Neuronal circuits for fine motor skills

January 06, 2021

Writing, driving a screw or throwing darts are only some of the activities that demand a high level of skill. How the brain masters such exquisite movements has now been described in the journal "Nature" by a team of researchers at the University of Basel and the Friedrich Miescher Institute for Biomedical Research. A map of brainstem circuits reveals which neurons control the fine motor skills of the arm and hand.

Picking up a pen and writing our name or reaching for a fork to eat spaghetti with tomato sauce are things we take for granted. However, holding a pen properly or bringing spaghetti to the mouth without making a mess requires precise arm movements and a high level of skill.

Underlying all our motor behavior is a perfect interplay between neurons in the brain, the spinal cord, and the muscles. But which neuronal circuits control the fine motor skills of the arms, hands and fingers? Prof. Silvia Arber's team has been addressing this question in recent work. The neurobiologists who work at both the Biozentrum of the University of Basel and at the Friedrich Miescher Institute for Biomedical Research (FMI) have been investigating how the nervous system controls motor behavior for many years.

Neurons in the brainstem control fine motor skills

Using a mouse model, the researchers have been able to demonstrate that a specific region of the brainstem is responsible for various fine motor activities of the forelimbs. For their investigations they applied so-called optogenetic and viral methods in order to mark neurons and observe their activity. This enabled the team to localize four neuronal subpopulations in this region and correlate with specific functions. For example, one group of neurons was able to elicit forelimb reaching, while another group controls handling of the food.

In terms of evolution, the brainstem is the oldest part of the brain and is the direct extension of the spinal cord. The brainstem is an important switchboard between higher order movement planning centers in the brain and the executive circuits in the spinal cord. In the spinal cord, information streams about movement ultimately reach motor neurons that are directly connected to muscles cells. These in turn control movement through contraction. It has only recently been discovered that the brainstem consists of many areas containing functionally specialized neuronal populations, engaged with the control of diverse forms of body movements.

Map of brainstem circuits for fine motor skills

In their study, Arber's team has defined the organization of the neurons in one of those brainstem regions called the "lateral rostral medulla» (latRM) and traced their communication pathways. This enabled the researchers to associate different behavioral activities with specific groups of latRM neurons. "Relatively simple forelimb actions such as reaching for food are accomplished by latRM neurons with direct projections to the spinal cord," explains the first author Ludwig Ruder.

Executing more complex forelimb movements, which also involve the fingers, i.e. grasping or bringing a piece of food to the mouth, are controlled by latRM neurons with connections to neurons in other brainstem regions. "The connections and circuits within the brainstem are indispensable for more complex motor skills," says Arber. "The neuronal populations we identified in the latRM very specifically control motor skills of the forelimbs. Notably, the generation of complex and precise forelimb movements such as throwing, grasping or writing require the communication between different brainstem regions."

Control of motor actions is similar in man and animals

The division of neuronal populations according to different forms of movements based on spatial organization and connectivity provides insights into the function of the brainstem and the control of motor behavior, in this case fine motor skills of the arm and hand. Many neuronal circuits of the brainstem are similar in humans and animals. It is therefore possible to hypothesize which neuronal populations control which movements or how diseases or injury may impair fine motor skills or other behaviors in humans.
-end-


University of Basel

Related Neurons Articles from Brightsurf:

Paying attention to the neurons behind our alertness
The neurons of layer 6 - the deepest layer of the cortex - were examined by researchers from the Okinawa Institute of Science and Technology Graduate University to uncover how they react to sensory stimulation in different behavioral states.

Trying to listen to the signal from neurons
Toyohashi University of Technology has developed a coaxial cable-inspired needle-electrode.

A mechanical way to stimulate neurons
Magnetic nanodiscs can be activated by an external magnetic field, providing a research tool for studying neural responses.

Extraordinary regeneration of neurons in zebrafish
Biologists from the University of Bayreuth have discovered a uniquely rapid form of regeneration in injured neurons and their function in the central nervous system of zebrafish.

Dopamine neurons mull over your options
Researchers at the University of Tsukuba have found that dopamine neurons in the brain can represent the decision-making process when making economic choices.

Neurons thrive even when malnourished
When animal, insect or human embryos grow in a malnourished environment, their developing nervous systems get first pick of any available nutrients so that new neurons can be made.

The first 3D map of the heart's neurons
An interdisciplinary research team establishes a new technological pipeline to build a 3D map of the neurons in the heart, revealing foundational insight into their role in heart attacks and other cardiac conditions.

Mapping the neurons of the rat heart in 3D
A team of researchers has developed a virtual 3D heart, digitally showcasing the heart's unique network of neurons for the first time.

How to put neurons into cages
Football-shaped microscale cages have been created using special laser technologies.

A molecule that directs neurons
A research team coordinated by the University of Trento studied a mass of brain cells, the habenula, linked to disorders like autism, schizophrenia and depression.

Read More: Neurons News and Neurons Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.