Courtship conditioning

How experience influences behavior is a central question in neuroscience. The ability to manipulate CaMKII activity in vivo is a prerequisite for the study of the role of the enzyme in behavior. Using transgenes to express inhibitors or mutant kinases, we are able to modulate CaMKII activity in both temporally and spatially restricted manners. To test the role of the kinase in learning and memory, we have used the courtship conditioning paradigm.

When presented with a female fly, male flies perform a mating ritual that includes orientation toward the female, wing extension and vibration to produce a courtship song, licking and eventually copulation. These behaviors occur sequentially, and steps are not skipped. This courtship behavior was thought for many years to be "hardwired": a behavioral program that could be turned on or off, but with no plastic features. This assumption was challenged by the finding of Siegel and Hall (1979) that courtship could be modulated by experience. Specifically, it was shown that male flies could be conditioned to suppress courtship by exposure to a mated female. Presentation of either a mated female or a virgin female during this time window elicited a subnormal amount of courtship.

Subsequent studies suggested that courtship conditioning was an associative behavior in which courtship by the male and an aversive pheromonal signal produced by the mated female were both required to get courtship suppression. In associative learning, a conditioned stimulus (CS) is paired with an unconditioned stimulus (US) which can be either a positive or negative reinforcer. The CS becomes associated with the response to the US, and eventually by itself will evoke the response. In courtship conditioning, we have a situation which is similar to this type of paradigm. The mated female presents the male with both a CS (a stimulatory pheromone and/or other courtship promoting sensory inputs) and a US (an aversive pheromone). Thus using the mated female for training is analogous to pairing CS and US. The virgin "tester" female presents the male with the CS only. While the chemical nature of these cues was unclear for many years (see below), their properties are quite well understood and have been looked at in some detail by a number of groups. Perhaps most tellingly, Ackerman and Siegel (1986) found that the effects of a mated female as a trainer can be mimicked by presentation of a virgin (as a CS) and quinine, an aversive stimulus that can act as a US.

Two behavioral outputs can be measured during courtship conditioning: a decrement in courtship of the mated female during training and a subsequent suppression of courtship of a female presented after training. The decrement in courtship during training was originally taken to be a real time reflection of the formation of the association between courtship and the aversive pheromone and to be equivalent to "learning". This viewpoint implied that the decrement would be required for the male to show a suppression of subsequent courtship of a female after training. This model is not supported by studies in which CaMKII activity was modulated (Joiner and Griffith, 1997). We have shown that the decrement with the mated female can be completely dissociated from the behavior of the male with a subsequently presented virgin or mated female. These results suggested that these two behaviors are separate outputs of the courtship conditioning circuit, or behaviors that occur as outputs of independent circuits. To address these circuitry questions, we have used spatially restricted expression of the ala peptide to identify the neurons responsible for plasticity in these behaviors.

Additional behavior topics:

• Courtship conditioning
• Anatomical mapping of behavioral circuits
• Bidirectional modulation of behavior with CaMKII
• Dissection of the chemical cues underlying courtship learning
• Motor Behaviors

 

Top of Page