Unravelling the Neurophysiological Systems Behind Efficient Reach, Grasp, release and Manipulation – What we discussed at the Advanced course at Walkergate Park, Newcastle!
BBTA Tutors: Clare Fraser and Debbie Strang
Debbie and I recently had the pleasure of working with a very motivated group of therapists interested in advancing their rehabilitation skills at Walkergate Park Hospital. The course was about the recovery of the upper limb and hand in neurological patients. The lectures, practical sessions and patient demonstrations focused on the application of the neurophysiology in our clinical practice.
The ability to reach, grasp, release and manipulate objects is a fundamental aspect of human function. It involves a complex interplay of neurophysiological systems that work in harmony to achieve precise and efficient movement control.
We thought some follow up blog posts, working through some of these aspects of functional movement control, would be a good idea!
In this blog post, we explore some of the key components involved in this process, including postural stability, anticipatory postural adjustments (APA) control, the straight line path to control degrees of freedom, shaping the grasp, and the role of visual streams. To provide insights into these systems, we will draw upon publications from notable authors, that we referenced during our Advanced Course, for example Takakusaki, Fornai, Simone, and Karthikbabu.
Postural stability forms the foundation for successful reaching and grasping. It relies on the integration of sensory information from cutaneous and proprioceptor receptors, the vestibular system, visual inputs and graviceptors. Takakusaki's research emphasizes the critical role of brainstem and basal ganglia in maintaining postural stability.
Anticipatory Postural Adjustments (APA) Control:
APA control involves pre-programmed adjustments in muscle activity prior to a movement. Fornai and colleagues have highlighted the significance of the cortico-basal ganglia-thalamo-cortical circuitry in modulating APAs. These adjustments provide a stable platform for reaching and grasping tasks, as the ‘feed forward’ control for any volitional movement, to prevent predictable displacements of the Centre of Mass.
Straight Line Path to Control Degrees of Freedom and improve efficiency:
Efficient reach patterns employ a straight-line path from A to B, allowing the central nervous system to use a minimal-jerk strategy to control multiple degrees of freedom during reaching and grasping. Simone's work supports the idea that the brain optimizes movements by minimizing energy expenditure and reducing variability.
Shaping the Grasp:
Efficient manipulation of objects involves shaping the grasp based on their physical properties. Karthikbabu's research suggests that the sensorimotor integration process is crucial in determining the appropriate grasp strategy, with the involvement of the parietal cortex and cerebellum.
Visual information plays a pivotal role in guiding reaching and grasping movements. The dorsal and ventral visual streams, as proposed by Goodale and Milner, respectively, are involved in the perception and transformation of visual cues into motor commands.
The neurophysiological systems involved in efficient reach, grasp, and manipulation of objects are a testament to the intricacy of human motor control. Understanding these systems, as explored through the works of many authors such as these, sheds light on the complex coordination and integration of various brain regions and circuits.
By unraveling and understanding these neurophysiological processes, we can gain insights into our patients’ motor impairments and the impact we see on their function. The practical sessions and the patient treatment sessions that we developed on the Advanced Course allowed the therapists to return to their work- places with lots of new treatment ideas and principles to develop and enhance their patients recovery, potential and therefore their quality of life.
Look out for our next blog in this series about the neurophysiology of reach, grasp, release and manipulate; and if you would like to consider joining the next Advanced Course to develop your rehabilitation skills go to www.bbta.org.uk.