Understanding Circuit Dynamics Using the Stomatogastric Nervous System of Lobsters and Crabs

Marder, Eve; Bucher, Dirk

doi:10.1146/annurev.physiol.69.031905.161516

Cited by 611 publications

(677 citation statements)

References 189 publications

(232 reference statements)

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“…Utilizing the activity of the previous cycle of a periodic solution, t = 0 corresponds to the end of a PY burst. (20) We can now substitute equations (17)- (20) into (15). Note however that if ḡ PY = 0, then LP stays in the active state until AB becomes active and (20) is replaced by w LP (t 1 ) = ŵ LP e −t 1 /τ w,LP .…”

Section: Resultsmentioning

confidence: 99%

“…The questions of interest center on the synaptic and intrinsic mechanisms that control the activity phase of the follower neurons and their dependence on cycle frequency. This network is modeled after the pyloric network of the crustacean stomatogastric ganglion which consists of an oscillatory pacemaker group of neurons AB and PD and four sets of follower neurons [20]. The pacemaker AB and PD neurons are always coactive, due to strong electrical coupling, and inhibit all follower neurons which, in turn, become active in two distinct (but sometimes overlapping) intervals in each cycle, thus producing a triphasic rhythm (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Maintaining phase of the crustacean tri-phasic pyloric rhythm

2007

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We construct and analyze a model network of the pyloric rhythm of the crustacean stomatogastric ganglion consisting of an oscillator neuron that inhibits two reciprocally inhibitory follower neurons. We derive analytic expressions that determine the phase of firing of the follower neurons with respect to the oscillator. An important aspect of the model is the inclusion of synapses that exhibit shortterm synaptic depression. We show that these type of synapses allow there to be a complicated relationship between the intrinsic properties of the neurons and the synapses between them in determining phase relationships. Our analysis reveals the circumstances and ranges of cycle periods under which these properties work in concert with or independently from one another. In particular, we show that phase maintenance over a range of oscillator periods can be enhanced through the interplay of the two follower neurons if the synapses between these neurons are depressing. Since our model represents the core of the oscillatory pyloric network, the results of our analysis can be compared to experimental data and used to make predictions about the biological network.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Maintaining phase of the crustacean tri-phasic pyloric rhythm

2007

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“…This study introduces neuroestrogens as a class of local modulators for the transition to burst firing, a processing mode that may be fundamental for sensory discrimination in the numerous estrogen-producing circuits that occur in the CNS of vertebrates (1,7). Although the cellular mechanisms for these effects are unknown, burst-mode firing is enabled by changing membrane ionic conductances (20,32), which can in turn be acutely modulated by estrogens (1). Long-term estrogen blockade in humans has been associated with cognitive impairments, including verbal memory deficits (33)(34)(35), and this study emphasizes that pharmacologic estrogen depletion could have as yet unknown consequences for moment-by-moment cortical function.…”

Section: Discussionmentioning

confidence: 99%

Brain estrogens rapidly strengthen auditory encoding and guide song preference in a songbird

Remage‐Healey

Coleman

Oyama

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

189

218

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Higher cognitive function depends on accurate detection and processing of subtle features of sensory stimuli. Such precise computations require neural circuits to be modulated over rapid timescales, yet this modulation is poorly understood. Brainderived steroids (neurosteroids) can act as fast signaling molecules in the vertebrate central nervous system and could therefore modulate sensory processing and guide behavior, but there is no empirical evidence for this possibility. Here we report that acute inhibition of estrogen production within a cortical-like region involved in complex auditory processing disrupts a songbird's ability to behaviorally respond to song stimuli. Identical manipulation of local estrogen levels rapidly changes burst firing of single auditory neurons. This acute estrogen-mediated modulation targets song and not other auditory stimuli, possibly enabling discrimination among species-specific signals. Our results demonstrate a crucial role for neuroestrogen synthesis among vertebrates for enhanced sensory encoding. Cognitive impairments associated with estrogen depletion, including verbal memory loss in humans, may therefore stem from compromised moment-by-moment estrogen actions in higher-order cortical circuits.I n vertebrates, steroid hormones can rapidly influence the activity of neurons and neural circuits (1-3), although the functional consequences for higher processing are unclear. The exquisite recognition of species-typical vocalizations (4, 5) and abundant production of neuroestrogens (6, 7) are both especially prominent in songbirds. A cortical-like auditory region (the caudomedial nidopallium, or NCM) of songbirds is a critical locus for song learning as well as auditory processing and song recognition (8-11). NCM exhibits rich expression of the estrogen-synthetic enzyme aromatase in both cell bodies and synaptic terminals (6, 12), and neuroestrogen levels within NCM fluctuate rapidly (<30 min) and independent of peripheral sex-steroid levels during social interactions, song playback, and after neurotransmitter activation (13). In songbirds, therefore, rapid changes in the local production of NCM neuroestrogens could in turn rapidly affect processing of complex auditory stimuli, such as song.Here, we test this hypothesis in male Australian zebra finches (Taeniopygia guttata). Our recent optimization of in vivo microdialysis in this species has enabled the measurement and manipulation of local estrogen production within discrete brain regions in awake, behaving males (13). We have further established that local estrogen levels are dependent on the activity of the enzyme aromatase within NCM, because retrodialysis (reverse delivery using microdialysis) of the aromatase inhibitor fadrozole (FAD) into NCM transiently suppresses local estradiol levels (13). ResultsIn Vivo Retrodialysis and Behavior. Adult zebra finches express a robust behavioral preference for acoustic playback of their tutor's song or bird's own song (BOS) compared with conspecific male song (CON) (4, 5, 8), and be...

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“…Despite the importance of the input pattern, we show that the intrinsic properties of heart motoneurons play a substantive role in determining their output. While it is well established that motoneuron intrinsic properties contribute to motor pattern generation in the pyloric (Marder and Bucher 2007) and gastric mill (Nusbaum and Beenhakker 2002) networks of the crustacean stomatogastric system, almost all of the neurons within those CPGs are themselves motoneurons, and the stomatogastric system is not segmentally distributed like the leech heartbeat system. Because we used the identical segmental input patterns used in our canonical ensemble model, any differences between the hybrid system and model phasing should be attributable to the additional intrinsic properties of the living heart motoneurons not present in the model motoneurons.…”

Section: Discussionmentioning

confidence: 99%

Contribution of motoneuron intrinsic properties to fictive motor pattern generation

Wright

Calabrese

2011

Journal of Neurophysiology

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Wright TM Jr, Calabrese RL. Contribution of motoneuron intrinsic properties to fictive motor pattern generation. J Neurophysiol 106: 538-553, 2011. First published May 11, 2011 doi:10.1152/jn.00101.2011.-Previously, we reported a canonical ensemble model of the heart motoneurons that underlie heartbeat in the medicinal leech. The model motoneurons contained a minimal set of electrical intrinsic properties and received a synaptic input pattern based on measurements performed in the living system. Although the model captured the synchronous and peristaltic motor patterns observed in the living system, it did not match quantitatively the motor output observed. Because the model motoneurons had minimal intrinsic electrical properties, the mismatch between model and living system suggests a role for additional intrinsic properties in generating the motor pattern. We used the dynamic clamp to test this hypothesis. We introduced the same segmental input pattern used in the model to motoneurons isolated pharmacologically from their endogenous input in the living system. We show that, although the segmental input pattern determines the segmental phasing differences observed in motoneurons, the intrinsic properties of the motoneurons play an important role in determining their phasing, particularly when receiving the synchronous input pattern. We then used trapezoidal input waveforms to show that the intrinsic properties present in the living system promote phase advances compared with our model motoneurons. Electrical coupling between heart motoneurons also plays a role in shaping motoneuron output by synchronizing the activity of the motoneurons within a segment. These experiments provide a direct assessment of how motoneuron intrinsic properties interact with their premotor pattern of synaptic drive to produce rhythmic output.

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Understanding Circuit Dynamics Using the Stomatogastric Nervous System of Lobsters and Crabs

Cited by 611 publications

References 189 publications

Maintaining phase of the crustacean tri-phasic pyloric rhythm

Maintaining phase of the crustacean tri-phasic pyloric rhythm

Brain estrogens rapidly strengthen auditory encoding and guide song preference in a songbird

Contribution of motoneuron intrinsic properties to fictive motor pattern generation

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