A study of the organization of apical dendrites in the somatic sensory cortex of the rat

Peters, Alan; Walsh, Timothy

doi:10.1002/cne.901440302

Cited by 177 publications

(70 citation statements)

References 11 publications

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“…Apical dendrites of layer V pyramidal neurons tend to form bundles (Peters and Walsh, 1972;Sethares, 1991, 1996;Jones, 2000;Rockland and Ichinohe, 2004;DeFelipe, 2005;Innocenti and Vercelli, 2010). However, in Crym-BAC-EGFP mice, many EGFP(ϩ) cells did not appear to form distinct dendritic bundles ( Fig.…”

Section: Relationship To Previously Characterized Neocortical Structuresmentioning

confidence: 95%

Periodic Organization of a Major Subtype of Pyramidal Neurons in Neocortical Layer V

Maruoka

Kubota²,

Kurokawa³

et al. 2011

J. Neurosci.

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A major question in neocortical research is the extent to which neuronal organization is stereotyped. Previous studies have revealed functional clustering and neuronal interactions among cortical neurons located within tens of micrometers in the tangential orientation (orientation parallel to the pial surface). In the tangential orientation at this scale, however, it is unknown whether the distribution of neuronal subtypes is random or has any stereotypy. We found that the tangential arrangement of subcerebral projection neurons, which are a major pyramidal neuron subtype in mouse layer V, was not random but significantly periodic. This periodicity, which was observed in multiple cortical areas, had a typical wavelength of 30 m. Under specific visual stimulation, neurons in single repeating units exhibited strongly correlated c-Fos expression. Therefore, subcerebral projection neurons have a periodic arrangement, and neuronal activity leading to c-Fos expression is similar among neurons in the same repeating units. These results suggest that the neocortex has a periodic functional micro-organization composed of a major neuronal subtype in layer V.

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Section: Relationship To Previously Characterized Neocortical Structuresmentioning

confidence: 95%

Periodic Organization of a Major Subtype of Pyramidal Neurons in Neocortical Layer V

Maruoka

Kubota²,

Kurokawa³

et al. 2011

J. Neurosci.

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“…At the level of layer 2/3, the apical dendrites begin to branch into terminal tufts, causing bundles to be less spatially confined. It is also evident that the layer 5B pyramidal cell bodies are located vertically below their apical dendrite and that apical dendrites in a given bundle originate from cell somata arranged in clusters (Peters and Walsh, 1972). Each bundle is made up of 5-10 main apical dendrites and their associated somata, with distances of 20 -40 m between the bundle centers.…”

Section: Characterization Of Bundles Formed By Apical Dendrites Of Lamentioning

confidence: 99%

“…It has been suggested that pyramidal neurons within a minicolumn are more densely interconnected, have larger EPSPs, and receive common inputs (Peters and Walsh, 1972;Peters and Yilmaz, 1993;Thomson and Deuchars, 1994;Mountcastle, 1997;Tanaka, 1998). Indeed, the definition of cells that are part of a minicolumn is that these cells share common response properties (Mountcastle, 2003).…”

Section: Synaptic Connectivity Between Layer 5 Pyramidal Neurons Withmentioning

confidence: 99%

“…The underlying anatomical substrate for a minicolumn has been proposed to be a columnar organization of cells ("pyramidal cell module") with bundled apical dendrites originating from layer 5 pyramidal neurons as the core element (Fleischhauer et al, 1972;Peters and Walsh, 1972;Escobar et al, 1986;Sethares, 1991, 1996;Peters and Yilmaz, 1993;White and Peters, 1993;DeFelipe, 2005), or vertically aligned rows of cells ("cell columns"), which do not necessarily contain layer 5 pyramidal cells with bundled apical dendrites, that are prominent in primate neocortex (Schlaug et al, 1995;Buxhoeveden et al, 2000). Examples of other repeating anatomical structures that could be components of minicolumns include dendrite bundles formed by layer 6 pyramidal cells, which in mouse neocortex are separate from layer 5 dendrite bundles (Escobar et al, 1986;Lev and White, 1997), and bundles of double bouquet cell axons (DeFelipe et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

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Synaptic Connections between Layer 5B Pyramidal Neurons in Mouse Somatosensory Cortex Are Independent of Apical Dendrite Bundling

2007

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Rodent somatosensory barrel cortex is organized both physiologically and anatomically in columns with a cross-sectional diameter of 100 -400 m. The underlying anatomical correlate of physiologically defined, much narrower minicolumns (20 -60 m in diameter) remains unclear. The minicolumn has been proposed to be a fundamental functional unit in the cortex, and one anatomical component of a minicolumn is thought to be a cluster of pyramidal cells in layer 5B (L5B) that contribute their apical dendrite to distinct bundles. In transgenic mice with fluorescently labeled L5B pyramidal cells, which project to the pons and thalamus, we investigated whether the pyramidal cells of a cluster also share functional properties. We found that apical dendrite bundles in the transgenic mice were anatomically similar to apical dendrite bundles previously proposed to be part of minicolumns. We made targeted whole-cell recordings in acute brain slices from pairs of fluorescently labeled L5B pyramidal cells that were located either in the same cluster or in adjacent clusters and subsequently reconstructed their dendritic arbors. Pyramids within the same cluster had larger common dendritic domains compared with pyramids in adjacent clusters but did not receive more correlated synaptic inputs. L5B pyramids within and between clusters have similar connection probabilities and unitary EPSP amplitudes. Furthermore, intrinsically bursting and regular spiking pyramidal cells were both present within the same cluster. In conclusion, intrinsic electrical excitability and the properties of synaptic connections between this subtype of L5B pyramidal cells are independent of the cell clusters defined by bundling of their apical dendrites.

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“…Minicolumns have been proposed to be the basic unit of the neocortex, which are composed of chains of neurons (typically ~80-120 in primates) spanning cortical layers whose cell bodies are vertically aligned within a diameter of ~40-50 μm; about ~50-80 minicolumns link together to form the structural basis of functional columns (Mountcastle, 2003). Another candidate is a related structure referred to as 'bundles', which mainly comprise closely associated apical dendrites of pyramidal cells whose cell bodies are located in different layers (Peters and Kara, 1987;Peters and Sethares, 1996;Peters and Walsh, 1972;Peters et al, 1997). However, both views have met ample criticism (Rockland and Ichinohe, 2004;da Costa and Martin, 2010).…”

Section: The Neocortical Columnmentioning

confidence: 99%

Lineage-dependent circuit assembly in the neocortex

et al. 2013

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The neocortex plays a key role in higher-order brain functions, such as perception, language and decision-making. Since the groundbreaking work of Ramón y Cajal over a century ago, defining the neural circuits underlying brain functions has been a field of intense study. Here, we review recent findings on the formation of neocortical circuits, which have taken advantage of improvements to mouse genetics and circuit-mapping tools. These findings are beginning to reveal how individual components of circuits are generated and assembled during development, and how early developmental processes, such as neurogenesis and neuronal migration, guide precise circuit assembly. Key words: Lineage, Neuronal circuits, Neocortex IntroductionThe mammalian cerebral cortex is composed of the archicortex (hippocampal region), the paleocortex (olfactory cortex) and the neocortex, with the last being the evolutionarily youngest region. The neocortex is composed of two major classes of neurons: glutamatergic projection neurons (see Glossary, Box 1), which elicit excitation in postsynaptic neurons and generate circuit output; and GABA (γ-aminobutyric acid)-ergic interneurons (see Glossary, Box 1), which typically trigger inhibition in postsynaptic neurons and are essential for shaping circuit output. It is generally accepted that two defining structural and functional features of the neocortex are lamination and radial columns (Douglas and Martin, 2004). Together, these features provide the basic framework on which neocortical circuits are built. Interestingly, both of these features are tightly linked to early developmental events, including neurogenesis and neuronal migration. In this Review, we discuss recent findings on the generation, migration and organization of excitatory and inhibitory neurons in the neocortex, with a focus on how the lineage history of neurons influences the assembly of functional circuits. Lamination: a hallmark of the neocortexThe neocortex is a continuous six-layered structure. All components of neocortical circuits, including afferents, excitatory cells, inhibitory cells and efferents, are organized with respect to the laminae (Douglas and Martin, 2004). Cortical lamination is generated as a result of radial migration of newborn excitatory neurons during development (Hatten, 1999;Rakic, 1971;Rakic, 1972). Glutamatergic excitatory neurons are produced from progenitor cells (Fig. 1A) that reside in the proliferative zone of the dorsal telencephalon (see Glossary, Box 1). In the earliest stages, the neural tube is composed of a single layer of neuroepithelial (NE) cells that proliferate rapidly (Breunig et al., 2011). A small fraction of NE cells undergoes asymmetric division to generate the first wave of postmitotic neurons, which migrate out radially and form a transient structure called the preplate (see Glossary, Box 1) (Del Río et al., 2000;Marin-Padilla, 1970;Marin-Padilla, 1971;Marin-Padilla, 1978). As development proceeds, NE cells transform into a more fate-restricted progenitor type: radial glial ...

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A study of the organization of apical dendrites in the somatic sensory cortex of the rat

Cited by 177 publications

References 11 publications

Periodic Organization of a Major Subtype of Pyramidal Neurons in Neocortical Layer V

Periodic Organization of a Major Subtype of Pyramidal Neurons in Neocortical Layer V

Synaptic Connections between Layer 5B Pyramidal Neurons in Mouse Somatosensory Cortex Are Independent of Apical Dendrite Bundling

Lineage-dependent circuit assembly in the neocortex

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