Neural basis for anxiety and anxiety-related physiological responses during simulated driving: An fMRI study

While the exteroceptive and interoceptive prediction of a negative event increases a person's anxiety in daily life situations, the relationship between the brain mechanism of anxiety and anxiety-related autonomic response have not been fully understood. In this fMRI study, we examined the neural basis of anxiety and anxiety-related autonomic responses in a daily driving situation. Participants viewed a driving video clip in the first-person perspective. In the middle of the video clip, participants were presented with a cue to indicate whether a subsequent crash could occur (attention condition) or not (safe condition). Compared with the safe condition, there were more activities in the anterior insula, bed nucleus of the stria terminalis, thalamus, and periaqueductal gray, and higher sympathetic nerve responses, such as pupil dilation and peripheral arterial stiffness in the attention condition. We also observed autonomic response-related functional connectivity in the visual cortex, cerebellum, brainstem, and MCC/PCC with the right anterior insula and its adjacent regions as seed regions. Thus, the right anterior insula and adjacent regions, collaborating with the other related regions, could play a fundamental role in eliciting anxiety based on the prediction of negative events by mediating anxiety-related autonomic responses according to interoceptive information.

Increasing the Spatial Extent of Attention Strengthens Surround Suppression

Here we investigate how the extent of spatial attention affects center-surround interaction in visual motion processing. To do so, we measured motion direction discrimination thresholds in humans using drifting gratings and two attention conditions. Under the narrow attention condition, attention was limited to the central part of the visual stimulus, whereas under the wide attention condition, it was directed to both the center and surround of the stimulus. We found stronger surround suppression under the wide attention condition. The magnitude of the attention effect increased with the size of the surround when the stimulus had low contrast, but did not change when it had high contrast. Results also showed that attention had a weaker effect when the center and surround gratings drifted in opposite directions. Next, to establish a link between the behavioral results and the neuronal response characteristics, we performed computer simulations using the divisive normalization model. Our simulations showed that the model can successfully predict the observed behavioral results using parameters derived from the medial temporal (MT) area of the cortex. These findings reveal the critical role of spatial attention on surround suppression and establish a link between neuronal activity and behavior. Further, these results also suggest that the reduced surround suppression found in certain clinical disorders (e.g., schizophrenia and autism spectrum disorder) may be caused by abnormal attention mechanisms.

Semantically Congruent Bimodal Presentation with Divided-Modality Attention Accelerates Unisensory Working Memory Retrieval

Although previous studies have shown that semantic multisensory integration can be differentially modulated by attention focus, it remains unclear whether attentionally mediated multisensory perceptual facilitation could impact further cognitive performance. Using a delayed matching-to-sample paradigm, the present study investigated the effect of semantically congruent bimodal presentation on subsequent unisensory working memory (WM) performance by manipulating attention focus. The results showed that unisensory WM retrieval was faster in the semantically congruent condition than in the incongruent multisensory encoding condition. However, such a result was only found in the divided-modality attention condition. This result indicates that a robust multisensory representation was constructed during semantically congruent multisensory encoding with divided-modality attention; this representation then accelerated unisensory WM performance, especially auditory WM retrieval. Additionally, an overall faster unisensory WM retrieval was observed under the modality-specific selective attention condition compared with the divided-modality condition, indicating that the division of attention to address two modalities demanded more central executive resources to encode and integrate crossmodal information and to maintain a constructed multisensory representation, leaving few resources for WM retrieval. Additionally, the present finding may support the amodal view that WM has an amodal central storage component that is used to maintain modal-based attention-optimized multisensory representations.

Brain Oscillation Entrainment by Perceptible and Non-perceptible Rhythmic Light Stimulation

Objective and Background: Decades of research in the field of steady-state visual evoked potentials (SSVEPs) have revealed great potential of rhythmic light stimulation for brain–computer interfaces. Additionally, rhythmic light stimulation provides a non-invasive method for entrainment of oscillatory activity in the brain. Especially effective protocols enabling non-perceptible rhythmic stimulation and, thereby, reducing eye fatigue and user discomfort are favorable. Here, we investigate effects of (1) perceptible and (2) non-perceptible rhythmic light stimulation as well as attention-based effects of the stimulation by asking participants to focus (a) on the stimulation source directly in an overt attention condition or (b) on a cross-hair below the stimulation source in a covert attention condition.Method: SSVEPs at 10 Hz were evoked with a light-emitting diode (LED) driven by frequency-modulated signals and amplitudes of the current intensity either below or above a previously estimated individual threshold. Furthermore, we explored the effect of attention by asking participants to fixate on the LED directly in the overt attention condition and indirectly attend it in the covert attention condition. By measuring electroencephalography, we analyzed differences between conditions regarding the detection of reliable SSVEPs via the signal-to-noise ratio (SNR) and functional connectivity in occipito-frontal(-central) regions.Results: We could observe SSVEPs at 10 Hz for the perceptible and non-perceptible rhythmic light stimulation not only in the overt but also in the covert attention condition. The SNR and SSVEP amplitudes did not differ between the conditions and SNR values were in all except one participant above significance thresholds suggested by previous literature indicating reliable SSVEP responses. No difference between the conditions could be observed in the functional connectivity in occipito-frontal(-central) regions.Conclusion: The finding of robust SSVEPs even for non-intrusive rhythmic stimulation protocols below an individual perceptibility threshold and without direct fixation on the stimulation source reveals strong potential as a safe stimulation method for oscillatory entrainment in naturalistic applications.

Superior Performance in Skilled Golfers Characterized by Dynamic Neuromotor Processes Related to Attentional Focus

The meshed control theory assumes that cognitive control and automatic processes work together in the natural attention of experts for superior performance. However, the methods adopted by previous studies limit their capacity to provide in-depth information on the neuromotor processes. This experiment tested the theory with an alternative approach. Twelve skilled golfers were recruited to perform a putting task under three conditions: (1) normal condition, with no focus instruction (NC), (2) external focus of attention condition (EC), and (3) internal focus of attention condition (IC). Four blocks of 10 putts each were performed under each condition. The putting success rate and accuracy were measured and electroencephalographies (EEGs) were recorded. The behavioral results showed that the NC produced a higher putting success rate and accuracy than the EC and IC. The EEG data showed that the skilled golfers’ attentional processes in the NC initially resembled those in the EC and then moved toward those in the IC just before putting. This indicates a switch from more automatic processes to cognitive control processes while preparing to putt. The findings offer support for the meshed control theory and indicate the dynamic nature of neuromotor processes for the superior performance of athletes in challenging situations.

Effects of the Attention Training Technique on Brain Activity in Healthy University Students Assessed by EEG Source Imaging

This study aimed to investigate the neurocognitive effects of the Attention Training Technique (ATT) on brain activity in healthy participants. The participants included 20 university students who were asked to practice ATT as a homework assignment for 20 days. The intracerebral source localization of their electroencephalogram during rest and the ATT task, which comprised selective attention, attention switching, and divided attention conditions, was evaluated by standardized low-resolution brain electromagnetic tomography. Brain activity during rest was subtracted from that during the ATT task, and that was compared before and after the homework assignment. The results for the divided attention condition indicated significantly decreased alpha 1 frequency band power in the left orbital frontal cortex (OFC) and alpha 2 power in the right inferior temporal cortex. Further, decreased alpha 1 power in the left OFC correlated with reduced subjective difficulty during the divided attention condition. One possibility is that the brain activity changed as the effect of ATT practice, although this study cannot confirm causality. Further studies are required which include a control group that would complete similar training without the ATT task.

Decoding of attentional state using high-frequency local field potential is as accurate as using spikes

Local field potentials (LFPs) in visual cortex are reliably modulated when the subject’s focus of attention is cued into versus out of the receptive field of the recorded sites, similar to modulation of spiking activity. However, human psychophysics studies have used an additional attention condition, neutral cueing, for decades. The effect of neutral cueing on spiking responses was examined recently and found to be intermediate between cued and uncued conditions. However, whether LFPs are also precise enough to represent graded states of attention is unknown. We found that LFPs during neutral cueing were intermediate between cued and uncued conditions, and, for a single electrode, attention was more discriminable using high frequency (>30 Hz) LFP power than spikes. Surprisingly, spikes did not outperform LFPs even when discriminability was computed using multiple electrodes. These results constrain the spatial scale attention operates over and highlight the usefulness of LFPs in studying attention.

Neural representations of covert attention across saccades: comparing pattern similarity to shifting and holding attention during fixation

We can focus visuospatial attention by covertly attending to relevant locations, moving our eyes, or both simultaneously. How does shifting versus holding covert attention during fixation compare with maintaining covert attention across saccades? We acquired fMRI data during a combined saccade and covert attention task. On Eyes-fixed trials, participants either held attention at the same initial location (“hold attention”) or shifted attention to another location midway through the trial (“shift attention”). On Eyes-move trials, participants made a saccade midway through the trial, while maintaining attention in one of two reference frames: The “retinotopic attention” condition involved holding attention at a fixation-relative location but shifting to a different screen-centered location, whereas the “spatiotopic attention” condition involved holding attention on the same screen-centered location but shifting relative to fixation. We localized the brain network sensitive to attention shifts (shift > hold attention), and used multivoxel pattern time course analyses to investigate the patterns of brain activity for spatiotopic and retinotopic attention. In the attention shift network, we found transient information about both whether covert shifts were made and whether saccades were executed. Moreover, in the attention shift network, both retinotopic and spatiotopic conditions were represented more similarly to shifting than to holding covert attention. An exploratory searchlight analysis revealed additional regions where spatiotopic was relatively more similar to shifting and retinotopic more to holding. Thus, maintaining retinotopic and spatiotopic attention across saccades may involve different types of updating that vary in similarity to covert attention “hold” and “shift” signals across different regions.Significance StatementTo our knowledge, this study is the first attempt to directly compare human brain activity patterns of covert attention (to a peripheral spatial location) across saccades and during fixation. We applied fMRI multivoxel pattern time course analyses to capture the dynamic changes of activity patterns, with specific focus on the critical timepoints related to attention shifts and saccades. Our findings indicate that both retinotopic and spatiotopic attention across saccades produce patterns of activation similar to “shifting” attention in the brain, even though both tasks could be interpreted as “holding” attention by the participant. The results offer a novel perspective to understand how the brain processes and updates spatial information under different circumstances to fit the needs of various cognitive tasks.

Tracking the Effects of Top–Down Attention on Word Discrimination Using Frequency-tagged Neuromagnetic Responses

Discrimination of words from nonspeech sounds is essential in communication. Still, how selective attention can influence this early step of speech processing remains elusive. To answer that question, brain activity was recorded with magnetoencephalography in 12 healthy adults while they listened to two sequences of auditory stimuli presented at 2.17 Hz, consisting of successions of one randomized word (tagging frequency = 0.54 Hz) and three acoustically matched nonverbal stimuli. Participants were instructed to focus their attention on the occurrence of a predefined word in the verbal attention condition and on a nonverbal stimulus in the nonverbal attention condition. Steady-state neuromagnetic responses were identified with spectral analysis at sensor and source levels. Significant sensor responses peaked at 0.54 and 2.17 Hz in both conditions. Sources at 0.54 Hz were reconstructed in supratemporal auditory cortex, left superior temporal gyrus (STG), left middle temporal gyrus, and left inferior frontal gyrus. Sources at 2.17 Hz were reconstructed in supratemporal auditory cortex and STG. Crucially, source strength in the left STG at 0.54 Hz was significantly higher in verbal attention than in nonverbal attention condition. This study demonstrates speech-sensitive responses at primary auditory and speech-related neocortical areas. Critically, it highlights that, during word discrimination, top–down attention modulates activity within the left STG. This area therefore appears to play a crucial role in selective verbal attentional processes for this early step of speech processing.