Tactile expectancy modulates occipital alpha oscillations in early blindness

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Sensory Processing

Background:

• Alpha oscillatory activity is linked to visual expectancy and occipital region engagement.
• Reduced occipital alpha in early blindness suggests dependence on visual experience.
• Occipital cortex recruitment for non-visual processing in blind individuals raises questions about alpha's role.

Purpose of the Study:

• To investigate if alpha oscillations reflect differential recruitment of task-relevant regions for expectancy in blind individuals during haptic tasks.
• To determine if posterior alpha activity's role in expectancy is dependent on visual experience.

Main Methods:

• Electroencephalography (EEG) was used to examine alpha oscillations in two haptic tasks (texture and shape discrimination).
• Sensor-level analyses and source reconstruction were employed to analyze parieto-occipital and middle occipital cortex activity.
• Comparisons were made between expected and unexpected conditions in early blind and sighted participants.

Main Results:

• Alpha suppression in parieto-occipital sites was significantly reduced in early blind individuals compared to sighted controls.
• Source reconstruction identified the middle occipital cortex as the origin of group differences.
• In the middle occipital cortex, expected trials showed greater alpha desynchronization in the early blind group only.

Conclusions:

• Posterior alpha activity, though reduced in blindness, remains sensitive to expectancy.
• Occipital alpha rhythms support tactile expectancy in early blind individuals, mirroring visual anticipation's role in sighted populations.
• Expectancy-dependent modulation of alpha oscillatory activity does not require visual experience, highlighting its cross-modal adaptability.