Representation Of Stimuli Research Articles

Children's Verbal, Visual and Spatial Processing and Storage Abilities: An Analysis of Verbal Comprehension, Reading, Counting and Mathematics.

The importance of working memory (WM) in reading and mathematics performance has been widely studied, with recent research examining the components of WM (i.e., storage and processing) and their roles in these educational outcomes. However, the differing relationships between these abilities and the foundational skills involved in the development of reading and mathematics have received less attention. Additionally, the separation of verbal, visual and spatial storage and processing and subsequent links with foundational skills and downstream reading and mathematics has not been widely examined. The current study investigated the separate contributions of processing and storage from verbal, visual and spatial tasks to reading and mathematics, whilst considering influences on the underlying skills of verbal comprehension and counting, respectively. Ninety-two children aged 7- to 8-years were assessed. It was found that verbal comprehension (with some caveats) was predicted by verbal storage and reading was predicted by verbal and spatial storage. Counting was predicted by visual processing and storage, whilst mathematics was related to verbal and spatial storage. We argue that resources for tasks relying on external representations of stimuli related mainly to storage, and were largely verbal and spatial in nature. When a task required internal representation, there was a draw on visual processing and storage abilities. Findings suggest a possible meaningful separability of types of processing. Further investigation of this could lead to the development of an enhanced WM model, which might better inform interventions and reasonable adjustments for children who struggle with reading and mathematics due to WM deficits.

Towards an animal model of consciousness based on the platform theory

The evolution of intellectual capacities has brought forth a continuum of consciousness levels subserved by neuronal networks of varying complexity. Brain pathologies, neurodegenerative, and mental diseases affect conscious cognition and behavior. Although impairments in consciousness are among the most devastating consequences of neurological and mental diseases, valid and reliable animal models of consciousness, that could be used for preclinical research are missing. The platform theory holds that the brain enters a conscious operation mode, whenever mental representations of stimuli, associations, concepts, memories, and experiences are effortfully maintained (in working memory) and actively manipulated. We used the platform theory as a framework and evaluation standard to categorize behavioral paradigms with respect to the level of consciousness involved in task performance. According to the platform theory, a behavioral paradigm involves conscious cognitive operations, when the problem posed is unexpected, novel or requires the maintenance and manipulation of a large amount of information to perform cognitive operations on them. Conscious cognitive operations are associated with a relocation of processing resources and the redirection of attentional focus. A consciousness behavioral test battery is proposed that is composed of tests which are assumed to require higher levels of consciousness as compared to other tasks and paradigms. The consciousness test battery for rodents includes the following tests: Working memory in the radial arm maze, episodic-like memory, prospective memory, detour test, and operant conditioning with concurrent variable-interval variable-ratio schedules. Performance in this test battery can be contrasted with the performance in paradigms and tests that require lower levels of consciousness. Additionally, a second more comprehensive behavioral test battery is proposed to control for behavioral phenotypes not related to consciousness. Our theory could serve as a guidance for the decryption of the neurobiological basis of consciousness.

Memory Model for Morphological Semantics of Visual Stimuli Using Sparse Distributed Representation

Recent achievements on CNN (convolutional neural networks) and DNN (deep neural networks) researches provide a lot of practical applications on computer vision area. However, these approaches require construction of huge size of training data for learning process. This paper tries to find a way for continual learning which does not require prior high-cost training data construction by imitating a biological memory model. We employ SDR (sparse distributed representation) for information processing and semantic memory model, which is known as a representation model of firing patterns on neurons in neocortex area. This paper proposes a novel memory model to reflect remembrance of morphological semantics of visual input stimuli. The proposed memory model considers both memory process and recall process separately. First, memory process converts input visual stimuli to sparse distributed representation, and in this process, morphological semantic of input visual stimuli can be preserved. Next, recall process can be considered by comparing sparse distributed representation of new input visual stimulus and remembered sparse distributed representations. Superposition of sparse distributed representation is used to measure similarities. Experimental results using 10,000 images in MNIST (Modified National Institute of Standards and Technology) and Fashion-MNIST data sets show that the sparse distributed representation of the proposed model efficiently keeps morphological semantic of the input visual stimuli.

Predicting explicit memory for meaningful cartoons from visual paired comparison in infants and toddlers

We tested the memory of 18-, 33-, and 39-month-olds (N = 120) for dynamic stimulus material (simple cartoons) after 6 months in a visual paired comparison (VPC) task. We also tested the explicit recognition memory (ERM) for the same material. Only the oldest age group (39-month-olds) showed a significant visual (familiarity) preference at the test. Similarly, only the oldest group reliably chose the correct cartoon in the ERM test. Data from the VPC and ERM tasks did not correlate in any age group. However, we suggested a novel score (coined ΔVPC) measuring how much visual preference changes during the test phase in the VPC task. We found that this ΔVPC score (and vocabulary) predicted children’s performance in the ERM task, whereas other potential predictors such as age and conventional novelty preference did not. We discuss the impact of these findings in relation to the development of implicit and explicit memory. Furthermore, we propose that VPC measures are associated with explicit memory only when the participants processed the stimuli conceptually. In such cases, we suggest that the ΔVPC score is an approximation of how demanding it is to construct the mental representation of the familiar stimulus during the test phase.

Multiplexed Representation of Itch and Mechanical and Thermal Sensation in the Primary Somatosensory Cortex.

The primary somatosensory cortex (S1) plays a critical role in processing multiple somatosensations, but the mechanism underlying the representation of different submodalities of somatosensation in S1 remains unclear. Using in vivo two-photon calcium imaging that simultaneously monitors hundreds of layer 2/3 pyramidal S1 neurons of awake male mice, we examined neuronal responses triggered by mechanical, thermal, or pruritic stimuli. We found that mechanical, thermal, and pruritic stimuli activated largely overlapping neuronal populations in the same somatotopic S1 subregion. Population decoding analysis revealed that the local neuronal population in S1 encoded sufficient information to distinguish different somatosensory submodalities. Although multimodal S1 neurons responding to multiple types of stimuli exhibited no spatial clustering, S1 neurons preferring mechanical and thermal stimuli tended to show local clustering. These findings demonstrated the coding scheme of different submodalities of somatosensation in S1, paving the way for a deeper understanding of the processing and integration of multimodal somatosensory information in the cortex.SIGNIFICANCE STATEMENT Cortical processing of somatosensory information is one of the most fundamental aspects in cognitive neuroscience. Previous studies mainly focused on mechanical sensory processing within the rodent whisking system, but mechanisms underlying the coding of multiple somatosensations remain largely unknown. In this study, we examined the representation of mechanical, thermal, and pruritic stimuli in S1 by in vivo two-photon calcium imaging of awake mice. We revealed a multiplexed representation for multiple somatosensory stimuli in S1 and demonstrated that the activity of a small population of S1 neurons is capable of decoding different somatosensory submodalities. Our results elucidate the coding mechanism for multiple somatosensations in S1 and provide new insights that improve the present understanding of how the brain processes multimodal sensory information.

Cross-modal perceptual enhancement of unisensory targets is uni-directional and does not affect temporal expectations

Temporal structures in the environment can shape temporal expectations (TE); and previous studies demonstrated that TEs interact with multisensory interplay (MSI) when multisensory stimuli are presented synchronously. Here, we tested whether other types of MSI – evoked by asynchronous yet temporally flanking irrelevant stimuli – result in similar performance patterns. To this end, we presented sequences of 12 stimuli (10 Hz) which consisted of auditory (A), visual (V) or alternating auditory-visual stimuli (e.g. A-V-A-V-…) with either auditory or visual targets (Exp. 1). Participants discriminated target frequencies (auditory pitch or visual spatial frequency) embedded in these sequences. To test effects of TE, the proportion of early and late temporal target positions was manipulated run-wise. Performance for unisensory targets was affected by temporally flanking distractors, with auditory temporal flankers selectively improving visual target perception (Exp. 1). However, no effect of temporal expectation was observed. Control experiments (Exp. 2–3) tested whether this lack of TE effect was due to the higher presentation frequency in Exp. 1 relative to previous experiments. Importantly, even at higher stimulation frequencies redundant multisensory targets (Exp. 2–3) reliably modulated TEs. Together, our results indicate that visual target detection was enhanced by MSI. However, this cross-modal enhancement – in contrast to the redundant target effect – was still insufficient to generate TEs. We posit that unisensory target representations were either instable or insufficient for the generation of TEs while less demanding MSI still occurred; highlighting the need for robust stimulus representations when generating temporal expectations.

Modeling incentive salience in Pavlovian learning more parsimoniously using a multiple attribute model.

We present a multi-attribute incentive salience (MAIS) model as a computational account of incentive salience in model-based Pavlovian learning. A model of incentive salience as a joint function of reward value and physiological state has been previously proposed by Zhang et al. (2009). In that model, the function takes additive or multiplicative forms depending on whether a preference shifts from positive to negative or vice versa. We demonstrate that arbitrarily varying this function is unnecessary to explain observed data. A multiplicative function is sufficient if one takes into account empirical data suggesting the incentive salience function for an incentive is comprised of multiple physiological signals. We compare our model to the previously proposed model on two datasets. We find the MAIS model predicts the outcomes equally well, fits empirical data describing multiple sensory representations of a single stimulus, better approximates the dual-structure appetitive-aversive nature of the reward system, is compatible with existing knowledge about incentive salience in Pavlovian learning, and better describes revaluation in Pavlovian learning. This model addresses a call (Dayan & Berridge, 2014) for algorithmic and computational models of model-based Pavlovian learning that consistently and fully explain empirical observations. Because a multi-attribute model is relevant even for simple Pavlovian associations, it should be useful in a wide variety of decision-making contexts, including agent modeling and addiction research.

Methylphenidate modulates interactions of anxiety with cognition

While a large body of literature documents the impairing effect of anxiety on cognition, performing a demanding task was shown to be effective in reducing anxiety. Here we explored the mechanisms of this anxiolytic effect by examining how a pharmacological challenge designed to improve attentional processes influences the interplay between the neural networks engaged during anxiety and cognition. Using a double-blind between-subject design, we pharmacologically manipulated working memory (WM) using a single oral dose of 20 mg methylphenidate (MPH, cognitive enhancer) or placebo. Fifty healthy adults (25/drug group) performed two runs of a WM N-back task in a 3 T magnetic resonance imaging scanner. This task comprised a low (1-Back) and high (3-Back) WM load, which were performed in two contexts, safety or threat of shocks (induced-anxiety). Analyses revealed that (1) WM accuracy was overall improved by MPH and (2) MPH (vs. placebo) strengthened the engagement of regions within the fronto-parietal control network (FPCN) and reduced the default mode network (DMN) deactivation. These MPH effects predominated in the most difficult context, i.e., threat condition, first run (novelty of the task), and 3-Back task. The facilitation of neural activation can be interpreted as an expansion of cognitive resources, which could foster both the representation and integration of anxiety-provoking stimuli as well as the top–down regulatory processes to protect against the detrimental effect of anxiety. This mechanism might establish an optimal balance between FPCN (cognitive processing) and DMN (emotion regulation) recruitment.

Aberrant neural representation of food stimuli in women with acute anorexia nervosa predicts treatment outcome and is improved in weight restored individuals

Anorexia nervosa (AN) has been associated with altered reward processing. We recently reported greater neural response in secondary visual areas when processing visual food stimuli in acutely underweight AN patients (acAN). In order to examine whether the observed alterations are indicative of acute undernutrition or a potential trait marker of AN, we set out to assess neural responses in acAN and in individuals weight-recovered from AN (recAN). FMRI data were collected from a total of 126 female volunteers, 35 acAN, 33 recAN, and 58 age-matched healthy controls (HC) while they viewed streams of food, social and neutral stimuli. A standard general linear model (GLM) was used to interrogate neural responses to the different stimuli in recAN vs. age-matched HC. Moreover, within-subject multivoxel pattern analyses (MVPA) in the two matched samples (acAN/HC and recAN/HC) were used to estimate neural representation of food vs. neutral, and social vs. neutral stimuli. A multiple regression analysis was conducted to test associations between the accuracy of the neural representation and treatment outcome. The GLM revealed no group differences between recAN and HC. The MVPAs showed greater classification accuracy of food stimuli in the posterior fusiform gyrus in acAN but not recAN. Classification accuracy was associated with better treatment outcome. Our findings suggest that the neural representation of food stimuli is altered in secondary visual areas in acAN and normalizes with weight recovery. Possibly this altered representation reflects attentional engagement motivating food intake, which may promote the recovery process.

Illness representations and psychological outcomes in chronic lymphocytic leukaemia.

Chronic lymphocytic leukaemia (CLL) is a lifelong cancer with subtle symptoms. Treatment is not curative and often involves repeated relapses and retreatments. Illness perceptions - cognitive and emotional representations of illness stimuli - were studied in CLL patients to: 1) identify illness perception 'profiles' prior to treatment; and 2) test whether profile membership predicts psychological responses 12 months later as treatment continued. CLL patients (N = 259), randomized to one of four cancer treatment trials testing targeted therapy, were assessed before starting treatment and at 12 months. The Brief Illness Perception Questionnaire (BIPQ) assessed perceived consequences, timeline, personal/treatment control, identity, comprehension, concern, and emotions toward CLL. Psychological outcomes were depressive symptoms (PHQ-9/BDI-II), negative mood (POMS), and cancer stress (IES-R). Latent profile analysis (LPA) determined number of profiles and differential BIPQ items for each profile. Multilevel models tested profiles as predictors of 12-month psychological outcomes. LPA selected the three-profile model, with profiles revealing Low (n = 150; 57.9%), Moderate (n = 21; 8.1%), and High-impact (n = 88; 34.0%) illness representations. Profiles were defined by differences in consequences, identity, concern, and emotions. Profile membership predicted all psychological outcomes (ps<.038). Low-impact profile patients endorsed minimal psychological symptoms; High-impact profile patients reported substantial symptoms. Results of the first CLL illness representation study provide directions for future clinical efforts. By identifying differences among patients' perceptions of CLL consequences, symptom burden, concerns, and emotional responses, an at-risk patient group might receive tailored psychological treatment. Treatments may address negative perceptions, to reduce psychological risk associated with chronic cancer.

Sensory Over-responsivity and Aberrant Plasticity in Cerebellar Cortex in a Mouse Model of Syndromic Autism

BackgroundPatients with autism spectrum disorder often show altered responses to sensory stimuli as well as motor deficits, including an impairment of delay eyeblink conditioning, which involves integration of sensory signals in the cerebellum. Here, we identify abnormalities in parallel fiber (PF) and climbing fiber (CF) signaling in the mouse cerebellar cortex that may contribute to these pathologies. MethodsWe used a mouse model for the human 15q11-13 duplication (patDp/+) and studied responses to sensory stimuli in Purkinje cells from awake mice using two-photon imaging of GCaMP6f signals. Moreover, we examined synaptic transmission and plasticity using in vitro electrophysiological, immunohistochemical, and confocal microscopic techniques. ResultsWe found that spontaneous and sensory-evoked CF-calcium transients are enhanced in patDp/+ Purkinje cells, and aversive movements are more severe across sensory modalities. We observed increased expression of the synaptic organizer NRXN1 at CF synapses and ectopic spread of these synapses to fine dendrites. CF–excitatory postsynaptic currents recorded from Purkinje cells are enlarged in patDp/+ mice, while responses to PF stimulation are reduced. Confocal measurements show reduced PF+CF-evoked spine calcium transients, a key trigger for PF long-term depression, one of several plasticity types required for eyeblink conditioning learning. Long-term depression is impaired in patDp/+ mice but is rescued on pharmacological enhancement of calcium signaling. ConclusionsOur findings suggest that this genetic abnormality causes a pathological inflation of CF signaling, possibly resulting from enhanced NRXN1 expression, with consequences for the representation of sensory stimuli by the CF input and for PF synaptic organization and plasticity.

Transformation of acoustic information to sensory decisions in parietal cortex

Integrating sensory information over time is fundamental for guiding perceptual decisions. This process is facilitated by the transformation of stimulus representations downstream of sensory cortex. Here, we ask how the neural representations of auditory information are transformed in the auditory-recipient parietal cortex, a region that is causally associated with sound-driven perceptual decisions. Wireless recordings of neural activity were conducted in parietal cortex while gerbils performed an alternative forced-choice (AFC) auditory temporal integration task. Gerbils were required to discriminate amplitude modulated (AM) noise at 4 vs 10 Hz across various signal durations (100–2000 ms). Task performance was poor at short AM durations (100–300 ms), improved with longer durations, and reached an optimum at ≥600 ms. During task performance, individual neurons displayed a rise in firing rate that peaked prior to the animals’ decision. Population activity from simultaneously recorded parietal cortex neurons was strongly correlated with behavior outcomes, leaving open whether parietal representation was purely motor-related or included a sensory component. Thus, we evaluated population activity during disengaged sessions, and found a representation of the acoustic stimulus. Our findings suggest that parietal cortex neurons represent both the acoustic stimulus and sound-driven decision, demonstrating the progression of auditory processing downstream of auditory cortex.

Expectation of self-generated sounds drives predictive processing in mouse auditory cortex

Behavior exerts a strong influence over sensory responses in the brain. In the auditory cortex, neural responses to self-generated sounds are suppressed, suggesting that prediction may play a critical role in local sensory processing. However, it is unclear whether this phenomenon derives from a precise movement-based prediction or how it affects the neural representation of incoming stimuli. We address these questions by designing a behavioral paradigm where mice learn to expect the predictable acoustic consequences of a simple forelimb movement. Dense neuronal recordings from auditory cortex revealed suppression of neural responses that was strongest for the expected tone during a narrow time window surrounding the specific sound-associated movement. Predictive suppression was concentrated in layers 2/3 and 5, preceded by the arrival of movement information in deep layers, and driven by motor-sensory coupling rather than task engagement, behavioral relevance, or reward association. Despite large-scale suppression at the population level, the auditory cortex retained a sparse representation of the expected self-generated sounds, while a substantial population of auditory cortex neurons in L2/3 and L5 encoded prediction errors. These findings illustrate that expectation, learned through motor-sensory experience, drives layer-specific predictive processing in the mouse auditory cortex.

The Immediate and Lasting Effect of Emotion Regulation in Adolescents: An ERP Study.

The immediate effect is an important index of the outcomes of emotion regulation. However, in daily life, whether the effect of emotion regulation lasts and the lasting mechanism have been examined less. The present research focused on the relationships between the immediate and lasting effect of the emotion regulation of adolescents. Electroencephalogram (EEG) was recorded from 51 adolescents (31 boys and 20 girls, Mage = 12.82) during online emotion regulation using the Reactivity and Regulation-Image Task (phase 1) and re-presentation of emotional stimuli after a period of time (phase 2). Event-related potentials (ERPs) related to emotion regulation, such as N2, P3, and the late positive potential (LPP), were examined in the two phases. The results showed that: (1) In both of the two phases, in negative emotion conditions, the amplitudes of P3 and LPP 300–600 of no-regulation conditions were significantly higher than those in reappraisal conditions. However, there was no significant difference under neutral conditions; (2) The amplitudes of P3, N2, and LPP 300–600 during emotion regulation in phase 1 positively predicted the amplitudes of P3, N2, and LPP300–600 in phase 2 in different experimental conditions. Results from the regression analysis implied that the immediate effect of online emotion regulation may predict the lasting effect when adolescents face the same emotions again. In addition, our findings provide neurological evidence that the use of cognitive reappraisal could effectively help adolescents to reduce the recruitment of cognitive resources when they regulate negative emotions and when they face those negative emotions again.

Neural representation of multiple visual stimuli moving transparently at different depths in cortical area MT

Neural representation of multiple visual stimuli moving transparently at different depths in cortical area MT

Reported confidence is based on imprecision in visual cortical stimulus representations

Reported confidence is based on imprecision in visual cortical stimulus representations

Social relevance modulates multivariate neural representations of threat generalization in children and adults.

Few studies have examined threat generalization across development and no developmental studies have compared the generalization of social versus nonsocial threat, making it difficult to identify contextual factors that contribute to threat learning across development. The present study assessed youth and adults' multivoxel neural representations of social versus nonsocial threat stimuli. Twenty adults (Mage =25.7 ± 4.9) and 16 youth (Mage =14.1±1.7) completed two conditioning and extinction recall paradigms: one social and one nonsocial paradigm. Three weeks after conditioning, participants underwent a functional magnetic resonance imaging extinction recall task that presented the extinguished threat cue (CS+), a safety cue (CS-), and generalization stimuli (GS) consisting of CS-/CS+ blends. Across age groups, neural activity patterns and self-reported fear and memory ratings followed a linear generalization gradient for social threat stimuli and a quadratic generalization gradient for nonsocial threat stimuli, indicating enhanced threat/safety discrimination for social relative to nonsocial threat stimuli. The amygdala and ventromedial prefrontal cortex displayed the greatest neural pattern differentiation between the CS+ and GS/CS-, reinforcing their role in threat learning and extinction recall. Contrary to predictions, age did not influence threat representations. These findings highlight the importance of the social relevance of threat on generalization across development.

Binocularly-driven competing neural responses and the perceptual resolution of color.

Competing rivalrous neural representations can be resolved at several levels of the visual system. Sustained percepts during interocular-switch rivalry (ISR), in which rivalrous left- and right-eye stimuli swap between eyes several times a second, often are attributed to competing binocularly driven neural representations of each rivalrous stimulus. An alternative view posits monocular neural competition together with a switch in eye dominance at the moment of each stimulus swap between eyes. Here, a range of experimental conditions was tested that would change the colors seen if mediated by eye dominance but not if by competition between binocularly driven responses. Observers viewed multiple chromatically rivalrous discs in various temporal and spatial patterns, and reported when all discs in view appeared the same color. Unlike typical ISR paradigms that swap the complete stimulus in each eye, some of the rivalrous discs were swapped at a different time, or faster frequency, than other discs. Monocular dominance of one eye at a time implies that all discs will rarely be seen as identical in color when some discs swap at a different frequency than others. On the other hand, competing binocularly driven neural responses are not affected by asynchronous swap timing among the individual discs. Results for every observer are in accord with competing responses at the level of binocularly driven, chromatically tuned neurons. Although an account based on eye dominance can be constructed using many small retinotopic zones that have independent timing for the moment of switching the dominant eye, competing binocularly driven responses are a more parsimonious explanation.

Sensory Recruitment Revisited: Ipsilateral V1 Involved in Visual Working Memory.

The "sensory recruitment hypothesis" posits an essential role of sensory cortices in working memory, beyond the well-accepted frontoparietal areas. Yet, this hypothesis has recently been challenged. In the present study, participants performed a delayed orientation recall task while high-spatial-resolution 3T functional magnetic resonance imaging (fMRI) signals were measured in posterior cortices. A multivariate inverted encoding model approach was used to decode remembered orientations based on blood oxygen level-dependent fMRI signals from visual cortices during the delay period. We found that not only did activity in the contralateral primary visual cortex (V1) retain high-fidelity representations of the visual stimuli, but activity in the ipsilateral V1 also contained such orientation tuning. Moreover, although the encoded tuning was faded in the contralateral V1 during the late delay period, tuning information in the ipsilateral V1 remained sustained. Furthermore, the ipsilateral representation was presented in secondary visual cortex (V2) as well, but not in other higher-level visual areas. These results thus supported the sensory recruitment hypothesis and extended it to the ipsilateral sensory areas, which indicated the distributed involvement of visual areas in visual working memory.

Mental Logout: Behavioral and Neural Correlates of Regulating Temptations to Use Social Media

Individuals sometimes use social media instead of sleeping or while driving. This fact raises the crucial need for—and challenge of—successfully self-regulating potent social-media temptations. To date, however, empirical evidence showing whether social-media temptations can be self-regulated and how self-regulation can be achieved remains scarce. Accordingly, the present within-participants study (N = 30 adults) provided causal evidence for self-regulation of social-media content and identified a potential underlying neural mechanism. We tested the premise that successful self-regulation requires limiting the mental representation of temptations in working memory. Specifically, we showed that loading working memory with neutral contents via attentional distraction, relative to passively watching tempting social-media stimuli, resulted in reduced self-reported desire to use social media, reduced initial attention allocation toward social-media stimuli (reduced late-positive-potential amplitudes), and reduced online representation of social-media stimuli in working memory (reduced contralateral-delay-activity amplitudes). These results have important implications for successfully navigating a social-media-saturated environment.