The base extracellular recording solution contained (in mM) 125 NaCl, 25 NaHCO3, 1.25 NaH2PO4, 25 glucose, 3 KCl, 2 CaCl2, 1 MgCl2 (pH = 7.3), and was oxygenated (95% O2, 5% CO2). The pipette solution for most experiments contained 125 Kgluconate, 2 MgCl2, 0.025 CaCl2, 1 EGTA, 2 NaATP, 0.5 NaGTP, 10 Hepes (pH=7.3 with KOH). Mitral cell IPSCs in Fig. 5C were recorded with a pipette solution in which Kgluconate was replaced with KCl.
Current and voltage signals were recorded with an Axopatch 200B amplifier (Axon Instruments), low pass filtered at 1 kHz using an eight-pole Bessel filter, and digitized at 10 kHz. LFP recordings were made with low resistance (1–5 MΩ) patch pipettes filled with extracellular solution and placed onto glomeruli. LFP signals were further bandpass filtered offline using a four-pole Butterworth filter at 0.5–20 Hz. Loose cell-attached recordings of action potentials were made in voltage clamp mode with patch pipettes (5–7 MΩ resistance) filled with extracellular solution. Data were acquired using Axograph software on a MacIntosh Power Mac G5 computer and analyzed using Axograph and Matlab software.
ON stimulation was most commonly done by placing a patch pipette in the ON layer, 50–100 μm superficial to the glomerular layer. Single stimulus pulses were applied (0.1 ms duration), with an inter-stimulus interval of 30 seconds. During experiments investigating the behavior of LLDs at perithreshold intensities, stimulation intensity was adjusted to evoke LLDs during 20–70% of trials. For the calcium imaging experiments inFig. 6 , 3 out of 10 slice experiments in which PG cells were imaged were done using ORN axon bundle stimulation as a stimulation method; all granule cell imaging experiments were done using ORN bundle stimulation.
Focal puff application of GABAA receptor blockers (gabazine and bicuculline methiodide) was conducted using a picospritzer (Parker Instrumentation). Spread of drug solution was monitored with 1% phenol red in the solution. In these puffer experiments, target glomeruli were determined by imaging the apical dendrites of Alexa-488-filled mitral cells.
Current and voltage signals were recorded with an Axopatch 200B amplifier (Axon Instruments), low pass filtered at 1 kHz using an eight-pole Bessel filter, and digitized at 10 kHz. LFP recordings were made with low resistance (1–5 MΩ) patch pipettes filled with extracellular solution and placed onto glomeruli. LFP signals were further bandpass filtered offline using a four-pole Butterworth filter at 0.5–20 Hz. Loose cell-attached recordings of action potentials were made in voltage clamp mode with patch pipettes (5–7 MΩ resistance) filled with extracellular solution. Data were acquired using Axograph software on a MacIntosh Power Mac G5 computer and analyzed using Axograph and Matlab software.
ON stimulation was most commonly done by placing a patch pipette in the ON layer, 50–100 μm superficial to the glomerular layer. Single stimulus pulses were applied (0.1 ms duration), with an inter-stimulus interval of 30 seconds. During experiments investigating the behavior of LLDs at perithreshold intensities, stimulation intensity was adjusted to evoke LLDs during 20–70% of trials. For the calcium imaging experiments in
Focal puff application of GABAA receptor blockers (gabazine and bicuculline methiodide) was conducted using a picospritzer (Parker Instrumentation). Spread of drug solution was monitored with 1% phenol red in the solution. In these puffer experiments, target glomeruli were determined by imaging the apical dendrites of Alexa-488-filled mitral cells.
