Model Organisms for Studying Decision-Making: A Phylogenetically Expanded Perspective

Abstract

This paper explores the use of model organisms in studying the cognitive phenomenon of decision-making. Drawing on the framework of biological control to develop a skeletal conception of decision-making, we show that two core features of decision-making mechanisms can be identified by studying model organisms, such as E. coli, jellyfish, C. elegans, lamprey, etc. First, decision mechanisms are distributed and heterarchically-structured. Second, they depend heavily on chemical information processing, such as those involving neuromodulators. We end by discussing the implications for studying distinctively human decision-making.

Decision Making in Plants: A Rooted Perspective

“…Among the supporting evidence is the discovery of 'control mechanisms' underlying locomotion. These are distributed, 'heterarchichally structured' mechanisms for obtaining information about the organism's internal and external conditions that facilitate the evaluation of alternative behaviours and the selection between them [19]. The efficacy of control mechanisms for producing adaptive behaviour is exemplified by locomotive chemotaxis in E. coli.…”

“…However, it is debatable whether the assumption holds in most forms of decision making. For instance, the medicinal leech (Hirudo verbena) selects between swimming and crawling but does not depend on a centralised neural mechanism, but rather on the emergent effect of 21 independent ganglia located between its 'head and tail brains' [23] (p. 3). Similarly, extensive work on domesticated cats, for example, has demonstrated that decision-making mechanisms in neural organisms with brains are distributed across cortical and subcortical structures.…”

“…Similarly, extensive work on domesticated cats, for example, has demonstrated that decision-making mechanisms in neural organisms with brains are distributed across cortical and subcortical structures. The neural circuitry responsible for decision making in these cases is critically modulated by a range of often broadly diffused chemical signals carrying information about the state of the environment and organism [19] (p. 1061). Brains, so the evidence shows, do not obviate heterarchical organisation, at the very least.…”

“…Brains, so the evidence shows, do not obviate heterarchical organisation, at the very least. In fact, some human behaviour may emerge from the coordinated activity of heterarchical control mechanisms as well (for extended discussion, see [22,23]).…”

“…Research on bacteria suggests that prokaryotes may serve as 'experimental organisms' for studying decision making more broadly (up to the level of non-conscious human decision making), with an emphasis placed on the fact that discovering the ability in question in simpler organisms assists in revealing the core characteristics of the mechanisms underlying that phenomenon. For example, Huang et al [19] argue that by identifying mechanisms for decision making in these (relatively) simple cases, we may gain insight into the mechanisms for decision making in more prototypical cases, as in humans and other animals (p. 1064). As we have seen, this lesson extends beyond prokaryotes to include other 'minimal' decision makers (see the example of slime moulds, which are eukaryotic), with the potential to include plants.…”