Memory & Learning
Part 2: Insect Behaviour
Objectives
At the end of this section you will know:
- How does learning and memory operate at the behavioral level?
- How can you train an insect?
- What are the different types of memory?
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Mini-lecture:Learning and memory: Different types of memory
Learning and memory can involve three main phases:
- Acquisition: the formation of the memory, such as associating a stimulus with a sugar reward or an aversive shock (training)
- Consolidation: neural changes occur to allow for the stabilization of the memory, which happens during the period after training
- Retrieval: the process of remembering the association or the memory, which is tested after training.
Learning and memory: Different types of conditioning
Just as with Pavlov’s dogs, insects can be trained to associate an unconditioned stimulus (US) with a conditioned stimulus (CS) with training.
- Rewarding learning: the association of a stimulus with a rewarding unconditioned stimulus (US), such as sugar
- Aversive conditioning: the association of a stimulus with an aversive unconditioned stimulus (US), such as heat or electric foot shocK
Learning and memory time courses
Memory can be divided into short-term (STM), middle-term (MTM), and long-term (LTM) memory.
In Drosophila, a fourth type of middle-term memory was discovered which is anaesthesia-resistant memory (ARM). While other mid-term memory can be blocked with placing the flies on ice a certain period of time after training, ARM survives the procedure.
The different types of memory have different time courses:
References:
Heisenberg M (1998) What do the mushroom bodies do for the insect brain? Learn Mem 5:1-10.
Heisenberg M (2003) Mushroom body memoir: from maps to models. Nat Rev Neurosci 4:266-75.
Learning and memory: types of training
Insects, and, really, any animal, can be trained to learn in several ways.
These different training regimes can trigger different short and long term memory pathways.
Learning, memory, and everything else insects do!
Learning and memory enables insects to adapt to their environment, their situations, and to become one of the most successful groups on the planet.
To study learning and memory, researchers have focused on two main model species:
The vinegar fly Drosophila melanogaster
The honeybee Apis mellifera
The vinegar fly, Drosophila melanogaster:
a model for understanding the role of genetics in learning and memory
Drosophila melanogaster has been essential for understanding the function of synapses, of neurons, and various aspects of the nervous system.
The genetic ‘toolkit’ available for studying the genetic mechanisms 
underlying behaviour has allowed researchers to dissect neural circuits while looking at animal behaviour.
The learning and memory assay: the paradigm to train large groups of flies to associate an odour with electrical foot shock
The benefits of Drosophila are listed at this website: http://en.wikipedia.org/wiki/Drosophila
The study of learning and memory have been addressed in Drosophila using the olfactory shock treatment. Using this population approach, numerous learning and memory mutants have been found.
Learning and memory: How to train a fly
Another setup involves tethering the fly to a post and using a torquemeter to detect when the fly tries to turn left or right, called the tethered flight arena setup.
Check out movies of arena flight online: http://www.physci.ucla.edu/research/frye/movies.htm
The fly can be trained to avoid ‘looking’ at one object when the object is associated with heat
References:
Heisenberg M (1998) What do the mushroom bodies do for the insect brain? Learn Mem 5:1-10.
Heisenberg M (2003) Mushroom body memoir: from maps to models. Nat Rev Neurosci 4:266-75.
Liu G, Seiler H, Wen A, Zars T, Ito K, Wolf R, Heisenberg M, Liu L (2006) Distinct memory traces for two visual features in the Drosophila brain. Nature. 439:551-556.
The honeybee, Apis mellifera: a model for understanding learning and memory
Honeybees have long been used and domesticated by humans for pollination.
They forage from a central site, have to navigate a terrain, and learn optimal foraging approaches.
They can be trained to learn colours, patterns, motion cues, etc.
Karl von Frisch, the researcher who discovered the honeybee waggle dance, also found honeybees can detect colour by training them to coloured objects.
References:
von Frisch K (1914) Der Farbensinn und Formensinn der Biene. Jb Abt Allg Zool Physiol 37: 1-238.
von Frisch K (1965) The Dance Language and Orientation of Bees. Cambridge: Belknap Witthöft W (1967) Absolute Anzahl und Verteilung der Zellen im Hirn der Honigbiene. Z Morph Tiere 1:160-184.
Numerous researchers have found that honeybees can perform complex behavioural tasks. The references below are examples of the tremendous visual learning capabilities of honeybees:
Dyer AG, Chittka L (2004). Fine colour discrimination requires differential conditioning in bumblebees. Naturwissenschaften 91: 224-227.
Dyer AG, Rosa MGP, Reser DH (2008) Honeybees can recognise images of complex natural scenes for use as potential landmarks. J Exp Biol 211: 1180-1186.
Giger A, Srinivasan MV (1996) Pattern recognition in honeybees: chromatic properties of orientation analysis. J Comp Physiol A 178:763-769.
Giger AD, Srinivasan MV (1995). Pattern recognition in honeybees: eidetic imagery and orientation discrimination. J Comp Physiol A 176: 791-795.
Giurfa M (2007) Behavioral and neural analysis of associative learning in the honeybee: a taste from the magic well. J Comp Physiol A 193:801-24.
Giurfa M, Eichmann B, Menzel R (1996) Symmetry perception in an insect. Nature 382: 458-461.
Giurfa M, Zhang SW, Jennett A, Menzel R, Srinivasan MV (2001) The concepts of sameness and difference in an insect. Nature 410:930-933.
Lehrer M, Srinivasan MV, Zhang SW, Horridge GA (1988) Motion cues provide the bee’s visual world with a third dimension. Nature 332:356-357.
Srinivasan MV (1993) Pattern recognition in the honeybee: recent progress. J Insect Physiol 40:183-194.
Srinivasan MV, Lehrer M (1988) Spatial acuity of honeybee vision and its spectral properties. J Comp Physiol A 162: 159-172.
Srinivasan MV, Zhang SW (1998) Probing perception in a miniature brain: Pattern recognition and maze navigation in honeybees. Zoology 101:246-259.
Srinivasan MV, Zhang S, Altwein M, Tautz J (2000). Honeybee navigation: nature and calibration of the ‘odometer’. Science 287: 851-853.
Srinivasan MV, Zhang SW, Bidwell NJ (1997). Visually mediated odometry in honeybees. J Exp Biol 200: 2513-2522.
Zhang SW, Bartsch K, Srinivasan MV (1996). Maze learning by honeybees. Neurobiol Learn Mem 66: 267-282.
Zhang SW, Lehrer M, Srinivasan MV (1999) Honeybee memory: navigation by associative grouping and recall of visual stimuli. Neurobiol Learn Mem 72: 180-201.
Learning and memory: How to train a bee
The honeybees can be trained to go to a specific area or visual cue by associating it with a sugar reward.
In honeybees (and bumblebees, below) can be trained to extend their proboscis with the application of sugar to the antenna, which is called the proboscis extension reflex (PER).
In this case, the sugar reward can be associated with an olfactory or visual cue.
Learning and memory: how does it work in the brain?
The next question: How can insects learn and what brain areas are involved?
Activities:
Find a paper on insect learning and find out how they trained the insects to learn, and be able to answer the following questions:
Did the researchers use mass training or spaced training?
Did the researchers train the insects to learn visual, mechanosensory, or olfactory cues?
Did they associate the learned cue with a rewarding (e.g. sucrose) cue or an aversive (e.g. electric shock) cue?
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TOPIC REVIEW
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Go on to the next module: Reproduction