GABAergic inhibition shapes frequency adaptation of cortical activity in a frequency-dependent manner.
Primary sensory cortical areas continuously receive thalamic inputs that arrive at different frequencies depending on the amount of sensory activity. The cortical response to repeated sensory stimuli rapidly adapts and different frequencies recruit cortical neuronal networks to different extents. GABAergic inhibition limits the spread of excitation within cortical neuronal networks. However, it is unknown how frequency adaptation of cortical network activity at different frequencies is shaped by GABAergic inhibition. Here, we find that in acute slices of visual cortex area V1 GABAergic inhibition affects frequency adaptation depending on the frequency of activity. Using voltage-sensitive dye imaging, we found that while increasing inhibitory postsynaptic currents (IPSCs) with flunitrazepam dampened the spread of cortical excitation, short-term adaptations to different stimulation frequencies were differentially affected. At high frequencies (40 Hz), facilitation of cortical excitation was no longer transient, but facilitation was sustained. At low frequencies (10 Hz) flunitrazepam decreased a depression of the excitation. In contrast, in mice lacking the GABA(A) receptor alpha1 subunit facilitation was reduced and depression enhanced. These findings suggest that GABAergic inhibition affects cortical excitation at different frequencies differentially, favoring facilitation at higher frequencies of excitation.
Heistek
Tim S
TS
Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University, The Netherlands.
Lodder
Johannes C
JC
Brussaard
Arjen B
AB
Bosman
Laurens W J
LW
Mansvelder
Huibert D
HD
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009473:Neuronal Plasticity / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D056969:Voltage-Sensitive Dye Imaging; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid