Email updates

Keep up to date with the latest news and content from Molecular Brain and BioMed Central.

Open Access Open Badges Research

Columnar distribution of activity dependent gabaergic depolarization in sensorimotor cortical neurons

Jaekwang Lee13, Junsung Woo3, Oleg V Favorov1, Mark Tommerdahl1, C Justin Lee3* and Barry L Whitsel12*

Author Affiliations

1 Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA

2 Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA

3 WCI Center for Functional Connectomics, Institute of Science and Technology (KIST), Seoul, 136-791, Korea

For all author emails, please log on.

Molecular Brain 2012, 5:33  doi:10.1186/1756-6606-5-33

Published: 24 September 2012



GABA, the major inhibitory neurotransmitter in CNS, has been demonstrated to paradoxically produce excitation even in mature brain. However activity-dependent form of GABA excitation in cortical neurons has not been observed. Here we report that after an intense electrical stimulation adult cortical neurons displayed a transient GABA excitation that lasted for about 30s.


Whole-cell patch recordings were performed to evaluate the effects of briefly applied GABA on pyramidal neurons in adult rodent sensorimotor cortical slice before and after 1 s, 20 Hz suprathreshold electrical stimulation of the junction between layer 6 and the underlying white matter (L6/WM stimulation). Immediately after L6/WM stimulation, GABA puffs produced neuronal depolarization in the center of the column-shaped region. However, both prior to or 30s after stimulation GABA puffs produced hyperpolarization of neurons. 2-photon imaging in neurons infected with adenovirus carrying a chloride sensor Clomeleon revealed that GABA induced depolarization is due to an increase in [Cl-]i after stimulation. To reveal the spatial extent of excitatory action of GABA, isoguvacine, a GABAA receptors agonist, was applied right after stimulation while monitoring the intracellular Ca2+ concentration in pyramidal neurons. Isoguvacine induced an increase in [Ca2+]i in pyramidal neurons especially in the center of the column but not in the peripheral regions of the column. The global pattern of the Ca2+ signal showed a column-shaped distribution along the stimulation site.


These results demonstrate that the well-known inhibitory transmitter GABA rapidly switches from hyperpolarization to depolarization upon synaptic activity in adult somatosensory cortical neurons.