3. Producción

Browse

Search Results

Now showing 1 - 9 of 9

Some of the metrics are blocked by your
consent settings
Experimental Research Methodology and Statistics Insights
(Springer, 2020-01-01)
Some of the metrics are blocked by your
consent settings
Influence of E/I balance and pruning in peri-personal space differences in schizophrenia: a computational approach
(Elsevier, 2021-09-09)
The encoding of the space close to the body, named peri-personal space (PPS), is thought to play a crucial role in the unusual experiences of the self observed in schizophrenia (SCZ). However, it is unclear why SCZ patients and high schizotypal (H-SPQ) individuals present a narrower PPS and why the boundaries of the PPS are more sharply defined in patients. We hypothesise that the unusual PPS representation observed in SCZ is caused by an imbalance of excitation and inhibition (E/I) in recurrent synapses of unisensory neurons or an impairment of bottom-up and top-down connectivity between unisensory and multisensory neurons. These hypotheses were tested computationally by manipulating the effects of E/I imbalance, feedback weights and synaptic density in the network. Using simulations we explored the effects of such impairments in the PPS representation generated by the network and fitted the model to behavioural data. We found that increased excitation of sensory neurons could account for the smaller PPS observed in SCZ and H-SPQ, whereas a decrease of synaptic density caused the sharp definition of the PPS observed in SCZ. We propose a novel conceptual model of PPS representation in the SCZ spectrum that can account for alterations in self-world demarcation, failures in tactile discrimination and symptoms observed in patients.
Some of the metrics are blocked by your
consent settings
Reduced synaptic plasticity and E/I imbalance drive peripersonal space boundaries expansion in schizophrenia
(Cold Spring Harbor Laboratory, 2024-07-23)
Abnormal encoding of peripersonal space (PPS) is believed to affect bodily self disruptions in schizophrenia (SCZ). Empirical studies show that SCZ patients exhibit a narrower PPS than controls but maintain its plasticity. Computational research links this smaller PPS to increased excitation of sensory neurons and reduced feedforward synaptic density. However, it is unclear how such differences influence learning during the expansion of PPS boundaries. We hypothesise that Hebbian plasticity can account for PPS expansion after active tool use training. To explore the effect of such mechanisms on PPS plasticity, we developed a SCZ network model which was fit to behavioural data before and after tool manipulation. We found that PPS expansion occurs in spite of E/I imbalance or reduced synaptic density, but does not match the post-training PPS representation of patients. A better fit was obtained after altering plasticity by either reducing the learning rate, increasing the forgetting rate or increasing the plasticity threshold. We discuss our findings in terms of dysfunctional plasticity in SCZ and highlight the key challenges in identifying the neurobiological correlates of reduced plasticity within PPS networks. Because current empirical data supports multiple viable mechanisms, we propose experiments to distinguish between the proposed plasticity accounts and clarify mixed findings on PPS representation in SCZ. Graphical Highlights Using a peripersonal space network model, we found that PPS expansion after tool-use occurs in spite of E/I imbalance or reduced synaptic density. Reduced feedforward synaptic plasticity is required to match the post-training PPS representation of patients. Such reduction of synaptic plasticity could be achieved by either reducing the learning rate, increasing the forgetting rate or increasing the plasticity threshold relative to a healthy control model. Our model predicts that measuring PPS at intermediate time points during a longer stimulation protocol would help distinguish between these plasticity differences.
Some of the metrics are blocked by your
consent settings
Increased excitation enhances the sound-induced flash illusion by impairing multisensory causal inference in the schizophrenia spectrum
(Cold Spring Harbor Laboratory, 2024-05-31)
The spectrum of schizophrenia is characterised by an altered sense of self with known impairments in tactile sensitivity, proprioception, body-self boundaries, and self-recognition. These are thought to be produced by failures in multisensory integration mechanisms, commonly observed as enlarged temporal binding windows during audiovisual illusion tasks. To our knowledge, there is an absence of computational explanations for multisensory integration deficits in patients with schizophrenia and individuals with high schizotypy, particularly at the neurobiological level. We implemented a multisensory causal inference network to reproduce the responses of individuals who scored low in schizotypy in a simulated double flash illusion task. Next, we explored the effects of recurrent excitation, cross-modal and feedback weights, and synaptic density on the visual illusory responses of the network. Using quantitative fitting to empirical data, we found that an increase in the weights of the recurrent excitatory connectivity in the network enlarges the temporal binding window and increases the overall proneness to experience the illusion, matching the responses of individuals scoring high in schizotypy. Moreover, we found that an increase in excitation increases the probability of inferring a common cause from the stimuli. We propose an E/I imbalance account of reduced temporal discrimination in the SCZ spectrum and discuss possible links with Bayesian theories of schizophrenia. We highlight the importance of adopting a multisensory causal inference perspective to address body-related symptomatology of schizophrenia.
Some of the metrics are blocked by your
consent settings
Qhali: A humanoid robot for assisting in mental health treatment
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-02-01)
In recent years, social assistive robots have gained significant acceptance in healthcare settings, particularly for tasks such as patient care and monitoring. This paper offers a comprehensive overview of the expressive humanoid robot, Qhali, with a focus on its industrial design, essential components, and validation in a controlled environment. The industrial design phase encompasses research, ideation, design, manufacturing, and implementation. Subsequently, the mechatronic system is detailed, covering sensing, actuation, control, energy, and software interface. Qhali’s capabilities include autonomous execution of routines for mental health promotion and psychological testing. The software platform enables therapist-directed interventions, allowing the robot to convey emotional gestures through joint and head movements and simulate various facial expressions for more engaging interactions. Finally, with the robot fully operational, an initial behavioral experiment was conducted to validate Qhali’s capability to deliver telepsychological interventions. The findings from this preliminary study indicate that participants reported enhancements in their emotional well-being, along with positive outcomes in their perception of the psychological intervention conducted with the humanoid robot.
Some of the metrics are blocked by your
consent settings
High orientation and low delayed recall in the standardisation of the Spanish version of the Montreal Cognitive Assessment (MoCA) in elders of Peru
(Cold Spring Harbor Laboratory, 2024-06-17)
The elderly in Peru face healthcare barriers in detecting cognitive impairment and dementia due to a lack of validated tools. The Montreal Cognitive Assessment (MoCA) effectively detects early dementia, assessing visuo-spatial function, executive function, naming, memory, attention, language, abstraction, and orientation. METHODS This study aims to standardise the Spanish version of the MoCA for the elderly in Lima. The test was administered to 338 elders from three institutions: Municipality of San Miguel District, San José Obrero Polyclinic, and EDMECON. Regression-based normed scores were computed, adjusted for age and education. RESULTS Our results show high orientation scores and low delayed recall, highlighting cognitive strengths and weaknesses in our sample. Age and education significantly influenced cognitive performance, with education as the strongest predictor. DISCUSSION This study offers normative data for the Peruvian elderly, aiding the clinical use of MoCA in Peru. We discuss appropriate cut-off points and cultural sensitivity in the Peruvian context.
Some of the metrics are blocked by your
consent settings
Nonlinear Control System for Humanoid Robot to Perform Body Language Movements
(MDPI, 2023-01-01)
In social robotics, especially with regard to direct interactions between robots and humans, the robotic movements of the body, arms and head must make an adequate displacement to guarantee an adequate interaction, both from a functional and social point of view. To achieve this, the use of closed-loop control techniques that consider the complex nonlinear dynamics and disturbances inherent in these systems is required. In this paper, an implementation of a nonlinear controller for the tracking of trajectories and a profile of speeds that execute the movements of the arms and head of a humanoid robot based on the mathematical model is proposed. First, the design and implementation of the arms and head are initially presented, then the mathematical model via kinematic and dynamic analysis was performed. With the above, the design of nonlinear controllers such as nonlinear proportional derivative control with gravity compensation, Backstepping control, Sliding Mode control and the application of each of them to the robotic system are presented. A comparative analysis based on a frequency analysis, the efficiency in polynomial trajectories and the implementation requirements allowed selecting the non-linear Backstepping control technique to be implemented. Then, for the implementation, a centralized control architecture is considered, which uses a central microcontroller in the external loop and an internal microcontroller (as internal loop) for each of the actuators. With the above, the selected controller was validated through experiments performed in real time on the implemented humanoid robot, demonstrating proper path tracking of established trajectories for performing body language movements.
Some of the metrics are blocked by your
consent settings
Normative data of the Spanish version of the Montreal Cognitive Assessment (MoCA) in older individuals from Peru
(Associação Neurologia Cognitiva e do Comportamento, 2025-01-01)
The Montreal Cognitive Assessment (MoCA) has proven to be an effective tool for detecting early dementia in older adults. However, in the Latin American region, there are few available norms of the Spanish version. The Peruvian population faces major healthcare barriers to early screening, so it is important to validate this instrument within this population. Objective: To standardise the Spanish version of the MoCA for the older population in Lima, addressing the critical need for culturally and demographically adapted cognitive evaluation tools in Peru. Methods: The test was administered to 338 ambulatory and homebound adults aged 60 to 80 (216 women) from three institutions: San Miguel District Municipality, San José Obrero Polyclinic in Barranco, and EDMECON in Surco. we computed regression-based norms adjusted for age and education. Results: Sex was not a predictor of the total scores of MoCA. Moreover, age (R2=0.12) and education (R2=0.24) significantly influenced cognitive performance, with education being the strongest predictor. A raw score above 18 indicates normal cognitive performance for the total sample. Conclusions: We provided normative data and cutoff scores for older Peruvians, supporting the clinical use of the MoCA in Peru and setting a benchmark for future test standardizations in the region.
1
Some of the metrics are blocked by your
consent settings
From modelling PPST to modelling bodily self-consciousness: Comment on “Computational models of peripersonal space representation” by T. Bertoni, I.S.J. Chauhan, J.P. Noel & A. Serino
(Elsevier BV, 2025-12-21)
1

3. Producción

Browse

Filters

Settings

Sort By

Results per page

Search Results