Ontogeny of Corticocortical Projections of Rat Somatosensory Cortex

Nicolelis, Miguel A. L.; Chapin, John K.; Lin, Chih-Hong

doi:10.3109/08990229109144743

Cited by 25 publications

(20 citation statements)

References 32 publications

(32 reference statements)

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“…The widespread tangential extent of the labeling pattern from subgriseal neurons is consistent with results of some previous studies (Nicolelis et al, 1991) but does not support earlier descriptions of a probable columnar organization for portions of these neurons (Divac et al, 1987;Reep and Goodwin, 1988). Continuous labeling, clusters of 1-10 labeled subgriseal cells, and single-labeled subgriseal cells were found rostrocaudal and lateromedial to the application sites.…”

Section: Widespread Labeling Of Subgriseal Neurons In Ipsilateral Hemsupporting

confidence: 80%

“…This distinction may be important because in mammals both layer I and subgriseal neurons are believed to develop fully prior to the development of neurons in layers II-VI (layer I is the first formed cortical layer; layer II, although directly subjacent, is the last generated layer; Bayer and Altman, 1990), and subplate connections to layer I form one of the first functional cortical relationships (Ramon y Cajal, 1955;Marin-Padilla, 1978;Kristt, 1979b;Chun et al, 1987;Friauf et al, 1990;Nicolelis et al, 1991). Nevertheless, it has commonly been believed that this subplatelayer I connection is lost in the mature cortex (MarinPadilla, 1998).…”

Section: Connections From Subgriseal Neurons To Cortical Layer I In Mmentioning

confidence: 99%

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Widespread projections from subgriseal neurons (layer VII) to layer I in adult rat cortex

Clancy

Cauller

1999

J. Comp. Neurol.

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Section: Widespread Labeling Of Subgriseal Neurons In Ipsilateral Hemsupporting

confidence: 80%

Section: Connections From Subgriseal Neurons To Cortical Layer I In Mmentioning

confidence: 99%

Widespread projections from subgriseal neurons (layer VII) to layer I in adult rat cortex

Clancy

Cauller

1999

J. Comp. Neurol.

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“…This study confirms that the projection from zona incerta to layer I of SI can be labeled by using other fluorescent tracers and that HRP does not label these cells. Similarly, Nicolelis et al (1991) found neurons in a dense band at the border between the dorsolateral cortex and the white matter following retrograde transport of fluorescent tracers from SI. Likewise, we find that these cells project to layer I of SI with the use of fluorescent tracers but not with HRP (Clancy and Cauller, 1995).…”

Section: Discussionmentioning

confidence: 99%

Backward cortical projections to primary somatosensory cortex in rats extend long horizontal axons in layer I

1998

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We have studied the origin and extent of axons within layer I of the primary somatosensory cortex (SI) of rats by using retrograde and anterograde tracers with an emphasis on reciprocal connections to layer I of SI from ipsilateral cortical areas that are the target of SI projections. Small crystals of 1,1',dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) labeled horizontal axons projecting in all directions within layer I, which extended for up to 4 mm with numerous terminal branches. Applications of horseradish peroxidase, Diamidino yellow, or fast blue to the pial surface of SI labeled a characteristic pattern of neurons below the application site that excluded neurons in layer IV of the barrel fields, unless the dye penetrated deeper than layer II. This provided a control for the effective depth of the layer I dye applications. Retrograde transport from layer I of SI was traced to the primary motor area, the lateral parietal areas, including the secondary somatosensory (SII) and agranular insular cortex ipsilaterally, as well as the homotopic areas of SI contralaterally. Injections of the anterograde tracer dextran amine at the same site as the SI surface application labeled dense fiber terminations in middle layers of these same secondary areas in the primary motor cortex (MI) or SII in the midst of cells labeled by retrograde transport from layer I of SI. Injections of dextran amine into these secondary cortical areas labeled fibers that coursed through deep layers to SI, where they ascended to layer I. These reciprocal corticocortical inputs to SI were concentrated in layer I, where they branched and extended horizontally across several SI barrels.

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“…The collaterals of layer II/III and V pyramidal cells have been found to provide long-range horizontal connections in those layers in a number of species and cortical areas including rat somatosensory cortex. 7,22 Interlaminar connections between layers II/III and V have also been described in rat somatosensory cortex. 5 The presence of long-range horizontal connectivity in layer VI similar to that observed in layers II/III and V has been documented in the somatosensory cortex of the rat using a number of different labeling techniques including rhodamine-coated microspheres 22 and biocytin.…”

Section: Comparison With Other Anatomical Neurophysiological and Opmentioning

confidence: 99%

“…7,22 Interlaminar connections between layers II/III and V have also been described in rat somatosensory cortex. 5 The presence of long-range horizontal connectivity in layer VI similar to that observed in layers II/III and V has been documented in the somatosensory cortex of the rat using a number of different labeling techniques including rhodamine-coated microspheres 22 and biocytin. 30 Projections from layer VI to layer IV are also known to exist, although whether they target predominantly inhibitory or excitatory interneurons has been a subject of debate.…”

Section: Comparison With Other Anatomical Neurophysiological and Opmentioning

confidence: 99%

Functional neocortical microcircuitry demonstrated with intrinsic signal optical imaging in vitro

et al. 1999

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Abstract-Intrinsic signal optical imaging was used to record the changes in light transmittance evoked by electrical stimulation in slices prepared from sensorimotor cortex of young adult rats. The spatial characteristics of the optical signal evoked by stimulation of layer II/III, IV, V, or VI were clearly different. Layer IV and V stimulation elicited a radially-oriented region of increased light transmittance which was "hourglass" shaped: its tangential extent was greatest in layers II/III and layer V, and least in layer IV. Layer VI stimulation also elicited a radially-oriented signal but the tangential extent of this signal was the same across layers II-VI-that is, it was column-shaped. Upper layer stimulation produced a signal whose tangential extent was much greater in the upper layers than its radial extent to the deeper layers. The spatial form of the stimulus-evoked intrinsic signal was not dependent on the cytoarchitectonic area in which it was elicited. The tangential and radial distribution of the signal evoked by stimulation of different layers appears to reflect the connectivity of cortex, particularly the horizontal connectivity present in layers II/III, V, and VI, and the interlaminar connections that exist between layers II/III and V and from layers VI to IV. The spatial characteristics of the intrinsic signal were independent of the strength of stimulation used. The idea that inhibitory mechanisms restrict the tangential extent of the signal was evaluated in experiments in which the intrinsic signal was recorded before and after the addition of 10 mM bicuculline methiodide. In all slices studied in this way (n 12), bicuculline methiodide drastically increased the tangential extent of the signal. In 4/12 slices, the tangential spread of the signal was asymmetric with respect to the stimulus site. Asymmetric spread of the signal occurred for both layer V and layer VI stimulation and, in 2/4 of those cases, could be attributed to a cytoarchitectonic border whose presence appeared to restrict the spread of the signal across the border. Although increasing stimulation strength did not change the spatial characteristics of the radially-oriented signal evoked by layer V or VI stimulation, at maximal stimulus intensity the signal evoked from these layers was often accompanied by a band of decreased light transmittance in the most superficial layers (layers I and II).It is concluded that in vitro intrinsic optical signal imaging allows one to image a response attributable to activation of local subsets of cortical connections. In addition, the opposite effects of high-intensity deep layer stimulation on the superficial layers vs layers III-VI of the same column raise the possibility that the most superficial layers may respond differently to repetitive input drive than the rest of the cortical column. ᭧ 1999 IBRO. Published by Elsevier Science Ltd.Key words: optical imaging, intrinsic signal, functional microcircuitry, somatosensory cortex.The intrinsic optical signal (IOS) is an activity-dependent cha...

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Ontogeny of Corticocortical Projections of Rat Somatosensory Cortex

Cited by 25 publications

References 32 publications

Widespread projections from subgriseal neurons (layer VII) to layer I in adult rat cortex

Widespread projections from subgriseal neurons (layer VII) to layer I in adult rat cortex

Backward cortical projections to primary somatosensory cortex in rats extend long horizontal axons in layer I

Functional neocortical microcircuitry demonstrated with intrinsic signal optical imaging in vitro

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