Different transmitter transients underlie presynaptic cell type specificity of GABA A,slow and GABA A,fast

Noradrenergic modulation of cortical circuits is involved in information processingLastly, we studied the effects of ␤-adrenergic modulation on mixed polysynaptic transmission within the GABAergic network. Isoproterenol depressed propagation of GABA A receptor-mediated synaptic currents, but did not change significantly direct GABAergic input, indicating that regulation of electrical coupling adds flexibility to the information flow generated by chemical synapses.In conclusion, activation of ␤-adrenergic receptors in stratum lacunosum-moleculare GABAergic networks reduces electrical synaptic transmission via a cAMP/PKA signaling cascade, and affects the degree of synaptic divergence within the circuit. We propose that this dynamic modulation and interplay between electrical and chemical synaptic transmission in GABAergic networks contributes to the tuning of memory processes in vivo, and prevents hypersynchronous activity.

Section: Gap Junctions Of Hippocampalmentioning

confidence: 99%

Noradrenergic Modulation of Electrical Coupling in GABAergic Networks of the Hippocampus

Zsiros¹,

Maccaferri²

2008

“…However, it remains to be investigated whether other interneurons innervating the perisomatic domain of pyramidal cells, such as axo-axonic and CCKexpressing interneurons, might provide differently timed GABAergic input during theta oscillations. Distinct GABAergic interneurons have been described to differentially modulate pyramidal cells and cell assemblies in vitro (Szabadics et al, 2007;Molnár et al, 2008). Recently, two populations of fast spiking interneuron, including PV-positive basket cells, were reported with different firing patterns in the frontal cortex in vivo (Puig et al, 2008).…”

Section: Prefrontal Pv؉/cb؉ Basket and Pyramidal Cell Firing In Vivomentioning

confidence: 99%

Distinct Firing Patterns of Identified Basket and Dendrite-Targeting Interneurons in the Prefrontal Cortex during Hippocampal Theta and Local Spindle Oscillations

Hartwich

Pollak²,

Klausberger³

2009

The medial prefrontal cortex is involved in working memory and executive control. However, the collective spatiotemporal organization of the cellular network has not been possible to explain during different brain states. We show that pyramidal cells in the prelimbic cortex fire synchronized to hippocampal theta and local spindle oscillations in anesthetized rats. To identify which types of interneurons contribute to the synchronized activity, we recorded and juxtacellularly labeled parvalbumin-and calbindin-expressing (PVϩ/CBϩ) basket cells and CB-expressing, PV-negative (CBϩ/PVϪ) dendrite-targeting interneurons during both network oscillations. All CBϩ/ PVϪ dendrite-targeting cells strongly decreased their firing rate during hippocampal theta oscillations. Most PVϩ/CBϩ basket cells fired at the peak of dorsal CA1 theta cycles, similar to prefrontal pyramidal cells. We show that pyramidal cells in the ventral hippocampus also fire around the peak of dorsal CA1 theta cycles, in contrast to previously reported dorsal hippocampal pyramidal cells. Therefore, prefrontal neurons might be driven by monosynaptic connections from the ventral hippocampus during theta oscillations. During prefrontal spindle oscillations, the majority of pyramidal cells and PVϩ/CBϩ basket cells fired preferentially at the trough and early ascending phase, but CBϩ/PVϪ dendrite-targeting cells fired uniformly at all phases. We conclude that PVϩ/CBϩ basket cells contribute to rhythmic responses of prefrontal pyramidal cells in relation to hippocampal and thalamic inputs and CBϩ/PVϪ dendrite-targeting cells modulate the excitability of dendrites and spines regardless of these field rhythms. Distinct classes of GABAergic interneuron in the prefrontal cortex contribute differentially to the synchronization of pyramidal cells during network oscillations.

“…4) (Fuentealba et al, 2008). IvyCs belong to the family of neurogliaform cells that are known to provide powerful, long-lasting inhibition to postsynaptic cells through their extremely dense axonal cloud (Tamás et al, 2003;Price et al, 2005;Szabadics et al, 2007). However, in contrast to hippocampal neurogliaform cells (Price et al, 2005), IvyCs release GABA onto the proximal dendritic region of pyramidal cells as they innervate the inner portion of stratum radiatum and stratum oriens (Fuentealba et al, 2008).…”

Section: Specific Description Of Cell Typesmentioning

confidence: 99%

“…As far as MF input properties are concerned, CA3 IvyCs were most similar to RSBCs, displaying rare but strong MF-euEPSCs on a background of lowfrequency spontaneous synaptic events. Although the properties of CA3 IvyCs will need to be studied further, it is likely that MF inputs to IvyCs contribute to the regulation of pyramidal cell dendritic excitability during behaviorally relevant network rhythms (Fuentealba et al, 2008) through slow IPSPs characteristic of neurons in the neurogliaform cell family (Tamás et al, 2003;Price et al, 2005;Szabadics et al, 2007).…”

Section: Mf Inputs To Slcs and Ivycsmentioning

confidence: 99%

Functional Specificity of Mossy Fiber Innervation of GABAergic Cells in the Hippocampus

Szabadics¹,

Soltész²

2009

105

One million mossy fibers in the rat provide individually sparse but functionally important synaptic connections between the dentate gyrus and hippocampus. Although the majority of mossy fiber targets are GABAergic cells, the functional organization of the feedforward GABAergic machinery modulating the interactions of granule cells and CA3 pyramidal cells are not yet understood. We used mossy fiber bouton to GABA neuron paired recordings in the CA3 to demonstrate that mossy fibers provide cell type-specific innervation to distinct GABAergic neurons with specialized intra-and extrahippocampal outputs. Our results show that mossy fibers contact the perisomatically projecting fast-spiking and regular-spiking basket cells, in addition to the dendritically projecting ivy cells, and the septum-projecting spiny stratum lucidum cells. Monosynaptic mossy fiber inputs to fast-spiking basket cells and spiny stratum lucidum cells were found to be numerous, but they were small in amplitude and displayed low transmission probabilities. In contrast, regular-spiking basket cells and ivy cells were less likely to be innervated by mossy fibers, but the amplitudes of mossy fiber EPSCs were large and the transmission probabilities were high. The dependence of the numbers and strengths of the mossy fiber inputs to CA3 GABAergic cells on the postsynaptic cell type was correlated with the frequency of the background synaptic events, so that cells with weak but numerous mossy fiber inputs received high rates of spontaneous synaptic events. Together, these results reveal the diverse components and high degree of functional specificity of the GABAergic cellular machinery underlying the dentate gyrus-CA3 interface.