Can people be characterized as left or right brained? This is a common perception and used in some educational programs, yet neuroscience has found no evidence that this is a factor (these are so-termed ‘neuromyths‘).
However, a new study does suggest that different sides of the brain do specialize and that hemispheric dominance does occur. This finding comes from Ruhr-Universität Bochum. Here the research team used a pigeon model to show how small differences in reaction time are the basis for hemispheric dominance.
In the brain, the left and right cerebral hemispheres are separated by a groove, the longitudinal fissure. While most brain functions are distributed across both hemispheres, there are some differences which researchers are investigating.
For the research, since birds are visually lateralized, the scientists tested the pigeons monocularly using a color discrimination task. At the same time the researchers focused on taking measurements from a single visuomotor forebrain neuron.
Although, as Laboratory Roots discusses, the neurons that the researchers were stimulating reacted at the same rate in both hemispheres, it was the left hemisphere which could trigger reactions faster. This analysis demonstrated that each bird learned faster and responded quickly with the right eye and left hemisphere. The study also found that a greater number of neurons were activated in the left hemisphere; plus, the neurons in the left hemisphere were able to alter the response in the right hemisphere.
This asymmetry was found to be based on three things. The first factor was that the ‘go-stimulus’ onset led to a higher left hemispheric proportion of excited relative to inhibited neurons. The second factor was that left-sided visuomotor neurons were able to trigger the bird’s response faster. The third factor was that the left hemisphere was able to adjust the timing of individual activity patterns of right hemispheric neurons.
The results were verified by the researchers occasionally blocking the activity of the neurons that communicate with the other hemisphere.
The results therefore showed that hemispheric dominance in birds occurs by lateralized activation of forebrain motor areas. Furthermore, this issue to dominance will probably occur in most animals, including humans.
The research shows that the subject of brain hemisphere dominance mechanisms are much more complex than hitherto assumed. The implications of the new study could impact on areas where reaction time is a significant factor, from piloting aircraft to playing computer games.
Report
The study has been published in the journal Cell Reports. The research is titled “Asymmetrical Commissural Control of the Subdominant Hemisphere in Pigeons.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we outlined a new sensor that can monitor oxygen levels inside the human body, by scanning the surface of the skin. The new device can be used to track the progress of oxygenation in relation to healing wounds in real time, providing valuable medical data.
The week before we weighed in on new Canadian research suggests that the origins of chocolate are older than any previous research has indicated.
