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Rapid Bidirectional Reorganization of Cortical Microcircuits.

Albieri G, Barnes SJ, de Celis Alonso B, Cheetham CE, Edwards CE, Lowe AS, Karunaratne H, Dear JP, Lee KC, Finnerty GT - Cereb. Cortex (2014)

Bottom Line: We found that there was rapid expansion followed by retraction of whisker cortical maps.Despite the rapid increase in local excitatory connectivity, the average strength and synaptic dynamics did not change, which suggests that new excitatory connections rapidly acquire the properties of established excitatory connections.Hence, the changes in local excitatory connectivity did not occur in all circuits involving pyramidal neurons.

View Article: PubMed Central - PubMed

Affiliation: MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK Current address: Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.

No MeSH data available.


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SI whisker representation expands without an increase in BOLD signal amplitude. (A) Single-animal statistical parametric map of the BOLD signal evoked by 5 Hz deflection of the right C1–4 whiskers after 3 days of whisker trimming. (B) Cumulative fraction plot of SI PBR volume from single-animal maps for controls (black, n = 26 rats), 3-day trim (red, n = 15 rats), and 7-day trim (blue, n = 28 rats). (C) Median SI PBR volume and interquartile range (error bars) after 3 and 7 days of whisker trimming (median SI PBR volume: controls, 20 [11–40] voxels, n = 26 rats; 3-day trim, 45 [24–69] voxels; n = 15 rats; 7-day trim, median volume, 26 [17–51] voxels, n = 28 rats). (D) Peak amplitude of BOLD signal (error bars, SEM) after whisker trimming (control, +0.50 ± 0.04%, n = 26 rats; 3-day trim, +0.43 ± 0.04%, n = 15 rats; 7-day trim, +0.53 ± 0.04%, n = 28 rats). (E) Cumulative fraction plot of the SI PBR volume in L1–4. Color code for (C–E) as (B).
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BHU098F2: SI whisker representation expands without an increase in BOLD signal amplitude. (A) Single-animal statistical parametric map of the BOLD signal evoked by 5 Hz deflection of the right C1–4 whiskers after 3 days of whisker trimming. (B) Cumulative fraction plot of SI PBR volume from single-animal maps for controls (black, n = 26 rats), 3-day trim (red, n = 15 rats), and 7-day trim (blue, n = 28 rats). (C) Median SI PBR volume and interquartile range (error bars) after 3 and 7 days of whisker trimming (median SI PBR volume: controls, 20 [11–40] voxels, n = 26 rats; 3-day trim, 45 [24–69] voxels; n = 15 rats; 7-day trim, median volume, 26 [17–51] voxels, n = 28 rats). (D) Peak amplitude of BOLD signal (error bars, SEM) after whisker trimming (control, +0.50 ± 0.04%, n = 26 rats; 3-day trim, +0.43 ± 0.04%, n = 15 rats; 7-day trim, +0.53 ± 0.04%, n = 28 rats). (E) Cumulative fraction plot of the SI PBR volume in L1–4. Color code for (C–E) as (B).

Mentions: The cortical representation of rats' whiskers may show marked variability in mapping studies (Riddle and Purves 1995; Chen-Bee and Frostig 1996). This has a direct impact on how best to quantify cortical reorganization with BOLD fMRI (Woods 1996; Petersson et al. 1999a, 1999b; Thirion et al. 2007). Group maps derived from a fixed effects model show small-amplitude changes in the BOLD signal. However, the group maps do not allow for interanimal variability in the location of the whisker map evident in single-animal data sets (Supplementary Fig. 2) and tend to give greater weight to animals with larger PBRs. Accordingly, we quantified the changes in the PBR in SI using single-animal statistical maps (Fig. 2A) (Alonso et al. 2008). SI PBR volume increased markedly after whisker trimming for 3 days (Fig. 2B,C) (median [interquartile range]: 3-day trim, 45 [24–69] voxels, n = 15 rats; controls, 20 [11–40] voxels, n = 26 rats; P < 0.001, Methods). Spared SI whisker representations had shrunk back after 7 days of whisker trimming (vs. 3-day trim volume, P = 0.008), but remained larger than control representations (7-day trim, 26 [17–51] voxels, n = 28 rats, P = 0.004; Fig. 2B,C). In contrast, the amplitude of the BOLD signal in contralateral SI after either 3 or 7 days of whisker trimming was similar to control values (Fig. 2D) (control, +0.50 ± 0.04%, n = 26 rats; 3-day trim, +0.43 ± 0.04%, n = 15 rats; 7-day trim, +0.53 ± 0.04%, n = 28 rats; P = 0.261, one-way ANOVA). We concluded that our BOLD imaging showed rapid reorganization, mainly at the periphery of spared whisker representations in SI.Figure 2.


Rapid Bidirectional Reorganization of Cortical Microcircuits.

Albieri G, Barnes SJ, de Celis Alonso B, Cheetham CE, Edwards CE, Lowe AS, Karunaratne H, Dear JP, Lee KC, Finnerty GT - Cereb. Cortex (2014)

SI whisker representation expands without an increase in BOLD signal amplitude. (A) Single-animal statistical parametric map of the BOLD signal evoked by 5 Hz deflection of the right C1–4 whiskers after 3 days of whisker trimming. (B) Cumulative fraction plot of SI PBR volume from single-animal maps for controls (black, n = 26 rats), 3-day trim (red, n = 15 rats), and 7-day trim (blue, n = 28 rats). (C) Median SI PBR volume and interquartile range (error bars) after 3 and 7 days of whisker trimming (median SI PBR volume: controls, 20 [11–40] voxels, n = 26 rats; 3-day trim, 45 [24–69] voxels; n = 15 rats; 7-day trim, median volume, 26 [17–51] voxels, n = 28 rats). (D) Peak amplitude of BOLD signal (error bars, SEM) after whisker trimming (control, +0.50 ± 0.04%, n = 26 rats; 3-day trim, +0.43 ± 0.04%, n = 15 rats; 7-day trim, +0.53 ± 0.04%, n = 28 rats). (E) Cumulative fraction plot of the SI PBR volume in L1–4. Color code for (C–E) as (B).
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BHU098F2: SI whisker representation expands without an increase in BOLD signal amplitude. (A) Single-animal statistical parametric map of the BOLD signal evoked by 5 Hz deflection of the right C1–4 whiskers after 3 days of whisker trimming. (B) Cumulative fraction plot of SI PBR volume from single-animal maps for controls (black, n = 26 rats), 3-day trim (red, n = 15 rats), and 7-day trim (blue, n = 28 rats). (C) Median SI PBR volume and interquartile range (error bars) after 3 and 7 days of whisker trimming (median SI PBR volume: controls, 20 [11–40] voxels, n = 26 rats; 3-day trim, 45 [24–69] voxels; n = 15 rats; 7-day trim, median volume, 26 [17–51] voxels, n = 28 rats). (D) Peak amplitude of BOLD signal (error bars, SEM) after whisker trimming (control, +0.50 ± 0.04%, n = 26 rats; 3-day trim, +0.43 ± 0.04%, n = 15 rats; 7-day trim, +0.53 ± 0.04%, n = 28 rats). (E) Cumulative fraction plot of the SI PBR volume in L1–4. Color code for (C–E) as (B).
Mentions: The cortical representation of rats' whiskers may show marked variability in mapping studies (Riddle and Purves 1995; Chen-Bee and Frostig 1996). This has a direct impact on how best to quantify cortical reorganization with BOLD fMRI (Woods 1996; Petersson et al. 1999a, 1999b; Thirion et al. 2007). Group maps derived from a fixed effects model show small-amplitude changes in the BOLD signal. However, the group maps do not allow for interanimal variability in the location of the whisker map evident in single-animal data sets (Supplementary Fig. 2) and tend to give greater weight to animals with larger PBRs. Accordingly, we quantified the changes in the PBR in SI using single-animal statistical maps (Fig. 2A) (Alonso et al. 2008). SI PBR volume increased markedly after whisker trimming for 3 days (Fig. 2B,C) (median [interquartile range]: 3-day trim, 45 [24–69] voxels, n = 15 rats; controls, 20 [11–40] voxels, n = 26 rats; P < 0.001, Methods). Spared SI whisker representations had shrunk back after 7 days of whisker trimming (vs. 3-day trim volume, P = 0.008), but remained larger than control representations (7-day trim, 26 [17–51] voxels, n = 28 rats, P = 0.004; Fig. 2B,C). In contrast, the amplitude of the BOLD signal in contralateral SI after either 3 or 7 days of whisker trimming was similar to control values (Fig. 2D) (control, +0.50 ± 0.04%, n = 26 rats; 3-day trim, +0.43 ± 0.04%, n = 15 rats; 7-day trim, +0.53 ± 0.04%, n = 28 rats; P = 0.261, one-way ANOVA). We concluded that our BOLD imaging showed rapid reorganization, mainly at the periphery of spared whisker representations in SI.Figure 2.

Bottom Line: We found that there was rapid expansion followed by retraction of whisker cortical maps.Despite the rapid increase in local excitatory connectivity, the average strength and synaptic dynamics did not change, which suggests that new excitatory connections rapidly acquire the properties of established excitatory connections.Hence, the changes in local excitatory connectivity did not occur in all circuits involving pyramidal neurons.

View Article: PubMed Central - PubMed

Affiliation: MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK Current address: Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.

No MeSH data available.


Related in: MedlinePlus