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. Author manuscript; available in PMC: 2012 Nov 1.
Published in final edited form as: Nat Neurosci. 2012 Mar 25;15(5):793–802. doi: 10.1038/nn.3078

Figure 5.

Figure 5

Effective silencing of induced population bursting in the hippocampal circuit in Emx1-Cre;Ai35 mice. (a) Schematic for the inhibition of presynaptic neurons in the hippocampal circuit. K+ (8 mM) induced population bursting in CA1 was recorded with an extracellular electrode (R). A white light source (LED, yellow circle) was positioned over CA3 to activate Arch-ER2 in presynaptic neurons. (b) Representative traces of the integrated (top) and raw (bottom) population bursting activity from CA1 before (expanded traces in inset 1), during (2), and following (3) the illumination of CA3. Raw population bursting activity is the direct measure of unit activity. Integrated population activity represents the change of unit activity (time constant = 200 ms). (c) Quantified response of population bursting from CA1 (n = 4 experiments) during 4 intervals: light-off control; the first (0) and final (4) minute of a 5-min exposure to white light; and 5 minutes after light exposure (recovery). Values were normalized to light-off control (** p < 0.01, repeated measures ANOVA; mean ± s.e.m.). (d) Schematic for the inhibition of postsynaptic neurons in the hippocampal circuit. Neurons were recorded simultaneously using dual extracellular electrodes (CA1: R, CA3: R1). A white LED was positioned over CA1 to activate Arch-ER2 in postsynaptic neurons. (e) Representative traces of the integrated (top) and raw (bottom) population bursting activity from CA3 and CA1 before (inset 1), during (2), and following (3) illumination to CA1. Light to CA1 led to suppressed bursting from that region, but bursting activity in CA3 was unaffected.