Development and motor control in humans is related to the influence of exteroceptive and interoceptive stimuli and to the acquisition of motor and cognitive skills.

Neuroscience has studied the implication of different areas of the brain on functional tasks, while new lines of research seek out the relationship between brain activation during the afference of different sensory stimuli.
As physical therapists, we use our hands as providers of stimulus. The central nervous system receives this information and responds in the best possible way to the stimulus. The method, the direction, the pressure of the stimulus are crucial to determining the brain response. Thanks to proper clinical reasoning, it is possible to provide a better therapeutic approach that can help improve damaged structures in neurological patients. At the same time, through repetition and learning, we can generate greater neuroplasticity. This reflection has led to the idea of researching what happens in the central nervous system during the application of a sensory stimulus and, especially, which zones are activated.
Vojta therapy is based on tactile and proprioceptive stimulation of specific zones and/or points of the body on a specific, well-defined postural base. Applying these stimuli triggers an innate locomotive program that is implicit in our central nervous system. In response to the stimuli, muscular synergies appear that contain the essential motor elements in human locomotion: straightening, coordinated phasic movement and posture control.

The general objective of this study was to discover the zones of greatest influence on the central nervous system during the application of a tactile and proprioceptive stimulus. The stimulus was applied according to the Vojta protocol for the first phase of turning in the Vojta descriptive group and a stimulus applied to the thigh in the simulated descriptive group.

Material and methods:
Descriptive observational study using functional magnetic resonance (fMRI) with 16 healthy subjects divided into two groups. The same paradigm and action protocol were used in both groups, applying a passive sensory stimulus by a specialized physical therapist. The difference between the two groups was the stimulation zone. According to this protocol, the subject is placed in a supine position with arms and legs relaxed. The stimulation is applied with the therapist’s thumb on the 7th and 8th intercostal space, with a pressure of between 1.4 and 1.8 kg. The stimulus follows a specific direction determined by a cranial vector, a medial vector and a dorsal vector towards the contralateral glenohumeral joint. This would be the Vojta descriptive group (VD group), while in the other group, called the simulated descriptive group, a tactile stimulation was applied with the same vectors as the VD group, but on the distal third of the thigh (DS group). This provided us with the possibility of interpreting some of the response mechanisms to the stimuli that the patients had during the therapy. The fMRI was used to map the brain during the application of the stimulus using a block design. This study was based on the magnetic properties of hemoglobin. Thus, it was possible to measure specifically the changes in regional blood oxygenation (these studies are known as BOLD: Blood Oxygenation Level Dependent), which can be considered an indirect measurement of the neural activity associated with functional processes. The block design is the model used most often, and the most simple for comparing the base state of a subject (control or resting block), compared to the state during the presence of as stimulus or when conducting a task (activity block). The data were analyzed using the general SPM12 linear model implemented at MATLAB.

Results:
To obtain all the results, a statistical significance level of p<0.001 was used. After comparing both groups at rest and direct comparison of the two, the activation of the frontal and temporal cortical zones, the subcortical areas of the thalamus, and basal and brainstem ganglia were of note. Of note in the cerebellum was the activation of the anterior lobe. There was also great activation in the temporal zones in the insular lob and in the brainstem. Activation of the medial frontal gyrus of the cortex corresponding to Brodmann area 6 is worth noting. Conclusions:
These results, together with the activation of the supplementary motor area, indicate the activation of motor circuits that put automatic systems in motion in humans, such as locomotion.
The most relevant is the idea of the existence of innate motor patterns that are activated during sensory stimulation in a specific zone.
The major activation that occurs in the basal ganglia structures indicate the importance of processing the sensory stimulus and putting in motion mechanisms that regulate movement. The ipsilateral activation of the stimulus zone of the putamen is especially significant and opens the possibility of a future line of research.

Ismael Sanz
Professor at the Grado en Fisioterapia