Biologically Feasible Generative Neural Network Architecture with Effective Concept Learning Capacity

Representations play an essential role in the learning of artificial and biological systems due to their capacity to identify characteristic patterns in the sensory environment. In this work we examined latent representations of several sets of images, such as basic geometric shapes and handwritten digits, produced by generative models in the process of unsupervised generative learning. A biologically feasible neural network architecture based on bi-directional synaptic connection equivalent in training and processing to a symmetrical autoencoder was proposed and defined. It was demonstrated that conceptual representations with good decoupling of concept regions can be produced with generative models of limited complexity; and that incremental evolution of architecture can result in improved ability to learn data of increasing conceptual complexity, including realistic images such as handwritten digits. The results demonstrate potential of conceptual representations produced as a natural platform for conceptual modeling of sensory environments and other intelligent behaviors.

Regular rhythmic and audio-visual stimulations enhance procedural learning of a perceptual-motor sequence in healthy adults: A pilot study

Procedural learning is essential for the effortless execution of many everyday life activities. However, little is known about the conditions influencing the acquisition of procedural skills. The literature suggests that sensory environment may influence the acquisition of perceptual-motor sequences, as tested by a Serial Reaction Time Task. In the current study, we investigated the effects of auditory stimulations on procedural learning of a visuo-motor sequence. Given that the literature shows that regular rhythmic auditory rhythm and multisensory stimulations improve motor speed, we expected to improve procedural learning (reaction times and errors) with repeated practice with auditory stimulations presented either simultaneously with visual stimulations or with a regular tempo, compared to control conditions (e.g., with irregular tempo). Our results suggest that both congruent audio-visual stimulations and regular rhythmic auditory stimulations promote procedural perceptual-motor learning. On the contrary, auditory stimulations with irregular or very quick tempo alter learning. We discuss how regular rhythmic multisensory stimulations may improve procedural learning with respect of a multisensory rhythmic integration process.

The goal-relevance of affective stimuli is dynamically represented in affective experience

Affect is a continuous and temporally dependent process that represents an individual's ongoing relationship with its environment. However, there is a lack of evidence on how factors defining the dynamic sensory environment modulate changes in momentary affective experience. Here, we show that goal-dependent relevance of stimuli is a key factor shaping momentary affect in a dynamic context. Participants ( N = 83) viewed sequentially presented images and reported their momentary affective experience after every fourth stimulus. Relevance was manipulated through an attentional task that rendered each image either task-relevant or task-irrelevant. Computational models were fitted to trial-by-trial affective responses to capture the key dynamic parameters explaining momentary affective experience. The findings from statistical analyses and computational models showed that momentary affective experience was shaped by the temporal integration of the affective impact of recently encountered stimuli, and that task-relevant stimuli, independent of stimulus affect, prompted larger changes in experienced pleasantness compared with task-irrelevant stimuli. These findings clearly show that dynamics of affective experience reflect goal-relevance of stimuli in our surroundings.

Natural sound characteristics explain perceptual categorization

As we interact with our surroundings, we encounter the same or similar objects from different perspectives and are compelled to generalize. For example, we recognize dog barks as a distinct class of sound, despite the variety of individual barks. While we have some understanding of how generalization is done along a single stimulus dimension, such as frequency or color, natural stimuli are identifiable by a combination of dimensions. To understand perception, measuring the interaction across stimulus dimensions is essential. For example, when identifying a sound, does our brain focus on a specific dimension or a combination, such as its frequency and duration? Furthermore, does the relative relevance of each dimension reflect its contribution to the natural sensory environment? Using a 2-dimension discrimination task for mice we tested untrained generalization across several pairs of auditory dimensions. We uncovered a perceptual hierarchy over the tested dimensions that was dominated by the sound’s spectral composition. A model tuned to the predictability inherent in natural sounds best explained the behavioral results, suggesting that the perceptual hierarchy parallels the predictive content of natural sounds.

Immersive virtual reality interferes with default head–trunk coordination strategies in young children

The acquisition of postural control is an elaborate process, which relies on the balanced integration of multisensory inputs. Current models suggest that young children rely on an ‘en-block’ control of their upper body before sequentially acquiring a segmental control around the age of 7, and that they resort to the former strategy under challenging conditions. While recent works suggest that a virtual sensory environment alters visuomotor integration in healthy adults, little is known about the effects on younger individuals. Here we show that this default coordination pattern is disrupted by an immersive virtual reality framework where a steering role is assigned to the trunk, which causes 6- to 8-year-olds to employ an ill-adapted segmental strategy. These results provide an alternate trajectory of motor development and emphasize the immaturity of postural control at these ages.

Resetting of Auditory and Visual Segregation Occurs After Transient Stimuli of the Same Modality

In the presence of a continually changing sensory environment, maintaining stable but flexible awareness is paramount, and requires continual organization of information. Determining which stimulus features belong together, and which are separate is therefore one of the primary tasks of the sensory systems. Unknown is whether there is a global or sensory-specific mechanism that regulates the final perceptual outcome of this streaming process. To test the extent of modality independence in perceptual control, an auditory streaming experiment, and a visual moving-plaid experiment were performed. Both were designed to evoke alternating perception of an integrated or segregated percept. In both experiments, transient auditory and visual distractor stimuli were presented in separate blocks, such that the distractors did not overlap in frequency or space with the streaming or plaid stimuli, respectively, thus preventing peripheral interference. When a distractor was presented in the opposite modality as the bistable stimulus (visual distractors during auditory streaming or auditory distractors during visual streaming), the probability of percept switching was not significantly different than when no distractor was presented. Conversely, significant differences in switch probability were observed following within-modality distractors, but only when the pre-distractor percept was segregated. Due to the modality-specificity of the distractor-induced resetting, the results suggest that conscious perception is at least partially controlled by modality-specific processing. The fact that the distractors did not have peripheral overlap with the bistable stimuli indicates that the perceptual reset is due to interference at a locus in which stimuli of different frequencies and spatial locations are integrated.

A cerebellar-prepontine circuit for tonic immobility triggered by inescapable threat

Sudden changes in the sensory environment are frequently perceived as threats and may provoke defensive behavioral states. One such state is tonic immobility, a conserved defensive strategy characterized by a powerful suppression of movement and motor reflexes. Tonic immobility has been associated with multiple brainstem regions and cell types, but the underlying circuit is not known. Here, we demonstrate that a strong vibratory stimulus evokes tonic immobility in larval zebrafish defined by suppression of exploratory locomotion and sensorimotor responses. Using a circuit-breaking screen and targeted neuron ablations we show that cerebellar granule cells and a cluster of glutamatergic ventral prepontine neurons (vPPNs) that express key stress-associated neuropeptides are critical components of the circuit that suppresses movement. The complete sensorimotor circuit transmits information from primary sensory neurons through the cerebellum to vPPNs to regulate reticulospinal premotor neurons. These results show that cerebellar regulation of a neuropeptide-rich prepontine structure governs a conserved and ancestral defensive behavior that is triggered by inescapable threat.

Effect of environmental enrichment and isolation on behavioral and histological indices following focal ischemia in old rats

Stroke is a disease of aging. In stroke patients, the enriched group that received stimulating physical, eating, socializing, and group activities resulted in higher activity levels including spending more time on upper limb, communal socializing, listening and iPad activities. While environmental enrichment has been shown to improve the behavioral outcome of stroke in young animals, the effect of an enriched environment on behavioral recuperation and histological markers of cellular proliferation, neuroinflammation, and neurogenesis in old subjects is not known. We used behavioral testing and immunohistochemistry to assess the effect of environment on post-stroke recovery of young and aged rats kept either in isolation or stimulating social, motor, and sensory environment (( +)Env). We provide evidence that post-stroke animals environmental enrichment ( +)Env had a significant positive effect on recovery on the rotating pole, the inclined plane, and the labyrinth test. Old age exerted a small but significant effect on lesion size, which was independent of the environment. Further, a smaller infarct volume positively correlated with better recovery of spatial learning based on positive reinforcement, working and reference memory of young, and to a lesser extent, old animals kept in ( +)Env. Histologically, isolation/impoverishment was associated with an increased number of proliferating inflammatory cells expressing ED1 cells in the peri-infarcted area of old but not young rats. Further, ( +)Env and young age were associated with an increased number of neuroepithelial cells expressing nestin/BrdU as well as beta III tubulin cells in the damaged brain area which correlated with an increased performance on the inclined plane and rotating pole. Finally, ( +)Env and an increased number of neurons expressing doublecortin/BrdU cells exerted a significant effect on performance for working memory and performance on the rotating pole in both age groups. A stimulating social, motor and sensory environment had a limited beneficial effect on behavioral recovery (working memory and rotating pole) after stroke in old rats by reducing neuroinflammation and increasing the number of neuronal precursors expressing doublecortin. Old age however, exerted a small but significant effect on lesion size, which was independent of the environment.

The reality of practicing sports activities modified for people with mild intellectual disabilities from the perspective of the teacher: واقع ممارسة الأنشطة الرياضية المكيفة للأشخاص ذوي الإعاقة الفكرية البسيطة من وجهة نظر المعلمين

The current study aimed to identify the reality of practicing sports activities modified for people with mild intellectual disabilities from the perspective of the teacher, in light of some variables including "Gender, Academic Qualification and Sector". The sample of the study included of (105) male and female current teachers of intellectually disabled in the governmental and private sectors. They were chosen randomly using the descriptive methodology, and the results concluded that the degree of applying modified sports activities with people with simple intellectual disabilities was moderate, with no statistically significant differences in the domain of (physical sensory environment for sports activities, the degree of availability of human resources qualified to train sports activities, and the role of the teachers of mentally disabled to activate sports activities) are attributed to the gender and the educational qualification variables, with statistically significant differences in the domain of (physical sensory environment for sports activities) attributed to the sector variable and came in favor of the private sector. The researcher recommended the importance of activating the various sporting activities for the intellectually disabled by qualified specialists in order to adopt planned and organized training programs.

Resetting of Auditory and Visual Segregation Occurs After Transient Stimuli of the Same Modality

In the presence of a continually changing sensory environment, maintaining stable but flexible awareness is paramount, and requires continual organization of information. Determining which stimulus features belong together, and which are separate is therefore one of the primary tasks of the sensory systems. Unknown is whether there is a global or sensory-specific mechanism that regulates the final perceptual outcome of this streaming process. To test the extent of modality independence in perceptual control, an auditory streaming experiment, and a visual moving-plaid experiment were performed. Both were designed to evoke alternating perception of an integrated or segregated percept. In both experiments, transient auditory and visual distractor stimuli were presented in separate blocks, such that the distractors did not overlap in frequency or space with the streaming or plaid stimuli, respectively, thus preventing peripheral interference. When a distractor was presented in the opposite modality as the bistable stimulus (visual distractors during auditory streaming or auditory distractors during visual streaming), the rate of percept switching was not significantly different than when no distractor was presented. Conversely, significant differences in switch rate were observed following within-modality distractors, but only when the pre-distractor percept was segregated. Due to the modality-specificity of the distractor-induced resetting, the results suggest that conscious perception is at least partially controlled by modality-specific processing. The fact that the distractors did not have peripheral overlap with the bistable stimuli indicates that the perceptual reset is due to interference at a locus in which stimuli of different frequencies and spatial locations are integrated.