A comparison of thalamocortical and other synaptic inputs to dendrites of two non‐spiny neurons in a single barrel of mouse SmI cortex

White, Edward L.; Rock, Michael P.

doi:10.1002/cne.901950207

Cited by 71 publications

(33 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Comparison of responsive and nonresponsive inhibitory interneurons suggested that, as in the comparison with excitatory neurons above, it was not the intrinsic properties of the interneuron that determined its responsiveness, but most likely the magnitude of the thalamocortical synaptic input it received. The differences in the magnitude of thalamic input onto different inhibitory interneurons are probably the functional correlates of the variability in the numbers and locations of thalamocortical synapses made on them (White and Rock, 1981;White et al, 1984;Keller and White, 1987).…”

Section: Only a Subset Of All Inhibitory Interneurons Are Activated Bmentioning

confidence: 99%

Diverse Types of Interneurons Generate Thalamus-Evoked Feedforward Inhibition in the Mouse Barrel Cortex

Porter¹,

Johnson²,

2001

View full text Add to dashboard Cite

Sensory information, relayed through the thalamus, arrives in the neocortex as excitatory input, but rapidly induces strong disynaptic inhibition that constrains the cortical flow of excitation both spatially and temporally. This feedforward inhibition is generated by intracortical interneurons whose precise identity and properties were not known. To characterize interneurons generating feedforward inhibition, neurons in layers IV and V of mouse somatosensory ("barrel") cortex in vitro were tested in the cell-attached configuration for thalamocortically induced firing and in the whole-cell mode for synaptic responses. Identification as inhibitory or excitatory neurons was based on intrinsic firing patterns and on morphology revealed by intracellular staining. Thalamocortical stimulation evoked action potentials in ϳ60% of inhibitory interneurons but in Ͻ5% of excitatory neurons. The inhibitory interneurons that fired received fivefold larger thalamocortical inputs compared with nonfiring inhibitory or excitatory neurons. Thalamocortically evoked spikes in inhibitory interneurons followed at short latency the onset of excitatory monosynaptic responses in the same cells and slightly preceded the onset of inhibitory responses in nearby neurons, indicating their involvement in disynaptic inhibition. Both nonadapting (fast-spiking) and adapting (regular-spiking) inhibitory interneurons fired on thalamocortical stimulation, as did interneurons expressing parvalbumin, calbindin, or neither calcium-binding protein.Morphological analysis revealed that some interneurons might generate feedforward inhibition within their own layer IV barrel, whereas others may convey inhibition to upper layers, within their own or in adjacent columns. We conclude that feedforward inhibition is generated by diverse classes of interneurons, possibly serving different roles in the processing of incoming sensory information.

show abstract

Section: Only a Subset Of All Inhibitory Interneurons Are Activated Bmentioning

confidence: 99%

Diverse Types of Interneurons Generate Thalamus-Evoked Feedforward Inhibition in the Mouse Barrel Cortex

Porter¹,

Johnson²,

2001

View full text Add to dashboard Cite

show abstract

“…Although a small fraction (ϳ20%) of these thalamic afferents terminate on aspinous, presumably GABAergic interneurons (White and Rock, 1981;White et al, 1984;Benshalom and White, 1986), their main target cells are excitatory spiny neurons in layer 4. Most of these neurons resemble spiny stellate cells, whereas a smaller fraction has been described as star pyramidal cells (Lund, 1984;Ahmed et al, 1994;Hirsch, 1995).…”

Section: Abstract: Barrel Cortex; Layer 4; Spiny Stellate Cell; Starmentioning

confidence: 99%

Columnar Organization of Dendrites and Axons of Single and Synaptically Coupled Excitatory Spiny Neurons in Layer 4 of the Rat Barrel Cortex

et al. 2000

View full text Add to dashboard Cite

Cortical columns are the functional units of the neocortex that are particularly prominent in the “barrel” field of the somatosensory cortex. Here we describe the morphology of two classes of synaptically coupled excitatory neurons in layer 4 of the barrel cortex, spiny stellate, and star pyramidal cells, respectively. Within a single barrel, their somata tend to be organized in clusters. The dendritic arbors are largely confined to layer 4, except for the distal part of the apical dendrite of star pyramidal neurons that extends into layer 2/3. In contrast, the axon of both types of neurons spans the cortex from layer 1 to layer 6. The most prominent axonal projections are those to layers 4 and 2/3 where they are largely restricted to a single cortical column. In layers 5 and 6, a small fraction of axon collaterals projects also across cortical columns. Consistent with the dense axonal projection to layers 4 and 2/3, the total number and density of boutons per unit axonal length was also highest there. Electron microscopy combined with GABA postimmunogold labeling revealed that most (>90%) of the synaptic contacts were established on dendritic spines and shafts of excitatory neurons in layers 4 and 2/3.The largely columnar organization of dendrites and axons of both cell types, combined with the preferential and dense projections within cortical layers 4 and 2/3, suggests that spiny stellate and star pyramidal neurons of layer 4 serve to amplify thalamic input and relay excitation vertically within a single cortical column.

show abstract

“…In the rodent whisker system, ascending thalamic input engages neuronal circuits in cortical layer 4 (L4), consisting of excitatory spiny stellate and pyramidal cells as well as aspiny interneurons (White and Rock, 1981;Beierlein et al, 2002Beierlein et al, , 2003Bruno and Simons, 2002) that provide feedforward and feedback inhibition to the local network (Agmon and Connors, 1991;Swadlow and Gusev, 2000;Porter et al, 2001;Swadlow, 2003;Staiger et al, 2004). This functional architecture leads to a precise sequence of excitation followed by inhibition in response to whisker deflection that may serve to sharpen the spike timing of suprathreshold responses and limit the time for integration of excitatory inputs (Pinto et al, 2000(Pinto et al, , 2003Pouille and Scanziani, 2001;Wehr and Zador, 2003;Wilent and Contreras, 2004;Blitz and Regehr, 2005;Mittmann et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Balanced Excitation and Inhibition Determine Spike Timing during Frequency Adaptation

Higley¹,

Contreras²

2006

J. Neurosci.

252

244

View full text Add to dashboard Cite

In layer 4 (L4) of the rat barrel cortex, a single whisker deflection evokes a stereotyped sequence of excitation followed by inhibition, hypothesized to result in a narrow temporal window for spike output. However, awake rats sweep their whiskers across objects, activating the cortex at frequencies known to induce short-term depression at both excitatory and inhibitory synapses within L4. Although periodic whisker deflection causes a frequency-dependent reduction of the cortical response magnitude, whether this adaptation involves changes in the relative balance of excitation and inhibition and how these changes might impact the proposed narrow window of spike timing in L4 is unknown. Here, we demonstrate for the first time that spike output in L4 is determined precisely by the dynamic interaction of excitatory and inhibitory conductances. Furthermore, we show that periodic whisker deflection results in balanced adaptation of the magnitude and timing of excitatory and inhibitory input to L4 neurons. This balanced adaptation mediates a reduction in spike output while preserving the narrow time window of spike generation, suggesting that L4 circuits are calibrated to maintain relative levels of excitation and inhibition across varying magnitudes of input.

show abstract

A comparison of thalamocortical and other synaptic inputs to dendrites of two non‐spiny neurons in a single barrel of mouse SmI cortex

Cited by 71 publications

References 26 publications

Diverse Types of Interneurons Generate Thalamus-Evoked Feedforward Inhibition in the Mouse Barrel Cortex

Diverse Types of Interneurons Generate Thalamus-Evoked Feedforward Inhibition in the Mouse Barrel Cortex

Columnar Organization of Dendrites and Axons of Single and Synaptically Coupled Excitatory Spiny Neurons in Layer 4 of the Rat Barrel Cortex

Balanced Excitation and Inhibition Determine Spike Timing during Frequency Adaptation

Contact Info

Product

Resources

About