Spatial integration of local transmitter responses in motoneurones of the turtle spinal cord in vitro
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Spatial integration of local transmitter responses in motoneurones of the turtle spinal cord in vitro. / Skydsgaard, Morten Arnika; Hounsgaard, J.
In: Journal of Physiology, Vol. 479 , No. 2, 1994, p. 233-246.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Spatial integration of local transmitter responses in motoneurones of the turtle spinal cord in vitro
AU - Skydsgaard, Morten Arnika
AU - Hounsgaard, J
PY - 1994
Y1 - 1994
N2 - 1. Integration of responses to local activation of transmitter receptors in the dendrites of motoneurones was investigated in a slice preparation of the turtle spinal cord. Membrane-active substances were applied from up to three independent iontophoresis electrodes during intracellular recording from the cell body. 2. Responses to glutamate could be evoked from dendrites closer than 20 microns from the tip of the glutamate electrode. The effects of other substances were more widespread. 3. In normal medium the configuration of a glutamate response was affected by time-dependent anomalous rectification. In the presence of muscarine the sum of glutamate responses from two different dendrites recruited a voltage-sensitive plateau potential. 4. The response to glutamate from one dendrite could be attenuated by local application of gamma-aminobutyric acid (GABA) without effects on soma conductance or glutamate responses from other dendrites. 5. The response to glutamate from one dendrite could be selectively enhanced by local application of tetraethylammonium (TEA) or N-methyl-D-aspartate (NMDA) without effects on soma conductance or glutamate responses from other dendrites. 6. NMDA could convert a tonic glutamate response from one dendrite into a phasic response without affecting the configuration of glutamate responses from other dendrites. 7. The effects of TEA and NMDA were facilitated by depolarization and reduced by hyperpolarization. 8. We conclude that the cable structure of motoneurones and the distribution of synapses and voltage-sensitive ion channels provide relative autonomy to non-linear synaptic processing and modulation in confined dendritic regions.
AB - 1. Integration of responses to local activation of transmitter receptors in the dendrites of motoneurones was investigated in a slice preparation of the turtle spinal cord. Membrane-active substances were applied from up to three independent iontophoresis electrodes during intracellular recording from the cell body. 2. Responses to glutamate could be evoked from dendrites closer than 20 microns from the tip of the glutamate electrode. The effects of other substances were more widespread. 3. In normal medium the configuration of a glutamate response was affected by time-dependent anomalous rectification. In the presence of muscarine the sum of glutamate responses from two different dendrites recruited a voltage-sensitive plateau potential. 4. The response to glutamate from one dendrite could be attenuated by local application of gamma-aminobutyric acid (GABA) without effects on soma conductance or glutamate responses from other dendrites. 5. The response to glutamate from one dendrite could be selectively enhanced by local application of tetraethylammonium (TEA) or N-methyl-D-aspartate (NMDA) without effects on soma conductance or glutamate responses from other dendrites. 6. NMDA could convert a tonic glutamate response from one dendrite into a phasic response without affecting the configuration of glutamate responses from other dendrites. 7. The effects of TEA and NMDA were facilitated by depolarization and reduced by hyperpolarization. 8. We conclude that the cable structure of motoneurones and the distribution of synapses and voltage-sensitive ion channels provide relative autonomy to non-linear synaptic processing and modulation in confined dendritic regions.
KW - Animals
KW - Dendrites
KW - Glutamic Acid
KW - Ionophores
KW - Motor Neurons
KW - N-Methylaspartate
KW - Quisqualic Acid
KW - Spinal Cord
KW - Synapses
KW - Synaptic Transmission
KW - Tetraethylammonium
KW - Tetraethylammonium Compounds
KW - Turtles
KW - gamma-Aminobutyric Acid
U2 - 10.1113/jphysiol.1994.sp020291
DO - 10.1113/jphysiol.1994.sp020291
M3 - Journal article
C2 - 7799223
VL - 479
SP - 233
EP - 246
JO - The Journal of Physiology
JF - The Journal of Physiology
SN - 0022-3751
IS - 2
ER -
ID: 264909