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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.


Related in: MedlinePlus

Inhibitory drive onto L2/3 pyramidal cells is not decreased by 3-day whisker deprivation. (A) Example trace of mIPSCs (filled arrow heads) in an L2/3 pyramidal neuron. Scale bar: 10 pA, 20 ms. (B) Cumulative fraction of mean mIPSC amplitude recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (grand mean rather than mIPSC amplitudes: deprived, 28.1 ± 1.4 pA, n = 16 neurons; control, 26.3 ± 1.1 pA, n = 15 neurons). (C) mIPSC frequency recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (mean of mean mIPSC frequencies: deprived, 4.3 [3.6–5.9] Hz, n = 16 neurons; control, 2.7 [2.4–4.5] Hz, n = 15 neurons).
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BHU098F5: Inhibitory drive onto L2/3 pyramidal cells is not decreased by 3-day whisker deprivation. (A) Example trace of mIPSCs (filled arrow heads) in an L2/3 pyramidal neuron. Scale bar: 10 pA, 20 ms. (B) Cumulative fraction of mean mIPSC amplitude recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (grand mean rather than mIPSC amplitudes: deprived, 28.1 ± 1.4 pA, n = 16 neurons; control, 26.3 ± 1.1 pA, n = 15 neurons). (C) mIPSC frequency recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (mean of mean mIPSC frequencies: deprived, 4.3 [3.6–5.9] Hz, n = 16 neurons; control, 2.7 [2.4–4.5] Hz, n = 15 neurons).

Mentions: It is widely thought that cortical reorganization involves changes not only in excitatory circuitry, but also in inhibitory circuitry (Jacobs and Donoghue 1991; Jones 1993; Froemke et al. 2007; Chen et al. 2011; Vogels et al. 2011; van Versendaal et al. 2012). One hypothesis is that disinhibition unmasks latent intracortical connections (Jacobs and Donoghue 1991). Therefore, we explored whether there were functional changes in inhibition in L2/3 of deprived cortex where we had found evidence of rewiring of local excitatory circuits. We first investigated whether there was a global reduction in inhibitory drive onto excitatory neurons by measuring the frequency and amplitude of mIPSCs in L2/3 pyramidal neurons. The mean mIPSC amplitude was not affected by deprivation (deprived, 28.1 ± 1.4 pA, n = 16 neurons; control, 26.3 ± 1.1 pA, n = 15 neurons; P = 0.33, t-test) (Fig. 5A,B). However, the frequency of mIPSCs was increased in deprived cortex (deprived, 4.3 [3.6–5.9] Hz, n = 16 neurons; control, 2.7 [2.4–4.5] Hz, n = 15 neurons; P = 0.023, Mann–Whitney rank sum test) (Fig. 5C). Hence, our data do not show a reduction in global inhibitory drive onto L2/3 pyramidal neurons in deprived cortex after 2–3 days of whisker trimming.Figure 5.


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)

Inhibitory drive onto L2/3 pyramidal cells is not decreased by 3-day whisker deprivation. (A) Example trace of mIPSCs (filled arrow heads) in an L2/3 pyramidal neuron. Scale bar: 10 pA, 20 ms. (B) Cumulative fraction of mean mIPSC amplitude recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (grand mean rather than mIPSC amplitudes: deprived, 28.1 ± 1.4 pA, n = 16 neurons; control, 26.3 ± 1.1 pA, n = 15 neurons). (C) mIPSC frequency recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (mean of mean mIPSC frequencies: deprived, 4.3 [3.6–5.9] Hz, n = 16 neurons; control, 2.7 [2.4–4.5] Hz, n = 15 neurons).
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BHU098F5: Inhibitory drive onto L2/3 pyramidal cells is not decreased by 3-day whisker deprivation. (A) Example trace of mIPSCs (filled arrow heads) in an L2/3 pyramidal neuron. Scale bar: 10 pA, 20 ms. (B) Cumulative fraction of mean mIPSC amplitude recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (grand mean rather than mIPSC amplitudes: deprived, 28.1 ± 1.4 pA, n = 16 neurons; control, 26.3 ± 1.1 pA, n = 15 neurons). (C) mIPSC frequency recorded from L2/3 pyramidal neurons in deprived (red) and control (black) cortex (mean of mean mIPSC frequencies: deprived, 4.3 [3.6–5.9] Hz, n = 16 neurons; control, 2.7 [2.4–4.5] Hz, n = 15 neurons).
Mentions: It is widely thought that cortical reorganization involves changes not only in excitatory circuitry, but also in inhibitory circuitry (Jacobs and Donoghue 1991; Jones 1993; Froemke et al. 2007; Chen et al. 2011; Vogels et al. 2011; van Versendaal et al. 2012). One hypothesis is that disinhibition unmasks latent intracortical connections (Jacobs and Donoghue 1991). Therefore, we explored whether there were functional changes in inhibition in L2/3 of deprived cortex where we had found evidence of rewiring of local excitatory circuits. We first investigated whether there was a global reduction in inhibitory drive onto excitatory neurons by measuring the frequency and amplitude of mIPSCs in L2/3 pyramidal neurons. The mean mIPSC amplitude was not affected by deprivation (deprived, 28.1 ± 1.4 pA, n = 16 neurons; control, 26.3 ± 1.1 pA, n = 15 neurons; P = 0.33, t-test) (Fig. 5A,B). However, the frequency of mIPSCs was increased in deprived cortex (deprived, 4.3 [3.6–5.9] Hz, n = 16 neurons; control, 2.7 [2.4–4.5] Hz, n = 15 neurons; P = 0.023, Mann–Whitney rank sum test) (Fig. 5C). Hence, our data do not show a reduction in global inhibitory drive onto L2/3 pyramidal neurons in deprived cortex after 2–3 days of whisker trimming.Figure 5.

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