Unmyelinated axons in the rat hippocampus hyperpolarize and activate an H current when spike frequency exceeds 1 Hz

Soleng, A. F.; Chiu, K.; Raastad, Morten

doi:10.1111/j.1469-7793.2003.00459.x

Cited by 30 publications

(63 citation statements)

References 52 publications

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“…To date, propagation in axons has been measured primarily with low-frequency trains or with high-frequency trains of Յ10 stimuli (Cox et al, 2000;Koester and Sakmann, 2000;Soleng et al, 2003). The present data indicate that, in Purkinje axons, reliable propagation at 200 spikes/sec can persist for Ն100 action potentials.…”

Section: Evidence For Specializations Of Axonal Channelsmentioning

confidence: 73%

Axonal Propagation of Simple and Complex Spikes in Cerebellar Purkinje Neurons

2005

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In cerebellar Purkinje neurons, the reliability of propagation of high-frequency simple spikes and spikelets of complex spikes is likely to regulate inhibition of Purkinje target neurons. To test the extent to which a one-to-one correspondence exists between somatic and axonal spikes, we made dual somatic and axonal recordings from Purkinje neurons in mouse cerebellar slices. Somatic action potentials were recorded with a whole-cell pipette, and the corresponding axonal signals were recorded extracellularly with a loose-patch pipette. Propagation of spontaneous and evoked simple spikes was highly reliable. At somatic firing rates of ϳ200 spikes/sec, Ͻ10% of spikes failed to propagate, with failures becoming more frequent only at maximal somatic firing rates (ϳ260 spikes/sec). Complex spikes were elicited by climbing fiber stimulation, and their somatic waveforms were modulated by tonic current injection, as well as by paired stimulation to depress the underlying EPSCs. Across conditions, the mean number of propagating action potentials remained just above two spikes per climbing fiber stimulation, but the instantaneous frequency of the propagating spikes changed, from ϳ375 Hz during somatic hyperpolarizations that silenced spontaneous firing to ϳ150 Hz during spontaneous activity. The probability of propagation of individual spikelets could be described quantitatively as a saturating function of spikelet amplitude, rate of rise, or preceding interspike interval. The results suggest that ion channels of Purkinje axons are adapted to produce extremely short refractory periods and that brief bursts of forward-propagating action potentials generated by complex spikes may contribute transiently to inhibition of postsynaptic neurons.

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Section: Evidence For Specializations Of Axonal Channelsmentioning

confidence: 73%

Axonal Propagation of Simple and Complex Spikes in Cerebellar Purkinje Neurons

2005

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“…But it will also be extremely important to use other probes that do not perturb the rather fragile equilibrium that underlies propagation. Non-invasive recording techniques such as extracellular recording from single axons will be extremely helpful 39,81,100,131 .…”

Section: Resultsmentioning

confidence: 99%

“…When the action potential fails to propagate along the axon, no signal can reach the output of the cell. Conduction failure filters communication with postsynaptic neurons, and has been observed experimentally in various axons including vertebrate spinal axons 68,69 , spiny lobster or crayfish motor neurons 33,64,70,71 , leech mechanosensory neurons [72][73][74][75][76] , thalamocortical axons 77 , rabbit nodose ganglion neurons 78 , rat dorsal root ganglion neurons 63,79 , neurohypophysial axons 17,80 and hippocampal pyramidal cells 39,66,81 . Several factors determine whether propagation along axons fails or succeeds.…”

Section: Propagation Failuresmentioning

confidence: 99%

“…The so-called 3/2 power law that was developed by Rall describes an ideal relationship between the geometry of mother and daughter branches 105 Several recent studies indicate that the hyperpolarization that is produced by repetitive stimulation could be dampened by hyperpolarization-induced cationic current (I h ) 26,81 . This inward current is activated at resting membrane potential and produces a tonic depolarization of the axonal membrane 26 .…”

Section: Box 1 | Theory Of Geometrical Constraints On Axonal Propagationmentioning

confidence: 99%

“…So, reduction of this current induces hyperpolarization and perturbs propagation. The pharmacological blockade of I h by ZD7288 or by external caesium can produce more failures in Schaffer collateral axons 81 . The peculiar biophysical properties of I h indicate that it might limit large hyperpolarizations or depolarizations that are produced by external and internal accumulation of ions.…”

Section: Box 1 | Theory Of Geometrical Constraints On Axonal Propagationmentioning

confidence: 99%

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Information processing in the axon

2004

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Adult‐onset hypothyroidism causes mechanical hypersensitivity due to peripheral nerve hyperexcitability based on voltage‐gated potassium channel downregulation in male mice

Suda

Takatsuru

Amano

et al. 2021

J of Neuroscience Research

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Thyroid hormones play an important role in the central and peripheral nervous system functions. Approximately 50% of adult‐onset hypothyroid patients have sensory symptoms including pain, possibly caused by peripheral neuropathy. However, the mechanism causing the pain has not been clarified. We generated an adult‐onset hypothyroid model animal by administering 50 ppm propylthiouracil (PTU) for 5 weeks to male mice. Female mice were not tested in this study. Mechanical hypersensitivity, determined by the von Frey hair test, was observed during the PTU exposure and recovered after the exposure termination. The sciatic nerve compound action potential was also analyzed. Under single‐pulse stimulation, no significant change in the threshold and conduction velocity was observed in the PTU‐administered group. On the other hand, under train‐pulse stimulation, the latency delay in the Aδ‐fiber component was less in the PTU‐administered group in Week 4 of PTU exposure, indicating relative hyperexcitability. Fluticasone, which is the anti‐inflammatory agent with an ability to activate the voltage‐gated potassium channel subfamily A (Kv1), restored the decrease in the latency change ratio by PTU exposure under the train‐pulse stimulation supporting our hypothesis that Kv1 may be involved in the conductivity change. Kv1.1 protein level decreased significantly in the sciatic nerve of the PTU‐administered group. These results indicate that adult‐onset hypothyroidism causes mechanical hypersensitivity owing to hyperexcitability of the peripheral nerve and that reduction of Kv1.1 level may be involved in such alteration.

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Unmyelinated axons in the rat hippocampus hyperpolarize and activate an H current when spike frequency exceeds 1 Hz

Cited by 30 publications

References 52 publications

Axonal Propagation of Simple and Complex Spikes in Cerebellar Purkinje Neurons

Axonal Propagation of Simple and Complex Spikes in Cerebellar Purkinje Neurons

Information processing in the axon

Adult‐onset hypothyroidism causes mechanical hypersensitivity due to peripheral nerve hyperexcitability based on voltage‐gated potassium channel downregulation in male mice

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