Table 1.

Comparison of neural processing underlying learning in three insect species

	Crickets ( Gryllus bimaculatus )	Fruit flies ( Drosophila melanogaster )	Honeybees ( Apis mellifera ) (A or B?)
Learning	A: OA and DA neurons mediate reward and punishment signals, respectively [7,18,19].	B: DA neurons mediate both reward and punishment signals; OA neurons send reward signal to DA neurons in appetitive learning [23,24,26].	A [16,20,21]
Memory retrieval	A: OA and DA neurons participate in appetitive and aversive memory retrieval, respectively [12].	B: OA or DA neurons do not participate in memory retrieval [15,24].	A [21]
STM formation	A: cAMP signaling does not participate in STM formation [32,35].	B: cAMP signaling participates in STM formation [4].	A [33]
LTM formation	A: NO-cGMP signaling participates in LTM formation [32,35].	B: There is no report on participation of NO-cGMP signaling in LTM formation.	A [43,44]

LTM: long-term memory: STM: short-term memory.