Sergio Ruiz

Pontifical Catholic University of Chile | UC · Departamento de Psiquiatría

Neuroimaging technologies such as brain–computer interfaces and neurofeedback have evolved rapidly as new tools for cognitive neuroscience and as potential clinical interventions. However, along with these developments, concern has grown based on the fear of the potential misuse of neurotechnology. In October 2021, Chile became the first country to...

Motor intention is a high-level brain function related to planning for movement. Although studies have shown that motor intentions can be decoded from brain signals before movement execution, it is unclear whether intentions relating to mental imagery of movement can be decoded. Here, we investigated whether differences in spatial and temporal patt...

Motor intention is a high-level brain function related to planning for movement. Although studies have shown that motor intentions can be decoded from brain signals before movement execution, it was unclear whether intentions relating to mental imagery of movement could be decoded. Here, we investigated whether differences in spatial and temporal p...

Most clinical neurofeedback studies based on functional magnetic resonance imaging use the patient's own neural activity as feedback. The objective of this study was to create a subject-independent brain state classifier as part of a real-time fMRI neurofeedback (rt-fMRI NF) system that can guide patients with depression in achieving a healthy brai...

Memory retrieval of consolidated memories has been extensively studied using “old-new tasks”, meaning tasks in which participants are instructed to discriminate between stimuli they have experienced before and new ones. Significant differences in the neural processing of old and new elements have been demonstrated using different techniques, such a...

Introducción: la resiliencia ha sido definida como la resistencia frente a experiencias psicosociales adversas. Tiene un rol importante en varios trastornos mentales, asociándose, por ejemplo, a la severidad en el trastorno depresivo mayor y a la calidad de vida en el trastorno afectivo bipolar. La esquizofrenia es un trastorno mental severo que de...

Objective: Brain-computer interface (BCI) is a tool that can be used to train brain self-regulation and influence specific activity patterns, including functional connectivity, through neurofeedback. The functional connectivity of the primary motor area (M1) and cerebellum play a critical role in motor recovery after a brain injury, such as stroke...

Adaptive threshold estimation procedures sample close to a subject’s perceptual threshold by dynamically adapting the stimulation based on the subject’s performance. Yet, perceptual thresholds not only depend on the observers’ sensory capabilities but also on any bias in terms of their expectations and response preferences, thus distorting the prec...

Recently, the Chilean Senate approved the main ideas of a constitutional reform and a Neuro-rights bill. This bill aims to protect people from the potential abusive use of “neuro-technologies”. Unfortunately, a literal interpretation of this law can produce severe negative effects both in the development of neuroscience research and medical practic...

Electroencephalography (EEG) source reconstruction estimates spatial information from the brain’s electrical activity acquired using EEG. This method requires accurate identification of the EEG electrodes in a three-dimensional (3D) space and involves spatial localization and labeling of EEG electrodes. Here, we propose a new approach to tackle thi...

Conscious perception of the emotional valence of faces has been proposed to involve top-down and bottom-up information processing. Yet, the underlying neuronal mechanisms of these two processes and the implementation of their cooperation is still unclear. We hypothesized that the key substrates enabling conscious perception are differential partici...

One of the most important and early impairments in autism spectrum disorder (ASD) is the abnormal visual processing of human faces. This deficit has been associated with hypoactivation of the fusiform face area (FFA), one of the main hubs of the face-processing network. Neurofeedback based on real-time fMRI (rtfMRI-NF) is a technique that allows th...

Depression, one of the leading causes of disability and (self-inflicted) death in the world, requires a more robust method of treatment for treatment-resistant patients. Due to imaging techniques like fMRI, real-time neurofeedback (NF) has been shown to aid healthy individuals and patients to voluntarily control their hemodynamic activity, leading...

Conscious perception of emotional valence of faces has been proposed to involve top-down and bottom-up information processing. Yet, the underlying neuronal mechanisms of these two processes and the implementation of their cooperation is still unclear. We hypothesized that the networks activated during the interaction of top-down and bottom-up proce...

Study objectives: To assess spindle activity as possible markers for neurocognitive consequences in children with mild obstructive sleep apnea. Methods: Children aged 6-11 years diagnosed with mild OSA (i.e., an apnea hypopnea index <5.0) were recruited and compared with age and gender-matched healthy controls. Polysomnographic recordings were a...

Bimanual movements involve the interactions between both primary motor cortices. These interactions are assumed to involve phase-locked oscillatory brain activity referred to as inter-hemispheric functional coupling. So far, inter-hemispheric functional coupling has been investigated as a function of motor performance. These studies report mostly a...

Kahneman and Tversky (1979) first demonstrated that when individuals decide whether or not to accept a gamble, potential losses receive more weight than possible gains in the decision. This phenomenon is referred to as loss aversion. We investigated how loss aversion in risky financial decisions is influenced by sudden changes to wealth, employing...

Neural Loss Aversion Differences from one run to the next in both the CONTINGENT and RANDOM tasks. The activation across the four runs in both task manipulations is shown for the brain areas listed in Table 1. The brain activity in Ventral Prefrontal Cortex/Rostral Anterior Cingulate Cortex (a1, a2), right Primary Somatosensory Cortex/Postcentral (...

Results: Studies show that consumption of benzodiazepines in the elderly population in Latin America is high, with a preponderance of long half-life benzodiazepines in women, and frequent self-medication. Conclusions: The revised articles establish the importance of further study of the phenomenon of the use of benzodiazepines in our elderly popula...

Introduction: A complex interaction exists between mental health (MH) and obesity. Weight loss surgery (WLS) is currently an alternative for a growing number of patients. Hence, the aim of this study is to do an up-to-date review of the several aspects on the relationship between WLS and MH. Methods: A comprehensive PubMed search was done, using th...

The learning process involved in achieving brain self-regulation is presumed to be related to several factors, such as type of feedback, reward, mental imagery, duration of training, among others. Explicitly instructing participants to use mental imagery and monetary reward are common practices in real-time fMRI (rtfMRI) neurofeedback (NF), under t...

Mounting evidence in the last years has demonstrated that self-regulation of brain activity can be achieved by neurofeedback (NF). These methodologies have constituted themselves as new tools for cognitive neuroscience, to establish causal links between volitionally controlled brain activations and cognition and behavior, and as potential clinical...

INTRODUCTION: Obsessive-compulsive disorder (OCD) is a common and chronic condition that can have disabling effects throughout the patient's lifespan. Frequent symptoms among OCD patients include fear of contamination and washing compulsions. Several studies have shown a link between contamination fears, disgust over-reactivity, and insula activati...

While earlier Brain-Computer Interface (BCI) studies have mostly focused on modulating specific brain regions or signals, new developments in pattern classification of brain states are enabling real-time decoding and modulation of an entire functional network. The present study proposes a new method for real-time pattern classification and neurofee...

Autism spectrum disorder (ASD) is a developmental disability characterized by early-onset difficulties in social communication and restricted repetitive behavior. One the most important impairments in ASD is the abnormal processes of human faces [1]. This deficit could be associated with an abnormal activity of fusiform face area (FFA) [2]. Therefo...

Introduction: Obsessive-compulsive disorder (OCD) is a common and chronic condition that can have disabling effects throughout the patient's lifespan. Frequent symptoms among OCD patients include fear of contamination and washing compulsions. Several studies have shown a link between contamination fears, disgust over-reactivity, and insula activat...

Coherence of neural activity between circumscribed brain regions has been implicated as an indicator of intracerebral communication in various cognitive processes. While neural activity can be volitionally controlled with neurofeedback, the volitional control of coherence has not yet been explored. Learned volitional control of coherence could eluc...

INTRODUCTION: Obsessive-compulsive disorder (OCD) is a common and chronic condition that can have disabling effects throughout the patient's lifespan. Frequent symptoms among OCD patients include fear of contamination and washing compulsions. Several studies have shown a link between contamination fears, disgust over-reactivity, and insula activati...

While earlier Brain-Computer Interface (BCI) studies have mostly focused on modulating specific brain regions or signals, new developments in pattern classification of brain states are enabling real-time decoding and modulation of an entire functional network. The present study proposes a new method for real-time pattern classification and neurofee...

This pilot study aimed to explore whether criminal psychopaths can learn volitional regulation of the left anterior insula with real-time fMRI neurofeedback. Our previous studies with healthy volunteers showed that learned control of the blood oxygenation-level dependent (BOLD) signal was specific to the target region, and not a result of general a...

According to recent surveys, there is a high prevalence of domestic violence (DV) in Chile. A systematic review was conducted in PubMed, Scielo, and Lilacs with the MesH terms "Chile", "Mental Health", "Health", "Domestic Violence", to explore the impact of DV on health in Chile. Eleven studies fulfilled the inclusion criteria. Two studies were pro...

According to recent surveys, there is a high prevalence of domestic violence (DV) in Chile. A systematic review was conducted in PubMed, Scielo, and Lilacs with the MesH terms "Chile", "Mental Health", "Health", "Domestic Violence", to explore the impact of DV on health in Chile. Eleven studies fulfilled the inclusion criteria. Two studies were pro...

For several decades, researchers have explored neurofeedback and related technologies to improve brain function and better understand brain plasticity. New methods to train people to improve functional connectivity or coherence could inspire new methods to treat a wide variety of brain disorders and conditions. This chapter first reviews functional...

It is hypothesized that a dysfunction of the supplementary motor area (SMA), secondary to a deficit of the nigrostriatal dopamine system, partially contributes to the symptomatology of Parkinson's disease (PD), i.e., akinesia. In this pilot study we investigated the effect of real-time fMRI neurofeedback based volitional up-regulation of SMA on han...

Self-regulation and voluntary control of circumscribed brain regions using real-time functional MRI (rt-fMRI) allows the establishment of a causal functional link between localized brain activity and behavior and cognition. A long tradition of research has clearly shown the brain's ability to learn volitional control of its own activity and effects...

With the advent of brain computer interfaces based on real-time fMRI (rtfMRI-BCI), the possibility of performing neurofeedback based on brain hemodynamics has become a reality. In the early stage of the development of this field, studies have focused on the volitional control of activity in circumscribed brain regions. However, based on the underst...

Considering that single locations of structural and functional abnormalities are insufficient to explain the diverse psychopathology of schizophrenia, new models have postulated that the impairments associated with the disease arise from a failure to integrate the activity of local and distributed neural circuits: the “abnormal neural connectivity...

Real-time functional magnetic resonance imaging (rtfMRI) is a novel technique that has allowed subjects to achieve self-regulation of circumscribed brain regions. Despite its anticipated therapeutic benefits, there is no report on successful application of this technique in psychiatric populations. The objectives of the present study were to train...

This chapter allows noninvasive assessment of brain function with high spatial resolution and whole brain coverage, by measuring changes of the blood oxygenation level- dependent (BOLD) signal. Although the BOLD response is an indirect measure of neural activity, there is accumulating evidence suggesting the close coupling between BOLD and electric...

An important question that confronts current research in affective neuroscience as well as in the treatment of emotional disorders is whether it is possible to determine the emotional state of a person based on the measurement of brain activity alone. Here, we first show that an online support vector machine (SVM) can be built to recognize two disc...

Studies with real-time functional magnetic resonance imaging (fMRI) demonstrate that humans volitionally regulate hemodynamic signals from circumscribed regions of the brain, leading to area-specific behavioral consequences. Methods to better determine the nature of dynamic functional interactions between different brain regions and plasticity due...

Working memory (WM) tasks usually elicit a P300 ERP component, whose amplitude decreases with increasing WM load. So far, this effect has not been studied in schizophrenics (SZs), a group that is considered to have an aberrant brain connectivity and impairments in WM capacity. The aim of this study was to determine the dependency of the P300 compon...

To characterize sick leaves prescription in a specialized psychiatric service. Methods: We recorded all of psychiatric attentions as well as all of sick-leaves prescribed during a three months period (July to September, 2009). Results: 3,105 attentions were done, whit a 12,7% (399 attentions) of them resulting in a sick-leave prescription, correspo...

Objetivo: Describir las características de la prescripción del reposo médico de causa psiquiátrica en un servicio de atención especializado. Métodos: Se registraron las atenciones psiquiátricas y las licencias médicas emitidas en un período de 3 meses (julio a septiembre 2009). Resultados: En el período se realizaron 3.105 consultas psiquiátricas,...

The disconnection hypothesis" in schizophrenia emphasizes that the core dysfunction of this disease corresponds to a global decrease of neuronal con-nectivity involving widespread neuronal networks, or in other words to an altera-tion of the functional connectivity of the brain. Synchronization of EEG activity at high oscillatory frequencies (20–10...

“The disconnection hypothesis” in schizophrenia emphasizes that the core dysfunction of this disease corresponds to a global decrease of neuronal connectivity involving widespread neuronal networks, or in other words to an alteration of the functional connectivity of the brain. Synchronization of EEG activity at high oscillatory frequencies (20 –10...

Introducción: En Chile, el consumo de Pasta Base de Cocaína (PBC) se ha asociado a marginalidad y micronarcotráfico. Es posible que en nuestro país exista una población de consumidores de PBC oculta a los estudios de población general y a los servicios sanitarios. El objetivo fue caracterizar una muestra de consumidores de PBC que no han recibido t...

Introduction. In Chile, an unknown number of crack cocaine users may be a hidden population due to the fact that crack use is generally associated with poverty and drug trafficking. Privileged access interviewing is one method that enables the reaching of hidden populations of drug users. Aim. To implement privileged access interviewing in Chile to...