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Clonally related visual cortical neurons show similar stimulus feature selectivity.

Li Y, Lu H, Cheng PL, Ge S, Xu H, Shi SH, Dan Y - Nature (2012)

Bottom Line: However, a direct correspondence between the ontogenetic and functional columns has not been demonstrated.Using a retroviral vector encoding green fluorescent protein to label radial clones of excitatory neurons, and in vivo two-photon calcium imaging to measure neuronal response properties, we found that sister neurons preferred similar orientations whereas nearby non-sister neurons showed no such relationship.Interestingly, disruption of gap junction coupling by viral expression of a dominant-negative mutant of Cx26 (also known as Gjb2) or by daily administration of a gap junction blocker, carbenoxolone, during the first postnatal week greatly diminished the functional similarity between sister neurons, suggesting that the maturation of ontogenetic into functional columns requires intercellular communication through gap junctions.

View Article: PubMed Central - PubMed

Affiliation: Division of Neurobiology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.

ABSTRACT
A fundamental feature of the mammalian neocortex is its columnar organization. In the visual cortex, functional columns consisting of neurons with similar orientation preferences have been characterized extensively, but how these columns are constructed during development remains unclear. The radial unit hypothesis posits that the ontogenetic columns formed by clonally related neurons migrating along the same radial glial fibre during corticogenesis provide the basis for functional columns in adult neocortex. However, a direct correspondence between the ontogenetic and functional columns has not been demonstrated. Here we show that, despite the lack of a discernible orientation map in mouse visual cortex, sister neurons in the same radial clone exhibit similar orientation preferences. Using a retroviral vector encoding green fluorescent protein to label radial clones of excitatory neurons, and in vivo two-photon calcium imaging to measure neuronal response properties, we found that sister neurons preferred similar orientations whereas nearby non-sister neurons showed no such relationship. Interestingly, disruption of gap junction coupling by viral expression of a dominant-negative mutant of Cx26 (also known as Gjb2) or by daily administration of a gap junction blocker, carbenoxolone, during the first postnatal week greatly diminished the functional similarity between sister neurons, suggesting that the maturation of ontogenetic into functional columns requires intercellular communication through gap junctions. Together with the recent finding of preferential excitatory connections among sister neurons, our results support the radial unit hypothesis and unify the ontogenetic and functional columns in the visual cortex.

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Two-photon imaging of clonally related sister cells and nearby layer 2/3 neuronsa, Left, fluorescence images at 190 - 260 μm from pia, showing two GFP-expressing cells that were nearly vertically aligned. Scale bar, 50 μm. Right, 3D reconstruction of the GFP pair. b, Two more examples of GFP cell pairs (arrow heads). Red, GFP; green, OGB. Left, 250 - 310 μm from pia; right, 150 - 240 μm. Scale bar, 100 μm. c, Single condition maps of fluorescence change (ΔF), computed by averaging the images during each stimulus and subtracting baseline (gray screen), for the experiment in a. Central panel, GFP (red) and OGB (green) labeling. Red circle, GFP cell. Scale bar, 50 μm. d, Orientation maps with visually responsive cells colored according to their preferred orientations, for a larger imaging area. White box, region shown in c. Scale bar, 50 μm.
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Figure 1: Two-photon imaging of clonally related sister cells and nearby layer 2/3 neuronsa, Left, fluorescence images at 190 - 260 μm from pia, showing two GFP-expressing cells that were nearly vertically aligned. Scale bar, 50 μm. Right, 3D reconstruction of the GFP pair. b, Two more examples of GFP cell pairs (arrow heads). Red, GFP; green, OGB. Left, 250 - 310 μm from pia; right, 150 - 240 μm. Scale bar, 100 μm. c, Single condition maps of fluorescence change (ΔF), computed by averaging the images during each stimulus and subtracting baseline (gray screen), for the experiment in a. Central panel, GFP (red) and OGB (green) labeling. Red circle, GFP cell. Scale bar, 50 μm. d, Orientation maps with visually responsive cells colored according to their preferred orientations, for a larger imaging area. White box, region shown in c. Scale bar, 50 μm.

Mentions: To identify clonally related sister cells, we used a GFP-expressing retrovirus, previously shown to label isolated ontogenetic columns of excitatory neurons7,11,12. The retrovirus was injected into the right ventricle in utero at embryonic day 15-17 (E15-E17, see Methods), the beginning of neurogenesis in cortical layer 2/3 (ref. 13). At postnatal day 12-17 (P12 - P17, soon after eye opening), in vivo two-photon imaging14,15 was performed in the primary visual cortex (V1) of injected mice under anesthesia. A low density of GFP-labeled neurons was observed in layer 2/3 (1.1 ± 0.9 (s.d.) per animal, within an imaging window ~500 μm in diameter at cortical depths up to 400 μm, n = 181 neurons, 161 mice). In some cases (n = 52), we found a pair of GFP-labeled neurons aligned nearly vertically (Fig. 1a, b), with no other GFP neurons nearby, suggesting that they were clonally related sister cells. Although large tangential dispersion has been observed in some clonally related cells16, here we focused on GFP-labeled neuronal pairs with < 120 μm horizontal separation (see Methods, Supplementary Fig. 1).


Clonally related visual cortical neurons show similar stimulus feature selectivity.

Li Y, Lu H, Cheng PL, Ge S, Xu H, Shi SH, Dan Y - Nature (2012)

Two-photon imaging of clonally related sister cells and nearby layer 2/3 neuronsa, Left, fluorescence images at 190 - 260 μm from pia, showing two GFP-expressing cells that were nearly vertically aligned. Scale bar, 50 μm. Right, 3D reconstruction of the GFP pair. b, Two more examples of GFP cell pairs (arrow heads). Red, GFP; green, OGB. Left, 250 - 310 μm from pia; right, 150 - 240 μm. Scale bar, 100 μm. c, Single condition maps of fluorescence change (ΔF), computed by averaging the images during each stimulus and subtracting baseline (gray screen), for the experiment in a. Central panel, GFP (red) and OGB (green) labeling. Red circle, GFP cell. Scale bar, 50 μm. d, Orientation maps with visually responsive cells colored according to their preferred orientations, for a larger imaging area. White box, region shown in c. Scale bar, 50 μm.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375857&req=5

Figure 1: Two-photon imaging of clonally related sister cells and nearby layer 2/3 neuronsa, Left, fluorescence images at 190 - 260 μm from pia, showing two GFP-expressing cells that were nearly vertically aligned. Scale bar, 50 μm. Right, 3D reconstruction of the GFP pair. b, Two more examples of GFP cell pairs (arrow heads). Red, GFP; green, OGB. Left, 250 - 310 μm from pia; right, 150 - 240 μm. Scale bar, 100 μm. c, Single condition maps of fluorescence change (ΔF), computed by averaging the images during each stimulus and subtracting baseline (gray screen), for the experiment in a. Central panel, GFP (red) and OGB (green) labeling. Red circle, GFP cell. Scale bar, 50 μm. d, Orientation maps with visually responsive cells colored according to their preferred orientations, for a larger imaging area. White box, region shown in c. Scale bar, 50 μm.
Mentions: To identify clonally related sister cells, we used a GFP-expressing retrovirus, previously shown to label isolated ontogenetic columns of excitatory neurons7,11,12. The retrovirus was injected into the right ventricle in utero at embryonic day 15-17 (E15-E17, see Methods), the beginning of neurogenesis in cortical layer 2/3 (ref. 13). At postnatal day 12-17 (P12 - P17, soon after eye opening), in vivo two-photon imaging14,15 was performed in the primary visual cortex (V1) of injected mice under anesthesia. A low density of GFP-labeled neurons was observed in layer 2/3 (1.1 ± 0.9 (s.d.) per animal, within an imaging window ~500 μm in diameter at cortical depths up to 400 μm, n = 181 neurons, 161 mice). In some cases (n = 52), we found a pair of GFP-labeled neurons aligned nearly vertically (Fig. 1a, b), with no other GFP neurons nearby, suggesting that they were clonally related sister cells. Although large tangential dispersion has been observed in some clonally related cells16, here we focused on GFP-labeled neuronal pairs with < 120 μm horizontal separation (see Methods, Supplementary Fig. 1).

Bottom Line: However, a direct correspondence between the ontogenetic and functional columns has not been demonstrated.Using a retroviral vector encoding green fluorescent protein to label radial clones of excitatory neurons, and in vivo two-photon calcium imaging to measure neuronal response properties, we found that sister neurons preferred similar orientations whereas nearby non-sister neurons showed no such relationship.Interestingly, disruption of gap junction coupling by viral expression of a dominant-negative mutant of Cx26 (also known as Gjb2) or by daily administration of a gap junction blocker, carbenoxolone, during the first postnatal week greatly diminished the functional similarity between sister neurons, suggesting that the maturation of ontogenetic into functional columns requires intercellular communication through gap junctions.

View Article: PubMed Central - PubMed

Affiliation: Division of Neurobiology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.

ABSTRACT
A fundamental feature of the mammalian neocortex is its columnar organization. In the visual cortex, functional columns consisting of neurons with similar orientation preferences have been characterized extensively, but how these columns are constructed during development remains unclear. The radial unit hypothesis posits that the ontogenetic columns formed by clonally related neurons migrating along the same radial glial fibre during corticogenesis provide the basis for functional columns in adult neocortex. However, a direct correspondence between the ontogenetic and functional columns has not been demonstrated. Here we show that, despite the lack of a discernible orientation map in mouse visual cortex, sister neurons in the same radial clone exhibit similar orientation preferences. Using a retroviral vector encoding green fluorescent protein to label radial clones of excitatory neurons, and in vivo two-photon calcium imaging to measure neuronal response properties, we found that sister neurons preferred similar orientations whereas nearby non-sister neurons showed no such relationship. Interestingly, disruption of gap junction coupling by viral expression of a dominant-negative mutant of Cx26 (also known as Gjb2) or by daily administration of a gap junction blocker, carbenoxolone, during the first postnatal week greatly diminished the functional similarity between sister neurons, suggesting that the maturation of ontogenetic into functional columns requires intercellular communication through gap junctions. Together with the recent finding of preferential excitatory connections among sister neurons, our results support the radial unit hypothesis and unify the ontogenetic and functional columns in the visual cortex.

Show MeSH
Related in: MedlinePlus