Characteristics of projections from primary sensory cortex to motorsensory cortex in cats

Thompson, William E.; Stoney, Susan; Asanuma, Hiroshi

doi:10.1016/0006-8993(70)90399-9

Cited by 53 publications

(12 citation statements)

References 14 publications

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“…Furthermore, several electrophysiology studies indicate that direct projections from SI to MI are capable of modulating neuronal responses in MI (Herman et al, 1985;Kosar et al, 1985;Zarzecki, 1986;Kaneko et al, 1994;Farkas et al, 1999;Kelly et al, 2001). Consistent with these findings, some reports indicate that neuronal activity in MI is altered by cutaneous stimulation and that these responses are often coordinated with SI responses during somesthesis-guided behaviors (Thompson et al, 1970;Murthy and Fetz, 1996a, b;Salinas and Romo, 1998;Farkas et al, 1999;Fetz et al, 2000;Luft et al, 2002;Kleinfeld et al, 2002).…”

supporting

confidence: 54%

Sensorimotor corticocortical projections from rat barrel cortex have an anisotropic organization that facilitates integration of inputs from whiskers in the same row

Hoffer

Hoover

Alloway

2003

J of Comparative Neurology

101

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We used a dual anterograde-tracing paradigm to characterize the organization of corticocortical projections from primary somatosensory (SI) barrel cortex. In one group of rats, biotinylated dextran amine (BDA) and Fluoro-Ruby (FR) were injected into separate barrel columns that occupied the same row of barrel cortex; in the other group, the tracers were deposited into barrel columns residing in different rows. The labeled corticocortical terminals in the primary motor (MI) and secondary somatosensory (SII) cortices were plotted, and digital reconstructions of these plots were quantitatively analyzed. In all cases, labeled projections from focal tracer deposits in SI barrel cortex terminated in elongated, row-like strips of cortex that corresponded to the whisker representations of the MI or SII cortical areas. When both tracers were injected into separate parts of the same SI barrel row, FR- and BDA-labeled terminals tended to merge into a single strip of labeled MI or SII cortex. By comparison, when the tracers were placed in different SI barrel rows, both MI and SII contained at least two row-like FR- and BDA-labeled strips that formed mirror image representations of the SI injection sites. Quantitative analysis of these labeling patterns revealed three major findings. First, labeled overlap in SII was significantly greater for projections from the same barrel row than for projections from different barrel rows. Second, in the infragranular layers of MI but not in the supragranular layers, labeled overlap was significantly higher for projections from the same SI barrel row. Finally, in all layers of SII and in the infragranular layers of MI, the amount of labeled overlap was proportional to the proximity of the tracer injection sites. These results indicate that SI projections to MI and SII have an anisotropic organization that facilitates the integration of sensory information received from neighboring barrels that represent whiskers in the same row.

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supporting

confidence: 54%

Sensorimotor corticocortical projections from rat barrel cortex have an anisotropic organization that facilitates integration of inputs from whiskers in the same row

Hoffer

Hoover

Alloway

2003

J of Comparative Neurology

101

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“…Anatomical studies have shown the presence of neurons directly projecting from area 2 to the motor cortex (Jones et al, 1978;Yumiya and Ghez, 1984;Ichikawa et al, 1985;Porter and Sakamoto, 1988). The type I responses identified in the present study are likely to be produced by activation of these corticocortical neurons and/or their descending axons, since we stimulated area 2 at a depth of about 1 mm (lower layer I11 to upper layer V), which has reportedly been the most effective depth to produce responses in the motor cortex (Thompson et al, 1970). There is, however, a possibility that the monosynaptic responses could be produced by activation of recurrent axon collaterals of the neurons that projected from the motor cortex to area 2.…”

Section: Monosynaptic Responsementioning

confidence: 61%

Information processing within the motor cortex. I. Responses of morphologically identified motor cortical cells to stimulation of the somatosensor cortex

Kaneko

Caría

Asanuma

1994

J of Comparative Neurology

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Inputs from the somatosensory cortex to the motor cortex have been proposed to function in learning of motor skills. In an attempt to analyze how these somatosensory inputs were processed in the motor cortex, neurons in the superficial layer of the cat motor cortex were classified into three groups on the basis of synaptic responses elicited by intracortical microstimulation (ICMS) of area 2. ICMS was delivered through seven electrodes implanted in area 2. When ICMS through one of the seven sites produced a response that was greater than 50% of the response produced by stimulating the seven sites at a time, the site was called a "dominant" site. Type I cells were those that had a dominant stimulation site and showed a constant response latency when examined by a double shock test. Type II cells were those that had a dominant site but displayed a variable latency. Type III cells had no dominant site and showed a variable latency. Latency of type I responses was 1.2-2.6 milliseconds, which was much shorter than that of type II and type III responses. Seventy-nine neurons in layers II/III of the motor cortex, which responded to ICMS in area 2, were stained by intracellular injection of biocytin. From the presence of an apical dendrite and rich spines on the dendrites, 23 type I, 21 type II, and 15 type III cells were classified as pyramidal cells. Type II pyramidal cells were located more superficially than type I and type III pyramidal cells. On the basis of the absence or sparseness of dendritic spines, three type I and four type II cells in layers II/III were classified as nonpyramidal cells. These cells consisted of five small multipolar cells in layer II and a large multipolar cell and a small bitufted cell in layer III. The remaining 11 cells were not classified because of insufficient staining. Since type I and type II cells are considered to represent monosynaptic and polysynaptic responses to stimulation of area 2, respectively, information flow from type I cells to more superficially located type II cells is presumed in layers II/III of the motor cortex. Type III responses suggest the presence of a convergent flow of impulses inside of and/or between areas 2 and 4.

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“…The sparse input for the pathway described here may explain the findings that electrical stimulation of cortico-cortical projections in cat sensorimotor cortex frequently elicits only subthreshold excitatory postsynaptic potentials (EPSPs) in target neurons (Thompson et al, 1970;Asanuma et al, 1982;Herman et al, 1985;Kosar et al, 1985). Likewise, the sparsity of intrinsic visual cortex connections (Kisvardy et al, 1986;Gabbott et al, 1987;McGuire et al, 1991;Kisvardy and Eysel, 1992) may provide the anatomical substrate for the weak cell-to-cell interactions reported in cross-correlation studies in cat visual cortex (Ts'o et al, 1986).…”

Section: Discussionmentioning

confidence: 73%

Morphological Characterization of a Cortico-cortical relay in the cat sensorimotor cortex

Porter

1997

Cerebral Cortex

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One feature of the cerebral cortex circuitry is the complex network of fibers which links its different functional regions. Our knowledge of the specific relationships between neurons which form these pathways is limited. The cortico-cortical connections between primary somatosensory cortex (SI) and primary motor cortex (MI) were the focus of the study. The aims were twofold: first, to identify characteristics of inter-areal cortico-cortical connections; and second, to determine if pathways exist which support the notion that peripheral signals are integrated in the somatosensory cortex before being relayed to the motor cortex. Neurons in area 2 of SI, which projected to the motor cortex were identified. The morphological characteristics of these neurons and the pattern of input that they received from area 3a were determined. The fluorescent retrograde tracer, fast blue, was injected into the electrophysiologically defined forepaw representation of motor cortex and the anterograde tracer, dextran-tetramethylrhodamine (DR), was injected into the somatotopically matched region of area 3a. Labeled neurons in area 2 which were located in a field of labeled axons arising from area 3a were identified in fixed tissue sections. Some of these labeled cells were impaled with a Lucifer yellow (LY)-filled micropipette and were intracellulary labeled by iontophoretic injection of LY. Cells in area 2 that projected to the motor cortex were located primarily in layers II-III. They were all classified as pyramidal neurons and were morphologically similar. Their apical dendrites for the most part did not extend beyond layer II. Their apical tufts exhibited 2-4 branches within layers II-III, while basal dendrites exhibited more numerous tertiary basal dendritic branches. Light microscopic (LM) examination revealed the presence of appositions between LY-filled profiles and DR-labeled axons. Appositions were observed between swellings along DR-labeled axons and dendritic shafts or spines of 1°, 2°and 3°branches of apical and 1°and 2°branches of basal dendrites. The appositions were primarily on proximal segments of labeled dendritic shafts. Fewer appositions with distal dendrites were observed and some of these were with dendritic spines. No appositions with the somata were observed. Only one or two appositions were observed for individual cells. The pattern of cortico-cortical synaptic input arising from area 3a onto this population of cells was predicted from these LM findings. An ultrastructural analysis was performed to confirm the existence of contacts and the predicted pattern of connectivity. Neurons in area 2 which projected to the motor cortex, and area 3a axons which projected to area 2, were identified with electron dense retrograde and anterograde tracers respectively. Labeled neurons located in a field of labeled axons were examined throughout a sequential series of ultrathin sections. Electron microscopic analysis revealed a similar pattern, but with a slightly higher density of synaptic input (1-8 contacts per targe...

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Characteristics of projections from primary sensory cortex to motorsensory cortex in cats

Cited by 53 publications

References 14 publications

Sensorimotor corticocortical projections from rat barrel cortex have an anisotropic organization that facilitates integration of inputs from whiskers in the same row

Sensorimotor corticocortical projections from rat barrel cortex have an anisotropic organization that facilitates integration of inputs from whiskers in the same row

Information processing within the motor cortex. I. Responses of morphologically identified motor cortical cells to stimulation of the somatosensor cortex

Morphological Characterization of a Cortico-cortical relay in the cat sensorimotor cortex

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