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21. Whole-cell recordings from motoneurones in rat spinal cord in vitro with attached dorsal and ventral roots
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Abstracts/Journal of Neuroscience Methods (1994) A1-A28
21. W H O L E - C E L L R E C O R D I N G S FROM MOT O N E U R O N E S IN RAT SPINAL CORD IN VITRO WITH ATFACHED DORSAL AND VENTRAL ROOTS
22. PHYSIOLOGY OF RETINOTECTAL TRANSMISSION IN THE EMBRYONIC AND HATCHLING CHICK
J.C. Dye, H.J. K a r t e n
C.Q. Cao a, R.H. Evans a, P.M. Headley
Departments of ~ Pharmacology and b Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
The purpose of this study was to record simultaneously both whole-cell currents of motoneurones and spinal root potentials. Hemisected spinal cords with attached dorsal and ventral roots from 5 to 8-day-old rats were superfused with artificial cerebrospinal fluid maintained at 2224°C. A small hole about 100/xM in depth was made by tearing the pia mater along the ventrolateral surface of the spinal cord using watchmaker's forceps. Gigaseals followed by whole-cell recordings were obtained following blind placement of patch pipettes onto neurones through the hole in the pia. The patch pipettes (3-6 MY2) were filled with solution as follows (mM): potassium gluconate, 130; KCI, 10; EGTA, 11; HEPES, 10; CaC12, 1; MgC12, 2; pH 7.4. Dorsal or ventral roots (L4-L5) were stimulated via glass suction electrodes with the cathode internal to evoke either synaptic currents or antidromic action currents in motoneurones. A similar suction electrode was placed on the ventral root to record the potentials evoked from the segmental ventral or dorsal root. Spontaneous and evoked whole-cell currents were recorded from a total of 23 physiologically identified motoneurones. The mean ( + SEM) input resistance and membrane potential of these cells were 2158 _+193 M O and - 69.9 _+ 1.2 mV respectively. In cells held near to their resting potentials, the mean amplitude of the antidromically evoked action currents was 4.09 _+ 0.49 nA and of the inward synaptic currents e v o k e d orthodromically by maximal stimulation of the dorsal root was 0.71 _+ 0.14 nA.
This method is well suited for whole-cell recording of motoneurones and it is especially useful when both whole-cell currents and spinal root potentials are required simultaneously. (Supported by the Wellcome Trust, the MRC and the Taberner Trust.)
Department of Neurosciences, 92093, USA
UCSD, La Jolla, CA
We have developed a brain slice preparation to study tectofugal visual pathways in the chick. Hemisections of midbrain containing the optic tectum and tectorecipient diencephalic structures were dissected out for sectioning. Slices (400 /xm) were taken in a plane, intermediate between sagittal and transverse, that parallels the path of entry of retinotectal fibers into the optic tectum. 'Patch' microelectrodes of 4-10 MI2 were used for whole-cell current and voltage clamp, loose-patch single-cell, and field potential recordings. Here we report results of field potential recordings in optic tectum. Stimulation was delivered with a concentric bipolar electrode positioned either in stratum opticum or in segments of optic tract rostral to tectum. Sectioning from rostrolateral to caudomedial provided at least five consecutive slices in which good tectal field potentials could be elicited. A measurable field potential was elicited generally only when a thick dark band of myelinated fibers was visible at the point of stimulation in stratum opticum, that is, where the plane of section locally paralleled retinal afferents. Establishing that the evoked field potential is principally consequent to retinal afferent excitation has been a primary concern. The evidence supporting this contention includes: (1) similarity in field potential and current source density profiles to those of intact and semi-intact preparations, (2) similarity in responses to stimulation of optic tract and stratum opticum, (3) asymmetrical response amplitudes, that is, larger responses in the direction of retinal afferent extension, (4) transmission delays appropriate for retinal afterents, and (5) postmortem histology from applications of Dil crystals to slices fixed after recording. Additionally, current source density calculations from recordings made in zero C a / h i g h Mg saline showed the distribution of terminals expected for retinal afferents. The prominence presynaptically generated field potentials offers the opportunity to examine presynaptic modulation of afferent terminals directly. Pharmacological manipulations carried out with bath applied antagonists of putative transmitters indicated that in this system, as in others, glutamate is the principal retinotectal transmitter. The broadly active glutamate receptor blocker, kynurenic acid (1-0.7 raM),
Abstracts/Journal of Neuroscience Methods (1994) A1-A28
21. W H O L E - C E L L R E C O R D I N G S FROM MOT O N E U R O N E S IN RAT SPINAL CORD IN VITRO WITH ATFACHED DORSAL AND VENTRAL ROOTS
22. PHYSIOLOGY OF RETINOTECTAL TRANSMISSION IN THE EMBRYONIC AND HATCHLING CHICK
J.C. Dye, H.J. K a r t e n
C.Q. Cao a, R.H. Evans a, P.M. Headley
Departments of ~ Pharmacology and b Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
The purpose of this study was to record simultaneously both whole-cell currents of motoneurones and spinal root potentials. Hemisected spinal cords with attached dorsal and ventral roots from 5 to 8-day-old rats were superfused with artificial cerebrospinal fluid maintained at 2224°C. A small hole about 100/xM in depth was made by tearing the pia mater along the ventrolateral surface of the spinal cord using watchmaker's forceps. Gigaseals followed by whole-cell recordings were obtained following blind placement of patch pipettes onto neurones through the hole in the pia. The patch pipettes (3-6 MY2) were filled with solution as follows (mM): potassium gluconate, 130; KCI, 10; EGTA, 11; HEPES, 10; CaC12, 1; MgC12, 2; pH 7.4. Dorsal or ventral roots (L4-L5) were stimulated via glass suction electrodes with the cathode internal to evoke either synaptic currents or antidromic action currents in motoneurones. A similar suction electrode was placed on the ventral root to record the potentials evoked from the segmental ventral or dorsal root. Spontaneous and evoked whole-cell currents were recorded from a total of 23 physiologically identified motoneurones. The mean ( + SEM) input resistance and membrane potential of these cells were 2158 _+193 M O and - 69.9 _+ 1.2 mV respectively. In cells held near to their resting potentials, the mean amplitude of the antidromically evoked action currents was 4.09 _+ 0.49 nA and of the inward synaptic currents e v o k e d orthodromically by maximal stimulation of the dorsal root was 0.71 _+ 0.14 nA.
This method is well suited for whole-cell recording of motoneurones and it is especially useful when both whole-cell currents and spinal root potentials are required simultaneously. (Supported by the Wellcome Trust, the MRC and the Taberner Trust.)
Department of Neurosciences, 92093, USA
UCSD, La Jolla, CA
We have developed a brain slice preparation to study tectofugal visual pathways in the chick. Hemisections of midbrain containing the optic tectum and tectorecipient diencephalic structures were dissected out for sectioning. Slices (400 /xm) were taken in a plane, intermediate between sagittal and transverse, that parallels the path of entry of retinotectal fibers into the optic tectum. 'Patch' microelectrodes of 4-10 MI2 were used for whole-cell current and voltage clamp, loose-patch single-cell, and field potential recordings. Here we report results of field potential recordings in optic tectum. Stimulation was delivered with a concentric bipolar electrode positioned either in stratum opticum or in segments of optic tract rostral to tectum. Sectioning from rostrolateral to caudomedial provided at least five consecutive slices in which good tectal field potentials could be elicited. A measurable field potential was elicited generally only when a thick dark band of myelinated fibers was visible at the point of stimulation in stratum opticum, that is, where the plane of section locally paralleled retinal afferents. Establishing that the evoked field potential is principally consequent to retinal afferent excitation has been a primary concern. The evidence supporting this contention includes: (1) similarity in field potential and current source density profiles to those of intact and semi-intact preparations, (2) similarity in responses to stimulation of optic tract and stratum opticum, (3) asymmetrical response amplitudes, that is, larger responses in the direction of retinal afferent extension, (4) transmission delays appropriate for retinal afterents, and (5) postmortem histology from applications of Dil crystals to slices fixed after recording. Additionally, current source density calculations from recordings made in zero C a / h i g h Mg saline showed the distribution of terminals expected for retinal afferents. The prominence presynaptically generated field potentials offers the opportunity to examine presynaptic modulation of afferent terminals directly. Pharmacological manipulations carried out with bath applied antagonists of putative transmitters indicated that in this system, as in others, glutamate is the principal retinotectal transmitter. The broadly active glutamate receptor blocker, kynurenic acid (1-0.7 raM),