Activation of two different kinds of neurons is necessary for appetitive and aversive memory recall in crickets. Researchers writing in the open access journal BMC Biology blocked octopaminergic (OA-ergic) and dopaminergic (DA-ergic) transmission and found that this resulted in the inability to recall pleasant and unpleasant memories, respectively.
Makoto Mizunami (now at Hokkaido University, Japan) led a team of researchers from Tohoku University, Japan, who carried out the tests. He said, "This is the first study to suggest that classical conditioning in insects involves neural mediation between an originally neutral stimulus and a pleasant or unpleasant stimulus and the activation of these neural responses for memory recall. Such neural responses are often called cognitive processes in classical conditioning in higher vertebrates".
Mizunami and his colleagues previously reported that, in crickets, OA-ergic neurons and DA-ergic neurons convey signals about reward and risk, respectively. In this report, they found that blockers of synaptic transmission from OA-ergic and DA-ergic neurons prevented the insects from recalling which stimuli were related to the reward, and, therefore, could be approached, and which stimuli were related to the risk, so should be avoided. According to Mizunami, "These findings are not consistent with conventional neural models of classical conditioning in insects. Instead, we suggest that the cognitive account of classical conditioning proposed for higher vertebrates is applicable to insects".
Notes to Editors
1. Roles of octopaminergic and dopaminergic neurons in appetitive and aversive memory recall in an insect
Makoto Mizunami, Sae Unoki, Yasuhiro Mori, Daisuke Hirashima, Ai Hatano and Yukihisa Matsumoto
BMC Biology (in press)
During embargo, article available here: http://www.
After the embargo, article available at journal website: http://www.
Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.
Article citation and URL available on request at firstname.lastname@example.org on the day of publication
2. BMC Biology - the flagship biology journal of the BMC series - publishes research and methodology articles of special importance and broad interest in any area of biology and biomedical sciences. BMC Biology (ISSN 1741-7007) is covered by PubMed, MEDLINE, BIOSIS, CAS, Scopus, EMBASE, Zoological Record, Thomson Reuters (ISI) and Google Scholar.
3. BioMed Central (http://www.