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Kinetics of synaptic conductances in mammalian central neurons
VI
A NEW ANGLE ON THE FORMATION OF NEURAL CIRCUITS TOSHIO TERASHIMA, Department Institute for Neuroscience, Ree 1er , an autosomal abnormal neurons.
visual
cortex, mutant
mutation which are
inferior
and auditory
colliculi,
5’ neurons
projectinq
cortex
respectively. to
the
to
By contrast, spinal
an experimental neurons and
dislocated 5 neurons
project cord.
Tokyo Metropolitan 183, Japan
in mice, causes cytoarchi tecton characterized by salposition of
mouse Provides
the connectivity between the layer In the normal controls, cortex,
FROM THE REELER MUTANT MOUSE
Anatomy and Enbrvoloqv. Musashidai, Fuchvu City
recessive
ities of cerebral Thus, the reeler
analyzing neurons.
of 2-6
in
the
model for their tarclet
sensory-motor
the spinal cord, superior in the reeler neocortex,
superior
and
inferior
ic
cortex,
and ‘layer
colliculi
are
suggesting that dislocated ‘layer radially scattered in the correspondinq area, 5’ neurons appropriately project to their targets. In .addition, developmental time schedules for axonal collateral systems arisinq from the dislocated ‘layer 5’ neurons the not
normal affect
in the sensory-motor cortex and visual cortex are quite similar suggesting intracortical positions of layer 5 neurons controls, the formation of neural circuits.
to do
ESTABLISHMENT OF ROSTROCAUDAL POLARITY OF THE OPTIC TECTUM AND RETINOTECTAL PROJECTION. HARUKAZU Department of Biology, Kyoto Prefectural University of Medicine, 13 NishitakatsukasaNAKAMURA, cho. Taishogun. Kita-ku. Kyoto 603. Japan Retinotectal projection in birds is organized in precise retinotopic manner. We have been studying establishment of rostrocaudal polarity of the tectum and retinotectal projection by quail-chick chimeric tecta. During tectum development, several developmental events take making In the E2 tectum. homeobox containing gene engrailed is place concerning rostrocaudal polarity. there is a rostrocaudal gradient in cytoarchitectonic expressed with caudorostral gradient, development, and there is a difference in chemical property of the surface of the tectum when the retinal fibers enter it. The tectum anlage of E2 has plasticity about its rostrocaudal polarity. Even when the tectum anlage is transplanted with its rostrocaudal direction inverted, the polarity of the transplant with regard to all 3 properties mentioned above is regulated by the host. The tectum-rotation experiment on E3 showed that the rostrocaudal polarity concerning engrailed expression and retinotectal projection map is fixed around the 25-somite stage. Since the mesencephalic alar plate is determined to be a tectum around the IO-somite stage, when it has plasticity concerning the rostrocaudal polarity, ectopic tecta are produced after transplantation of the mesencephalon into the diencephalon. In the ectopic tecta, the engrailed expression pattern was inverted compared with the original fate of the transplant. Subsequent cytoarchitectonic differentiation of the ectopic tecta followed the inverted gradient of en_ It is suggested that engrailed expression pattern well coincides with the following grailed. developmental events.
E. Receptor-operated
Channel kinetics
KINETICS OF SYNAPTIC CONDUCTANCES IN MAMMALIAN
CENTRAL NEURONS
HUGH P.C. ROBINSON, NIT Basic Research Laboratories. 9-11 Midori-cho 3-chome, Musashino-shi. Tokyo 180, Ianan. Information processing in central neurons occurs through complex interactions between input synaptic conductance transients, active conductances and the distributed capacitance of the dendritic membrane. Here, we describe two recently developed approaches which offer a detailed view of synaptic conductances and their function. Firstly, nonsrufionury j7ucruarionnnalysiswas used to study spontaneous inhibitory and excitatory synaptic currents in cultured rat hippocampal neurons.In this technique, the noise within the decay phases of post-synaptic currents is isolated by least-squares scaling of the mean current followed by subtraction, and its amplitude and frequency distributions are analysed to measure the underlying single channel amplitude and kinetics, respectively, enabling detailed comparison with the properties of channels activated by artificial applications of agonist. Secondly, the process of synaptic integration in the unclamped neuron was investigated, using a novel technique termed conducrance injection. A combination of a current-clamp amplifier and a computer is used to inject a current into the neuron, based on instantaneous feedback of the membrane potential, so as to mimic exactly the presence of a time-varying ionic conductance of defined equilibrium potential. Thus the model of the conductance, which runs in real time, is able to interact with the real cable structure and nonlinear membrane conductances of the neuron under study. We have used this technique to measure quantitatively the physiological input-output relationship of cultured rat hippocampal neurons - the relationship between the amplitude of defined “synaptic” conductance transients and the ensuing trajectory of membrane potential - and also to investigate nonlinear temporal summation of “synaptic” conductance inputs.
A NEW ANGLE ON THE FORMATION OF NEURAL CIRCUITS TOSHIO TERASHIMA, Department Institute for Neuroscience, Ree 1er , an autosomal abnormal neurons.
visual
cortex, mutant
mutation which are
inferior
and auditory
colliculi,
5’ neurons
projectinq
cortex
respectively. to
the
to
By contrast, spinal
an experimental neurons and
dislocated 5 neurons
project cord.
Tokyo Metropolitan 183, Japan
in mice, causes cytoarchi tecton characterized by salposition of
mouse Provides
the connectivity between the layer In the normal controls, cortex,
FROM THE REELER MUTANT MOUSE
Anatomy and Enbrvoloqv. Musashidai, Fuchvu City
recessive
ities of cerebral Thus, the reeler
analyzing neurons.
of 2-6
in
the
model for their tarclet
sensory-motor
the spinal cord, superior in the reeler neocortex,
superior
and
inferior
ic
cortex,
and ‘layer
colliculi
are
suggesting that dislocated ‘layer radially scattered in the correspondinq area, 5’ neurons appropriately project to their targets. In .addition, developmental time schedules for axonal collateral systems arisinq from the dislocated ‘layer 5’ neurons the not
normal affect
in the sensory-motor cortex and visual cortex are quite similar suggesting intracortical positions of layer 5 neurons controls, the formation of neural circuits.
to do
ESTABLISHMENT OF ROSTROCAUDAL POLARITY OF THE OPTIC TECTUM AND RETINOTECTAL PROJECTION. HARUKAZU Department of Biology, Kyoto Prefectural University of Medicine, 13 NishitakatsukasaNAKAMURA, cho. Taishogun. Kita-ku. Kyoto 603. Japan Retinotectal projection in birds is organized in precise retinotopic manner. We have been studying establishment of rostrocaudal polarity of the tectum and retinotectal projection by quail-chick chimeric tecta. During tectum development, several developmental events take making In the E2 tectum. homeobox containing gene engrailed is place concerning rostrocaudal polarity. there is a rostrocaudal gradient in cytoarchitectonic expressed with caudorostral gradient, development, and there is a difference in chemical property of the surface of the tectum when the retinal fibers enter it. The tectum anlage of E2 has plasticity about its rostrocaudal polarity. Even when the tectum anlage is transplanted with its rostrocaudal direction inverted, the polarity of the transplant with regard to all 3 properties mentioned above is regulated by the host. The tectum-rotation experiment on E3 showed that the rostrocaudal polarity concerning engrailed expression and retinotectal projection map is fixed around the 25-somite stage. Since the mesencephalic alar plate is determined to be a tectum around the IO-somite stage, when it has plasticity concerning the rostrocaudal polarity, ectopic tecta are produced after transplantation of the mesencephalon into the diencephalon. In the ectopic tecta, the engrailed expression pattern was inverted compared with the original fate of the transplant. Subsequent cytoarchitectonic differentiation of the ectopic tecta followed the inverted gradient of en_ It is suggested that engrailed expression pattern well coincides with the following grailed. developmental events.
E. Receptor-operated
Channel kinetics
KINETICS OF SYNAPTIC CONDUCTANCES IN MAMMALIAN
CENTRAL NEURONS
HUGH P.C. ROBINSON, NIT Basic Research Laboratories. 9-11 Midori-cho 3-chome, Musashino-shi. Tokyo 180, Ianan. Information processing in central neurons occurs through complex interactions between input synaptic conductance transients, active conductances and the distributed capacitance of the dendritic membrane. Here, we describe two recently developed approaches which offer a detailed view of synaptic conductances and their function. Firstly, nonsrufionury j7ucruarionnnalysiswas used to study spontaneous inhibitory and excitatory synaptic currents in cultured rat hippocampal neurons.In this technique, the noise within the decay phases of post-synaptic currents is isolated by least-squares scaling of the mean current followed by subtraction, and its amplitude and frequency distributions are analysed to measure the underlying single channel amplitude and kinetics, respectively, enabling detailed comparison with the properties of channels activated by artificial applications of agonist. Secondly, the process of synaptic integration in the unclamped neuron was investigated, using a novel technique termed conducrance injection. A combination of a current-clamp amplifier and a computer is used to inject a current into the neuron, based on instantaneous feedback of the membrane potential, so as to mimic exactly the presence of a time-varying ionic conductance of defined equilibrium potential. Thus the model of the conductance, which runs in real time, is able to interact with the real cable structure and nonlinear membrane conductances of the neuron under study. We have used this technique to measure quantitatively the physiological input-output relationship of cultured rat hippocampal neurons - the relationship between the amplitude of defined “synaptic” conductance transients and the ensuing trajectory of membrane potential - and also to investigate nonlinear temporal summation of “synaptic” conductance inputs.