Synaptic sequences in mouse SmI cortex involving pyramidal cells labeled by retrograde filling with horseradish peroxidase

White, Edward L.; Hersch, Steven M.; Rock, Michael P.

doi:10.1016/0304-3940(80)90186-x

Cited by 33 publications

(8 citation statements)

References 24 publications

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“…The appearance of HRP labelled neuronal elements in thin sections was consistent with previous reports (e.g., White et al, 1980;White, 1981, 1982;Hersch, 1981, 1982). Labelled profiles contained a high concentration of electron dense material that was easily visualized in thin sections (Fig.…”

Section: Comparison Of Dendritic Cluster Composition In Msl and Smlsupporting

confidence: 91%

Organization of Pyramidal Cell Apical Dendrites and Composition of Dendritic Clusters in the Mouse: Emphasis on Primary Motor Cortex

Lev

White

1997

Eur J of Neuroscience

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It has been proposed that neurons in sensory cortices are organized into modules that centre on clusters of apical dendrites belonging to layer V pyramidal neurons. In the present study, sections reacted for microtubule-associated protein (MAP2) were examined in order to determine the three-dimensional inter-relationships of pyramidal cell dendrites in mouse primary motor cortex (MsI) cortex. Results indicate that pyramidal cell dendrites in MsI cortex can be interpreted to be arranged in a modular fashion, and that these modules are organized similarly to those in the sensory areas of the cortex. Also included in the present study are experiments designed to determine if the clusters of apical dendrites, around which the modules are centred, are composed of dendrites belonging to one or to more than one type of projection cell. Callosal neurons in MsI cortex were labelled by the retrograde transport of horseradish peroxidase deposited onto severed callosal fibres in the contralateral hemisphere. Examination of tangential thin sections through layer IV of MsI cortex shows clusters of apical dendrites in which every dendrite is labelled with horseradish peroxidase. Adjacent clusters are composed of unlabelled dendrites, suggesting that the apical dendrites of callosal neurons aggregate to form clusters that are composed exclusively of dendrites belonging to this type of projection cell. These findings suggest a hitherto unsuspected degree of specificity in the cellular composition of cortical modules.

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Section: Comparison Of Dendritic Cluster Composition In Msl and Smlsupporting

confidence: 91%

Organization of Pyramidal Cell Apical Dendrites and Composition of Dendritic Clusters in the Mouse: Emphasis on Primary Motor Cortex

Lev

White

1997

Eur J of Neuroscience

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“…A line-scan was performed through every visible dendritic spine on a targeted dendritic branch in an orientation that was parallel to the dendritic spine neck and orthogonal to the dendritic shaft. In addition, line-scans were performed through a long axis of dendritic branches to detect non-spiny synapses (White et al, 1980). A similar method was previously used to effectively detect excitatory synapses on aspiny neurons (Goldberg et al, 2003).…”

Section: Methodsmentioning

confidence: 99%

Connectivity Patterns Revealed by Mapping of Active Inputs on Dendrites of Thalamorecipient Neurons in the Auditory Cortex

Richardson

Blundon²,

Bayazitov³

et al. 2009

J. Neurosci.

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Despite being substantially outnumbered by intracortical inputs on thalamorecipient neurons, thalamocortical projections efficiently deliver acoustic information to the auditory cortex. We hypothesized that thalamic projections may achieve effectiveness by forming synapses at optimal locations on dendritic trees of cortical neurons. Using two-photon calcium imaging in dendritic spines, we constructed maps of active thalamic and intracortical inputs on dendritic trees of thalamorecipient cortical neurons in mouse thalamocortical slices. These maps revealed that thalamic projections synapse preferentially on stubby dendritic spines within 100 m of the soma, whereas the locations and morphology of spines that receive intracortical projections have a less-defined pattern. Using two-photon photolysis of caged glutamate, we found that activation of stubby dendritic spines located perisomatically generated larger postsynaptic potentials in the soma of thalamorecipient neurons than did activation of remote dendritic spines or spines of other morphological types. These results suggest a novel mechanism of reliability of thalamic projections: the positioning of crucial afferent inputs at optimal synaptic locations.

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“…Under certain conditions, HRP transported in the retrograde direction fills neuronal processes emanating from the cell body, including dendrites and their spines and local axon collaterals Hersch, 1981, 1982;White et al, 1980). The bidirectional transport of HRP means that "target" areas of the brain reciprocally connected with an injection site are liable to contain HRP labeled axon terminals from two different sources.…”

Section: Experimental Approachmentioning

confidence: 98%

Synapses made by axons of callosal projection neurons in mouse somatosensory cortex: Emphasis on intrinsic connections

White

Czeiger

1991

J of Comparative Neurology

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This is one of a series of papers aimed at identifying the synaptic output patterns of the local and distant projections of subgroups of pyramidal neurons. The subgroups are defined by the target site to which their main axon projects. Pyramidal neurons in areas 1 and 40 of mouse cerebral cortex were labeled by the retrograde transport of horseradish peroxidase (HRP) transported from severed callosal axons in the contralateral hemisphere. Terminals of the local axon collaterals of these neurons ("intrinsic" terminals) were identified in somatosensory areas 1 and 40, and their distribution and synaptic connectivity were examined. Also examined were the synaptic connections of "extrinsic" callosal axon terminals labeled by lesion induced degeneration consequent to the severing of callosal fibers. A post-lesion survival time of 3 days was chosen because by this time the extrinsic terminals were all degenerating, whereas the intrinsic terminals were labeled by HRP. Both intrinsic and extrinsic callosal axon terminals occurred in all layers of the cortex where they formed only asymmetrical synapses. Layers II and III contained the highest concentrations of both types of callosal axon terminal. Analyses of serial thin sections through layers II and III in both areas 1 and 40 yielded similar results: 97% of the extrinsic (277 total sample) and of the intrinsic (1215 total sample) callosal axon terminals synapsed onto dendritic spines, likely those of pyramidal neurons; the remainder synapsed onto dendritic shafts of both spiny and nonspiny neurons. Thus the synaptic output patterns of intrinsic vs. extrinsic callosal axon terminals are strikingly similar. Moreover, the high proportion of axospinous synapses formed by both types of terminal contrasts with the proportion of asymmetrical, axospinous synapses that occur in the surrounding neuropil where only about 80% of the asymmetrical synapses are onto spines. This result is in accord with previous quantitative studies of the synaptic connectivities of both extrinsic and intrinsic axonal pathways in the cortex (White and Keller, 1989: Cortical Circuits; Boston: Birkhauser): in all instances, axonal pathways are highly selective for the types of elements with which they synapse.

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Synaptic sequences in mouse SmI cortex involving pyramidal cells labeled by retrograde filling with horseradish peroxidase

Cited by 33 publications

References 24 publications

Organization of Pyramidal Cell Apical Dendrites and Composition of Dendritic Clusters in the Mouse: Emphasis on Primary Motor Cortex

Organization of Pyramidal Cell Apical Dendrites and Composition of Dendritic Clusters in the Mouse: Emphasis on Primary Motor Cortex

Connectivity Patterns Revealed by Mapping of Active Inputs on Dendrites of Thalamorecipient Neurons in the Auditory Cortex

Synapses made by axons of callosal projection neurons in mouse somatosensory cortex: Emphasis on intrinsic connections

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