Action potential of the motoneurons of the hypoglossus nucleus

Nó, R. Lorente de

doi:10.1002/jcp.1030290303

Cited by 280 publications

(101 citation statements)

References 11 publications

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“…This is consistent with other MEG experiments evaluating memory and spatial navigation which have also reported hippocampal effects at slower theta frequencies (Cornwell et al, 2008;Kaplan et al, 2012;Staudigl and Hanslmayr, 2013). Although it has been suggested that the hippocampus may form a closed electric field due to its sym metrical morphology (Lorente de No, 1947), this would require that the entire structure be simultaneously activated, a rather unlikely sce nario under typical experimental conditions. Moreover, a closer look at hippocampal slices reveals asymmetrical sections and an uneven dis tribution of pyramidal neurons, further reducing its effective symmetry.…”

Section: Successful Reconstruction Of Slow Theta Sources In the Hipposupporting

confidence: 90%

Slow-theta power decreases during item-place encoding predict spatial accuracy of subsequent context recall

et al. 2016

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a b s t r a c tHuman hippocampal theta oscillations play a key role in accurate spatial coding. Associative encoding involves similar hippocampal networks but, paradoxically, is also characterized by theta power decreases. Here, we inves tigated how theta activity relates to associative encoding of place contexts resulting in accurate navigation. Using MEG, we found that slow theta (2 5 Hz) power negatively correlated with subsequent spatial accuracy for vir tual contextual locations in posterior hippocampus and other cortical structures involved in spatial cognition. A rare opportunity to simultaneously record MEG and intracranial EEG in an epilepsy patient provided crucial in sights: during power decreases, slow theta in right anterior hippocampus and left inferior frontal gyrus phase led the left temporal cortex and predicted spatial accuracy. Our findings indicate that decreased slow theta activ ity reflects local and long range neural mechanisms that encode accurate spatial contexts, and strengthens the view that local suppression of low frequency activity is essential for more efficient processing of detailed information.

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Section: Successful Reconstruction Of Slow Theta Sources In the Hipposupporting

confidence: 90%

Slow-theta power decreases during item-place encoding predict spatial accuracy of subsequent context recall

et al. 2016

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“…Lorente de No, 1947a;Fatt, 1957a). On this ground, diphasicity at the focal electrode would not constitute evidence of actively propagated events (Lorente de No, 1947b;Brooks & Eccles, 1947;Barakan, Downman & Eccles, 1949;Bishop & Clare, 1953).…”

Section: Discussionmentioning

confidence: 99%

“…The focal sink which develops in the region of the cell body can draw current from widely dispersed portions of the motoneuronal dendritic tree; thus the current density at any one focus in the source area should be quite small (Lorente de N6, 1947a). The high gradients of electrotonic decrement which must occur in the thin terminal branches would minimize interfering current flows and allow the source activity to reflect with accuracy the time course of current flow toward the ventral sink.…”

Section: Discussionmentioning

confidence: 99%

Potential fields initiated during monosynaptic activation of frog motoneurones

Brookhart¹,

Fadiga²

1960

The Journal of Physiology

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It has been noted that the patterns of discharge evoked in frog spinal motoneurones are significantly different when a presynaptic volley is initiated in dorsal root fibres and when the excitation arrives over a system of fibres in the lateral column . Anatomical studies (Liu & Chambers, 1957) raise the possibility that the differences may be ascribed to variations in the site of synaptic terminations on the motoneurones or to differences in the number of interneurones involved in the two pathways, or both. The present study was undertaken in order to determine which of these possibilities is the more likely. The technique of focal recording from within the spinal cord, and comparison of the temporal relations of simplified responses, have permitted a test of the hypothesis suggested by anatomical findings. METHODSThe experiments have been performed on isolated spinal cords of frogs (Rana pipiens) during winter and spring months. The arrangement has been similar to that described previously . Micropipettes of 5-15 MQ resistance, filled with potassium citrate, were used for depth recording. Ipsilateral evoked focal potentials were recorded unipolarly through an impedance-matching preamplifier, a high-gain, RC-coupled amplifier (time constant 1 sec), and photographed from an oscilloscope screen. A second oscilloscope was usually used to monitor ipsilateral ventral root responses. A thermistor thermometer in contact with the cord made possible temperature control in the range from 15-17°C.The method of preserving function in isolated dorsal and ventral roots was important to the success of these experiments. The root was extended laterally on a small slip of ifiter paper coated with thinned petroleum jelly. The root was laid over hooked platinum electrodes and a complete covering of petroleum jelly delivered from a syringe and hypodermic needle was built around the entire root. This procedure not only preserved the fibres of the root, but also prevented troublesome electrical instability and provided the necessary insulation of the ventral root from the fluid surrounding the cord. In recording from the ventral root, the distance between proximal lead and cord varied in different experiments from 3 to 5 mm; the distal lead was always applied as far as possible from the cord on the crushed end of the root.

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“…The response to ventral root stimulation as seen in the ventral horn (Fig. 2 B) consisted of a triphasic positive-negative-positive wave form typical of action potential propagation in volume conductors (Lorente de No, 1947 initial positivity was sometimes obscured by the stimulus artifact and the presence of the second positivity depended on the location of the recording electrode (Nelson & Frank, 1964). The break in the rising phase of the field (arrowhead, Fig.…”

Section: Field Potentialsmentioning

confidence: 96%

Electrophysiological properties of neonatal rat motoneurones studied in vitro.

Fulton¹,

Walton²

1986

The Journal of Physiology

215

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SUMMARY1. The electroresponsive properties of neonatal lumbar spinal motoneurones were studied using isolated, hemisected spinal cords from neonatal rats aged [3][4][5][6][7][8][9][10][11][12] days. The extracellular and intracellular responses to electrical stimulation of the ventral and dorsal root were studied as well as. the intracellular response to current injection.2. Field potentials recorded in the lateral motor area following electrical stimulation of lumbar ventral roots had a triphasic positive-negative-positive wave form. The negative component did not return to the base line smoothly but exhibited a ' shoulder' where the negativity increased in duration. Following electrical stimulation of the dorsal root, presynaptic field potentials were recorded upon activation of the afferent axons as well as following synaptic activation of interneurones and motoneurones.3. The input resistances of neonatal motoneurones determined from the slope of current-voltage plots were high compared with the adult. The resistance decreased with age with a mean of 18-1 MC for animals 3-5 days old, 8-8 M0 for animals 6-8 days old and 5-4 MC for animals 9-11 days old. Values for the membrane time constant were similar to those in the adult with a mean of 4-5 ms.4. Action potentials elicited by ventral or dorsal root stimulation or by intracellular current injection were marked by a pronounced after-depolarization (a.d.p.) and an after-hyperpolarization (a.h.p.). The amplitude of the a.h.p. varied with that of the a.d.p.5. The amplitude of excitatory post-synaptic potentials (e.p.s.p.s) elicited by electrical stimulation ofthe dorsal root was affected by intracellular current injection. Two types of e.p.s.p.s were distinguished: those with a biphasic reversal (early phase first) and those in which the early phase was unaffected by inward current injection while the later phase was reversed. Unlike in the adult, the reversals could be achieved with low current levels and the amplitude of both types of e.p.s.p. was increased by inward current injection. (b) there is a low maximum firing frequency (near 30 Hz) and (c) the slope of the firing frequency-injected current (f-I) plot has a high gain.8. These results are discussed with respect to previous findings in adult rat and cat and with reference to the properties of the developing nervous and muscular systems.

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Action potential of the motoneurons of the hypoglossus nucleus

Cited by 280 publications

References 11 publications

Slow-theta power decreases during item-place encoding predict spatial accuracy of subsequent context recall

Slow-theta power decreases during item-place encoding predict spatial accuracy of subsequent context recall

Potential fields initiated during monosynaptic activation of frog motoneurones

Electrophysiological properties of neonatal rat motoneurones studied in vitro.

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