Brain network that controls use of tools identified

Scientists have discovered that there is a specific network in the brain for using tools. Researchers from Technische Universitat Munchen (TUM) and the Klinikum rechts der Isar hospital in Germany have analysed the brain networks that control the use of tools or other utensils.

Their chosen method of functional magnetic resonance imaging (fMRI) showed the areas of the brain that are activated when a person thinks, moves and performs actions. “Numerous studies are investigating the neural processes at play when we pick up a tool,” said Professor Joachim Hermsdorfer from TUM’s Chair of Human Movement Science.

“But many of these studies are restricted to test subjects observing an action, miming it, or simply visualising it,” Hermsdorfer said.

In the study, the subjects received ten everyday objects, including a hammer, a bottle-opener, a key, a lighter and a scissors as well as some unfamiliar objects. Their task was to either use the objects or simply lift them up and place them down again, first with the left and then with the right hand.

When they analysed the data, the scientists looked at the planning phase and the actual execution phase separately.In this way, they were able to identify the brain networks that were activated while the subjects planned and used a tool and those that controlled execution.

One important finding was that the left hemisphere was activated when the subjects planned to use a tool - regardless of the hand they held it in. In addition, the researchers recognised a distributed network responsible for both planning and execution. When working with unfamiliar objects, these regions of the brain were less activated.

The ‘tool network’ consists of brain regions of the parietal and frontal lobes as well as regions in the posterior temporal lobe and another area in the lateral occipital lobe.

Researchers found a neural activation pattern that covered all elements of a complex action. This includes recognising the objects as tools, understanding how they are used, and the motor action to actually use the tool.

“The study also allowed us to confirm that there are different streams of perception in the brain for different tasks,” said Hermsdorfer.

The dorsal stream of perception conducts signals to the posterior parietal lobe and is generally responsible for controlling actions.

“It can be divided into two function-specific processing pathways. The dorso-dorsal stream controls basic gripping and movement processes, regardless of whether the person is familiar with the object or not. A second ventro-dorsal stream becomes active when we use tools that are familiar to us,” Hermsdorfer said.

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