encounters with the Asian hornet, a fierce bee predator, decrease brain dopamine levels and thus foraging. Stop signals, used to terminate the waggle dances of receivers, have the same effect, showing the power of bee communication.

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In contrast to extensive investigations on bee cognition, the cognitive capacities of wasps remain largely unexplored despite their key role as pollinators and predators of insect pests. Here we studied learning and memory in the neotropical wasp using a Pavlovian conditioning in which harnessed wasps respond with conditioned movements of their mouthparts to a learned odorant. We focused on the different castes, sexes, and ages coexisting within a nest and found that adults of .

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Trace conditioning is a form of Pavlovian learning in which the conditioned stimulus (CS) and the unconditioned stimulus (US) are separated by a temporal gap. Insects learn trace associations of variable nature (appetitive, aversive) and involving CSs of different sensory modalities (olfactory, visual). The accessibility of the insect neural system in behaving animals allowed identifying neural processes driving trace conditioning: the existence of prolonged neural responses to the CS after stimulus offset and the anticipation of US responses during the free-stimulus gap.

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Together with other anthropogenic factors, pesticides play a major role in pollinator decline worldwide. Most studies on their influence on pollinators have focused on honey bees given the suitability of this insect for controlled behavioral testing and raising. Yet, studies on pesticide impact should also contemplate tropical species, which contribute a major part of biodiversity and which have remained so far neglected.

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Recent developments allowed establishing virtual-reality (VR) setups to study multiple aspects of visual learning in honey bees under controlled experimental conditions. Here, we adopted a VR environment to investigate the visual learning in the buff-tailed bumble bee Bombus terrestris. Based on responses to appetitive and aversive reinforcements used for conditioning, we show that bumble bees had the proper appetitive motivation to engage in the VR experiments and that they learned efficiently elemental color discriminations.

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The question of whether individuals perform consistently across a variety of cognitive tasks is relevant for studies of comparative cognition. The honey bee (Apis mellifera) is an appropriate model to study cognitive consistency as its learning can be studied in multiple elemental and non-elemental learning tasks. We took advantage of this possibility and studied if the ability of honey bees to learn a simple discrimination correlates with their ability to solve two tasks of higher complexity, reversal learning and negative patterning.

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The "mental number line" (MNL) is a form of spatial numeric representation that associates small and large numbers with the left and right spaces, respectively. This spatio-numeric organization can be found in adult humans and has been related to cultural factors such as writing and reading habits. Yet, both human newborns and birds order numbers consistently with an MNL, thus raising the question of whether culture is a main explanation for MNL.

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Bee memory has been well characterized in laboratory experiments, but its relevance for foraging in an ecological context is less well studied. A new study shows that short-term memory in bumble bees correlates with springtime foraging efficiency, when floral resources are abundant, but not with summer foraging efficiency, when resources are scarce.

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Although insects of a same species appear similar when seen through human eyes, they exhibit considerable differences in behavioral performances, including learning success in conditioning tasks. New work on olfactory conditioning in fruit flies Drosophila melanogaster shows that these insects vary in their idiosyncratic learning proficiency and that this proficiency is consistent across days and variants of the trained task, thus uncovering the existence of different learning profiles within groups of flies.

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Martin Giurfa.

Curr Biol

July 2022

Interview with Martin Giurfa, who studies learning and memory in insects at Paul Sabatier University.

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A recent study revealed neural mechanisms underlying visual trace conditioning in flies. To associate visual stimuli with heat punishment, the activity of visual- and heat-processing circuits was extended into the gap between them. Distractors delivered during the gap disrupted learning, raising the question of the cognitive processes at play.

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