Graph-Based Analysis of Visual Scanning Patterns: A Developmental Study on Green and Normal Images.

The present study investigated the visual scanning pattern of children with typical development in three different age groups(4-6,6-8,8-10 years old). We used a data set from one related research, which included images with different low-level features: Green and Normal. This study analyzed age-associated inter-individual differences and was intended to show that graph profiling combined with a fixation time approach could help us to better understand the developmental visual pattern. Thus, degree centrality as one of the graph theory measures was implied to analyze gaze distribution. We explored the influence of bottom-up features, comparing the first 2 s (early phase) with the interval from 4 to 6 s (late phase) of scene exploration during age development. Our results indicated that degree centrality and fixation time increased with age. Furthermore, it was found that the effects of saliency are short-lived but significant. Moreover, we found that Green images during the early phase play an important role in visual anchoring, and the children's performance was significantly different between 4-6 y and 6-8y-group. This comparative study underscores the ability of degree centrality as a developing innovative measure to perform eye-tracking data analyses.

Coexistence of Stochastic Oscillations and Self-Organized Criticality in a Neuronal Network: Sandpile Model Application.

Self-organized criticality (SOC) and stochastic oscillations (SOs) are two theoretically contradictory phenomena that are suggested to coexist in the brain. Recently it has been shown that an accumulation-release process like sandpile dynamics can generate SOC and SOs simultaneously. We considered the effect of the network structure on this coexistence and showed that the sandpile dynamics on a small-world network can produce two power law regimes along with two groups of SOs-two peaks in the power spectrum of the generated signal simultaneously. We also showed that external stimuli in the sandpile dynamics do not affect the coexistence of SOC and SOs but increase the frequency of SOs, which is consistent with our knowledge of the brain.

Bifurcation Theory Approach to Neuro-Developmental Language Impairment in Autistic Children.

Autism Spectrum Disorders (ASD) is defined by a spectrum of deficits in social interactions and limited or stereotyped patterns of behaviours. Consequently, language as the result and the tool of communication is impaired in individuals affected by ASD. Thus, a better knowledge of language impairment leads to a better solution of the communicating problems. "Dynamical systems theory" could help us understand the development of language and the related impairments. Based on this theory, language development can be considered as a dynamical system with the trajectory of variation. In the present study, we hypothesised that a kind of bifurcation happens in language development trajectory of autistic children when they reach a higher level of language like pragmatics.

Scale-freeness of dominant and piecemeal perceptions during binocular rivalry.

When two eyes are simultaneously stimulated by two inconsistent images, the observer's perception switches between the two images every few seconds such that only one image is perceived at a time. This phenomenon is named binocular rivalry (BR). However, sometimes the perceived image is a piecemeal mixed of two stimuli known as piecemeal perceptions. In this study, a BR task was designed in which orthogonal gratings are presented to the two eyes. The subjects were trained to report 3 states: dominant perceptions (two state matching to perceived grating orientation) and the piecemeal perceptions (third state). We explored the scale-freeness of the BR percept durations considering the two dominant monocular states as well as the piecemeal transition state using detrended fluctuation analysis. Our results reproduced the previous finding of memory in the perceptual switches between the monocular perception states. Moreover, we showed that such memory also exists in the transitory periods of dichoptic piecemeal perceptions. These results support our hypothesis that the pool of unstable piecemeal perceptions could be regarded as separate multiple low-depth basin in the perceptual state landscape. Likewise, the transitions from these piecemeal state basins and stable monocular state basins are faced with resistance. Therefore there is inertia and memory (i.e. positive serial correlation) for the piecemeal dichoptic perception states as well as the monocular states.

Screening of autism based on task-free fMRI using graph theoretical approach.

Studies on autism spectrum disorder (ASD) have indicated several dysfunctions in the structure, and functional organization of the brain. However, findings have not been established as a general diagnostic tool yet. In this regard, current study proposed an automatic screening method for recognition of ASDs from healthy controls (HCs) based on their brain functional abnormalities. In this paradigm, brain functional networks of 60 adolescent and young adult males (29 ASDs and 31 HCs) were estimated from subjects' task-free fMRI data. Then, autism screening was developed based on characteristics of the functional networks using the following steps: A) local and global parameters of the brain functional network were calculated using graph theory. B) network parameters of the ASDs were statistically compared to the HCs. C) significantly altered parameters were used as input features of the screening system. D) performance of the system was verified using various classification techniques. The support vector machine showed superiority to others with an accuracy of 92%. Subsequently, reliability of the results was examined using an independent dataset including 20 ASDs and 20 HCs. Our findings suggest that local parameters of the brain functional network, despite the individual variability, can potentially be used for autism screening.

The role of driver nodes in managing epileptic seizures: Application of Kuramoto model.

Synchronization is an important global phenomenon which could be found in a wide range of complex systems such as brain or electronic devices. However, in some circumstances the synchronized states are not desirable for the system and should be suppressed. For example, excessively synchronized activities in the brain network could be the root of neuronal disorders like epileptic seizures. According to the controllability theory of the complex networks, a minimum set of driver nodes has the ability to control the entire system. In this study, we examine the role of driver nodes in suppressing the excessive synchronization in a generalized Kuramoto model, which consists of two types of oscillators: contrarian and regular ones. We used two different structural topologies: Barabási-Albert scale-free (BASF) network and Caenorhabditis elegans (C.elegans) neuronal network. Our results show that contrarian driver nodes have the sufficient ability to break the synchronized level of the systems. In this case, the system coherency level is not fully suppressed that is avoiding dysfunctions of normal brain functions which require the neuronal synchronized activities. Moreover, in this case, the oscillators grouped in two distinct synchronized clusters that could be an indication of chaotic behavior of the system known as resting-state activity of the brain.

Sexual function among married menopausal women in Amol (Iran).

BACKGROUND: Sexual activity is an important part of the human being's life but this instinct could be influenced by some factors such as diseases, drug using, aging, and menopause. But information about that is limited. AIM: The aim of this study is to determine the status of sexual activity among married menopausal women in Amol, Iran. MATERIALS AND METHODS: This descriptive analytical study was conducted to describe the sexual activity and sexual dysfunction of women after menopause. Data were collected from health centers in Amol from 280 married women using a questionnaire (self-completed or by interview). FINDING: Mean age of subjects were 55.9 ± 6.02 years. 23.4% of subjects reported that their sexual intercourse had been low. 70% of subjects reported a decrease in their sexual activities after menopause. Sexual dysfunctions includes sexual desire disorder 80% arousal dysfunction 80%, orgasmic dysfunction 25%, dyspareunia 55.6%, and lack of sexual satisfaction 43.2%. CONCLUSION: Findings revealed high percentage of sexual desire disorder and sexual arousal disorder in menopausal women. Therefore, we should have emphasis on counseling and education about sexual activities during the menopause period.

Modeling schizophrenic-like neuronal patterns using nonlinear delayed differential equations.

We examined the simultaneous effect of altered dopamine and glutamate level on pyramidal cells using a mathematical model. The simulation results suggest that increased dopamine brings about irregular and aperiodic activity, interpreted as schizophrenic state. Hypoglutamatergic conditions have the same effect on the membrane potential of pyramidal cells. Increased glutamate level was able to neutralize the effects of the hyperdopamine state and normal periodic bursting behavior appeared. We suggest that glutamate receptor activation may have therapeutic results in schizophrenic patients. Surely, this hypothesis must be evaluated in the light of experimental studies on animal models or clinical trials.

Saccadic and smooth pursuit eye movements: computational modeling of a common inhibitory mechanism in brainstem.

The oculomotor system coordinates different types of eye movements in order to orient the visual axis, including saccade and smooth pursuit,. It was traditionally thought that the premotor pathways for these different eye movements are largely separate. In particular, a group of midline cells in the pons called omnipause neurons were considered to be part of only the saccadic system. Recent experimental findings have shown activity modulation of these brainstem premotor neurons during both kinds of eye movements. In this study, we propose a new computational model of the brainstem circuitry underlying the generation of saccades and smooth pursuit eye movements. Similar models have been developed earlier, but mainly looking at pure saccades. Here, we integrated recent neurophysiological findings on omnipause neuron activity during smooth pursuit. Our computational model can mimic some new experimental findings as the similarity of "eye velocity profile" with "omnipause neuron pattern of activity" in pursuit movement. We showed that pursuit neuron activity is augmented during catch-up saccades; this increment depends on the initial pursuit velocity in catch-up saccade onset. We conclude that saccadic and pursuit components of catch-up saccades are added to each other nonlinearly.