A team of Scientists have identified the areas of brain who are activated when a person becomes aware of self and his thoughts. This enigmatic process seems to be controlled by thalamus, a central region of the brain already known for its filter function between sensory signals and the cerebral cortex, the part of the brain which governs higher level processes such as memory, thought and personality.
Conscious perception is the capacity of human beings to become aware of the stimuli received by their senses. It is a different state of simple awakening, where the sensations are processed automatically and in an unplugged manner. Conscious perception rather requires a detailed and voluntary analysis of external stimuli. For example, we can breathe automatically, but we can also be aware of our breathing and modify its rhythm. Likewise, when listening to a song, we can pay attention and differentiate the instruments that make it up.
Recently, neurologists have decided to find the part of the brain where this change in perception occurs. The researchers traditionally suspected that such a function should be controlled by the cerebral cortex, because this is where the treatment of the advanced brain occurs. The thalamus has never been excluded to participate in a conscious perception, but it was generally attributed to a minor role as a filter which prepares sensory information in the cortex. A new study recently published in Science redefines this point of view, positioning thalamus as a participant active in conscious perception.
Most studies on consciousness involving thalamus have been faced with skepticism, either because they lack the key observation data from Thalamus at work or, if they are highlighted with the data, due to the controversial manner in which this data has probably been obtained. To see if the region of the brain of a patient “lights up” with an activity during the aware attention of something, it is necessary that this patient is aware of the stimuli – that is to say being aware – while simultaneously having his brain interviewed with invasive sensors.
But in this new research, a team from the Normal University of Beijing in China turned to a group of people who already had thin electrodes inserted in their brain in the context of experimental headache therapy, bypassing the ethical question of knowing whether this type of research justifies an invasive operation.
Researchers administered a visual perception test to these patients. A flashing object has been displayed on a screen, which would be hidden during half the time of the test. These characteristics meant that patients had to pay attention to the object and adjust their eyes and focus to continue looking at it, rather than simply considering the screen without analyzing it. This therefore facilitated conscious perception, with the electrodes already established, then recording the brain activity which accompanied it.
The researchers say that this is one of the first simultaneous recordings of conscious perception, and the information they have recorded, they say, offers solid evidence for the hypothesis that the region of Thalamus acts a sort of gateway to conscious perception. “The results indicate that the medial intralamine and thalamic nuclei regulate conscious perception. This conclusion represents a significant progression in our understanding of the network which constitutes the basis of visual consciousness in humans,” write the authors.
This story originally appeared on Cable in Spanish and was translated from Spanish.
