Pupil Size and the Alpha Band of Neural Oscillations Mirror Cognition

Being able to simply observe the world through our own eyes, some people may take for granted the processes of thinking, feeling, and imagination. In fact, cognitive processes enable us to form cultures, societies, friendships, and professions—many crucial facets of human existence. Two parameters have been connected with cognition; neural oscillation (alpha band) and pupil size. The role of oscillatory brain activity is a topic of intense and expanding attention in the field of cognitive neuroscience.Eye

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Cognition can be measured

Neural oscillations are a representation of the neural activity of the brain. These are synchronized rhythmic electrical patterns in the brain. They have been linked to various cognitive functions like perception, motor control, memory, and lots more. The alpha oscillations have been discovered to be the dominant oscillation. Also, it has long been known that a person’s pupil size changes depending on how much cognitive effort they put into a task and it has been linked to hearing and listening. The theory says that pupil dilation increases as speech comprehension difficulty increases due to acoustic degradation, acoustic making, or linguistic complexity. Another theory regarding oscillation suggests that there is an increase in alpha power when audio-related cognitive demand increases and a decrease in alpha power during a visual-related cognitive function.

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A study was carried out by a group of scientists to investigate this hypothesis. 24 adults; 7 males and 17 females, all right-handed were used for this experiment. The written content was gotten and the appropriate guidelines were followed. Visual stimulation was delivered through a computer monitor in the sound booth via the stimulation computer while the sound was delivered through headphones. A four-button response box was used to respond.

The right eye’s pupil size and eye movement were continuously measured. Electroencephalogram(EEG) data were recorded and analyzed. Performance in single and hard tasks was analyzed for accuracy and speed. On result evaluation, it was discovered that Cognitive demand altered both pupil size and alpha power. According to behavioral data, people preferred performing auditory tasks over visual ones. There was increased dilation of pupils following visual and auditory stimulation and the distinctive time evolution of the needed cognitive task demands in each modality was reflected by the temporal dynamics of the pupil size.

Clinical significance

These findings prove useful. With the knowledge of the effect of cognition on pupil size and oscillation, scientists can monitor brain functions and it can lead the way to discover new ways to tackle cognition disorders.

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The study created a huge connection between pupil dilation, brain oscillation, and cognition. It shows that the dynamics that occur in the brain cells are multi-faceted and depend on audio and visual task conditions.


Neural alpha oscillations and pupil size differentially index cognitive demand under competing audio-visual task conditions



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