Attention-dependent switching between intrinsic-muscle and extrinsic-visual coordinates during bimanual movements.

Inter-limb coordination is achieved through multiple levels of motor control based on intrinsic-muscle and extrinsic-visual coordinates. Online visual feedback affects which of these coordinates is dominant, and visual perception is involved in the switching of motor coordination across the two hands; however, it remains unclear whether there is any role for attention in inter-limb coordination. Therefore, we evaluated the effects of attention on the dominance of intrinsic-muscle and extrinsic-visual coordinates by investigating inter-limb interference in the right or left hand during bimanual reaching movements, as induced by visual perturbations. We first showed an effect of differences in online visual feedback on bimanual coordination (Experiment 1). We then revealed that attention to visual cursors that directly affected the hand movement led to the dominance of the intrinsic-muscle coordinates, which synchronized homologous muscle activities. In contrast, attention to an integrated visual object controlled by bilateral hand movements was associated with a preference for extrinsic-visual coordinates to synchronize bilateral movement directions (Experiment 2). Thus, attention-dependent switching between intrinsic-muscle and extrinsic-visual coordinates was observed during bimanual movements; extrinsic-visual coordinates may enable goal-directed bimanual movements at least for particular task requirements.

Monitoring the Cortical Activity of Children and Adults during Cognitive Task Completion.

In this paper, we used an EEG system to monitor and analyze the cortical activity of children and adults at a sensor level during cognitive tasks in the form of a Schulte table. This complex cognitive task simultaneously involves several cognitive processes and systems: visual search, working memory, and mental arithmetic. We revealed that adults found numbers on average two times faster than children in the beginning. However, this difference diminished at the end of table completion to 1.8 times. In children, the EEG analysis revealed high parietal alpha-band power at the end of the task. This indicates the shift from procedural strategy to less demanding fact-retrieval. In adults, the frontal beta-band power increased at the end of the task. It reflects enhanced reliance on the top-down mechanisms, cognitive control, or attentional modulation rather than a change in arithmetic strategy. Finally, the alpha-band power of adults exceeded one of the children in the left hemisphere, providing potential evidence for the fact-retrieval strategy. Since the completion of the Schulte table involves a whole set of elementary cognitive functions, the obtained results were essential for developing passive brain-computer interfaces for monitoring and adjusting a human state in the process of learning and solving cognitive tasks of various types.

Attentional modulation differentially affects ventral and dorsal face areas in both normal participants and developmental prosopagnosics.

Face-selective cortical areas that can be divided into a ventral stream and a dorsal stream. Previous findings indicate selective attention to particular aspects of faces have different effects on the two streams. To better understand the organization of the face network and whether deficits in attentional modulation contribute to developmental prosopagnosia (DP), we assessed the effect of selective attention to different face aspects across eight face-selective areas. Our results from normal participants found that ROIs in the ventral pathway (OFA, FFA) responded strongly when attention was directed to identity and expression, and ROIs in the dorsal pathway (pSTS-FA, IFG-FA) responded the most when attention was directed to facial expression. Response profiles generated by attention to different face aspects were comparable in DPs and normals. Our results demonstrate attentional modulation affects the ventral and dorsal steam face areas differently and indicate deficits in attentional modulation do not contribute to DP.

Spatial specificity in attentional modulation of prepulse inhibition of the startle reflex in rats.

Prepulse inhibition (PPI), the suppression of the startle reflex when the startling stimulus is shortly preceded by a weaker non-startling sensory stimulus (prepulse), can be enhanced by selective attention to the prepulse with a marked prepulse-feature specificity. To determine if the attentional modulation of PPI in rats can also be perceptual location specific, this study investigated whether fear-conditioning of a prepulse perceived at a location can enhance PPI only when the conditioned prepulse is perceived at that conditioned location. A continuous narrowband noise (NBN) was delivered by each of the two spatially separated loudspeakers in the frontal azimuth with a silent gap embedded in each NBN. The inter-loudspeaker interval was 1 ms (either left or right loudspeaker leading). Due to the precedence effect, both the NBN and gap images were perceived at the leading loudspeaker. The perceptually fused gap was used as the prepulse. To fear-condition one gap prepulse, which was perceived at one loudspeaker, the prepulse was paired with footshock in a temporally precise manner and the other gap (the conditioning-control prepulse) perceived at the other (opposite) loudspeaker was paired with footshock in a random manner. Compared to PPI before conditioning, PPI induced by the fear-conditioned gap perceived at the fear-conditioned loudspeaker, but not that by the conditioning-control gap, was significantly enhanced. Thus, attentional modulation of PPI can be not only prepulse-feature specific, but also perceptual location specific, and involves combined central processes for content and location information.

Attention Stabilizes Representations in the Human Hippocampus.

Attention and memory are intricately linked, but how attention modulates brain areas that subserve memory, such as the hippocampus, is unknown. We hypothesized that attention may stabilize patterns of activity in human hippocampus, resulting in distinct but reliable activity patterns for different attentional states. To test this prediction, we utilized high-resolution functional magnetic resonance imaging and a novel "art gallery" task. On each trial, participants viewed a room containing a painting, and searched a stream of rooms for a painting from the same artist (art state) or a room with the same layout (room state). Bottom-up stimulation was the same in both tasks, enabling the isolation of neural effects related to top-down attention. Multivariate analyses revealed greater pattern similarity in all hippocampal subfields for trials from the same, compared with different, attentional state. This stability was greater for the room than art state, was unrelated to univariate activity, and, in CA2/CA3/DG, was correlated with behavior. Attention therefore induces representational stability in the human hippocampus, resulting in distinct activity patterns for different attentional states. Modulation of hippocampal representational stability highlights the far-reaching influence of attention outside of sensory systems.

Neural dynamics underlying target detection in the human brain.

Sensory signals must be interpreted in the context of goals and tasks. To detect a target in an image, the brain compares input signals and goals to elicit the correct behavior. We examined how target detection modulates visual recognition signals by recording intracranial field potential responses from 776 electrodes in 10 epileptic human subjects. We observed reliable differences in the physiological responses to stimuli when a cued target was present versus absent. Goal-related modulation was particularly strong in the inferior temporal and fusiform gyri, two areas important for object recognition. Target modulation started after 250 ms post stimulus, considerably after the onset of visual recognition signals. While broadband signals exhibited increased or decreased power, gamma frequency power showed predominantly increases during target presence. These observations support models where task goals interact with sensory inputs via top-down signals that influence the highest echelons of visual processing after the onset of selective responses.

Pupil size reflects the focus of feature-based attention.

We measured pupil size in adult human subjects while they selectively attended to one of two surfaces, bright and dark, defined by coherently moving dots. The two surfaces were presented at the same location; therefore, subjects could select the cued surface only on the basis of its features. With no luminance change in the stimulus, we find that pupil size was smaller when the bright surface was attended and larger when the dark surface was attended: an effect of feature-based (or surface-based) attention. With the same surfaces at nonoverlapping locations, we find a similar effect of spatial attention. The pupil size modulation cannot be accounted for by differences in eye position and by other variables known to affect pupil size such as task difficulty, accommodation, or the mere anticipation (imagery) of bright/dark stimuli. We conclude that pupil size reflects not just luminance or cognitive state, but the interaction between the two: it reflects which luminance level in the visual scene is relevant for the task at hand.

Responsiveness and functional connectivity of the scene-sensitive retrosplenial complex in 7-11-year-old children.

Brain imaging studies have identified two cortical areas, the parahippocampal place area (PPA) and the retrosplenial complex (RSC), that respond preferentially to the viewing of scenes. Contrary to the PPA, little is known about the functional maturation and cognitive control of the RSC. Here we used functional magnetic resonance imaging and tasks that required attention to scene (or face) images and suppression of face (or scene) images, respectively, to investigate task-dependent modulation of activity in the RSC and whole-brain functional connectivity (FC) of this area in 7-11-year-old children and young adults. We compared responsiveness of the RSC with that of the PPA. The RSC was selectively activated by scene images in both groups, albeit less than the PPA. Children modulated activity between the tasks similarly in the RSC and PPA, and to the same extent as adults in PPA, whereas adults modulated activity in the RSC less than in PPA. In children, the whole brain FC of the RSC was stronger in the Sf than Fs task between the left RSC and right fusiform gyrus. The between groups comparison suggested stronger FC in children than adults in the Sf task between the right RSC and the left inferior parietal lobule and intraparietal sulcus. Together the results suggest that the function of the RSC and the related networks undergo dynamic changes over the development from 7-11-year-old children to adulthood.

Dissociable neuronal substrates of visual feature attention and working memory.

Attention and working memory (WM) are distinct cognitive functions, yet given their close interactions, it is often assumed that they share the same neuronal mechanisms. We show that in macaques performing a WM-guided feature attention task, the activity of most neurons in areas middle temporal (MT), medial superior temporal (MST), lateral intraparietal (LIP), and posterior lateral prefrontal cortex (LPFC-p) displays attentional modulation or WM coding and not both. One area thought to play a role in both functions is LPFC-p. To test this, we optogenetically inactivated LPFC-p bilaterally during different task periods. Attention period inactivation reduced attentional modulation in LPFC-p, MST, and LIP neurons and impaired task performance. In contrast, WM period inactivation did not affect attentional modulation or performance and minimally affected WM coding. Our results suggest that feature attention and WM have dissociable neuronal substrates and that LPFC-p plays a critical role in feature attention, but not in WM.

Different mechanisms are responsible for dishabituation of electrophysiological auditory responses to a change in acoustic identity than to a change in stimulus location.

Repeated exposure to an auditory stimulus leads to habituation of the electrophysiological and immediate-early-gene (IEG) expression response in the auditory system. A novel auditory stimulus reinstates this response in a form of dishabituation. This has been interpreted as the start of new memory formation for this novel stimulus. Changes in the location of an otherwise identical auditory stimulus can also dishabituate the IEG expression response. This has been interpreted as an integration of stimulus identity and stimulus location into a single auditory object, encoded in the firing patterns of the auditory system. In this study, we further tested this hypothesis. Using chronic multi-electrode arrays to record multi-unit activity from the auditory system of awake and behaving zebra finches, we found that habituation occurs to repeated exposure to the same song and dishabituation with a novel song, similar to that described in head-fixed, restrained animals. A large proportion of recording sites also showed dishabituation when the same auditory stimulus was moved to a novel location. However, when the song was randomly moved among 8 interleaved locations, habituation occurred independently of the continuous changes in location. In contrast, when 8 different auditory stimuli were interleaved all from the same location, a separate habituation occurred to each stimulus. This result suggests that neuronal memories of the acoustic identity and spatial location are different, and that allocentric location of a stimulus is not encoded as part of the memory for an auditory object, while its acoustic properties are. We speculate that, instead, the dishabituation that occurs with a change from a stable location of a sound is due to the unexpectedness of the location change, and might be due to different underlying mechanisms than the dishabituation and separate habituations to different acoustic stimuli.

An ethogram identifies behavioural markers of attention to humans in European herring gulls (Larus argentatus).

Herring gulls (Larus argentatus) are one of few species thriving in anthropogenic landscapes. Their history of urbanisation and familiarity with people makes them a good target for studies of human-wildlife interactions. Previous research highlights a connection between food-stealing behaviour, success in anthropogenic areas, and increased attention towards humans, raising questions about the exact extent of a gull's knowledge of human food cues. To explore these, behavioural responses to human cues in a food-related context were investigated and presented in a systematic ethogram, which identified three distinct markers of attention. Head turns, approaches, and angular body position all differed significantly between control and food conditions, showing that attention towards humans in a food-related context was upregulated and reflected in behaviour. In food condition trials, head turns occurred more often and gulls faced more towards the experimenter with occasional approaches that were never seen in control conditions. Acoustic and behavioural human food-like cues alone seemed insufficient to elicit these responses, indicating that gulls specifically paid attention to the details of human behaviour or had specific knowledge of anthropogenic food items. These results show situation-dependent attentional modulation in gulls and provide a description of attentive behaviours that can be used in further study.

Negative emotion-conditioned prepulse induces the attentional enhancement of prepulse inhibition in humans.

Prepulse inhibition (PPI) is a reduction of the acoustic startle reflex (ASR) when the startling stimulus is preceded by a weaker and non-startling stimulus (i.e., prepulse). Previous studies have revealed that PPI can be top-down modulated by selective attention to the fear-conditioned prepulse in animals. However, few researchers have tested this assumption in humans. Thus, in this study, the negative emotional-conditioned prepulse (CS+) was used to explore whether it could improve participants' attention, and further improve the PPI. The results showed that the CS+ prepulse increased the PPI only in females, PPI produced by CS+ prepulse was larger in females than in males, and the perceptual spatial attention further improved the PPI in both females and males. The results suggested that the PPI was affected by emotional, perceptual spatial attention, and sex. These findings highlight an additional method to measure top-down attentional regulation of PPI in humans. Which may offer a useful route to enhance the diagnosis of affective disorders, such as anxiety, depression, and post-traumatic stress disorder.

Spatial Tuning in Nociceptive Processing Is Driven by Attention.

When the source of nociception expands across a body area, the experience of pain increases due to the spatial integration of nociceptive information. This well-established effect is called spatial summation of pain (SSp) and has been the subject of multiple investigations. Here, we used cold-induced SSp to investigate the effect of attention on the spatial tuning of nociceptive processing. Forty pain-free volunteers (N = 40, 20 females) participated in this experiment. They took part in an SSp paradigm based on three hand immersions into cold water (5°C): Participants either immersed the radial segment ("a"), ulnar segment ("b") or both hand segments ("a+b") and provided overall pain ratings. In some trials based on "a+b" immersions, they were also asked to provide divided (ie, first pain in "a" then in "b"; or reversed) and directed attention ratings (ie, pain only in "a" or "b"). Results confirmed a clear SSp effect in which reported pain during immersions of "a" or "b" was less intense than pain during immersions of "a+b" (P < .001). Data also confirmed that spatial tuning was altered. SSp was abolished when participants provided two ratings in a divided fashion (P < .001). Furthermore, pain was significantly lower when attention was directed only to one segment ("a" OR "b") during "a+b" immersion (P < .001). We conclude that spatial tuning is dynamically driven by attention as reflected in abolished SSp. Directed attention was sufficient to focus spatial tuning and abolish SSp. Results support the role of cognitive processes such as attention in spatial tuning. PERSPECTIVE: This article presents experimental investigation of spatial tuning in pain and offers mechanistic insights of contiguous spatial summation of pain in healthy volunteers. Depending on how pain is evaluated in terms of attentional derivative (overall pain, directed, divided attention) the pain is reduced and spatial summation abolished.

Perceptual spatial position induces the attentional enhancement of prepulse inhibition and its neural mechanism.

Prepulse inhibition (PPI) is a sensorimotor gating process that reduces the startling response when a weaker sensory stimulus precedes a sudden startling stimulus. Perceptual spatial separation (PSS) between the prepulse and the background noise was found to enhance PPI compared to perceptual spatial co-location (PSC). However, little is known about the perceptual characteristics of prepulses in the PSS that induce more inhibition of the startling response and the associated neural mechanism. The dorsocentral striatum (DCS) was the convergence of spatial information from the cortical and thalamic circuits. Our study investigated whether the perceptual spatial position of prepulses induced spatial attentional modulation of PPI. In addition, whether the DCS was involved in spatial attentional modulation's neural circuits of PPI. In our study, the relative perceptual image positions of the prepulse and masker were controlled by the playback time difference between the two loudspeakers, i.e., PSS and PSC. The specific spatial attention of the prepulse was conditioned by foot shock. The results revealed that PPI was generally enhanced after fear conditioning/conditioning-control manipulation across all rats. Further enhancement of PPI in the PSS condition occurred only in the fear conditioning position, not in the conditioning-control position. We first found that PPI did not show specific spatial enhancement in the drug-blocking bilateral DCS rats with 2 mM kynurenic acid. These results demonstrated that the perceptual spatial position modulated the spatial attention of prepulse and improved PPI. DCS was involved in the attentional modulation neural circuits of PPI and processed spatial information of prepulse.

The Effects of Attention on the Syllable-Induced Prepulse Inhibition of the Startle Reflex and Cortical EEG Responses against Energetic or Informational Masking in Humans.

Prepulse inhibition (PPI) is the reduction in the acoustic startle reflex (ASR) when the startling stimulus (pulse) is preceded by a weaker, non-starting stimulus. This can be enhanced by facilitating selective attention to the prepulse against a noise-masking background. On the other hand, the facilitation of selective attention to a target speech can release the target speech from masking, particularly from speech informational masking. It is not clear whether attentional regulation also affects PPI in this kind of auditory masking. This study used a speech syllable as the prepulse to examine whether the masker type and perceptual spatial attention can affect the PPI or the scalp EEG responses to the prepulse in healthy younger-adult humans, and whether the ERPs evoked by the prepulse can predict the PPI intensity of the ASR. The results showed that the speech masker produced a larger masking effect than the noise masker, and the perceptual spatial separation facilitated selective attention to the prepulse, enhancing both the N1 component of the prepulse syllable and the PPI of the ASR, particularly when the masker was speech. In addition, there was no significant correlation between the PPI and ERPs under any of the conditions, but the perceptual separation-induced PPI enhancement and ERP N1P2 peak-to-peak amplitude enhancement were correlated under the speech-masking condition. Thus, the attention-mediated PPI is useful for differentiating noise energetic masking and speech informational masking, and the perceptual separation-induced release of the prepulse from informational masking is more associated with attention-mediated early cortical unmasking processing than with energetic masking. However, the processes for the PPI of the ASR and the cortical responses to the prepulse are mediated by different neural mechanisms.

Strength of Attentional Modulation on Cortical Auditory Evoked Responses Correlates with Speech-in-Noise Performance in Bimodal Cochlear Implant Users.

Auditory selective attention is a crucial top-down cognitive mechanism for understanding speech in noise. Cochlear implant (CI) users display great variability in speech-in-noise performance that is not easily explained by peripheral auditory profile or demographic factors. Thus, it is imperative to understand if auditory cognitive processes such as selective attention explain such variability. The presented study directly addressed this question by quantifying attentional modulation of cortical auditory responses during an attention task and comparing its individual differences with speech-in-noise performance. In our attention experiment, participants with CI were given a pre-stimulus visual cue that directed their attention to either of two speech streams and were asked to select a deviant syllable in the target stream. The two speech streams consisted of the female voice saying "Up" five times every 800 ms and the male voice saying "Down" four times every 1 s. The onset of each syllable elicited distinct event-related potentials (ERPs). At each syllable onset, the difference in the amplitudes of ERPs between the two attentional conditions (attended - ignored) was computed. This ERP amplitude difference served as a proxy for attentional modulation strength. Our group-level analysis showed that the amplitude of ERPs was greater when the syllable was attended than ignored, exhibiting that attention modulated cortical auditory responses. Moreover, the strength of attentional modulation showed a significant correlation with speech-in-noise performance. These results suggest that the attentional modulation of cortical auditory responses may provide a neural marker for predicting CI users' success in clinical tests of speech-in-noise listening.

Midbrain activity shapes high-level visual properties in the primate temporal cortex.

Recent fMRI experiments identified an attention-related region in the macaque temporal cortex, here called the floor of the superior temporal sulcus (fSTS), as the primary cortical target of superior colliculus (SC) activity. However, it remains unclear which aspects of attention are processed by fSTS neurons and how or why these might depend on SC activity. Here, we show that SC inactivation decreases attentional modulations in fSTS neurons by increasing their activity for ignored stimuli in addition to decreasing their activity for attended stimuli. Neurons in the fSTS also exhibit event-related activity during attention tasks linked to detection performance, and this link is eliminated during SC inactivation. Finally, fSTS neurons respond selectively to particular visual objects, and this selectivity is reduced markedly during SC inactivation. These diverse, high-level properties of fSTS neurons all involve visual signals that carry behavioral relevance. Their dependence on SC activity could reflect a circuit that prioritizes cortical processing of events detected subcortically.

Neurofeedback Training of Auditory Selective Attention Enhances Speech-In-Noise Perception.

Selective attention enhances cortical responses to attended sensory inputs while suppressing others, which can be an effective strategy for speech-in-noise (SiN) understanding. Emerging evidence exhibits a large variance in attentional control during SiN tasks, even among normal-hearing listeners. Yet whether training can enhance the efficacy of attentional control and, if so, whether the training effects can be transferred to performance on a SiN task has not been explicitly studied. Here, we introduce a neurofeedback training paradigm designed to reinforce the attentional modulation of auditory evoked responses. Young normal-hearing adults attended one of two competing speech streams consisting of five repeating words ("up") in a straight rhythm spoken by a female speaker and four straight words ("down") spoken by a male speaker. Our electroencephalography-based attention decoder classified every single trial using a template-matching method based on pre-defined patterns of cortical auditory responses elicited by either an "up" or "down" stream. The result of decoding was provided on the screen as online feedback. After four sessions of this neurofeedback training over 4 weeks, the subjects exhibited improved attentional modulation of evoked responses to the training stimuli as well as enhanced cortical responses to target speech and better performance during a post-training SiN task. Such training effects were not found in the Placebo Group that underwent similar attention training except that feedback was given only based on behavioral accuracy. These results indicate that the neurofeedback training may reinforce the strength of attentional modulation, which likely improves SiN understanding. Our finding suggests a potential rehabilitation strategy for SiN deficits.

Attentional modulation of unconscious inhibitory visuomotor processes: An EEG study.

The present study examined the role of attention in unconscious inhibitory visuomotor processes in three experiments that employed a mixed paradigm including a spatial cueing task and masked prime task. Spatial attention to the prime was manipulated. Specifically, the valid-cue condition (in which the prime obtained more attentional resources) and invalid-cue condition (in which the prime obtained fewer attentional resources) were included. The behavioral results showed that the negative compatibility effect (a behavioral indicator of inhibitory visuomotor processing) in the valid-cue condition was larger than that in the invalid-cue condition. Most importantly, lateralized readiness potential results indicated that the prime-related activation was stronger in the valid-cue condition than in the invalid-cue condition and that the followed inhibition in the compatible trials was also stronger in the valid-cue condition than in the invalid-cue condition. In line with the proposed attentional modulation model, unconscious visuomotor inhibitory processing is modulated by attentional resources.

The medial agranular cortex mediates attentional enhancement of prepulse inhibition of the startle reflex.

The startle reflex, which interferes with on-going cognitive/behavioral activities, is of important protective function for humans and animals. Prepulse inhibition (PPI), as an operational measure of sensorimotor gating, is the suppression of the startle reflex in response to an intense startling stimulus (pulse) when this startling stimulus is shortly preceded by a weaker non-startling stimulus (prepulse). In both humans and laboratory animals, PPI can be enhanced by facilitating selective attention to the prepulse, suggesting that higher-order cognitive/perceptual processes modulate PPI. It has been well known that both the cholinergic system located in the basal forebrain and the deep layers of the superior colliculus in the PPI-mediating circuit are top-down modulated by the medial agranular cortex (AGm), which is a subdivision of the medial prefrontal cortex (PFC) and has wide axonal connections with both cortical regions (including the posterior parietal cortex) and subcortical structures critical for attention/orientation processes. This study investigated whether the AGm is involved in attentional modulation of PPI. The results showed that PPI was enhanced by fear conditioning of the prepulse, and then further enhanced by perceived spatial separation between the conditioned prepulse and a back-ground masking noise based on the auditory precedence effect. Bilateral injection of 2-mM kynurenic acid, a broad spectrum antagonist of glutamate receptors, into the AGm, but not the primary somatosensory cortex, eliminated these two types of attentional enhancement of PPI. Thus, the AGm plays a role in facilitating attention to the prepulse and is involved in the top-down modulation of PPI.