Biology subjects

ElShafei, H. A.

Publications and source records attributed to ElShafei, H. A..

5 recordsLinked to original sources

bioRxiv2022

When do we become more prone to distraction? Progressive evolution of the different components of distractibility from early to late adulthood.

Life expectancy has steadily increased for over a century; we thus live longer and are more likely to experience cognitive difficulties such as increased distractibility which can hamper autonomy. This cross-sectional behavioral study aimed to characterize the decline of the cognitive components of distractibility during typical aging, and the onset of this decline. 191 participants from 21 to 86 years old, distributed within seven age groups, were tested using the Competitive Attention Test. Results indicate that cognitive components contributing to distractibility follow different trajectories with aging: voluntary orienting remains stable from 21 to 86 years old, sustained attention decreases while distraction increases between 26 and 86 years old, finally, impulsivity is lower in older compared to younger adults. Increased distractibility in older adults thus seems to result from a dominance of involuntary over voluntary attention processes, whose detrimental effect on performance is partly compensated by enhanced recruitment of motor control.

neuroscience↗

bioRxiv2021

The impact of eye closure on anticipatory alpha activity in a tactile discrimination task

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. 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.

animal behavior and cognition↗

bioRxiv2020

No behavioral evidence for rhythmic facilitation of perceptual discrimination

It has been hypothesized that internal oscillations can synchronize (i.e., entrain) to external environmental rhythms, thereby facilitating perception and behavior. To date, evidence for the link between the phase of neural oscillations and behavior has been scarce and contradictory; moreover, it remains an open question whether the brain can use this tentative mechanism for active temporal prediction. In our present study, we conducted a series of auditory pitch discrimination tasks with 181 healthy participants in an effort to shed light on the proposed behavioral benefits of rhythmic cueing and entrainment. In the three versions of our task, we observed no perceptual benefit of purported entrainment: targets occurring in-phase with a rhythmic cue provided no perceptual benefits in terms of discrimination accuracy or reaction time when compared with targets occurring out-of-phase or targets occurring randomly, nor did we find performance differences for targets preceded by rhythmic vs. random cues. However, we found a surprising effect of cueing frequency on reaction time, in which participants showed faster responses to cue rhythms presented at higher frequencies. We therefore provide no evidence of entrainment, but instead a tentative effect of covert active sensing in which a faster external rhythm leads to a faster communication rate between motor and sensory cortices, allowing for sensory inputs to be sampled earlier in time.

neuroscience↗

bioRxiv2019

Attentional alterations in migraine: a behavioral and M/EEG study

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSObjectivesC_ST_ABSTo evaluate alterations of top-down and/or bottom-up attention in migraine and their cortical underpinnings. Methods19 migraineurs between attacks and 19 matched control participants performed a task evaluating jointly top-down and bottom-up attention, using visually-cued target sounds and unexpected task-irrelevant distracting sounds. Behavioral responses and MEG/EEG were recorded. Event-related potentials and fields (ERPs/ERFs) were processed and source reconstruction was applied to ERFs. ResultsAt the behavioral level, neither top-down nor bottom-up attentional processes appeared to be altered in migraine. However, migraineurs presented heightened evoked responses following distracting sounds (orienting component of the N1 and Re-Orienting Negativity, RON) and following target sounds (orienting component of the N1), concomitant to an increased recruitment of the right temporo-parietal junction. They also displayed an increased effect of the cue informational value on target processing resulting in the elicitation of a negative difference (Nd). ConclusionsMigraineurs appear to display increased bottom-up orienting response to all incoming sounds, and an enhanced recruitment of top-down attention. SignificanceThe interictal state in migraine is characterized by an exacerbation of the orienting response to attended and unattended sounds. These attentional alterations might participate to the peculiar vulnerability of the migraine brain to all incoming stimuli. HO_SCPLOWIGHLIGHTSC_SCPLOWO_LIMigraineurs performed as well as healthy participants in an attention task. C_LIO_LIHowever, EEG markers of both bottom-up and top-down attention are increased. C_LIO_LIMigraine is also associated with a facilitated recruitment of the right temporo-parietal junction. C_LI

neuroscience↗

bioRxiv2018

What is in Your Gamma? Activation of The Ventral Fronto-Parietal Attentional Network in Response to Distracting Sounds

Auditory attention operates through top-down (TD) and bottom-up (BU) mechanisms that are supported by dorsal and ventral brain networks, respectively, with the main overlap in the lateral prefrontal cortex (lPFC). A good TD/BU balance is essential to be both task-efficient and aware of our environment, yet it is rarely investigated. Oscillatory activity is a novel method to probe the attentional dynamics with evidence that gamma activity (>30Hz) could signal BU processing and thus would be a good candidate to support the activation of the ventral BU network. MEG data were collected from 21 young adults performing the Competitive Attention Task which enables simultaneous investigation of BU and TD attentional mechanisms. Distracting sounds elicited an increase in gamma activity in regions of the BU ventral network. TD attention modulated these gamma responses in regions of the inhibitory cognitive control system: the medial prefrontal and anterior cingulate cortices. Finally, distracting-sound-induced gamma activity was synchronous between the auditory cortices and several distant brain regions, notably the lPFC. We provide novel insight into the role of gamma activity (1) in supporting the activation of the BU ventral network, and (2) in subtending the TD/BU attention balance in the prefrontal cortex.

neuroscience↗