Learning allows animals to adapt their behaviour to changes in the environment. In humans and other mammals, memories are stored in the hippocampus and cerebellum, whereas in insects, they are stored inside the mushroom bodies (MB). Here, MB-intrinsic Kenyon cells (KCs) form plastic synapses to MB output neurons (MBONs) that are modulated by the reinforcing action of dopaminergic neurons (DANs). Despite decades of research on the MB, the main neurotransmitter underlying the plastic KC → MBON synapse has remained a mystery. Here, I show that this synapse is cholinergic in the fruit fly Drosophila melanogaster. MBONs show fast excitatory responses to direct acetylcholine (ACh) application. KCs synthesise ACh-related proteins ChAT and VAChT. MBONs express and require nicotinic ACh receptors (nAChRs) to become fully activated by odour presentation. Lastly, artificial activation of KCs leads to MBON calcium responses that are blocked by nicotinic antagonists and genetic reduction of VAChT in KCs. Short neuropeptide F (sNPF) may play a role as a modulatory co-transmitter that can either excite or inhibit specific MBONs and DANs. The retrieval of memories is state-dependent and known to potentially change the original memory. Fruit flies need to be hungry to express appetitive memories. Hunger state depends on insulin signalling that activates the GABAergic MBON MVP2, while appetitive memory retrieval depends on decreased activity in M4/6 MBONs. Here, I show that optogenetic MVP2 activation acutely inhibits M4/6 odour responses, rendering MVP2 an inhibitory MBON interneuron. I also show that other MBONs are functionally connected to DANs, thus linking memory reinforcement and retrieval pathways in a way that enables the updating of the original memory. These findings show that associative memories in Drosophila are initially formed at cholinergic-MBON synapses, and can be retrieved and modified through an intricate KC-MBON-DAN network.

Gender is a pervasive and regulating social institution that is operationalized in mainstream Western culture as a natural extension of the ontological difference perceived to exist between the binarily sexed bodies of male and female. Feminist theory has widely established, however, that gender is done - i.e., gender is not a naturally occurring phenomenon, but is an ongoing construction engaged and replicated by individual actors and which, while compulsory, is nevertheless optional. Within this canon is a small number of feminist theorists, notably Judith Lorber, Judith Bulter, and Nancy Tuana, who argue that the constructive manifestations of gender performativity (that is, doing of gender) are not limited to the social sphere. They argue the role of gender in the construction of the material body, asserting that doing gender has a constructive role in physical embodiment: what we do influences, and in fact creates, what our bodies are. This study engages feminist theory on the production of the body through a qualitative exploration of the lived experience of gendered bodily change, as described in the first-hand narratives of trans-identified individuals. I predict that the analysis of the narratives in the sample will show that in comparison to cisgender individuals, trans individuals possess a heightened awareness of the performative nature of gender, and that trans individuals consciously engage performativity in order to conform to the normative expectations associated with the desired gender role. I further predict that trans individuals experience sexually dimorphic bodily change to be a direct result of changes to their gender identity. The interview analysis findings provide mixed support for the first hypothesis, demonstrating that while trans individuals in the sample do demonstrate a heightened awareness of the ways in which gender is performed, the respondents’ insights came largely from their experiences in their compulsorily cisgender, pre-transition lives, rather than their current gender embodiments. The concept of performativity and its perceived implication of artificiality clashed with the respondents’ sense of their gendered actions as an expression of an authentic self, and my analysis thus addresses performativity as a necessarily polemic concept located between the subjectivity of the individual narratives and the theoretical position that gender is done. The findings provide a substantial level of support for the second hypothesis that trans individuals understand experienced bodily change to be a direct result of changes in gender identity. This study’s exploration of trans experiences of lived bodily change contributes a narrative perspective to the ongoing discussion in feminist theory which surrounds the role of gender in the production of the material body.