One of the very first observations made regarding alpha oscillations (8-14 Hz), is that they increase in power over posterior areas when awake participants close their eyes. Recent work, especially in the context of (spatial) attention, suggests that alpha activity reflects a mechanism of functional inhibition. However, it remains unclear how eye closure impacts anticipatory alpha modulation observed in attention paradigms, and how this affects subsequent behavioral performance. Here, we recorded magnetoencephalography (MEG) in 33 human participants performing a tactile discrimination task with their eyes open vs. closed. We replicated the hallmarks of previous somatosensory spatial attention studies: alpha lateralization across the somatosensory cortices as well as alpha increase over posterior (visual) regions. Furthermore, we found that eye closure leads to (i) reduced task performance, (ii) widespread increase in alpha power, and (iii) reduced anticipatory visual alpha modulation (iv) with no effect on somatosensory alpha lateralization.Regardless of whether participants had their eyes open or closed, increased visual alpha power and somatosensory alpha lateralization improved their performance. Thus, we provide evidence that eye closure does not alter the impact of anticipatory alpha modulations on behavioral performance. We propose there is an optimal visual alpha level for somatosensory task performance, which can be achieved through a combination of eye closure and top-down anticipatory attention. 3 Significance StatementAlpha oscillations are dominant when awake participants have their eyes closed. Furthermore, alpha is known to modulate with anticipatory attention, and has been ascribed a role of active functional inhibition. Surprisingly, the link between anticipatory alpha and eye closure remains unclear. Here we collected MEG data while human participants performed a tactile discrimination task either with their eyes open or closed. Eye closure led to a widespread increase in alpha power, and affected anticipatory visual alpha modulation but not somatosensory alpha lateralization.Importantly, eye closure did not affect the correlation between alpha and task performance. Our findings provide novel insights into how eye closure impacts anticipatory alpha modulation, and how optimal alpha levels for task performance can be achieved differently.

One of the very first observations made regarding alpha oscillations (8-14 Hz), is that they increase in power over posterior areas when awake participants close their eyes. Recent work, especially in the context of (spatial) attention, suggests that alpha activity reflects a mechanism of functional inhibition. However, it remains unclear how eye closure impacts anticipatory alpha modulation observed in attention paradigms, and how this affects subsequent behavioral performance. Here, we recorded magnetoencephalography (MEG) in 33 human participants performing a tactile discrimination task with their eyes open vs. closed. We replicated the hallmarks of previous somatosensory spatial attention studies: alpha lateralization across the somatosensory cortices as well as alpha increase over posterior regions. Furthermore, we found that eye closure leads to (i) reduced task performance, (ii) widespread increase in alpha power, and (iii) reduced anticipatory visual alpha modulation (iv) with no effect on somatosensory alpha lateralization. Regardless of whether participants had their eyes open or closed, increased posterior alpha power and somatosensory alpha lateralization improved their performance. Thus, we provide evidence that eye closure does not alter the impact of anticipatory alpha modulations on behavioral performance. We propose there is an optimal posterior alpha level for somatosensory task performance, which can be achieved through a combination of eye closure and top-down anticipatory attention.