Duration of the unconditioned stimulus in appetitive conditioning of honeybees differentially impacts learning, long-term memory strength, and the underlying protein synthesis

Abstract

This study examines the role of stimulus duration in learning and memory formation of honeybees (Apis mellifera). In classical appetitive conditioning honeybees learn the association between an initially neutral, conditioned stimulus (CS) and the occurrence of a meaningful stimulus, the unconditioned stimulus (US). Thereby the CS becomes a predictor for the US eliciting a conditioned response (CR). Here we study the role of US duration in classical conditioning by examining honeybees conditioned with different US durations. We quantify the CR during acquisition, memory retention, and extinction of the early long-term memory (eLTM), and examine the molecular mechanisms of eLTM by interfering with protein synthesis. We find that the US duration affects neither the probability nor the strength of the CR during acquisition, eLTM retention, and extinction 24 h after conditioning. However, we find that the resistance to extinction 24 h after conditioning is susceptible to protein synthesis inhibition depending on the US duration. We conclude that the US duration does not affect the predictability of the US but modulates the protein synthesis underlying the eLTM's strength. Thus, the US duration differentially impacts learning, eLTM strength, and its underlying protein synthesis.

Omega-3 deficiency impairs honey bee learning

“…In tactile conditioning, performance of the control groups tended to decline. We conclude that omega-3 deficiency hinders acquisition, but we do not find an effect on early longterm memory retention (58).…”

A pragmatic comparison of noise burst and electric shock unconditioned stimuli for fear conditioning research with many trials

“…Nevertheless, one can speculate about potential mechanisms that facilitated fear conditioning with the noise burst. Mechanisms such as a stronger habituation to the electric shock (Çevik, ; Dycus & Powers, ; Jordan, Todd, Bucci, & Leaton, ), the use of different US‐calibration procedures for shock versus noise burst (Baker, Mercier, Gabel, & Baker, ; Lipp, ; Randich & LoLordo, ), different US durations (Gallistel & Gibbon, ; Lipp, ; Marter et al, ), different levels of belongingness (Hamm et al, ), and the involvement of different neural pathways (LeDoux, ) may have contributed to better learning in the noise burst versus shock group.…”

“…Various animal and human studies have examined the influence of US duration on fear acquisition. Some studies found better conditioning for longer US durations (Ashton, Bitgood, & Moore, ; Bitterman, Reed, & Krauskopf, ; Burkhardt & Ayres, ; Overmier, ), but there are also contradictory results (Frey & Butler, ; Kawai & Imada, ; Marter et al, ; Meiselman & Moore, ; Tait, Kehoe, & Gormezano, ; Wegner & Zeaman, ). Consequently, better conditioning with white noise burst could partially be related to a longer US duration and a longer CS−US overlap.…”

Redefining Single-Trial Memories in the Honeybee

“…We used puromycin labeling to assess the effect of Eme on protein synthesis at different periods following injection. This method, which is based on the incorporation of puromycin into nascent peptide chains, has been used to detect changes in protein synthesis levels in various animal models, including mammals, Drosophila, and the honeybee (Schmidt et al, 2009;Marter et al, 2014;Deliu et al, 2017).…”