A Direct Comparison of Whole Cell Patch and Sharp Electrodes by Simultaneous Recording From Single Spinal Neurons in Frog Tadpoles

Abstract

. A direct comparison of whole cell patch and sharp electrodes by simultaneous recording from single spinal neurons in frog tadpoles. J Neurophysiol 92: 380 -386, 2004; 10.1152/jn.01238.2003. High-impedance, sharp intracellular electrodes were compared with whole cell patch electrodes by recording from single spinal neurons in immobilized frog tadpoles. A range of neuron properties were examined using sharp or patch test electrodes while making simultaneous recordings with a second control patch electrode. Overall, test patch electrodes did not significantly alter the activity recorded by the control electrode, and recordings from the two electrodes were essentially identical. In contrast, sharp electrode recordings differed from initial control patch recordings. In some cases, differences were due to real changes in neuron properties: the resting membrane potential became less negative and the neuron input resistance (R i ) fell; this fall was larger for neurons with a higher R i . In other cases, the control patch electrode revealed that differences were due to the recording properties of the sharp electrode: tip potentials were larger and more variable; resting potentials appeared to be more negative; and spike amplitude was attenuated. However, sharp electrode penetration did not, in most cases, significantly alter the pattern of neuron firing in response to injected current or the normal pattern of activity following sensory stimulation or during fictive swimming. We conclude that sharp electrodes introduce a significant leak to the membrane of tadpole spinal neurons compared with patch electrodes but that this does not change the fundamental firing characteristics or activity of the neurons. I N T R O D U C T I O NThe whole cell recording technique rapidly took over from conventional sharp electrode intracellular recording in preparations of cultured cells and in vitro studies after its introduction in 1981 (Fenwick et al. 1982;Hamill et al. 1981). The whole cell technique is believed to result in less damage to the recorded cell and lead to a more faithful recording of the cell's electrical signals. However, recording from neurons in vivo with patch pipettes has proven to be quite a challenge, and sharp electrode recording is still being used. The advantages and disadvantages of both recording techniques have been extensively compared in single-electrode recordings or computer models (small model neurons, Ince et al. 1986; salamander olfactory neurons, Pongracz et al. 1991; hippocampus neurons, Staley et al. 1992; turtle spinal cord, Svirskis et al. 1997; rat spinal neurons, Thurbon et al. 1998). In some cases in recordings from small neurons, it has been suggested that the effects of recording with sharp electrodes could be so serious that researchers may draw radically different conclusions if the recordings were made with patch pipettes (Aiken et al. 2003;Dale 1995;Dale and Kuenzi 1997). To evaluate these concerns, a direct comparison of the two methods applied to neurons was required. The only prev...

Irregular Firing and High-Conductance States in Spinal Motoneurons during Scratching and Swimming

“…This suggests that the relative conductance increase during network activity is determined by other factors than the cell size. In addition, the relation between the resting conductance and the conductance increase during network activity may be quenched by the artifactual shunt induced by the recording electrode, particularly in small cells (Li et al, 2004). We also found that the conductance increase for a given motoneuron was surprisingly similar during scratching and swimming.…”

“…In contrast, insignificant or small changes in input conductance have been reported for motoneurons during locomotor activity (Shefchyk and Jordan, 1985;MacDonell et al, 2015). It has also been shown that conductance increases can be behavior-related (Perreault, 2002).…”

Persistent Responses to Brief Stimuli: Feedback Excitation among Brainstem Neurons

“…The dorsal parts of rostral myotomes were removed, and the roof of the nervous system was opened to the neurocoel to improve access. The methods for whole-cell patch using electrodes containing 0.1% neurobiotin (Vector Laboratories, Burlingame, CA) and Alexa Fluor-488 (Invitrogen, Eugene, OR), extracellular recording, and processing for neuronal anatomy have been described recently (Li et al, 2002(Li et al, , 2004b. Patch pipettes were filled with 0.1% neurobiotin and 0.1% Alexa Fluor 488 (Invitrogen) in intracellular solution (in mM: 100 K-gluconate, 2 MgCl 2 , 10 EGTA, 10 HEPES, 3 Na 2 ATP, 0.5 NaGTP adjusted to pH 7.3 with KOH) and had resistances of ϳ10 M⍀.…”

Role of type-specific neuron properties in a spinal cord motor network

“…4(B) in Li et al (2004c). Typically, this burst follows a delay which is preceded by a single, initial spike (Fig.…”

“…Nothing is known about the function of one class of possible neural canal receptor neuron (Dale et al, 1987). For the remaining neuron classes, using single-cell recordings (including a new wholecell patch recording method (Li et al, 2004c), in the spinal cord of immobilized tadpoles, we have defined the typespecific properties of individual neurons whose anatomical features were revealed by neurobiotin injection. These include: their passive and active responses to current injection, the transmitter pharmacology of synapses they make and receive (where some synaptic conductances have been studied in voltage-clamp recordings), and their activity during responses to sensory stimuli.…”