Neurophysiological investigation of the lateral prefrontal cortex during the task of binocular flash suppression

Multistable visual phenomena, wherein unchanging sensory input elicits in an observer, perceptual fluctuations, have been instrumental in unravelling the neural correlates of conscious perception. Such paradigms, when combined with single unit recordings in macaques trained to report their perception, have allowed neurophysiologists to elucidate, if the cells in various regions of the brain are correlated with subjective experience or respond to the invariant retinal input. Results obtained from such an approach has so far revealed that the proportion of feature selective cells which fire in concordance with perception, increase as one progresses in the ventral visual pathway, with this fraction being up to 90% in the temporal lobe. The next station in the ventral stream of vision is the lateral prefrontal cortex (LPFC), which has reciprocal connectivity with the inferotemporal cortex and displays responses which are selective for complex visual stimuli. However, it’s not clear if this feature selective neural activity is just the result of sensory input or is related to subjective perception. Utilizing the task of binocular flash suppression (BFS), a psychophysical paradigm capable of dissociating perception from the retinal message, we probed the neural responses in the LPFC. The results revealed a robust perceptual modulation of both the spiking activity as well as high frequency gamma oscillations in this region of the brain. Even though single unit activity is robustly modulated according to perceptual content, a measure of effective functional connectivity between pairs of neurons, such as correlated variability could be revealing of interactions among neuronal populations during visual ambiguity. We therefore computed the spike count correlations across pairs of simultaneously recorded neurons during subjective visual perception. Interestingly, such interneuronal correlations among single units which preferred the same stimulus were close to zero during incongruent visual input, thus reflecting a modulation of the correlation structure during visual perception. Simulations with biophysically realistic networks suggested that the source of decorrelation was an active suppression of input fluctuations. This suggests that such a decorrelated state might be critical for representation of conscious content during visual conflict. These results together provide credence to the ‘frontal lobe hypothesis’ proposed by Crick and Koch, which suggested that the planning stages of the brain must have explicit access to the conscious visual percept so as to direct motor output. Such access is essential, if the LPFC needs to carry out one of its major function which is of cognitive control. Interestingly, when a control related signal, namely the modulation pattern of the beta band oscillations in the LPFC was analyzed, its modulation pattern was unchanged not only across monocular and incongruent visual stimulation but also during perceptual dominance and suppression. This suggests that a signal which is related to control processes is unaffected by local conscious or unconscious neural processing. Lastly, we observed an enormous diversity among the patterns of single unit activity recorded in the LPFC and the neurons which displayed visual preference were just a minority. In order to elucidate, if there were any other patterns of activity which were related to the task, we clustered the neuronal responses using a non-negative matrix factorization (NNMF) method. This revealed five sequential dominant response patterns (or components) whose peaks were temporally distributed across various phases of the trial. A majority of the units with firing profiles similar to the patterns obtained, maintained their responses across monocular or incongruent stimulation suggesting that visual conflict did not affect their spiking modulation. Interestingly, an assessment of the effective functional connectivity across the pairs of neurons belonging to different temporally distributed components revealed that such correlated variability was maximum among units which were temporally coincident. However, we observed successive decorrelation as the pairs of units were chosen from temporally separated populations. This suggests a computational principle mediating a representation of sequential patterns of activity in the LPFC. Together, the results presented in this thesis suggest a role for the LPFC in representation of conscious content. At the same time, we find that such a role of this region is coexistent with other major functions typically attributed to this area, such as cognitive control or temporal encoding of task events through sequential neural activity

Privacy Violation and Detection Using Pattern Mining Techniques

Privacy, its violations and techniques to bypass privacy violation have grabbed the centre-stage of both academia and industry in recent months. Corporations worldwide have become conscious of the implications of privacy violation and its impact on them and to other stakeholders. Moreover, nations across the world are coming out with privacy protecting legislations to prevent data privacy violations. Such legislations however expose organizations to the issues of intentional or unintentional violation of privacy data. A violation by either malicious external hackers or by internal employees can expose the organizations to costly litigations. In this paper, we propose PRIVDAM; a data mining based intelligent architecture of a Privacy Violation Detection and Monitoring system whose purpose is to detect possible privacy violations and to prevent them in the future. Experimental evaluations show that our approach is scalable and robust and that it can detect privacy violations or chances of violations quite accurately. Please contact the author for full text at [email protected]

Immediate placement of dental implants in non vascularised iliac graft after resection of anterior mandible : A case report

This case report presents a combination of surgical and prosthetic rehabilitation applied to a case in postsurgical reconstructed mandible. We report a patient suffering from desmoplastic ameloblastoma of mandible, who underwent Enbloc resection and reconstruction with iliac bone graft with simultaneous placement of dental implant in anterior mandible. Two dental implants were placed at both ends of the graft. At five years follow up, favourable osseointegration with healthy peri-implant tissue was reported

Formulation, Development and Evaluation of Fast Dissolving Oral Film of Antidepressant Drug

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Glucometric Guardianship

It is a well-known fact that the knowledge of their current glucose readings empowered people with diabetes to evaluate and monitor the trends in glucose fluctuations and take informed decisions on adjusting their medicines, food intake, and physical activity. Glucose monitoring technology has undergone a technological evolution and has improved diabetes care in patients living with type 2 diabetes. This has also made the need to efficiently and effectively utilize blood glucose monitoring tools. Given the above, the article has reviewed the significance of glucometric guardianship. Glucometric checklists offer a standardized approach to glucometric guardianship which is necessary to improve the process of drug choice and dose titration. The stepwise factors included in the glucometric guardianship checklist include procurement, distribution, pre-testing hygiene, testing, recording, action, disposal, quality control, and procedure safety

Development of Micro-Emulsion Gel Based Topical Delivery of Salicylic Acid and Neem Oil for the Management of Psoriasis

Microemulsions (MEs) are clear, thermodynamically stable systems. They were used to solubilise drugs and to improve topical drug availability. Salicylic acid (SA) is a keratolytic agent used in topical products with antimicrobial actions. This study aimed to formulate an optimized SA micro emulsion gel for the slow, variable and incomplete oral drug absorption in patient suffering from psoriasis infection. The dispersion solubility of SA was studied in various oils, surfactants and co-surfactants and by constructing pseudo phase ternary diagram, micro emulsion area was identified. The optimized formulations of micro emulsion were subjected to thermodynamic stability tests. After stability study, stable formulation was characterized for droplet size, pH determination, centrifugation, % drug content in micro emulsion, zeta Potential and vesicle size measurement and then micro emulsion gel were prepared and characterized for spreadability, measurement of viscosity, drug content, In-vitro diffusion, in-vitro release data. Labrasol was selected as surfactant, plurol oleique as co surfactant and neem oil as oil component based on solubility study. The optimized formulation contained SA 0.05 (%w/w), labrasol (24%), plurol oleique (8 %) and neem oil (8%). The in vitro drug release from SA micro emulsion gel was found to be considerably higher in comparison to that of the pure drug. The in-vitro diffusion of micro emulsion gel was significantly good. Based on this study, it can be concluded the solubility and permeability of SA can be increased by formulating into micro emulsion gel. Keywords: Salicylic Acid, Neem Oil, Micro-emulsion, In-vitro diffusion, Zeta potential, Stability, Labraso