Rapid Bidirectional Reorganization of Cortical Microcircuits.
Mature neocortex adapts to altered sensory input by changing neural activity in cortical circuits. The underlying cellular mechanisms remain unclear. We used blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to show reorganization in somatosensory cortex elicited by altered whisker sensory input. We found that there was rapid expansion followed by retraction of whisker cortical maps. The cellular basis for the reorganization in primary somatosensory cortex was investigated with paired electrophysiological recordings in the periphery of the expanded whisker representation. During map expansion, the chance of finding a monosynaptic connection between pairs of pyramidal neurons increased 3-fold. 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. During map retraction, entire excitatory connections between pyramidal neurons were lost. In contrast, connectivity between pyramidal neurons and fast spiking interneurons was unchanged. Hence, the changes in local excitatory connectivity did not occur in all circuits involving pyramidal neurons. Our data show that pyramidal neurons are recruited to and eliminated from local excitatory networks over days. These findings suggest that the local excitatory connectome is dynamic in mature neocortex.
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.
Giorgia
G
Albieri
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK Current address: MRC Centre for Developmental Neurobiology King's College London, Guy's Hospital Campus, London SE1 1UL, UK.
Samuel J
SJ
Barnes
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK Current address: Faculty of Physics and Mathematics, prior to the University, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
Benito
B
de Celis Alonso
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK Current address: National Institutes of Health, Bethesda, MD, USA.
Claire E J
CE
Cheetham
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK.
Clarissa E
CE
Edwards
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK Current address: MRC Centre for Developmental Neurobiology King's College London, Guy's Hospital Campus, London SE1 1UL, UK.
Andrew S
AS
Lowe
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK.
Harini
H
Karunaratne
Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK.
John P
JP
Dear
Division of Engineering, King's College London, Strand, London WC2R 2LS, UK.
Kalok C
KC
Lee
MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry (Box44), London SE5 8AF, UK.
Gerald T
GT
Finnerty
D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000098:blood supply / Q000166:cytology / Q000502:physiology*; D049229:Dendritic Spines; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D008564:Membrane Potentials; D009415:Nerve Net / Q000098:blood supply / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000098:blood supply / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010100:Oxygen / Q000097:blood; D018408:Patch-Clamp Techniques; D010812:Physical Stimulation; D051381:Rats; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D014738:Vibrissae / Q000294:innervation
D010100:Oxygen
connectome; cortical microcircuit; experience-dependent plasticity; fMRI; inhibition; rewiring