External Tufted Cells: A Major Excitatory Element That Coordinates Glomerular Activity
Open Access
- 28 July 2004
- journal article
- Published by Society for Neuroscience in Journal of Neuroscience
- Vol. 24 (30), 6676-6685
- https://doi.org/10.1523/jneurosci.1367-04.2004
Abstract
The glomeruli of the olfactory bulb are the first site of synaptic processing in the olfactory system. The glomeruli contain three types of neurons that are referred to collectively as juxtaglomerular (JG) cells: external tufted (ET), periglomerular (PG), and short axon (SA) cells. JG cells are thought to interact synaptically, but little is known about the circuitry linking these neurons or their functional roles in olfactory processing. Single and paired whole-cell recordings were performed to investigate these questions. ET cells spontaneously fired rhythmic spike bursts in the theta frequency range and received monosynaptic olfactory nerve (ON) input. In contrast, all SA and most PG cells lacked monosynaptic ON input. PG and SA cells exhibited spontaneous, intermittent bursts of EPSCs that were highly correlated with spike bursts of ET cells in the same but not in different glomeruli. Paired recording experiments demonstrated that ET cells provide monosynaptic excitatory input to PG/SA cells; the ET to PG/SA cell synapse is mediated by glutamate. ET cells thus are a major excitatory linkage between ON input and other JG cells. Spontaneous bursting is highly correlated among ET cells of the same glomerulus, and ET cell activity remains correlated when all fast synaptic activity is blocked. The findings suggest that multiple, synchronously active ET cells synaptically converge onto single PG/SA cells. Synchronous ET cell bursting may function to amplify transient sensory input and coordinate glomerular output.Keywords
This publication has 49 references indexed in Scilit:
- Olfactory Bulb Glomeruli: External Tufted Cells Intrinsically Burst at Theta Frequency and Are Entrained by Patterned Olfactory InputJournal of Neuroscience, 2004
- AMPA autoreceptors drive correlated spiking in olfactory bulb glomeruliNature Neuroscience, 2002
- Dopaminergic modulation at the olfactory nerve synapseBrain Research, 2000
- Reliable synaptic connections between pairs of excitatory layer 4 neurones within a single ‘barrel’ of developing rat somatosensory cortexThe Journal of Physiology, 1999
- Compartmental organization of the olfactory bulb glomerulusJournal of Comparative Neurology, 1999
- Temporal overlap of excitatory and inhibitory afferent input in guinea‐pig CA1 pyramidal cellsThe Journal of Physiology, 1999
- Bursts as a unit of neural information: making unreliable synapses reliableTrends in Neurosciences, 1997
- Precisely correlated firing in cells of the lateral geniculate nucleusNature, 1996
- Integrator or coincidence detector? The role of the cortical neuron revisitedTrends in Neurosciences, 1996
- Presynaptic colocalization of carnosine and glutamate in olfactory neuronesNeuroReport, 1993