Neural Processing Mechanisms Research Articles

Clinical high risk for psychosis syndrome is associated with reduced neural responding to unpleasant images.

Deficits in emotion processing are core features of psychotic disorders. Electrophysiology research in schizophrenia suggests deficits in sustained engagement with emotional content (indexed by the late positive potential [LPP]) may contribute to emotion processing impairments. Despite similar behavioral emotion processing dysfunction in those at clinical high risk (CHR) for psychosis, limited research has examined neural mechanisms of impaired emotion processing in the high-risk period, where research can inform risk models. To examine mechanisms of emotion processing deficits in those at CHR for psychosis, the present study used a passive viewing task to elicit the LPP in response to emotionally engaging and neutral stimuli in 28 CHR and 32 control participants (60% female). Relative to controls, CHR participants showed reduced LPP amplitude when viewing unpleasant images (d = 0.75, p = .005) but similar LPP amplitude in response to both neutral (d = 0.35, p = .19) and pleasant images (d = 0.31, p = .24). This pattern suggests that individuals at CHR for psychosis exhibit a deficit in sustained engagement with unpleasant stimuli. Clinical and trait questionnaires were administered to examine potential exploratory explanations for group differences in LPP amplitude. Consistent with evidence suggesting LPP amplitude reflects engagement of approach/avoidance motivational systems, greater LPP amplitude was associated with greater trait-level behavioral avoidance in control participants (r = .42, p = .032) but not CHR participants (r = -.21, p = .40). Together, the present research is consistent with LPP studies in psychosis and implicates reduced sustained engagement with emotional content in the high-risk period. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Mega-scale movie-fields in the mouse visuo-hippocampal network

Natural visual experience involves a continuous series of related images while the subject is immobile. How does the cortico-hippocampal circuit process a visual episode? The hippocampus is crucial for episodic memory, but most rodent single unit studies require spatial exploration or active engagement. Hence, we investigated neural responses to a silent movie (Allen Brain Observatory) in head-fixed mice without any task or locomotion demands, or rewards. Surprisingly, a third (33%, 3379/10263) of hippocampal –dentate gyrus, CA3, CA1 and subiculum– neurons showed movie-selectivity, with elevated firing in specific movie sub-segments, termed movie-fields, similar to the vast majority of thalamo-cortical (LGN, V1, AM-PM) neurons (97%, 6554/6785). Movie-tuning remained intact in immobile or spontaneously running mice. Visual neurons had >5 movie-fields per cell, but only ~2 in hippocampus. The movie-field durations in all brain regions spanned an unprecedented 1000-fold range: from 0.02s to 20s, termed mega-scale coding. Yet, the total duration of all the movie-fields of a cell was comparable across neurons and brain regions. The hippocampal responses thus showed greater continuous-sequence encoding than visual areas, as evidenced by fewer and broader movie-fields than in visual areas. Consistently, repeated presentation of the movie images in a fixed, but scrambled sequence virtually abolished hippocampal but not visual-cortical selectivity. The preference for continuous, compared to scrambled sequence was eight-fold greater in hippocampal than visual areas, further supporting episodic-sequence encoding. Movies could thus provide a unified way to probe neural mechanisms of episodic information processing and memory, even in immobile subjects, across brain regions, and species.

Neural mechanisms of working memory dysfunction in patients with chronic insomnia disorder

ObjectiveThis study aimed to investigate the neural mechanisms underlying working memory impairment in patients with chronic insomnia disorder (CID) using event-related potentials (ERP) and resting-state functional connectivity (rsFC) approaches. MethodsParticipants, including CID patients and healthy controls (HCs), completed clinical scales and underwent electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). EEG analysis compared reaction times, P3 amplitudes, event-related spectral perturbations (ERSP), and inter-trial phase synchronisation (ITPS) between CID patients and HCs. Subsequently, frontal regions (i.e., the Superior Frontal Gyrus [SFG] and Middle Frontal Gyrus [MFG]) corresponding to the EEG were selected as seeds for rsFC analysis. Correlation analyses were conducted to further investigate the relationship between functional connectivity abnormalities in brain regions and clinical symptom severity and P3 amplitude in CID patients. ResultsCompared to HCs, CID patients exhibited slower reaction times across all working memory conditions, with the deficits becoming more pronounced as memory load increased. ERP analysis revealed increased P3 amplitude, theta wave power, and reduced inter-trial synchrony in CID patients. rsFC analysis showed decreased connectivity of SFG-posterior cingulated cortex (PCC), SFG-MFG, and MFG-frontal pole (FP), and increased connectivity of MFG- Middle Temporal Gyrus (MTG)in CID patients. Importantly, a significant correlation was found between the rsFC of SFG-MTG and P3 amplitude during 1-back. ConclusionThis study confirms deficits in working memory capacity in patients with CID, specifically in the neural mechanisms of cognitive processing that vary depending on the level of cognitive load. Alterations in connectivity patterns within and between the frontal and temporal regions may be the neural basis of the cognitive impairment.

Mothers exhibit higher neural activity ingaining rewards fortheir children than forthemselves.

Are people willing to exert greater effort to obtain rewards for their children than they are for themselves? Although previous studies have demonstrated that social distance influences neural responses to altruistic reward processing, the distinction between winning rewards for oneself and winning them for one's child is unclear. In the present study, a group of 31 mothers performed a monetary incentive delay task in which cue-induced reward anticipations of winning a reward for themselves, their children and donation to a charity program were manipulated trial-wise, followed by performance-contingent feedback. Behaviorally, the anticipation of winning a reward for their children accelerated participants' responses. Importantly, the electroencephalogram results revealed that across the reward anticipation and consumption phases, the child condition elicited comparable or higher brain responses of participants than the self condition did. The source localization results showed that participants' reward anticipations for their children were associated with more activation in the social brain regions, compared to winning a reward for themselves or a charity donation. Overall, these findings advance our understanding of the neural mechanisms of altruistic reward processing and suggest that the priority of winning a reward for one's child may transcend the limits of the self-advantage effect in reward processing.

Single neuron responses underlying face recognition in the human midfusiform face-selective cortex

Faces are critical for social interactions and their recognition constitutes one of the most important and challenging functions of the human brain. While neurons responding selectively to faces have been recorded for decades in the monkey brain, face-selective neural activations have been reported with neuroimaging primarily in the human midfusiform gyrus. Yet, the cellular mechanisms producing selective responses to faces in this hominoid neuroanatomical structure remain unknown. Here we report single neuron recordings performed in 5 human subjects (1 male, 4 females) implanted with intracerebral microelectrodes in the face-selective midfusiform gyrus, while they viewed pictures of familiar and unknown faces and places. We observed similar responses to faces and places at the single cell level, but a significantly higher number of neurons responding to faces, thus offering a mechanistic account for the face-selective activations observed in this region. Although individual neurons did not respond preferentially to familiar faces, a population level analysis could consistently determine whether or not the faces (but not the places) were familiar, only about 50 ms after the initial recognition of the stimuli as faces. These results provide insights into the neural mechanisms of face processing in the human brain.

Spatiotemporal motor learning with reward-modulated Hebbian plasticity in modular reservoir computing

Generation of complex patterns at a specific timing is crucial to most forms of learning and behavior, which are acquired through dopamine-modulated plasticity in the striatum. However, the neural mechanisms of such reward-based spatiotemporal processing remain unknown. Inspired by the cortico-striatal circuits, this study developed a new reservoir computing method, a class of recurrent neural networks, based on reward-modulated Hebbian learning (RMHL) for the spatiotemporal motor learning. We utilized a reservoir of basal dynamics (reBASICS), which generated self-sustained limit cycle oscillations with various frequencies, as a reservoir structure. Then, the oscillations were linearly integrated as readout output, in which readout weights were modulated with RMHL. The simulations showed that reBASICS-based RMHL was able to accomplish both motor timing and pattern drawing tasks, for which existing reservoir-based RMHL failed. Further, introducing an eligibility trace mechanism into RMHL allowed the model to learn motor timing even when reward-based modulation was delayed. In conclusion, this model is proposed as a new computational model of temporal processing of the striatum, where the cortical areas generate stable oscillations. From the oscillatory dynamics, spatiotemporal patterns are learned using RMHL in the striatum.

Aberrant Effective Connectivity During Eye Gaze Processing Is Linked to Social Functioning and Symptoms in Schizophrenia

BackgroundPatients with schizophrenia show abnormal gaze processing, which is associated with social dysfunction. These abnormalities are related to aberrant connectivity among brain regions that are associated with visual processing, social cognition, and cognitive control. In this study, we investigated 1) how effective connectivity during gaze processing is disrupted in schizophrenia and 2) how this may contribute to social dysfunction and clinical symptoms. MethodsThirty-nine patients with schizophrenia/schizoaffective disorder (SZ) and 33 healthy control participants completed an eye gaze processing task during functional magnetic resonance imaging. Participants viewed faces with different gaze angles and performed explicit and implicit gaze processing. Four brain regions—the secondary visual cortex, posterior superior temporal sulcus, inferior parietal lobule, and posterior medial frontal cortex—were identified as nodes for dynamic causal modeling analysis. ResultsBoth the SZ and healthy control groups showed similar model structures for general gaze processing. Explicit gaze discrimination led to changes in effective connectivity, including stronger excitatory, bottom-up connections from the secondary visual cortex to the posterior superior temporal sulcus and inferior parietal lobule and inhibitory, top-down connections from the posterior medial frontal cortex to the secondary visual cortex. Group differences in top-down modulation from the posterior medial frontal cortex to the posterior superior temporal sulcus and inferior parietal lobule were noted, such that these inhibitory connections were attenuated in the healthy control group but further strengthened in the SZ group. Connectivity was associated with social dysfunction and symptom severity. ConclusionsThe SZ group showed notably stronger top-down inhibition during explicit gaze discrimination, which was associated with more social dysfunction but less severe symptoms among patients. These findings help pinpoint neural mechanisms of aberrant gaze processing and may serve as future targets for interventions that combine neuromodulation with social cognitive training.

The neural model of front-of-package label processing.

Front-of-package (FOP) labels have been adopted in many countries to battle the obesity pandemic and its serious health consequences by providing clearer and easier-to-understand nutrition and health information. The effectiveness of FOP labels has been generally confirmed, with some contextual and individual factors modifying their effectiveness. Existing theories (eg, the dual-process theory) and shifting priorities for self-control, provide some explanations for the FOP label effect. However, the cognitive and neural mechanisms underlying the processing of FOP labels remain unknown. Here, a new model, namely, the neural model of FOP label processing, has been proposed to fill this gap by providing an integrated account of FOP label processing while simultaneously considering multiple important situational and individual factors in the same framework. This neural model is built on the core eating network (ie, the ventral reward pathway and the dorsal control pathway) for food cue processing and actual food consumption. The new model explains how FOP labels may facilitate attention, influence the core eating network, and thus alter food choices. It also demonstrates how motivation may modify FOP label processing in 2 ways: affecting attention (the indirect way) and changing the process of evaluating the food (the direct way). It further explains how some contextual and individual factors (eg, ego depletion, time pressure, and health knowledge) influence the process. Thus, the neural model integrates evidence from behavioral, eye-tracking, and neuroimaging studies into a single, integrated account, deepening understanding of the cognitive and neural mechanisms of FOP label processing. This model might facilitate consensus on the most successful FOP label. Moreover, it could provide insights for consumers, food industries, and policy makers and encourage healthy eating behaviors.

Design and Simulation of a Hierarchical Parallel Distributed Processing Model for Orientation Selection Based on Primary Visual Cortex.

The study of the human visual system not only helps to understand the mechanism of the visual system but also helps to develop visual aid systems to help the visually impaired. As the systematic study of neural signal processing mechanisms in early biological vision continues, the hierarchical structure of the visual system is gradually being dissected, bringing the possibility of building brain-like computational models from a bionic perspective. In this paper, we follow the objective facts of neurobiology and propose a parallel distributed processing computational model of primary visual cortex orientation selection with reference to the complex process of visual signal processing and transmission between the retina to the primary visual cortex, the hierarchical receptive field structure between cells in each layer, and the very fine-grained parallel distributed characteristics of cortical visual computation, which allow for high speed and efficiency. We approach the design from a brain-like chip perspective, map our network model on the field programmable gate array (FPGA), and perform simulation experiments. The results verify the possibility of implementing our proposed model with programmable devices, which can be applied to small wearable devices with low power consumption and low latency.

Contrastive Learning of Subject-Invariant EEG Representations for Cross-Subject Emotion Recognition

EEG signals have been reported to be informative and reliable for emotion recognition in recent years. However, the inter-subject variability of emotion-related EEG signals still poses a great challenge for the practical applications of EEG-based emotion recognition. Inspired by recent neuroscience studies on inter-subject correlation, we proposed a Contrastive Learning method for Inter-Subject Alignment (CLISA) to tackle the cross-subject emotion recognition problem. Contrastive learning was employed to minimize the inter-subject differences by maximizing the similarity in EEG signal representations across subjects when they received the same emotional stimuli in contrast to different ones. Specifically, a convolutional neural network was applied to learn inter-subject aligned spatiotemporal representations from EEG time series in contrastive learning. The aligned representations were subsequently used to extract differential entropy features for emotion classification. CLISA achieved state-of-the-art cross-subject emotion recognition performance on our THU-EP dataset with 80 subjects and the publicly available SEED dataset with 15 subjects. It could generalize to unseen subjects or unseen emotional stimuli in testing. Furthermore, the spatiotemporal representations learned by CLISA could provide insights into the neural mechanisms of human emotion processing.

Neural mechanisms of event visibility in sign languages

ABSTRACT In unrelated sign languages event structure is reflected in the dynamic form of verbs, and hearing non-signers are known to be able to recognise these visual event structures. This study assessed the time course of neural processing mechanisms in non-signers to examine the pathways for incorporation of physical-perceptual motion features into the linguistic system. In an EEG study, hearing non-signers classified telic/atelic verb signs (two-choice lexical decision task). The ERP effects reflect differences in perceptual processing of verb types (early anterior ERP effects) and integration of perceptual and linguistic processing required by the task (later posterior ERP effects). Non-signers appear to segment signed input into discrete events as they try to map the sign to a linguistic concept. This might indicate the potential pathway for co-optation of perceptual features into the linguistic structure of sign languages.

Neural mechanisms of temporal and rhythmic structure processing in non-musicians.

Music is increasingly being used as a therapeutic tool in the field of rehabilitation medicine and psychophysiology. One of the main key components of music is its temporal organization. The characteristics of neurocognitive processes during music perception of meter in different tempo variations technique have been studied by using the event-related potentials technique. The study involved 20 volunteers (6 men, the median age of the participants was 23 years). The participants were asked to listen to 4 experimental series that differed in tempo (fast vs. slow) and meter (duple vs. triple). Each series consisted of 625 audio stimuli, 85% of which were organized with a standard metric structure (standard stimulus) while 15% included unexpected accents (deviant stimulus). The results revealed that the type of metric structure influences the detection of the change in stimuli. The analysis showed that the N200 wave occurred significantly faster for stimuli with duple meter and fast tempo and was the slowest for stimuli with triple meter and fast pace.

Auditory brainstem response in autistic children: implications for sensory processing

Purpose Autistic individuals frequently experience sensory processing difficulties. Such difficulties can significantly impact important functions and quality of life. We are only beginning to understand the neural mechanisms of atypical sensory processing. However, one established way to measure aspects of auditory function is the auditory brainstem response (ABR). While ABR has been primarily hypothesised thus far as a means of early detection/diagnosis in autism, it has the potential to aid in examining sensory processing in this population. Method Thus, we investigated standard ABR waveform characteristics in age-matched groups of autistic and typically developing children during various stimulus and intensity conditions. We also examined within ear waveform cross-correlations and inter-aural cross-correlations (IACC) to assess replicability and synchrony of participants’ ABRs, which was a novel approach to ABR analysis in this population. Results We observed longer peak latencies (esp. wave III and V) and interpeak latencies in the autism and typically developing groups in different conditions. There were no statistically significant results in cross-correlation or IACC. Conclusions These results suggest that brainstem auditory function may differ slightly, but is mostly similar, between autistic and typically developing children. We discuss these findings in terms of their implications for sensory processing and future utility.

Studying rhythm processing in speech through the lens of auditory-motor synchronization

Continuous speech is organized into a hierarchy of rhythms. Accurate processing of this rhythmic hierarchy through the interactions of auditory and motor systems is fundamental to speech perception and production. In this mini-review, we aim to evaluate the implementation of behavioral auditory-motor synchronization paradigms when studying rhythm processing in speech. First, we present an overview of the classic finger-tapping paradigm and its application in revealing differences in auditory-motor synchronization between the typical and clinical populations. Next, we highlight key findings on rhythm hierarchy processing in speech and non-speech stimuli from finger-tapping studies. Following this, we discuss the potential caveats of the finger-tapping paradigm and propose the speech-speech synchronization (SSS) task as a promising tool for future studies. Overall, we seek to raise interest in developing new methods to shed light on the neural mechanisms of speech processing.

Auditory processing for action selection in bats

Bats are auditory specialists, processing acoustic signals to guide their behaviors, including prey tracking, navigation and communication. In this talk I will provide an overview of my work related to how bats analyze and process signals for action-selection; specifically prey tracking and background clutter segregation—work inspired by research from Jim Simmons’s lab. I will also give an overview of the line of research of my current lab, neural mechanisms for auditory processing of communication signals. There is strong evidence that context plays a role in the processing of acoustic signals. Yet, the mechanisms that govern this process are still not fully understood. Eptesicus fuscus bats emit a wide array of communication calls, including food claiming calls, aggressive calls and appeasement calls. We developed a novel competitive foraging task to explore the role of behavioral context in auditory responses to social calls. With this approach, we recorded neural population responses from the IC of freely interacting bats. Analysis of our neural recordings from the IC show stronger population responses to individual calls during behaviorally aggressive events. These results indicate that behavioral context plays a role in the modulation of neuronal population responses to social vocalizations in the bat IC.

Visual boundaries in sign motion: processing with and without lip-reading cues

Sign languages demonstrate a higher degree of iconicity than spoken languages. Studies on a number of unrelated sign languages show that the event structure of verb signs is reflected in the phonological form of the signs (Wilbur (2008), Malaia & Wilbur (2012), Krebs et al. (2021)). Previous research showed that hearing non-signers (with no prior exposure to sign language) can use the iconicity inherent in the visual dynamics of a verb sign to correctly identify its event structure (telic vs. atelic). In two EEG experiments, hearing non-signers were presented with telic and atelic verb signs unfamiliar to them, which they had to classify in a two-choice lexical decision task in their native language. The first experiment assessed the timeline of neural processing mechanisms in non-signers processing telic/atelic signs without access to lip-reading cues in their native language, to understand the pathways for incorporation of physical perceptual motion features into linguistic processing. The second experiment further probed the impact of visual information provided by lip-reading (speech decoding based on visual information from the face of the speaker, most importantly, the lips) on the processing of telic/atelic signs in non-signers.

Neural Correlates of Audiovisual Speech Processing in Autistic and Non-Autistic Youth.

Autistic youth demonstrate differences in processing multisensory information, particularly in temporal processing of multisensory speech. Extensive research has identified several key brain regions for multisensory speech processing in non-autistic adults, including the superior temporal sulcus (STS) and insula, but it is unclear to what extent these regions are involved in temporal processing of multisensory speech in autistic youth. As a first step in exploring the neural substrates of multisensory temporal processing in this clinical population, we employed functional magnetic resonance imaging (fMRI) with a simultaneity-judgment audiovisual speech task. Eighteen autistic youth and a comparison group of 20 non-autistic youth matched on chronological age, biological sex, and gender participated. Results extend prior findings from studies of non-autistic adults, with non-autistic youth demonstrating responses in several similar regions as previously implicated in adult temporal processing of multisensory speech. Autistic youth demonstrated responses in fewer of the multisensory regions identified in adult studies; responses were limited to visual and motor cortices. Group responses in the middle temporal gyrus significantly interacted with age; younger autistic individuals showed reduced MTG responses whereas older individuals showed comparable MTG responses relative to non-autistic controls. Across groups, responses in the precuneus covaried with task accuracy, and anterior temporal and insula responses covaried with nonverbal IQ. These preliminary findings suggest possible differences in neural mechanisms of audiovisual processing in autistic youth while highlighting the need to consider participant characteristics in future, larger-scale studies exploring the neural basis of multisensory function in autism.

The cognitive neural mechanism of response inhibition and error processing to fearful expressions in adolescents with high reactive aggression.

Reactive aggression in adolescents is characterized by high levels of impulsivity. This is associated with deficits in response inhibition and error processing and spontaneous emotion-driven responses to a perceived threat. However, the characteristics and cognitive neural mechanisms of response inhibition and error processing to indirect threat in adolescents with high levels of reactive aggression are unclear. This study explored the characteristics and cognitive neural mechanisms of response inhibition and error processing to fearful expressions in adolescents with high levels of reactive aggression using an emotional Go/No-Go paradigm combined with ERP recordings. Adolescents with high levels of reactive aggression (n = 31) and a control group (n = 30) took part in this study. Results showed that when presented with fearful expressions, adolescents with high levels of reactive aggression showed a smaller No-Go P3 effect and smaller ERN amplitudes following commission errors on the No-Go task than the control group. Results suggested that when presented with fearful expressions, adolescents with high levels of reactive aggression have impaired response inhibition in the later stage of actual inhibitory control of the motor system and impaired error processing in the early stage of fast and automatic initial error detection.

Neural similarities and differences between native and second languages in the bilateral fusiform cortex in Chinese-English bilinguals

In the field of bilingualism, researchers have proposed an assimilation hypothesis that posits that bilinguals apply the neural network of their native language to process their second language. In Chinese-English bilinguals, the bilateral fusiform gyrus has been identified as the key brain region showing the assimilation process. Specifically, in contrast to left-lateralized activation in the fusiform gyrus in native English speakers, Chinese-English bilinguals recruit the bilateral fusiform cortex to process English words as they do in the processing of Chinese characters. Nevertheless, it is unclear which type of information processing is assimilated in the fusiform gyrus. Using representational similarity analysis (RSA) and psychophysiological interaction (PPI) analysis, this study examined the differences in information representation and functional connectivity between both languages in the fusiform subregions in Chinese-English bilinguals. Univariate analysis revealed that both Chinese and English naming elicited strong activations in the bilateral fusiform gyrus, which confirmed the assimilation process at the activation intensity level. RSA indicated that the neural pattern of English phonological information was assimilated by Chinese in the anterior and middle right fusiform gyrus, while those of orthographic and visual form information were not. Further PPI analysis demonstrated that the neural representation of English phonological information in the right anterior fusiform subregion was related to its interaction with the frontotemporal areas for high-level linguistic processing, while the neural representation of English orthographic information in the right middle fusiform subregion was linked to its interaction with the left inferior occipital cortex for visual processing. These results suggest that, despite the recruitment of similar neural resources in one's native and second languages, the assimilation of information representation is limited in the bilateral fusiform cortex. Our results shed light on the neural mechanisms of second language processing.

Adaptive changes in sensorimotor processing in patients with acute low back pain

In low back pain (LBP), primary care and secondary prevention of recurrent and persistent LBP are not always successful. Enhanced understanding of neural mechanisms of sensorimotor processing and pain modulation in patients with acute LBP is mandatory. This explorative fMRI study investigated sensorimotor processing due to mechanosensory stimulation of the lumbar spine. We studied 19 adult patients with acute LBP (< 4 weeks of an acute episode) and 23 healthy controls. On a numeric rating scale, patients reported moderate mean pain intensity of 4.5 out of 10, while LBP-associated disability indicated mild mean disability. The event-related fMRI analysis yielded no between-group differences. However, the computation of functional connectivity resulted in adaptive changes in networks involved in sensorimotor processing in the patient group: Connectivity strength was decreased in the salience and cerebellar networks but increased in the limbic and parahippocampal networks. Timewise, these results indicate that early connectivity changes might reflect adaptive physiological processes in an episode of acute LBP. These findings raise intriguing questions regarding their role in pain persistence and recurrences of LBP, particularly concerning the multiple consequences of acute LBP pain. Advanced understanding of neural mechanisms of processing non-painful mechanosensations in LBP may also improve therapeutic approaches.