Mutual Coupling Between the Ocular Circadian Pacemakers of
            <i>Bulla gouldiana</i>

Roberts, Michael H.; Block, Gene D.

doi:10.1126/science.6857272

Cited by 41 publications

(7 citation statements)

References 12 publications

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“…Early work in the cockroach (Page, ), cricket (Tomioka, ) and the mollusc Bulla gouldiana (Roberts & Block, ; Page & Nalovic, ) indicate that bilaterally repeated pacemakers are mutually coupled. In the insect systems, there is evidence that neurons containing the neuropeptide pigment‐dispersing hormone play a role in coupling the bilateral pacemakers (e.g.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of bilateral communication in the suprachiasmatic nucleus

Michel

Marek

vanderLeest

et al. 2013

Eur J of Neuroscience

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The central circadian pacemaker of the suprachiasmatic nuclei (SCN) is a bilaterally symmetrical structure. Little is known about the physiological mechanisms underlying communication between the left and right SCN and yet the degree of synchronization between SCN neurons can have a critical impact on the properties of the circadian system. In this study, we used electrophysiological tools and calcium (Ca(2+) ) imaging to examine the mechanisms underlying bilateral signaling in mouse SCN. Electrical stimulation of one SCN produced responses in the contralateral SCN with a short delay (approximately 5 ms) and Ca(2+) -dependence that are consistent with action potential-mediated chemical synaptic transmission. Patch-clamp recordings of stimulated cells revealed excitatory postsynaptic inward-currents (EPSCs), which were sufficient in magnitude to elicit action potentials. Electrical stimulation evoked tetrodotoxin-dependent Ca(2+) transients in about 30% of all contralateral SCN neurons recorded. The responding neurons were widely distributed within the SCN with a highest density in the posterior SCN. EPSCs and Ca(2+) responses were significantly reduced after application of a glutamate receptor antagonist. Application of antagonists for receptors of other candidate transmitters inhibited the Ca(2+) responses in some of the cells but overall the impact of these antagonists was variable. In a functional assay, electrical stimulation of the SCN produced phase shifts in the circadian rhythm in the frequency of multiunit activity rhythm in the contralateral SCN. These phase shifts were blocked by a glutamate receptor antagonist. Taken together, these results implicate glutamate as a transmitter required for communication between the left and right SCN.

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Section: Discussionmentioning

confidence: 99%

Mechanism of bilateral communication in the suprachiasmatic nucleus

Michel

Marek

vanderLeest

et al. 2013

Eur J of Neuroscience

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“…Since we have shown that extracellular calcium is not required for circadian rhythm generation in Bulla, it appears unlikely that membrane potential or underlying membrane conductances are essential elements of the causal loop generating the circadian periodicity. Rather, as proposed previously, calcium flux couples the pacemaker to environmental timing signals (McMahon and Block, 1987a;Khalsa and Block, 1988) and perhaps to synchronizing signals from other circadian pacemakers (Roberts and Block, 1983;Page and Nalovic, 1992).…”

Section: Discussionmentioning

confidence: 72%

The Role of Extracellular Calcium in Generating and in Phase-Shifting the Bulla Ocular Circadian Rhythm

Khalsa¹,

Ralph

Block³

1993

J Biol Rhythms

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Since extracellular calcium is known to be involved in the entrainment of the circadian pacemaker in the retina of Bulla gouldiana, we have assessed the requirement for extracellular calcium in the generation of the circadian rhythm. To enable us to assay the state of the pacemaker during low-calcium treatment, which often obscures rhythmicity, long-duration pulses of low-calcium artificial seawater (no added calcium, 10 mM EGTA, calculated calcium concentration = 4.5 x 10(-10) M) were applied, and the phase of the subsequent rhythm was measured. Pulse treatments started at zeitgeber time (ZT) 6, and durations ranged from 4 to 72 hr. Although no phase shifts followed pulses ending before the next projected dawn (ZT 24), phase delays of up to 4 hr followed pulses ending after projected dawn, and delays of up to 8 hr followed pulses spanning two dawns. Some activity records exhibited unequivocal circadian rhythmicity during the long low-calcium treatments, with phases and periods similar to untreated control eye records; this finding suggests that the phase delays observed following long low-calcium pulses are attributable to the pulsatile nature of the treatment. These data suggest that extracellular calcium is not an essential requirement for the pacemaker in generating the circadian rhythm.

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“…For example, the two pacemakers are only weakly coupled to each other in the beetle Blaps 9igas (Koehler and Fleissner 1978) and in the cricket Teleogryllus commodus (Wiedenmann 1983;Wiedenmann et al 1988). The ocular pacemakers of mollusks Bulla 9ouldiana and Bursatella leachi plei show a relatively strong coupling (Roberts and Block 1983;Roberts et al 1987). In the cricket Gryllus bimaculatus, a pair of functionally identical circadian pacemakers reside in the optic lobes (Tomioka and Chiba 1984, 1986, 1992.…”

Section: Introductionmentioning

confidence: 99%

Neural pathways involved in mutual interactions between optic lobe circadian pacemakers in the cricket Gryllus bimaculatus

Yukizane

Tomioka

1995

J Comp Physiol A

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The circadian locomotor rhythm of the cricket Gryllus bimaculatus is primarily generated by a pair of optic lobe circadian pacemakers. The two pacemakers mutually interact to keep a stable temporal structure in the locomotor activity. The interaction has two principal effects on the activity rhythm, i.e., phasedependent modulation of the freerunning period and phase-dependent suppression of activity driven by the partner pacemaker. Both effects were mediated by neural pathways, since they were immediately abolished after the optic stalk connecting the optic medulla to the lobula was unilaterally severed. The neural pathways were examined by recording locomotor activity, under a 13 h light to 13 h dark cycle, after the optic nerves were unilaterally severed and the contralateral optic stalk was partially destroyed near the lobula. When the dorsal half of the optic stalk was severed, locomotor rhythm mostly split into two components: one was readily entrained to the given light-dark cycle and the other freeran with a marked fluctuation in freerunning period, where the period of the freerunning component was lengthened or shortened when the onset of the entrained component occurred during its subjective night or day, respectively. The phase-dependent modulation of activity was also observed in both components. However, severance of the ventral half of the optic stalk resulted in appearance only of the freerunning component; neither the phase-dependent modulation of its freerunning period nor the change in activity level was observed. These results suggest that neurons driving the mutual interaction and the overt activity rhythm run in the ventral half of the proximal optic stalk that includes axons of large medulla neurons projecting to the cerebral lobe and the contralateral medulla.

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Mutual Coupling Between the Ocular Circadian Pacemakers of Bulla gouldiana

Cited by 41 publications

References 12 publications

Mechanism of bilateral communication in the suprachiasmatic nucleus

Mechanism of bilateral communication in the suprachiasmatic nucleus

The Role of Extracellular Calcium in Generating and in Phase-Shifting the Bulla Ocular Circadian Rhythm

Neural pathways involved in mutual interactions between optic lobe circadian pacemakers in the cricket Gryllus bimaculatus

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