Evidence for long-lasting subcortical facilitation by transcranial direct current stimulation in the cat

J Physiol, 2013 · DOI: 10.1113/jphysiol.2012.244764 · Published: March 18, 2013

Simple Explanation

Transcranial direct current stimulation (tDCS) is increasingly used to improve motor and cognitive functions. This study on anaesthetized cats reveals that tDCS affects not only cortical neurons but also subcortical motor systems. The study demonstrates that the facilitation of subcortical neurons lasts for hours after the tDCS application, suggesting plasticity at subcortical levels. These subcortical effects of tDCS may significantly contribute to the treatment of motor impairments in clinical practice.

Study Duration

Not specified

Participants

12 deeply anaesthetized cats weighing 2.2–3.4 kg

Evidence Level

Level IV, Experimental study

Key Findings

1
Transcranial polarization facilitates transsynaptic activation of both rubrospinal and reticulospinal neurons.
2
The facilitation of subcortical neurons is potentiated by repeated applications of tDCS and outlasts the polarization by at least 1–2 h.
3
The beneficial effects of tDCS on motor performance may stem from efficient activation of both cortical and subcortical neuronal systems.

Research Summary

This study examined the effects of transcranial polarization on rubro- and reticulospinal neurons in deeply anaesthetized cats. The results indicate that tDCS facilitates transsynaptic activation of subcortical descending tract neurons, and this facilitation outlasts the tDCS. Combined actions of tDCS on cortical and subcortical neurones might improve recovery of motor functions during rehabilitation after central injuries.

Practical Implications

Clinical Applications

The subcortical effects of tDCS should be considered in the rehabilitation of motor impairments after spinal cord injury or stroke.

Mechanism of Action

Further investigation is needed to understand the mechanisms underlying the subcortical effects of tDCS.

Potential Enhancement

Parameters of transcranial polarization and placement of electrodes may be adjusted to enhance the subcortical effects of tDCS.

Study Limitations

1
The study was conducted on anaesthetized cats, which may not fully represent the effects in awake humans.
2
The exact mechanisms underlying the subcortical effects of tDCS remain to be investigated.
3
The general state of the animal could affect the results.

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