P80 pipette puller

Sharp electrodes (∼80–120 MΩ) were pulled from 1.0 mm diameter borosilicate glass capillaries (World Precision Instruments, Inc.; Sarasota, FL) on a Sutter Instruments P80 pipette puller (Novato, CA). Tips were initially backfilled with a bolus of 1.25 mM OGB-1, pH 7.4 (ThermoFisher Scientific, Catalog number: O6806; Waltham, MA). The rest of the electrode was filled with 1 M potassium methyl sulfate (KMeSO₄) in 10 mM HEPES. A bipolar stimulating electrode was placed on the Schaffer collaterals (SC) for stimulation (0.1 ms duration) and the sharp electrode was slowly advanced through stratum pyramidale of field CA1 to record primary neurons. A stimulator (SD9K, Astro Med Inc., Grass Instruments; Warwick, RI) was used for synaptic activation. Responses were recorded through an AxoClamp-2B amplifier (Molecular Devices LLC.; San Jose, CA) and digitized at ∼5–10 KHz with a Digidata® 1550B (Molecular Devices LLC.). Data were processed through pClamp (v10.7, Molecular Devices LLC.). While other cell types, including interneurons and astrocytes, are present in field CA1, compactness of the pyramidal layer, morphology of the cell imaged, and spiking properties of the cell were used to limit our recordings to only primary pyramidal neurons.

Sharp electrodes (∼80–120 MΩ) were pulled from 1.0 mm diameter borosilicate glass capillaries (World Precision Instruments, Inc.; Sarasota, FL) on a Sutter Instruments P80 pipette puller (Novato, CA). Electrode tips were first backfilled with a bolus of 1.25 mM OGB-1, pH 7.4 (ThermoFisher Scientific, Catalog number: O6806; Waltham, MA), while the rest of the electrode was filled with a 1 M potassium methyl sulfate (KMeSO4) in 10 mM HEPES. A bipolar stimulating electrode was placed on the Shaffer collaterals and the recording electrode was slowly guided through stratum pyramidale of area CA1. An SD9K stimulator (Astro Med Inc., Grass Instruments; Warwick, RI) was used to synaptically stimulate the tissue slice. Responses were obtained through an AxoClamp-2B amplifier (Molecular Devices LLC.; San Jose, CA) and digitized at ∼5–10 KHz using a Digidata® 1550B (Molecular Devices LLC.; San Jose, CA). Data was processed using pClamp 10.7 software (Molecular Devices LLC.; San Jose, CA).