Long-term memory (LTM) depends on the synthesis of new proteins. Using a temperature-sensitive ribosome-inactivating toxin to acutely inhibit protein synthesis, we screened individual neurons making new proteins after olfactory associative conditioning in Drosophila. Surprisingly, LTM was impaired after inhibiting protein synthesis in two dorsal-anterior-lateral (DAL) neurons but not in the mushroom body (MB), which is considered the adult learning and memory center. Using a photoconvertible fluorescent protein KAEDE to report de novo protein synthesis, we have directly visualized cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB)-dependent transcriptional activation of calcium/calmodulin-dependent protein kinase II and period genes in the DAL neurons after spaced but not massed training. Memory retention was impaired by blocking neural output in DAL during retrieval but not during acquisition or consolidation. These findings suggest an extra-MB memory circuit in Drosophila: LTM consolidation (MB to DAL), storage (DAL), and retrieval (DAL to MB).

Memory is initially labile and gradually consolidated over time through new protein synthesis into a long-lasting stable form. Studies of odor-shock associative learning in Drosophila have established the mushroom body (MB) as a key brain structure involved in olfactory long-term memory (LTM) formation. Exactly how early neural activity encoded in thousands of MB neurons is consolidated into protein-synthesis-dependent LTM remains unclear. Here, several independent lines of evidence indicate that changes in two MB vertical lobe V3 (MB-V3) extrinsic neurons are required and contribute to an extended neural network involved in olfactory LTM: (i) inhibiting protein synthesis in MB-V3 neurons impairs LTM; (ii) MB-V3 neurons show enhanced neural activity after spaced but not massed training; (iii) MB-V3 dendrites, synapsing with hundreds of MB α/β neurons, exhibit dramatic structural plasticity after removal of olfactory inputs; (iv) neurotransmission from MB-V3 neurons is necessary for LTM retrieval; and (v) RNAi-mediated downregulation of oo18 RNA-binding protein (involved in local regulation of protein translation) in MB-V3 neurons impairs LTM. Our results suggest a model of long-term memory formation that includes a systems-level consolidation process, wherein an early, labile olfactory memory represented by neural activity in a sparse subset of MB neurons is converted into a stable LTM through protein synthesis in dendrites of MB-V3 neurons synapsed onto MB α lobes.L ong-term memory (LTM) and long-term synaptic plasticity require de novo protein synthesis, which is regulated at transcriptional and/or translational levels in a synapse-specific manner (1-3). Synapse-specific plasticity during LTM formation in some contexts may involve local regulation of protein translation by a family of RNA-binding proteins, the cytoplasmic polyadenylation element-binding proteins (CPEBs) (2). Neuronal CPEBs have two conformational states. The inactive state predominates at low levels of CPEB expression and represses translation from nascent mRNAs. The active state is achieved either via a self-perpetuating prion-like state when expression levels surpass a threshold or via Ca 2+ /calmoduline-dependent protein kinase II (CaMKII)-mediated phosphorylation, and translation is initiated by elongation of an mRNA's poly-A tail (4-6). In other species, CPEB1 has been shown to contribute to long-term facilitation or potentiation (5, 7). In Drosophila, oo18 RNA-binding protein 2 (ORB2) appears required for long-term memory formation after courtship conditioning (8, 9). Any role for ORB in fruit fly memory formation, however, remains unclear.Drosophila can learn to associate an odor (conditioned stimulus, CS) with foot-shock punishment (unconditioned stimulus, US). This odor-shock association initially is labile, lasting for only about a day after one training session. With repetitive, spaced training (ST) sessions (rest intervals between each session), a protein synthesis-dependent, LTM is formed. With repetitive, massed training (MT) ses...

Excitation curves and angular distributions for the reaction Si(d, p) 9Si have been measured over the range of bombarding energy from 2.0 to 4.2 MeV. The proton groups leading to the five lowest states of 2~Si were measured. The results are analyzed by the methods of fluctuation theory and of average angular distribution using the Hauser-Feshbach formula and the distorted-wave Born-approximation theory. Ratios of the direct reaction to the compound nucleus cross section obtained from the two methods are compared. The average total level width (I') =29 keV, the average level space of spinless DO=1.38 keV, spin cutoff parameter 0 =2. 5, nuclear temperature t =1.8 MeV, and moment of inertia I=0.6x10 4 MeVsec of P around 14.78-MeV excitation energy are obtained.

10 intermediate resonances with their spins and parities were identified in this study. The average width is 160 + 60 keV, which is consistent with the value 153 keV predicted by Hsu s relationship.NUCLEAR REACTION~Si(d, P), E =2.0-4.2 MeV measured o P 8)~8 =15-