THE ROLE OF INHIBITION IN THE GENESIS OF MOVEMENTS

Research project

Description

Being able to suppress a pending action is a fundamental ability for surviving in an unpredictable world. Sudden events, such as the appearance of a physical obstacle, might require a quick change of the planned motor strategy. The first step toward this goal is to suppress the pre-programmed actions. Understanding the functional characteristics and the neural underpinnings of inhibition is a primary aim, both for the treatment of such diseases as attention-deficit hyperactivity disorder, where the decision-making abilities are severely impaired, and for the development of efficient brain–machine interfaces.
The countermanding task is one of the most efficient tasks in the study of behavioral inhibition [1]. This paradigm allows estimation of the duration of the process of cancellation (stop-signal reaction time; SSRT), a phenomenon which is not directly measurable because when an action is inhibited the subject remains still in the starting position. The SSRT allows quantification of the ability of subjects to suppress an act and thus permits comparisons among different types of movements and/or among different groups of volunteers. Furthermore, the SSRT represents a key behavioral parameter for evaluating changes in neural activity. Brain regions where changes in activity are recorded when a movement is executed with respect to when the movement is cancelled before the end of the SSRT are taken as neural substrates of inhibitory processes. In fact, in these regions neural activity changes before the end of the behavior and therefore it can influence it.
Even though in the last 10 years the countermanding task has been employed in several studies, on healthy subjects (e.g. [2], [3], [4]), on patients (e.g. [5]) and on experimental animals (e.g. [6], [7], [8]), several questions remain open. This project will shed light on four different topics.
First of all we will try to quantify whether, as all the other brain functions, even the inhibitory control of movements can change according to the experience of the individual. We will compare the performance in the countermanding task of trap-shooting athletes , sportspersons in whom the required inhibitory control is maximal, with that of healthy non-trained subjects. At the laboratories of Scienze Motorie of L’Aquila University, we will recruit athletes with different skills ranging from the local level to the national and international levels. The working hypothesis is that the excellence of an individual might be reflected in a higher degree of inhibitory control (that is, in a progressive decrease in the SSRT). Beyond this, we will verify whether the greater control acquired is limited to the body segment utilized in a given discipline; in other words, does an improved performance with the hand determine an improvement in the performance with the foot or not?
The second line of research will investigate the role of subthalamic nucleus (STN) in inhibitory processes. Aron et al [2] proposed that the right STN belongs to a network of right brain regions which control suppression of motor acts. To verify this model, at Neuromed Hospital in Pozzilli (IS) we will recruit Parkinsonian patients in whom, to decrease the symptoms, deep-brain stimulators (DBS) were inserted into the STN of both hemispheres. The bilaterality of the implant will allow study of their performance in the countermanding task in four conditions: a) DBS OFF on both sides; b) DBS ON on both sides; c) DBS ON only on the right side; d) DBS ON only on the left side. It has been shown that bilateral activation of DBS decreases the length of the SSRT [9]. If the right STN has a key role in inhibition we expect that a similar effect should be obtained by turning off only the right stimulator.
The third line of research, in collaboration with the unit of Prof Gentilucci, aims to understand whether inhibitory processes might be influenced by language. As the reading of verbs or adjectives correlated with
StatusActive
Effective start/end date1/1/10 → …

Funding

  • MIUR

Fingerprint

Brain
Inhibition (Psychology)
Subthalamic Nucleus
Athletes
Neural Inhibition
Brain-Computer Interfaces
Attention Deficit Disorder with Hyperactivity
Reaction Time
Foot
Volunteers
Decision Making
Healthy Volunteers