The calyx of Held is a giant nerve terminal that forms a synapse directly onto the principal cells of the medial nucleus of the trapezoid body (MNTB) in the mammalian auditory brain stem. This central synapse, which is involved in sound localization, has become widely used for studying synaptic transmission. Anatomical studies of this nucleus have indicated that each principal cell is innervate...

During the formation of neuronal circuits, axon pathfinding decisions specify the location of synapses on the correct brain side and in correct target areas. We investigated a possible link between axon midline crossing and the subsequent development of output synapses formed by these axons. Conditional knockout of Robo3 in the auditory system forced a large commissural synapse, the calyx of He...

The calyx of Held is a giant glutamatergic synapse in the mammalian auditory pathway designed to ensure faithful transmission of high frequency action potential trains. Preand postsynaptic recordings from this synapse reveal several forms of facilitation and depression. A computational model of synaptic transmission has been developed to investigate the mechanisms underlying modulation at the c...

Whether a quantal packet of transmitter saturates postsynaptic receptors is a fundamental question in central synaptic transmission. However, this question remains open with regard to saturation at mature synapses. The calyx of Held, a giant glutamatergic synapse in the auditory brainstem, becomes functionally mature during the fourth postnatal week in rats. During postnatal development, the me...

The Lophotrochozoa includes disparate tentacle-bearing sessile protostome animals, which apparently appeared in the Cambrian explosion, but lack an uncontested fossil record. Here we describe abundant well preserved material of Cotyledion tylodes Luo et Hu, 1999, from the Cambrian (Series 2) Chengjiang deposits, reinterpreted here as a stem-group entoproct. The entoproct affinity is supported b...

Previously, we demonstrated that visual and olfactory associative memories of Drosophila share mushroom body (MB) circuits (Vogt et al., 2014). Unlike for odor representation, the MB circuit for visual information has not been characterized. Here, we show that a small subset of MB Kenyon cells (KCs) selectively responds to visual but not olfactory stimulation. The dendrites of these atypical KC...

The alpha-amino-3-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is an ionotropic receptor mediating excitatory synaptic transmission, but it can also interact with intracellular messengers. Here we report that, at the calyx of Held in the rat auditory brainstem, activation of AMPARs induced inward currents in the nerve terminal and inhibited presynaptic Ca2+ currents (I(pCa)), thereby att...

A multitude of synaptic proteins interact at the active zones of nerve terminals to achieve the high temporal precision of neurotransmitter release in synchrony with action potentials. Though synaptotagmin has been recognized as the Ca2+ sensor for synchronous release, it may have additional roles of action. We address this question at the calyx of Held, a giant presynaptic terminal, that allow...

Various Synaptotagmin (Syt) isoform genes are found in mammals, but it is unknown whether Syts can function redundantly in a given nerve terminal, or whether isoforms can be switched during the development of a nerve terminal. Here, we investigated the possibility of a developmental Syt isoform switch using the calyx of Held as a model synapse. At mature calyx synapses, fast Ca(2+)-driven trans...