Neural Mechanisms and Information Processing in Recognition Systems

Abstract

Nestmate recognition is a hallmark of social insects. It is based on the match/mismatch of an identity signal carried by members of the society with that of the perceiving individual. While the behavioral response, amicable or aggressive, is very clear, the neural systems underlying recognition are not fully understood. Here we contrast two alternative hypotheses for the neural mechanisms that are responsible for the perception and information processing in recognition. We focus on recognition via chemical signals, as the common modality in social insects. The first, classical, hypothesis states that upon perception of recognition cues by the sensory system the information is passed as is to the antennal lobes and to higher brain centers where the information is deciphered and compared to a neural template. Match or mismatch information is then transferred to some behavior-generating centers where the appropriate response is elicited. An alternative hypothesis, that of “pre-filter mechanism”, posits that the decision as to whether to pass on the information to the central nervous system takes place in the peripheral sensory system. We suggest that, through sensory adaptation, only alien signals are passed on to the brain, specifically to an “aggressive-behavior-switching center”, where the response is generated if the signal is above a certain threshold.

Ants Discriminate Between Different Hydrocarbon Concentrations

“…In contrast, the U-present model is based on a more parsimonious assumption, and does not require a point-bypoint matching: only extra, but not missing, components elicit aggression. The U-present model is also compatible with the hypothesis of a "pre-filter mechanism" for nestmate recognition (Ozaki and Hefetz, 2014) and with the "distributed nestmate recognition model" (Esponda and Gordon, 2015). The study by Guerrieri et al (2009) only tested the effects of adding extra hydrocarbons that are not naturally present on the cuticle of the test species.…”

“…The receptors then transmit signals to the antennal lobes (AL), the first integration relay of the central nervous system (Hildebrand and Shepherd, 1997). Thus, the template-label matching could also occur at the level of the ALs (Leonhardt et al, 2007;Guerrieri et al, 2009;Stroeymeyt et al, 2010;Ozaki and Hefetz, 2014), where signals from olfactory receptors elicit specific patterns of glomerular activity (Galizia and Szyszka, 2008). As a final alternative, the template could be stored in higher brain centers (e.g., the mushroom bodies), using long-term memory to match the new recognition signal with the colony template.…”

“…Specifically, it remains unclear how the information about colony identity is encoded in the cuticular hydrocarbon profile (Martin and Drijfhout, 2009;van Zweden and d'Ettorre, 2010), and how this information is perceived and processed by the insect nervous system (Bos and d 'Ettorre, 2012;d'Ettorre, 2013;Ozaki and Hefetz, 2014). Particularly within a species, differences in the cuticular chemical profile are usually quantitative rather than qualitative, with non-nestmate conspecifics having the same compounds present in their profiles, but in different relative proportions (review in d 'Ettorre and Lenoir, 2010).…”

The defensive response of the honeybee Apis mellifera

“…Current theories posit that guards have an 'internal template' of the colony odour, although the exact nature of this template remains debated (Breed et al, 2004a;Ozaki and Hefetz, 2014;Page et al, 1991). Because the colony odour can change (e.g.…”

Biological activity of the enantiomers of 3-methylhentriacontane, a queen pheromone of the antLasius niger

“…Alternatively, queens might parsimoniously produce only a single enantiomer, the (S)-isomer, fulfilling both functions. In this case, one would expect to see the other enantiomer having a lesser or no effect (depending on the specificity of the receptor for the pheromone), or conversely, this enantiomer should elicit only an aggressive behavioral response if it were simply perceived as unnatural or foreign, analogous to the aggressive responses elicited by the cuticular lipids of non-nestmates (van Zweden and d 'Ettorre, 2010;Ozaki and Hefetz, 2014). However, there are cases in which the non-natural stereoisomer actually has a higher bioactivity than the naturally occurring one (Eliyahu et al, 2004), which would match our results if the (S)-isomer does not occur naturally in L. niger.…”