Olfactory Learning in Drosophila

Abstract

Studies of olfactory learning in Drosophila have provided key insights into the brain mechanisms underlying learning and memory. One type of olfactory learning, olfactory classical conditioning, consists of learning the contingency between an odor with an aversive or appetitive stimulus. This conditioning requires the activity of molecules that can integrate the two types of sensory information, the odorant as the conditioned stimulus and the aversive or appetitive stimulus as the unconditioned stimulus, in brain regions where the neural pathways for the two stimuli intersect. Compelling data indicate that a particular form of adenylyl cyclase functions as a molecular integrator of the sensory information in the mushroom body neurons. The neuronal pathway carrying the olfactory information from the antennal lobes to the mushroom body is well described. Accumulating data now show that some dopaminergic neurons provide information about aversive stimuli and octopaminergic neurons about appetitive stimuli to the mushroom body neurons. Inhibitory inputs from the GABAergic system appear to gate olfactory information to the mushroom bodies and thus control the ability to learn about odors. Emerging data obtained by functional imaging procedures indicate that distinct memory traces form in different brain regions and correlate with different phases of memory. The results from these and other experiments also indicate that cross talk between mushroom bodies and several other brain regions is critical for memory formation.

Conceptual learning by miniature brains

“…Insects have historically fascinated biologists because they offer the possibility of studying sophisticated behaviours [11][12][13][14] and simultaneously accessing the neural bases of such behaviours [15][16][17][18]. Among insects, the honeybee has emerged as a powerful model for the study of associative learning [12,14,15,[19][20][21].…”

Cyclic nucleotide–gated channels, calmodulin, adenylyl cyclase, and calcium/calmodulin-dependent protein kinase II are required for late, but not early, long-term memory formation in the honeybee

“…Insect models have largely contributed to our understanding of the molecular underpinnings of memory (e.g., Menzel 1999;Davis 2005;Margulies et al 2005;Eisenhardt 2006;Schwärzel and Müller 2006;Busto et al 2010). Among insects, the honeybee Apis mellifera has played an influential role in the study of memory as it provides both behavioral access to learning and memory in controlled laboratory protocols and invasive techniques that can trace behavioral plasticity to cellular and molecular levels (Menzel 1999(Menzel , 2001Giurfa 2007;Giurfa and Sandoz 2012).…”

Gene–environment interplay inDrosophila melanogaster: Chronic food deprivation in early life affects adult exploratory and fitness traits

“…The MBs are a candidate brain region for determining exploratory behavior. They are bilateral structures in the Drosophila brain that are composed of five lobes (α, α′, β, β′, and γ) with apparent functional specializations (51,52). The MBs are centers of learning, memory, and sensory integration (52), and they influence both exploratory behavior (37,53) and locomotion (54) in Drosophila.…”