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Long-term memory (LTM) formation depends on the conversed cAMP response element-binding protein (CREB)-dependent gene transcription followed by de novo protein synthesis. Thirsty fruit flies can be trained to associate an odor with water reward to form water-reward LTM (wLTM), which can last for over 24 hours without a significant decline. The role of de novo protein synthesis and CREB-regulated gene expression changes in neural circuits that contribute to wLTM remains unclear. Here, we show that acute inhibition of protein synthesis in the mushroom body (MB) αβ or γ neurons during memory formation using a cold-sensitive ribosome-inactivating toxin disrupts wLTM. Furthermore, adult stage-specific expression of dCREB2b in αβ or γ neurons also disrupts wLTM. The MB αβ and γ neurons can be further classified into five different neuronal subsets including αβ core, αβ surface, αβ posterior, γ main, and γ dorsal. We observed that the neurotransmission from αβ surface and γ dorsal neuron subsets is required for wLTM retrieval, whereas the αβ core, αβ posterior, and γ main are dispensable. Adult stage-specific expression of dCREB2b in αβ surface and γ dorsal neurons inhibits wLTM formation. In vivo calcium imaging revealed that αβ surface and γ dorsal neurons form wLTM traces with different dynamic properties, and these memory traces are abolished by dCREB2b expression. Our results suggest that a small population of neurons within the MB circuits support long-term storage of water-reward memory in Drosophila., Author summary Unlike short-term memory (STM), the formation of long-term memory (LTM) requires de novo protein synthesis and CREB-mediated gene transcription in many animals. To date, the mechanism underlying LTM formation remains poorly understood. Thirsty fruit flies can be trained to associate an odor with water to form a water-reward LTM (wLTM), which requires de novo protein synthesis and dCREB2 activity. In this study, we found that dCREB2 activity in the mushroom body (MB) αβ surface and γ dorsal neuron subsets is essential for wLTM formation. Neurotransmission from αβ surface and γ dorsal neurons is specifically required for retrieval, but not for acquisition or consolidation of wLTM. Moreover, wLTM traces are formed in the αβ surface and γ dorsal neurons with different neural dynamics, which require normal dCREB2 functions. These findings highlight that dCREB2-dependent wLTM is located within a specific brain circuitry in fruit flies.

The intake of water is important for the survival of all animals and drinking water can be used as a reward in thirsty animals. Here we found that thirsty Drosophila melanogaster can associate drinking water with an odour to form a protein-synthesis-dependent water-reward long-term memory (LTM). Furthermore, we found that the reinforcement of LTM requires water-responsive dopaminergic neurons projecting to the restricted region of mushroom body (MB) β′ lobe, which are different from the neurons required for the reinforcement of learning and short-term memory (STM). Synaptic output from α′β′ neurons is required for consolidation, whereas the output from γ and αβ neurons is required for the retrieval of LTM. Finally, two types of MB efferent neurons retrieve LTM from γ and αβ neurons by releasing glutamate and acetylcholine, respectively. Our results therefore cast light on the cellular and molecular mechanisms responsible for processing water-reward LTM in Drosophila., Distinct subsets of dopaminergic PAM neurons have been shown to be involved in short-term and long-term memory for sugar reward. Here the authors report the neural circuits and the cellular and molecular mechanisms for short-term and long-term memory for water reward in thirsty Drosophila.

Given the availability of multiple orthogonal channels and multimedia transmission rate requirements from multiple wireless OFDMA users, we are interested in a joint channel, power and rate assignment scheme that satisfies the given requirements with the minimum total transmit power. Algorithms for finding suboptimal and optimal solutions to sum power minimization resource allocation problems in OFDMA-based networks haven been proposed. But the complexity of finding the optimal solution is prohibitively high. We present two efficient algorithms with which each channel (subcarrier) is assigned to at most one user. The first approach, which gives near-optimal solutions, employs a dynamic programming (DP) based tree search and adopts a fair initial condition that offers every user all available channels and removes a channel from all but one user at each stage. Each removal is based on the criterion of the least total power increase. Using the DP-based solution as the initial upper bound and the partial path cost used in the DP approach as the lower bound for each visited node, we develop an efficient branch-and-bound based algorithm that guaranteed to lead to the optimal solution. The average complexities of both algorithms are evaluated and effective schemes to further reduce the required complexity are proposed. We also provide performance and complexity comparisons with other suboptimal algorithms that are modified from the existing ones.

A novel chiral monomer end-capped with a cholesteryl group and threaded with β-cyclodextrin was synthesized in order to induce the formation of a helical polymer. 1H NMR studies revealed that one or two cyclodextrin molecules were threaded onto the synthesized chiral monomer, leading to the formation of a helical construction of self-assembled inclusion complexes. The formation of a self-assembled inclusion complex was identified using SEM and TEM. The monomeric self-assembled inclusion complex was further polymerized using benzoyl peroxide as a photoinitiator. Both the highly ordered alignment and the helical structure of self-assembled supramolecules were confirmed using polarized optical microscopy and circular dichroism spectroscopy, respectively. We have first demonstrated an easy process for the fabrication of helical polymers via self-assembled monomers threaded with a β-cyclodextrin end and capped with a chiral moiety.

Acute and chronic subdural hemorrhage in a 33 year old woman with severe headache from occipital to frontal regions and dull neck pain was diagnosed on magnetic resonance image, which revealed cerebrospinal fluid leakage at C2-3 with spontaneous intracranial hypotension. Successful treatment was performed by epidural blood patch from the level of T7-T8 with injection of 20 mL of autologous blood.

Motivational states modulate how animals value sensory stimuli and engage in goal-directed behaviors. The motivational states of thirst and hunger are represented in the brain by shared and unique neuromodulatory systems. However, it is unclear how such systems interact to coordinate the expression of appropriate state-specific behavior. We show that the activity of two brain neurons expressing leucokinin neuropeptide is elevated in thirsty and hungry flies, and that leucokinin release is necessary for state-dependent expression of water- and sugar-seeking memories. Leucokinin inhibits two types of mushroom-body-innervating dopaminergic neurons (DANs) to promote thirst-specific water memory expression, whereas it activates other mushroom-body-innervating DANs to facilitate hunger-dependent sugar memory expression. Selection of hunger- or thirst-appropriate memory emerges from competition between leucokinin and other neuromodulatory hunger signals at the level of the DANs. Therefore, coordinated modulation of the dopaminergic system allows flies to prioritize the expression of the relevant state-dependent motivated behavior. The Drosophila neuropeptide leucokinin mediates hunger- and thirst-dependent expression of learned behaviors. State-relevant selection of appropriate memory emerges from competition between leucokinin and other modulators onto dopaminergic neurons.