Description: Animals negotiating complex natural terrain must consider cues around them and alter movement parameters accordingly. In the arthropod brain, the central complex (CC) receives bilateral sensory relays and sits immediately upstream of premotor areas, suggesting that it may be involved in the context-dependent control of behavior. In previous studies, CC neurons in various insects responded to visual, chemical, and mechanical stimuli, and genetic or physical lesions affected locomotor behaviors. Additionally, electrical stimulation of the CC led to malformed chirping movements by crickets, and pharmacological stimulation evoked stridulation in grasshoppers, but no more precise relationship has been documented between neural activity in the CC and movements in a behaving animal. We performed tetrode recordings from the CC of cockroaches walking in place on a slippery surface. Neural activity in the CC was strongly correlated with, and in some cases predictive of, stepping frequency. Electrical stimulation of the
Authors: Bender, JA;Pollack, AJ;Ritzmann, RE
Source: Current biology : CB; 20, 10, 921-6; 2010 May 25
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Description: Abstract: The marine mollusk Aplysia is a fascinating model organism for studying molecular mechanisms underlying learning and memory. However, evolutionary studies about Aplysia have been limited by the lack of its genomic information. Recently, large-scale expressed sequence tag (EST) databases have been acquired by sequencing cDNA libraries from A. californica and A. kurodai. The closeness between the two species allowed us to investigate rapidly evolving genes by comparing their orthologs. Using this method, we found that a subset of signal transduction genes in neurons showed rates of protein evolution higher than those of housekeeping genes. Moreover, we were also able to find several candidate genes that may be involved in learning and memory or synaptic plasticity among genes showing relatively higher K(a)/K(s) ratios. We also investigated the relationship between evolutionary rates and tissue distribution of Aplysia genes. They propose that the estimation of evolutionary rates cannot be a good marker
Authors: Choi, SL;Lee, YS;Rim, YS;Kim, TH;Moroz, LL;Kandel, ER;Bhak, J;Kaang, BK
Source: Journal of neurogenetics; 24, 2, 75-82; 2010 Jul
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Description: Nitric oxide (NO), an intercellular signaling molecule, helps coordinate neuronal network activity. Here we examine NO generation in the Aplysia central nervous system using 4,5-diaminofluorescein diacetate (DAF-2 DA), a fluorescent reagent that forms 4,5-diaminofluorescein triazole (DAF-2T) upon reaction with NO. Recognizing that other fluorescence products are formed within the biochemically complex intracellular environment, we validate the observed fluorescence as being from DAF-2T; using both capillary electrophoresis and mass spectrometry we confirm that DAF-2T is formed from tissues and cells exposed to DAF-2 DA. We observe three distinct subcellular distributions of fluorescence in neurons exposed to DAF-2 DA. The first shows uniform fluorescence inside the cell, with these cells being among previously confirmed NOS-positive regions in the Aplysia cerebral ganglion. The second, seen inside buccal neurons, exhibits point sources of fluorescence, 1.5 +/- 0.7 microm in diameter. Interestingly, the number
Tags: Aplysia, NO
Authors: Ye, X;Xie, F;Romanova, EV;Rubakhin, SS;Sweedler, JV
Source: ACS chemical neuroscience; 1, 3, 182-193; 2010 Mar 17
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Description: Neuromodulation is well known to provide plasticity in pattern generating circuits, but few details are available concerning modulation of motor pattern coordination. We are using the crustacean stomatogastric nervous system to examine how co-expressed rhythms are modulated to regulate frequency and maintain coordination. The system produces two related motor patterns, the gastric mill rhythm that regulates protraction and retraction of the teeth and the pyloric rhythm that filters food. These rhythms have different frequencies and are controlled by distinct mechanisms, but each circuit influences the rhythm frequency of the other via identified synaptic pathways. A projection neuron, MCN1, activates distinct versions of the rhythms and we show that hormonal dopamine concentrations modulate the MCN1 elicited rhythm frequencies. Gastric mill circuit interactions with the pyloric circuit lead to changes in pyloric rhythm frequency that depend on gastric mill rhythm phase. Dopamine increases pyloric frequency du
Tags: STG, dopamine, neuromodulation
Authors: Wood DE, Dr;Varrecchia, M;Papernov, M;Cook, D;Crawford, DC
Source: Journal of neurophysiology; 2010 Jun 2
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Description: Until recently, the literature on learning-related synaptic plasticity in invertebrates has been dominated by models assuming plasticity is mediated by presynaptic changes, whereas the vertebrate literature has been dominated by models assuming it is m...
Tags: synaptic plasticity, evolution
Authors: Glanzman, David L.
Source: Current Biology; 20, 1, R31-R36; 12 January 2010
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Description: The first molecular phylogeny is presented for the highly diverse, opisthobranch molluscan Cladobranchia. This study, the most comprehensive for Cladobranchia to date, used new sequences of two mitochondrial and one nuclear genes for 95 specimens from 22 families and 38 genera with a species of Pleurobranchoidea as outgroup. Although our results do not resolve all the relationships within the Cladobranchia, there are significant findings that have implications for the systematics of the Cladobranchia. Cladobranchia represents a monophyletic group within the Nudibranchia with the exception of a clade containing species of Melibe. These species share a deletion of four codons in the COI gene that may account for their strong divergence from the remainder of the Cladobranchia. Bornellidae is the sister group to the rest of Cladobranchia, but this relationship is weakly supported. A series of well-supported clades within Cladobranchia show little structure as to their relationships to each other in the current an
Authors: Pola M, Gosliner TM.
Source: Mol Phylogenet Evol.; 2010
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