Processing Of External Stimuli Research Articles

Brain-Inspired Architecture for Spiking Neural Networks.

Spiking neural networks (SNNs), using action potentials (spikes) to represent and transmit information, are more biologically plausible than traditional artificial neural networks. However, most of the existing SNNs require a separate preprocessing step to convert the real-valued input into spikes that are then input to the network for processing. The dissected spike-coding process may result in information loss, leading to degenerated performance. However, the biological neuron system does not perform a separate preprocessing step. Moreover, the nervous system may not have a single pathway with which to respond and process external stimuli but allows multiple circuits to perceive the same stimulus. Inspired by these advantageous aspects of the biological neural system, we propose a self-adaptive encoding spike neural network with parallel architecture. The proposed network integrates the input-encoding process into the spiking neural network architecture via convolutional operations such that the network can accept the real-valued input and automatically transform it into spikes for further processing. Meanwhile, the proposed network contains two identical parallel branches, inspired by the biological nervous system that processes information in both serial and parallel. The experimental results on multiple image classification tasks reveal that the proposed network can obtain competitive performance, suggesting the effectiveness of the proposed architecture.

Sensory processing sensitivity as a predictor of health-related quality of life outcomes via stress and sleep quality

Sensory processing sensitivity (SPS), linked to processing external and internal stimuli, has drawn attention to its associations with clinical factors, particularly with health-related quality of life (HRQOL) variables. This study examined the relationships among SPS, stress, sleep quality, and HRQOL, establishing an explanation model. Eight hundred adults (M = 26.66 years, SD = 12.24; range age: 18–85 years) completed self-administered questionnaires on SPS, stress, sleep quality, and HRQOL. Correlation analysis and structural equation modeling (SEM) were used to analyze HRQOL pathways. Stress positively correlated with sleep quality disturbances (r = 0.442, p < 0.001), and SPS (r = 0.344, p < 0.001). Sleep quality disturbances were weakly positively associated with SPS (r = 0.242, p < 0.001). Weak negative correlations emerged between stress and physical (r = -0.283, p < 0.001) and mental (r = − 0.271, p < 0.001) health, HRQOL main dimensions. SEM results showed SPS positively influenced sleep quality disturbances (β = 0.242, p < 0.05) stress (β = 0.413, p < 0.001) while negatively affecting physical health (β = − 0.126, p < 0.001). Sleep quality disturbances negatively affected physical (β = − 0.168, p < 0.001), and mental (β = − 0.189 , p < 0.001) health, and stress on mental health (β = − 0.492, p < 0.01). Indirect effects between SPS and physical (β = -0.036, p < 0.001) and mental (β = − 0.091, p < 0.001) health through sleep were observed, as well as a mediation of stress between SPS and mental health (β = − 0.196, p < 0.001). SPS, sleep quality disturbances, and stress emerged as significant predictors of self-rated physical and mental health in adults.

Frontal midline theta power during the cue-target-interval reflects increased cognitive effort in rewarded task-switching

Cognitive performance largely depends on how much effort is invested during task-execution. This also means that we rarely perform as good as we could. Cognitive effort is adjusted to the expected outcome of performance, meaning that it is driven by motivation. The results from recent studies suggest that the expenditure of cognitive control is particularly prone to being affected by modulations of cognitive effort. Although recent EEG studies investigated the neural underpinnings of the interaction of effort and control, reports on how cognitive effort is reflected by oscillatory activity of the EEG are quite sparse. It is the goal of the present study to bridge this gap by performing an exploratory analysis of high-density EEG data from a switching-task using manipulations of monetary incentives. A beamformer approach is used to localize the sensor-level effects in source-space. The results indicate that the manipulation of cognitive effort was successful. The participants reported significantly higher motivation and cognitive effort in high versus low reward trials. Performance was also significantly increased. The analysis of the EEG data revealed that the increase of cognitive effort was reflected by an increased mid-frontal theta activity during the cue-target interval, suggesting an increased use of proactive control. This interpretation is supported by the result from a regression analysis performed on single-trial data, showing higher mid-frontal theta power prior to target-onset being associated with faster responses. Alpha-desynchronization throughout the trial was also more pronounced in high reward trials, signaling a bias of attention towards the processing of external stimuli. Source reconstruction suggests that these effects are located in areas related to cognitive control, and visual processing.

Understanding Mass Panic

Mass panics can arise in response to a variety of situations, such as the spread of pathogens, bank failures, or insecurities about economic supplies. Such panics can produce contagious behaviors such as fleeing social contacts, bank withdrawals, and panic buying. In such situations, the processing of external stimuli, mediated by the perceptions and biases of the individual, can reach a threshold point at which panic behaviors are triggered. Due to the human propensity to imitate the behavior of others in uncertain crisis situations, one individual’s panic behavior can spread contagiously. This paper looks at the similarities among case studies of mass panic around the world and from these cases synthesizes a conceptual model to aid our understanding. Decision-makers can use this model to strengthen national resilience against panic-generated behaviors and ensure an orderly and successful public response to future biological, financial, or economic crises.

Reward contingency gates selective cholinergic suppression of amygdala neurons.

Basal forebrain cholinergic neurons modulate how organisms process and respond to environmental stimuli through impacts on arousal, attention, and memory. It is unknown, however, whether basal forebrain cholinergic neurons are directly involved in conditioned behavior, independent of secondary roles in the processing of external stimuli. Using fluorescent imaging, we found that cholinergic neurons are active during behavioral responding for a reward - even prior to reward delivery and in the absence of discrete stimuli. Photostimulation of basal forebrain cholinergic neurons, or their terminals in the basolateral amygdala (BLA), selectively promoted conditioned responding (licking), but not unconditioned behavior nor innate motor outputs. In vivo electrophysiological recordings during cholinergic photostimulation revealed reward-contingency-dependent suppression of BLA neural activity, but not prefrontal cortex. Finally, ex vivo experiments demonstrated that photostimulation of cholinergic terminals suppressed BLA projection neuron activity via monosynaptic muscarinic receptor signaling, while also facilitating firing in BLA GABAergic interneurons. Taken together, we show that the neural and behavioral effects of basal forebrain cholinergic activation are modulated by reward contingency in a target-specific manner.

Reward contingency gates selective cholinergic suppression of amygdala neurons

Basal forebrain cholinergic neurons modulate how organisms process and respond to environmental stimuli through impacts on arousal, attention, and memory. It is unknown, however, whether basal forebrain cholinergic neurons are directly involved in conditioned behavior, independent of secondary roles in the processing of external stimuli. Using fluorescent imaging, we found that cholinergic neurons are active during behavioral responding for a reward – even prior to reward delivery and in the absence of discrete stimuli. Photostimulation of basal forebrain cholinergic neurons, or their terminals in the basolateral amygdala (BLA), selectively promoted conditioned responding (licking), but not unconditioned behavior nor innate motor outputs. In vivo electrophysiological recordings during cholinergic photostimulation revealed reward-contingency-dependent suppression of BLA neural activity, but not prefrontal cortex. Finally, ex vivo experiments demonstrated that photostimulation of cholinergic terminals suppressed BLA projection neuron activity via monosynaptic muscarinic receptor signaling, while also facilitating firing in BLA GABAergic interneurons. Taken together, we show that the neural and behavioral effects of basal forebrain cholinergic activation are modulated by reward contingency in a target-specific manner.

Sensory gating and gaining in sleep: the balance between the protection of sleep and the safeness of life (a review).

Sleep is a brain state characterised by a low vigilance level and diminished consciousness. Reaction to and processing of external stimuli is attenuated in sleep. During sleep, the reticular thalamic nucleus reduces the flow of sensory activity to the cerebral cortex through inhibition of the thalamus. This sensory gating process facilitates sleep. After reaching the afferent layers of primary cortex, the reduced sensory flow is adjusted, gained, and processed within various cortical layers before being transferred by the corticofugal system back to appropriate subdivisions of the thalamus as feedback. Thalamic subdivisions then dispatch this sensory information to related areas of the cerebral cortex, where it is (sub)consciously perceived. When necessary, a sleeping individual can be awakened by a wake-up call, either by stimuli indicating danger, or by personally meaningful stimuli. It is safe for a sleeping individual that it can be aroused when necessary. Evidently, there are two processes by which the brain adjusts the response to sensory stimuli before entering (sub)consciousness. Firstly 'sensory gating', a process favourable to the maintenance of sleep by reducing the sensory input to the brain through the reticular thalamic nucleus and secondly 'sensory gaining', a process implying that the gained preserved sensory input is continuously analysed by the corticofugal system to detect dangerous and relevant environmental elements, indispensable for safeness and well-being of the sleeper.

Association of Intrinsic Functional Connectivity between the Locus Coeruleus and Salience Network with Attentional Ability.

The locus coeruleus (LC) is a brainstem region associated with broad neural arousal because of norepinephrine production, but it has increasingly been associated with specific cognitive processes. These include sustained attention, with deficits associated with various neuropsychological disorders. Neural models of attention deficits have focused on interrupted dynamics between the salience network (SAL) with the frontoparietal network, which has been associated with task-switching and processing of external stimuli, respectively. Conflicting findings for these regions suggest the possibility of upstream signaling leading to attention dysfunction, and recent research suggests LC involvement. In this study, resting-state functional connectivity and behavioral performance on an attention task was examined within 584 individuals. Analysis revealed significant clusters connected to LC activity in the SAL. Given previous findings that attention deficits may be caused by SAL network switching dysfunctions, findings here further suggest that dysfunction in LC-SAL connectivity may impair attention.

Region-based analysis of sensory processing using diffusion tensor imaging.

The caudate nucleus has been thought to be involved in the control of motor commands by the cerebrum, and recent studies suggest that it may play a role in the control of attachment behavior, cognition, emotion, and mental functions. Implied by the basal ganglia's involvement in the execution, planning and control of movement, the caudate nucleus functions in a situation-dependent manner where processing of external stimuli is important on the basis of learning and memory. Sensory processing, which determines the response to external stimuli, has been shown to be related to various brain regions but it remains unknown how sensory processing is associated with the structure of the caudate nucleus and white matter microstructures of the caudate. Using four diffusion parameters derived from diffusion tensor imaging (DTI) (i.e., fractional anisotropy (FA), mean diffusivity (MD), axonal diffusivity (AD), and radial diffusivity (RD)) and the Adolescent/Adult Sensory Profile (AASP) questionnaire of 99 healthy subjects [42 males and 57 females; mean age:26.9 years, standard deviation 6.9], we investigated the relationship between white matter structure in the caudate nucleus and sensory processing. In consistent with what had been suggested by the results of previous studies, we found significant correlations between AD, MD and tactile sensation. Furthermore, we found a significant correlation between AD, MD and tactile sensory avoidance, the AASP sub-scores regarding the tactile senses. To the best of our knowledge, this is the first study to show that DTI diffusion parameters correlate with AASP scores in specific brain regions.

The Plant Consciousness: Understanding and Developing Proto-languages Between Plants and Humans

Plants are among the oldest and most complex organisms on our world. The complexity lies, first of all, from the cellular point of view, which has a greater compartmentalization than the animal cell. Also evolved as terrestrial organisms, plants have developed complex forms of electrochemical communication, developed to the point of suggesting that plants possessed a sort of nervous system, similar to that found in the animal world and in organisms with a high degree of evolution. Over the course of history, numerous researchers, especially in the last century, have alternated trying to penetrate the functional complexity of plants, obtaining results that allowed to tip the scales towards the presence not only of a nervous system, but a complex processing capacity, comparable to a consciousness. The experiment described here, using a polygraphic apparatus connected to an artificial intelligence computerized processing system, made it possible to evaluate the physiopathological responses of a plant subjected to external stimuli of an invasive and non-invasive nature. The technique involved addressing the vegetable "directly" during the experimentation. The results obtained have highlighted a logical succession of responses, which have allowed us to conclude that plants possess an advanced capacity for processing external stimuli and also of the human voice.

Processing of linguistic deixis in people with schizophrenia, with and without auditory verbal hallucinations

Auditory verbal hallucinations (AVH) are a key symptom of schizophrenia (SZ) defined by anomalous perception of speech. Anomalies of processing external speech stimuli have also been reported in people with AVH, but it is unexplored which specific dimensions of language are processed differently. Using a speech perception task (passive listening), we here targeted the processing of deixis, a key dimension of language governing the contextual anchoring of speech in interpersonal context. We designed naturalistic speech stimuli that were either non-personal and fact-reporting (‘low-deixis’ condition), or else involved rich deictic devices such as the grammatical first and second persons, direct questions, and vocatives (‘high-deixis’). We asked whether neural correlates of deixis obtained with fMRI would distinguish patients with and without frequent hallucinations (AVH + vs AVH−) from controls and each other. Results showed that high-deixis relative to low-deixis was associated with clusters of increased activation in the bilateral middle temporal gyri extending into the temporal poles and the inferior parietal cortex, in all groups. The AVH + and AVH− groups did not differ. When unifying them, the SZ group as a whole showed altered activity in the precuneus, midline regions and inferior parietal cortex. These results fail to confirm deictic processing anomalies specific to patients with AVH, but reveal such anomalies across SZ. Hypoactivation of this network may relate to a cognitive mechanism for attributing and anchoring thought and referential speech content in context.

Criticality Creates a Functional Platform for Network Transitions Between Internal and External Processing Modes in the Human Brain.

Continuous switching between internal and external modes in the brain appears important for generating models of the self and the world. However, how the brain transitions between these two modes remains unknown. We propose that a large synchronization fluctuation of brain networks, emerging only near criticality (i.e., a balanced state between order and disorder), spontaneously creates temporal windows with distinct preferences for integrating the network’s internal information or for processing external stimuli. Using a computational model, electroencephalography (EEG) analysis, and functional magnetic resonance imaging (fMRI) analysis during alterations of consciousness in humans, we report that synchronized and incoherent networks, respectively, bias toward internal and external information with specific network configurations. In the brain network model and EEG-based network, the network preferences are the most prominent at criticality and in conscious states associated with the bandwidth 4−12 Hz, with alternating functional network configurations. However, these network configurations are selectively disrupted in different states of consciousness such as general anesthesia, psychedelic states, minimally conscious states, and unresponsive wakefulness syndrome. The network preference for internal information integration is only significant in conscious states and psychedelic states, but not in other unconscious states, suggesting the importance of internal information integration in maintaining consciousness. The fMRI co-activation pattern analysis shows that functional networks that are sensitive to external stimuli–such as default mode, dorsal attentional, and frontoparietal networks–are activated in incoherent states, while insensitive networks, such as global activation and deactivation networks, are dominated in highly synchronized states. We suggest that criticality produces a functional platform for the brain’s capability for continuous switching between two modes, which is crucial for the emergence of consciousness.

Природа и мозг человека: парадигмы обмена информацией

The new modern world has entered a complex society. Nature its new material world of the Universe and its natural habitat, become more variable, over shorter periods of time. The system of nature–society–human is a holistic, dynamic, wave, open, steadily non-equilibrium system, with the isolation not only of internal ties, but also of external ones - with the space environment. Modern science views man, humanity and the biosphere as a single system, with growing demographic, food and medical problems. Human brains are biological, biophysical, neurophysiological and medico-social paradigms of information exchange. Modern communications are multilevel, multi-paradigm and interdisciplinary models of information exchange. The new competencies of psychoneuroimmunoendocrinology and psychoneuroimmunology play a strategic role in interdisciplinary science and interdisciplinary planning and decision-making. The introduction of multi-vector neurotechnologies of artificial intelligence and the principles of digital health care will contribute to the development of modern neuroscience and neuromarketing. The introduction of biocomputer nanoplatforms and modules consisting of small molecules, polymers, nucleic acids or proteins/peptides, nanoplatforms are programmed to detect and process external stimuli, such as magnetic fields or light, or internal stimuli, such as nucleic acids, enzymes or pH, using three different mechanisms: system assembly, system disassembly or system transformation. Current biocomputer nanoplatforms are invaluable for many applications, including medical diagnostics, biomedical imaging, environmental monitoring, and delivery of therapeutic drugs to target cell populations. Integration of different sources of information will allow researchers to obtain a new holistic picture of the pathophysiological process of the disease, which will cover from molecular changes to cognitive manifestations. Cognitive memory is a continuous act of creation, one of the largest and most capacious concepts that represents the main function of memory in general. The knowledge that a person receives during training is first perceived as something external, but then gradually they turn into experience and beliefs. Cognitive memory retains all the knowledge gained, representing a kind of “library”, and the process of assimilation and preservation becomes more complicated as the information received becomes more complex.

Биоинформатика и искусственный интеллект: геронтологические и гериатрические компоненты медико-социального сопровождения к активному здоровому долголетию

The “cognitive reserve” construct is a set of variables, including intelligence, education, and mental stimulation, that presumably allows the brain to adapt to underlying pathologies, supporting cognitive function despite underlying neural changes. Brain Homo Sapiens also points to resistance to neuropathological damage and can be defined as the ability to optimize or maximize performance through an effective set of neural networks and/or alternative cognitive strategies. Learning in childhood, the level of education and activities for adults — all this independently contributes to the formation of a cognitive reserve. The introduction of biocomputer nanoplatforms and modules consisting of small molecules, polymers, nucleic acids or proteins/peptides, nanoplatforms are programmed to detect and process external stimuli, such as magnetic fields or light, or internal stimuli, such as nucleic acids, enzymes or pH, using three different mechanisms: system assembly, system disassembly or system transformation. Current biocomputer nanoplatforms are invaluable for many applications, including medical diagnostics, biomedical imaging, environmental monitoring, and delivery of therapeutic drugs to target cell populations. The future implementation of systems biology and systems neurophysiology paradigms based on complex analysis of large and deep heterogeneous data sources will be crucial to achieve a deeper understanding of the pathophysiology of Alzheimer’s disease, using current brain-computer and artificial intelligence interface technologies, in order to increase information that can be extracted from preclinical and clinical indicators. Integration of different sources of information will allow researchers to obtain a new holistic picture of the pathophysiological process of the disease, which will cover from molecular changes to cognitive manifestations. The new competencies of psychoneuroimmunoendocrinology and psychoneuroimmunology play a strategic role in interdisciplinary science and interdisciplinary planning and decision-making. The introduction of multi-vector neurotechnologies of artificial intelligence and the principles of digital health care will contribute to the development of modern neuroscience and neuromarketing. Medical and social support for active healthy longevity is possible when synchronizing information systems of medical organizations and social institutions, introducing a single neurophysiological circuit and modern neurointerfaces, a combined and hybrid cluster in the diagnosis, treatment, prevention and rehabilitation of cognitive disorders and cognitive disorders. A key factor in medical and social support is the participation of interdisciplinary business employees and data processing specialists (their support, monitoring), as well as the availability of sufficient staff literacy in data management.

Network organization during probabilistic learning via taste outcomes

Reinforcement learning guides food decisions, yet how the brain learns from taste in humans is not fully understood. Existing research examines reinforcement learning from taste using passive condition paradigms, but response-dependent instrumental conditioning better reflects natural eating behavior. Here, we examined brain response during a taste-motivated reinforcement learning task and how measures of task-based network structure were related to behavioral outcomes. During a functional MRI scan, 85 participants completed a probabilistic selection task with feedback via sweet taste or bitter taste. Whole brain response and functional network topology measures, including identification of communities and community segregation, were examined during choice, sweet taste, and bitter taste conditions. Relative to the bitter taste, sweet taste was associated with increased whole brain response in the hippocampus, oral somatosensory cortex, and orbitofrontal cortex. Sweet taste was also related to differential community assignment of the ventromedial prefrontal cortex and ventrolateral prefrontal cortex compared to bitter taste. During choice, increasing segregation of a community containing the amygdala, hippocampus, and right fusiform gyrus was associated with increased sensitivity to punishment on the task's posttest. Further, normal BMI was associated with differential community structure compared to overweight and obese BMI, where high BMI reflected increased connectivity of visual regions. Together, results demonstrate that network topology of learning and memory regions during choice is related to avoiding a bitter taste, and that BMI is associated with increased connectivity of area involved in processing external stimuli. Network organization and topology provide unique insight into individual differences in brain response to instrumental conditioning via taste reinforcers.

Tracking the Dynamic Functional Network Interactions During Goal-Directed Auditory Tasks by Brain State Clustering.

Both perceiving and processing external sound stimuli as well as actively maintaining and updating relevant information (i.e., working memory) are critical for communication and problem solving in everyday acoustic environments. The translation of sensory information into perceptual decisions for goal-directed tasks hinges on dynamic changes in neural activity. However, the underlying brain network dynamics involved in this process are not well specified. In this study, we collected functional MRI data of participants engaging in auditory discrimination and auditory working memory tasks. Independent component analysis (ICA) was performed to extract the brain networks involved and the sliding-window functional connectivity (FC) among networks was calculated. Next, a temporal clustering technique was used to identify the brain states underlying auditory processing. Our results identified seven networks configured into four brain states. The number of brain state transitions was negatively correlated with auditory discrimination performance, and the fractional dwell time of State 2-which included connectivity among the triple high-order cognitive networks and the auditory network (AN)-was positively correlated with working memory performance. A comparison of the two tasks showed significant differences in the connectivity of the frontoparietal, default mode, and sensorimotor networks (SMNs), which is consistent with previous studies of the modulation of task load on brain network interaction. In summary, the dynamic network analysis employed in this study allowed us to isolate moment-to-moment fluctuations in inter-network synchrony, find network configuration in each state, and identify the specific state that enables fast, effective performance during auditory processing. This information is important for understanding the key neural mechanisms underlying goal-directed auditory tasks.

EEG Alpha Power Is Modulated by Attentional Changes during Cognitive Tasks and Virtual Reality Immersion

Variations in alpha rhythm have a significant role in perception and attention. Recently, alpha decrease has been associated with externally directed attention, especially in the visual domain, whereas alpha increase has been related to internal processing such as mental arithmetic. However, the role of alpha oscillations and how the different components of a task (processing of external stimuli, internal manipulation/representation, and task demand) interact to affect alpha power are still unclear. Here, we investigate how alpha power is differently modulated by attentional tasks depending both on task difficulty (less/more demanding task) and direction of attention (internal/external). To this aim, we designed two experiments that differently manipulated these aspects. Experiment 1, outside Virtual Reality (VR), involved two tasks both requiring internal and external attentional components (intake of visual items for their internal manipulation) but with different internal task demands (arithmetic vs. reading). Experiment 2 took advantage of the VR (mimicking an aircraft cabin interior) to manipulate attention direction: it included a condition of VR immersion only, characterized by visual external attention, and a condition of a purely mental arithmetic task during VR immersion, requiring neglect of sensory stimuli. Results show that: (1) In line with previous studies, visual external attention caused a significant alpha decrease, especially in parieto-occipital regions; (2) Alpha decrease was significantly larger during the more demanding arithmetic task, when the task was driven by external visual stimuli; (3) Alpha dramatically increased during the purely mental task in VR immersion, whereby the external stimuli had no relation with the task. Our results suggest that alpha power is crucial to isolate a subject from the environment, and move attention from external to internal cues. Moreover, they emphasize that the emerging use of VR associated with EEG may have important implications to study brain rhythms and support the design of artificial systems.

Psychometric Properties and Validation of a German High Sensitive Person Scale (HSPS-G)

Abstract. High sensitivity is an individual disposition to perceive and process external and internal stimuli more intensely than the average population. For measuring high sensitivity, Aron and Aron (1997) developed a unidimensional self-report questionnaire. However, Smolewska, McCabe, and Woody (2006) fitted a model with three correlated factors: ease of excitation, aesthetic sensitivity, and low sensory threshold. Both models were questioned by Evans and Rothbart (2008) who postulated a two-factor structure: negative affect and orienting sensitivity. Nonetheless, the studies presented so far are based on small samples and did not address the issues of the ordinal data and measurement invariance. We presented the first study that compared all postulated models, thereby taking the ordinal data into account, and evaluated the measurement invariance. We adopted the High Sensitive Person (HSP)-Scale for German-speaking populations and found that a three-factor model provided the best fit. However, we excluded 13 items because of their low factor loadings or high intercorrelations. The revised HSP-Scale fit a three-factor model. Furthermore, we could establish a high level of measurement invariance (strict invariance), indicating equality of loadings, thresholds, and residual variances across sex. The scale showed good psychometric properties and high test-retest reliability. Finally, relationships with psychological symptoms were presented.

Reduced Target Facilitation and Increased Distractor Suppression During Mind Wandering.

The perceptual decoupling hypothesis suggests a general mechanism that while mind wandering, our attention is detached from our environment, resulting in diminished processing of external stimuli. This study focused on examining two possible specific mechanisms: the global suppression of all external stimuli, and a combination of reduced target facilitation and increased distractor suppression. An attentional capture task was used in which certain trials measured distractor suppression effects and others assessed target facilitation effects. The global suppression account predicts negative impacts on both types of trials, while the combined mechanisms of reduced target facilitation and increased distractor suppression suggest that only target-present trials would be affected. Results showed no cost of mind wandering on target-absent trials, but significant distractor suppression and target facilitation effects during mind wandering on target-present trials. These findings suggest that rather than perceptual decoupling globally suppressing all stimuli, it is more selective, falling in line with evidence on strong top-down modulation.

Testing the role of the posterior cingulate cortex in processing salient stimuli in cannabis users: an rTMS study.

The posterior cingulate cortex (PCC) and precuneus are hubs in the default mode network and play a role in processing external salient stimuli. Accordingly, activation in these regions has been associated with response to salient stimuli using drug cue‐reactivity paradigms in substance using populations. These studies suggest that the PCC and precuneus may underlie deficits in processing salient stimuli that contribute toward the development of substance use disorders. The goal of this study was to directly test this hypothesis using repetitive transcranial magnetic stimulation (rTMS). Using a double‐blind, placebo‐controlled design, we used rTMS to target the PCC and precuneus with a double‐cone coil at 10 Hz (high frequency) and 1 Hz (low frequency) in 10 adult cannabis users and 10 age‐ and sex‐matched non‐using controls. Electroencephalography data were collected before and after rTMS during a modified oddball paradigm with neutral, oddball, self‐relevant, and cannabis‐related stimuli. Cannabis users exhibited increased amplitude in P3 and faster latencies in the P3, N2, and P2 components in response to self‐relevant stimuli compared to controls during baseline that normalized after rTMS. These results suggest that cannabis users exhibited heightened salience to external self‐relevant stimuli that were modulated after rTMS. PCC dysfunction in cannabis users may be related to abnormalities in processing salient stimuli, such those during cue‐reactivity, and provides a potential target for cannabis use disorder intervention.