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An analysis of blocking in odorant mixtures: an increase but not a decrease in intensity of reinforcement produces
1Department of Entomology, Ohio State University, Columbus 43210-1220, USA. bsmith@magnus.acs.ohio-state.edu
Behavioral Neuroscience
|February 1, 1997
Summary
Honey bee conditioning reveals that unconditioned stimulus (US) intensity plays a key role in blocking. High US intensity during pretraining facilitated blocking, while changes in intensity during odorant mixture testing led to unblocking.
Area of Science:
- Animal Behavior
- Neuroscience
- Sensory Processing
Background:
- Blocking is a phenomenon where prior conditioning to one stimulus hinders learning about a second stimulus when both are presented together.
- Understanding blocking helps elucidate how animals process complex sensory information and mixtures.
- The role of unconditioned stimulus (US) intensity in blocking, particularly within the same sensory modality, requires further investigation.
Purpose of the Study:
- To investigate the influence of unconditioned stimulus (US) intensity on blocking in honey bees using proboscis-extension conditioning.
- To test predictions derived from theoretical models of blocking concerning US intensity variations.
- To compare findings in honey bees with existing data on vertebrate blocking.
Main Methods:
- Honey bees (Apis mellifera) were subjected to proboscis-extension conditioning.
- Odorant mixtures were used as stimuli, with varying unconditioned stimulus (US) intensities.
- One-trial blocking was assessed under different pretraining US concentrations (high vs. low).
- Unblocking was examined by altering US intensity during the mixture phase.
Main Results:
- One-trial blocking occurred when honey bees were pretrained with a high US concentration, but not with a low concentration.
- Increasing US intensity during the mixture phase resulted in unblocking.
- Decreasing US intensity during the mixture phase did not produce unblocking.
- The degree of unblocking was similar whether the US intensity increase occurred on the first or second mixture-phase trial.
Conclusions:
- Unconditioned stimulus (US) intensity is a critical factor modulating blocking in honey bees during olfactory learning.
- Findings suggest that increases, but not decreases, in US intensity can disrupt established blocking.
- The observed patterns of US intensity-dependent blocking in bees show parallels with vertebrate blocking studies, suggesting potential conserved mechanisms.