Table 1.

Orthologous gene expression correspondences in hippocampus and mushroom body.

mouse/rat hippocampus	Drosophila/honey bee mushroom body
Neurl1: Encodes ubiquitin ligase protein, Neuralized 1. Promotes protein-synthesis-dependent long-term memory [8]	Neur: Encodes ubiquitin ligase protein, Neuralized. Promotes protein-synthesis-dependent long-term memory [9]
Prkar1b: Encodes neuronal isoform of cAMP-dependent protein kinase A type I regulatory subunit. Role in hippocampal long-term depression and depotentiation [10]	PKA-RI: Expressed at high levels in mushroom bodies. Role in associative learning [11]
PRKACA: Encodes PKA-Cα, involved in the regulation of hippocampus-dependent memory [12]	DC0: Required for synthesis of cAMP-dependent protein kinase A (PKA) catalytic subunit DCO. Required for cAMP regulation [13–15]
Adcyap1: Encodes PACAP (pituitary adenylate cyclase-activating polypeptide), promotes long-term facilitation; NMDA receptor regulation in CA1 pyramidal cells [16–18]	Amn: Encodes PACAP-like neuropeptide required for memory retention, olfactory memory [19–21]
Egr1: Early Growth Response Protein 1 expressed during initial phase of spatial learning [22,23]	Egr (in honey bee): Early Growth Response Protein. Expressed during initial phase of spatial learning [24]
CPEB gene family: Encode cytoplasmic polyadenylation element binding proteins, which regulate synaptic plasticity in the hippocampus [8,25]	Orb/Orb2: Encode Drosophila CPEB proteins necessary in mushroom body neurons for long-term memory formation [26,27]
Itga3: Encodes the α3 integrin subunit, which facilitates long-term potentiation (LTP) in Schaffer collateral-CA1 synapses in the hippocampus and is required for working memory behaviour [28]	vol: Encodes αPS3-integrin, preferentially expressed in mushroom bodies. Required for formation of short-term memory [29]
EGFR: Encodes epidermal growth factor receptor, which is expressed at relatively high levels in the hippocampus. Epidermal growth factor in the hippocampus facilitates induction of LTP [30,31]	EGFR: Epidermal growth factor receptor required in the mushroom bodies of Drosophila larvae for olfactory learning [32]
mDach1: Encodes a nuclear protein with activity in the forebrain and especially CA1 field of the hippocampus [33]	dac: Encodes a transcription factor necessary for proper mushroom body development [34]
Pax6: Encodes transcription factor Pax6 necessary during CNS development, for hippocampus-dependent short-term memory, and plays a role in adult hippocampal neurogenesis [35]	toy: Encodes a Pax6 protein necessary for proper mushroom body development [36]
Rheb: Encodes small GTP-binding protein Rheb, expressed at high levels in the hippocampus. Rheb expression is up-regulated in hippocampus granule cells following LTP induction [37]	Rheb: Encodes small GTP-ase Rheb, which regulates mushroom body neuron growth and induction of long-term memory [38]
Fmr1: Encodes fragile × Mental Retardation Protein (FMRP), necessary for proper hippocampal development and social/cognitive behaviours [39,40]	dfmr1: Encodes the FMRP orthologue dFMRP, highly enriched in the mushroom bodies and necessary for proper development of these structures [41,42]
NCAM: Encodes Neural Cell Adhesion Molecule (NCAM), necessary for proper synaptic targeting of hippocampal mossy fibre projections as well as for olfactory learning. Role in LTP [43–45]	Fas2: Encodes cell adhesion molecule fasciclin II, orthologous to NCAM. Necessary for proper mushroom body development, particularly lobe morphology [46]
L1CAM: Encodes L1-cell adhesion molecule (L1CAM), necessary for axonal and dendritic bundling of hippocampal neurons. Role in LTP [44,47]	Nrg: Encodes L1CAM orthologue Neuroglian, necessary for mushroom body axon development [48]
CaMKII: Encodes a calcium/calmodulin-activated protein kinase. CaMKIIα protein expression is highest in the dentate gyrus, CA1 and CA3 of the hippocampus. Dysfunction implicated in Angelman syndrome [49,50]	CaMKII: Encodes a calcium/calmodulin-activated protein kinase. CaMKII immunoreactivity is most highly concentrated in the mushroom body lobes and calyces [51]
14-3-3ζ: Encodes 14-3-3 proteins necessary for neurodevelopment and social cognition [52]	leo: Encodes 14-3-3ζ orthologue Leonardo, enriched in mushroom bodies and necessary for olfactory learning and memory [53]