Features of cortical neuroplasticity associated with multidirectional novel motor skill training: a TMS mapping study

Abstract

Given the evidence that the primary motor cortex (MI) consists of subpopulations of upper motor neurons tuned to different directional parameters of a motor movement, this study hypothesized that novel motor skill training involving either a bidirectional or more complex multidirectional tongue-typing movement should produce distinct training-related features of tongue MI neuroplasticity in humans. Novel motor skill training consisted of tongue typing using custom-made intra-oral keypads for 30-min over two consecutive days. The bidirectional keypad consisted of three sensors positioned along the upper palatal midline as a 3 × 1 array, whereas the multidirectional keypad consisted of nine sensors arranged as a 3 × 3 array that was centred along the upper palatal midline. Each sensor corresponded to one letter and participants were asked to type sequences of letters by accurately placing the tongue over the correct sensor. Before and after each training session, excitability of the tongue MI was assessed with transcranial magnetic stimulation (TMS)-motor evoked potentials (MEPs) over 13 motor map sites and TMS-MEP stimulus-response curves were constructed for the first dorsal interosseous (FDI, as an internal control). Tongue-typing performance improved within and across training days for both groups; although bidirectional training displayed greater success. Bidirectional and multidirectional training were associated with increases and decreases in a number of cortical motor map sites from where tongue activity could be evoked, however; multidirectional training was associated with a greater number of cortical motor map sites with increased excitability and a shift in the centre of gravity of the motor map. No effects of training were found on the FDI TMS-MEP stimulus-response curves. This study revealed distinct training-related features of tongue MI neuroplasticity and proposes that a greater amount of functionally related neuronal populations may be 'trained' by the inclusion of different and more complex directional parameters within a novel motor task.

Primary motor and sensory cortical areas communicate via spatiotemporally coordinated networks at multiple frequencies

“…To investigate cortico-cortical interactions between these areas, we measured coherence of spiking and local field potentials (LFPs) recorded simultaneously from MIo and SIo of the left hemisphere as monkeys learned a simple and controlled tongue protrusion task. Several studies using this behavioral paradigm have reported neuroplasticity and modulation of neuronal activity related to tongue protrusion separately in MIo and SIo (13)(14)(15)(16)(17). Here, we show that interactions between MIo and SIo involve coherent networks at multiple frequencies.…”

“…2A) These measures of coherence are presumed to represent the correlation of the outputs from both areas (MS) and the correlation of the outputs from one area with the inputs in the other (MSf and SMf). For each of the 5 sampled training days, D1-D5, we estimated coherence by using a 0.5-s sliding window with 0.01-s steps to show a time-resolved coherence profile in the theta (2-6 Hz), alpha (6-13 Hz), beta (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma (30-50 Hz) bands. Coherence in these frequency bands is believed to play a role in attention, memory, motor control, and plasticity (16,(18)(19)(20).…”

Chronic Pain: We Should Not Underestimate the Contribution of Neural Plasticity

“…Visual attention toward the limb during training also appears to be an important factor for modulating the magnitude and duration of analgesia. 224 It is known that attention and task complexity enhance neural plasticity during motor learning 226,227 and it is apparent that this also applies to neuroplastic changes in the sensory system during sensory training. Clinically, this would mean that progressively graded sensory discrimination training that requires the patient's attention would be most beneficial.…”

Towards an understanding of motor system impairments in individuals with unilateral lateral epicondylalgia

“…Several techniques can help to activate an inactive muscle. First, motor learning induces neuroplastic changes within the brain (Boudreau et al, 2013). Exercises that focus on activation of the ECRB muscle whilst limiting activation of EDC might prove beneficial.…”

“…cerebral cortex) to change as a result of internal and external stimuli and changes in behaviour, environment, and emotions (Pascual-Leone et al, 2011). Although pain is a strong driver of neuroplasticity (Coderre, Katz, Vaccarino, & Melzack, 1993), neuroplastic changes can be motivated by motor learning/training (Boudreau et al, 2013). Less discrete cortical organisation might be related to less individualised control of muscles and/or a simplified motor control in chronic pain conditions.…”