Impacto de problemas de salud mental y apoyo social en la calidad de sueño: Seguimiento longitudinal antes y durante la pandemia de COVID-19 en universitarios chilenos / Impact of mental health problems and social support on sleep quali-ty: Follow-up before and during the first eight months of the COVID-19 pandemic in Chilean university student

Introducción: Antecedentes refieren altos índices de problemas de salud mental en universitarios antes y durante la pandemia por COVID-19, con efectos sobre la baja calidad de sueño; sin embargo, el apoyo social percibido actuaría como un factor protector. Objetivo: Evaluar el impacto de la salud mental (ansiedad, depresión y estrés) sobre la calidad de sueño, de forma transversal y longitudinal, antes y durante la pandemia por COVID-19 en universitarios chilenos, verificando si el apoyo social percibido podría moderar esta relación. Material y Métodos: 1.619 universitarios en el año 2019 y 1.862 en el año 2020 respondieron cuestionarios orientados a medir depresión, ansiedad, estrés, calidad del sueño y apoyo social percibido. Con una fracción de la muestra que respondió en ambos años (n = 325) se realizó análisis longitudinal y se contrastaron los puntajes de los instrumentos entre ambos años, mediante una matriz de transición y un modelo de regresión múltiple. Resultados: Se encuentran altas prevalencias de problemas de salud mental, aumentando en el año 2020 la sintomatología moderada y grave. Se agudizan los problemas de sueño y la percepción de bajo apoyo social. Todas las variables de salud mental pueden predecir la calidad del sueño, excepto el apoyo social y longitudinalmente, aumenta la severidad de la baja calidad de sueño y la depresión. No se encuentran moderaciones significativas entre apoyo social percibido y el resto de las variables. Conclusiones: El efecto de la pandemia en la salud mental es complejo, requiriéndose acciones concretas para apoyar psicológicamente a los estudiantes.(AU)

Introduction: Research has revealed high rates of mental health problems in university students before and during the COVID-19 pan-demic, with effects on poor sleep quality; however, perceived social sup-port appears to act as a protective factor. Objective: To assess the impact of mental health (anxiety, depression, and stress) on sleep quality, cross-sectionally and longitudinally, before and during the COVID-19 pandemic in Chilean university students, verifying whether perceived social support could act as a moderatorin this relationship.Material and Methods: 1,619 university students in 2019 and 1,862 in 2020 answered questionnaires aimed at measuring depression, anxiety, stress, sleep quality, and perceived social support. Longitudinal analysis was per-formed with afraction of the sample that responded in both years (n= 325). The scores of the instruments for both years were contrasted using a transition matrix and a multiple regression model. Results: High prevalence rates of mental health problems were found, with moderate and severe symptoms increasing in 2020. Sleep problems and the perception of low social support worsened. All mental health variables were found to predict sleep quality except for social support; longitudinally, the severity of poor sleep quality and depression increased. No significant moderation effects were found between perceived social support and the rest of the variables. Conclusions: The effect of the pandemic on mental health is complex, re-quiring concrete actions to provide students with psychological suppor.(AU)

Tri-process model of interpersonal mindfulness: theoretical framework and study protocol.

According to the Center for Disease Control and Prevention, over 14% of the US population practice mindfulness meditation. The effects of mindfulness training on physical and mental health have been consistently documented, but its effects on interpersonal relationships are not yet fully understood or investigated. Interpersonal relationships play a crucial role in the wellbeing of individuals and society, and therefore, warrants further study. The aim of this paper is to present a tri-process theoretical model of interpersonal mindfulness and a study protocol to validate the proposed model. Specifically, according to the proposed model, mindfulness meditation training increases the self-awareness, self-regulation, and prosociality of those receiving the training, which ameliorates the quality of interpersonal interactions and the socioemotional support provided to other individuals. Finally, better socioemotional support increases the support receiver's ability to regulate their emotions. Using a multiphasic longitudinal design involving 640 participants randomized into 480 dyads, the proposed protocol aims to validate the tri-process model and to investigate its mechanisms of actions. The proposed study has important theoretical and social implications and will allow devising new and more effective interpersonal mindfulness programs with applications in multiple fields.

Effects of the self-perceived sensorimotor demand and immersion during video gaming on visual-attention skills.

Playing specific genres of video games (e.g., action video games) has been linked to improvements in cognitive skills mostly related to attentional phenomena. Nonetheless, do video games have features or dimensions in common that impact cognitive improvements beyond the game genre? Here, we argue that the sensorimotor demand-the amount of demand for precise coordination between movement and perception-is a key element in the improvements associated with playing video games. We conducted a two-part study to test this hypothesis: a self-report online gaming instrument development and validation and an in-lab behavioural and electrophysiological study. In the first study, data from 209 participants were used to devise the sensorimotor demand instrument (SMDI). The SMDI was split into three dimensions of video game playing: sensorimotor contingency, immersion and unfocused gaming. Criterion validity related to video gamers' characteristics supported that the SMDI is sensitive to the input device (e.g., keyboard or touchscreens), and the most recent experience gained during gaming sessions while not being sensitive to the game genre. In the second study, data from 20 participants who performed four visual-attentional tasks previously reported in the literature showed that the SMDI's dimensions were associated with behavioural performance measures and the latency and amplitude of event-related potentials (N1, P2 and P3). Despite the challenge of studying the video gamer population, our study remarks on the relevance of sensorimotor demands in the performance of attentional tasks and its potential use as a dimension to characterize the experience of playing video games beyond the game genre.

Non-pharmacological prevention of postoperative delirium by occupational therapy teams: A randomized clinical trial.

Background: Patients who develop postoperative delirium (POD) have several clinical complications, such as increased morbidity, increased hospital stays, higher hospital costs, cognitive and functional impairment, and higher mortality. POD is a clinical condition preventable by standard non-pharmacological measures An intensive Occupational Therapy (OT) intervention has been shown to be highly effective in preventing delirium in critically ill medical patients, but it is unknown the effect in surgical patients. Thus, we designed a prospective clinical study with the aim to determine whether patients undergoing intervention by the OT team have a lower incidence of POD compared to the group treated only with standard measures. Methods: A multicenter, single-blind, randomized clinical trial was conducted between October 2018 and April 2021, in Santiago of Chile, at a university hospital and at a public hospital. Patients older than 75 years undergoing elective major surgery were eligible for the trial inclusion. Patients with cognitive impairment, severe communication disorder and cultural language limitation, delirium at admission or before surgery, and enrolled in another study were excluded. The intervention consisted of OT therapy twice a day plus standard internationally recommended non-pharmacological prevention intervention during 5 days after surgery. Our primary outcome was development of delirium and postoperative subsyndromal delirium. Results: In total 160 patients were studied. In the interventional group, treated with an intensive prevention by OT, nine patients (12.9%) developed delirium after surgery and in the control group four patients (5.5%) [p = 0.125, RR 2.34 CI 95 (0.75-7.27)]. Whereas subsyndromal POD was present in 38 patients in the control group (52.1%) and in 34 (48.6%) in the intervention group [p = 0.4, RR 0.93 CI95 (0.67-1.29)]. A post hoc analysis determined that the patient's comorbidity and cognitive status prior to hospitalization were the main risk factors to develop delirium after surgery. Discussion: Patients undergoing intervention by the OT team did not have a lower incidence of POD compared to the group treated only with standard non-pharmacological measures in adults older than 75 years who went for major surgery. Clinical trial registration: www.ClinicalTrials.gov, identifier NCT03704090.

Embodied Mindfulness Questionnaire: Scale Development and Validation.

Recently developed mindfulness scales have integrated aspects of the body in measuring mindfulness unlike other established scales. However, these scales focused solely on body awareness and did not embrace all aspects of mindfulness and the body. Specifically, they did not integrate embodiment in mindfulness. The proposed Embodied Mindfulness Questionnaire (EMQ) aims to operationalize the proposed notion of "embodied mindfulness" by grounding it into five dimensions, each representing a set of skills that can be cultivated through training and practice: (a) Detachment from Automatic Thinking, (b) Attention and Awareness of Feelings and Bodily Sensations, (c) Connection with the Body, (d) Awareness of the Mind-Body Connection, and (e) Acceptance of Feelings and Bodily Sensations. The EMQ items were developed through consultations with a panel of eight graduate students and a group of 10 experts in the field. Results from a series of three studies supported the proposed five subscales of EMQ and suggested that these subscales are independent and supported by convergent and discriminant evidence. In addition, results suggested that scores of EMQ subscales are different in terms of sensitivity to mindfulness training or meditation practice and experience. Limitations, as well as theoretical and practical implications of the EMQ subscales, are thoroughly discussed.

Voluntary self-initiation of the stimuli onset improves working memory and accelerates visual and attentional processing.

The ability of an organism to voluntarily control the stimuli onset modulates perceptual and attentional functions. Since stimulus encoding is an essential component of working memory (WM), we conjectured that controlling the initiation of the perceptual process would positively modulate WM. To corroborate this proposition, we tested twenty-five healthy subjects in a modified-Sternberg WM task under three stimuli presentation conditions: an automatic presentation of the stimuli, a self-initiated presentation of the stimuli (through a button press), and a self-initiated presentation with random-delay stimuli onset. Concurrently, we recorded the subjects' electroencephalographic signals during WM encoding. We found that the self-initiated condition was associated with better WM accuracy, and earlier latencies of N1, P2 and P3 evoked potential components representing visual, attentional and mental review of the stimuli processes, respectively. Our work demonstrates that self-initiated stimuli enhance WM performance and accelerate early visual and attentional processes deployed during WM encoding. We also found that self-initiated stimuli correlate with an increased attentional state compared to the other two conditions, suggesting a role for temporal stimuli predictability. Our study remarks on the relevance of self-control of the stimuli onset in sensory, attentional and memory updating processing for WM.

The Impact of Baseline Mindfulness Scores on Mindfulness-Based Intervention Outcomes: Toward Personalized Mental Health Interventions.

A growing body of evidence has portrayed mindfulness as a useful tool for dealing with a broad range of psychological problems and disorders. This has created the impression that mindfulness-based interventions (MBIs) can be used to treat nearly all psychological difficulties, in all cases. Nonetheless, little research has been done on how individual differences may contribute to intervention outcomes. The goal of this study was to evaluate the role of baseline mindfulness on participants' outcomes by examining three prior Randomized Controlled Trials that addressed the impact of MBIs on mental health and mindfulness measures. The participants were 164 people, aged between 12 and 45, from both clinical and non-clinical samples. Our findings indicate that at least two thirds of the change produced by these interventions in terms of mindfulness scores can be predicted by the baseline scores of the same variables. We also found that many trajectories are not only strongly influenced by the initial status of the participants, but also by the intervention performed, as attested to by the significant interactions found. These results stress the need to continue doing research in a way that considers the diversity of participants' trajectories, increasing the room for intervention improvements aligned with a more personalized health care model.

Social and Economic Factors Associated With Subthreshold and Major Depressive Episode in University Students During the COVID-19 Pandemic.

Depression is one of the most frequent mental health disorders in college students and variations according to social and economic factors have been reported, however, whether social and economic variations also exist in subthreshold depression is still unknown, especially during the COVID-19 pandemic. The aim of this study was to estimate the prevalence of subthreshold depressive episode (SDE) and major depressive episode (MDE) and to examine the association between social and economic factors with SDE and MDE in undergraduate students during the COVID-19 pandemic. The participants were 1,577 college students from a university in the south of Chile (64.6% females, 22 years old on average). The participants took an online survey in November 2020 which collected information about social and economic variables, depressive symptoms, and perceived social support. Bivariate and multinomial logistic regression analysis were used. The results showed a high prevalence of SDE (14.3%) and MDE (32.3%) in the sample. Belonging to a social group and perceiving positive social support were the only variables examined that were associated with SDE. Instead, female sex, poorer quintiles, living with other relatives but not parents, economic difficulties due to the pandemic, being a parent, and perceiving positive social support were associated with MDE. Subthreshold and threshold depressive symptoms are frequent in college students, and associations with social and economic factors differ according to the level of such symptoms. These results should be considered in the development of tailored preventive and early interventions for depression in college students.

Cancer History Is Associated with Slower Speed of Cognitive Decline in Patients with Amnestic Cognitive Impairment.

BACKGROUND: Several epidemiological studies report a negative association between Cancer and Alzheimer's disease (AD). OBJECTIVE: To characterize the trajectories of memory loss in individuals with early amnestic cognitive impairment with and without history of previous cancer. METHODS: Cognitive deterioration was assessed using the Montreal Cognitive Assessment (MoCA) or MoCA-Memory Index Score (MoCA-MIS) biannually in subjects with early amnestic cognitive impairment followed-up retrospectively from 2007 to 2021. History of Cancer was obtained from clinical records. Simple linear regressions of MoCA-MIS scores were calculated for each subject and analyzed with K-means cluster analysis to identify subgroups with different cognitive decline trajectories. χ2 and t tests were used for descriptive categorical and continuous variables and mixed multiple linear regressions to determine cognitive decline covariates. RESULTS: Analysis of the trajectory of cognitive decline in 141 subjects with early amnestic cognitive impairment identified two subgroups: Fast (n = 60) and Slow (n = 81) progressors. At baseline Fast progressors had better MoCA-MIS (p < 0.001) and functionality (CDR p = 0.02, AD8 p = 0.05), took less anti-dementia medications (p = 0.005), and had higher depression rates (p = 0.02). Interestingly, Fast progressors slowed their speed of memory decline (from 1.6 to 1.1 MoCA-MIS points/year) and global cognitive decline (from 2.0 to 1.4 total MoCA points/year) when Cancer history was present. CONCLUSION: Two trajectories of amnestic cognitive decline were identified, possibly derived from different neurophysiopathologies or clinical stages. This study suggests that a history of previous Cancer slows down amnestic cognitive decline, specifically in a subgroup of subjects with depression at baseline and accelerated deterioration at follow-up.

Population attributable fraction of modifiable risk factors for dementia in Chile.

INTRODUCTION: Projected dementia incidence in Latin America and the Caribbean for the next decades is overwhelming. Access to local data, stratified by sex, is imperative for planning precise dementia-prevention strategies. METHODS: We analyzed the individual and overall weighted population attributable fraction (PAF) of nine modifiable risk factors for dementia, in dementia-free subjects ≥45-years-old, using the 2016-2017 Chilean National Health Survey. RESULTS: The overall weighted PAF for modifiable risk factors was 45.8% (42.2% to 49.3%). Variables with the highest PAF were lower education, high blood pressure, hearing loss, and obesity. Women showed a greater overall weighted PAF: 50.7% (45.3% to -56.1%), compared to men: 40.2% (35.4% to 45.0%), driven by a higher PAF for physical inactivity and depression in women. DISCUSSION: The PAF for modifiable risk factors for dementia in Chile is higher than in previous world reports, due to a greater prevalence of cardiovascular risk factors. Women have a higher potential for dementia prevention. HIGHLIGHTS: The proportion of dementia associated to modifiable risk factors in Chile is 45.8%.The main modifiable risk factors are high blood pressure, obesity, and hearing loss.Women had a greater prevalence of physical inactivity and depression than men.Chile had a greater prevalence of metabolic risk factors than other world regions.

Interpersonal Mindfulness Questionnaire: Scale Development and Validation.

Objectives: Previously developed mindfulness measures focused on its intrapersonal dimensions and did not measure the interpersonal aspects of mindfulness. Furthermore, recently developed interpersonal mindfulness measures were either specific to a certain context (e.g., parenting, conjugal, teaching) or omitted/minimized the role of the body in the interpersonal dynamic. The proposed Interpersonal Mindfulness Questionnaire (IMQ) aims to operationalize the theoretical notion of embodied and embedded mindfulness by grounding it into four dimensions, each representing a set of skills that can be cultivated through training and practice: (1) Detachment from the Mind, (2) Body-Anchored Presence, (3) Attention to and Awareness of the Other Person, and (4) Mindful Responding. Methods: The IMQ subscales were developed through consultations with a panel of eight graduate students and ten experts in the field. Three studies were conducted to evaluate the construct, internal consistency, reliability, convergent validity, and utility of the IMQ. Results: Findings from the three studies supported the proposed four subscales of IMQ and suggested that these four subscales are independent and supported by convergent evidence. In addition, results suggested that IMQ subscales' scores are sensitive to meditation experience and are associated with better intrapersonal and interpersonal outcomes. Conclusions: IMQ subscales are valid and are consistent with the proposed embodied and embedded conception of interpersonal mindfulness. IMQ subscales are associated with intrapersonal mindfulness, but not strongly enough to be conceived as the same phenomenon. Limitations, as well as theoretical and practical implications of IMQ subscales, are thoroughly discussed. Supplementary Information: The online version contains supplementary material available at 10.1007/s12671-022-01855-1.

Erratum: Are eavesdroppers multimodal? Sensory exploitation of floral signals by a non-native cockroach Blatta orientalis.

[This corrects the article DOI: 10.1093/czoolo/57.2.162.].

Extending the integrate-and-fire model to account for metabolic dependencies.

It is widely accepted that the brain, like any other physical system, is subjected to physical constraints that restrict its operation. The brain's metabolic demands are particularly critical for proper neuronal function, but the impact of these constraints continues to remain poorly understood. Detailed single-neuron models are recently integrating metabolic constraints, but these models' computational resources make it challenging to explore the dynamics of extended neural networks, which are governed by such constraints. Thus, there is a need for a simplified neuron model that incorporates metabolic activity and allows us to explore the dynamics of neural networks. This work introduces an energy-dependent leaky integrate-and-fire (EDLIF) neuronal model extension to account for the effects of metabolic constraints on the single-neuron behavior. This simple, energy-dependent model could describe the relationship between the average firing rate and the Adenosine triphosphate (ATP) cost as well as replicate a neuron's behavior under a clinical setting such as amyotrophic lateral sclerosis (ALS). Additionally, EDLIF model showed better performance in predicting real spike trains - in the sense of spike coincidence measure - than the classical leaky integrate-and-fire (LIF) model. The simplicity of the energy-dependent model presented here makes it computationally efficient and, thus, suitable for studying the dynamics of large neural networks.

Neural links between facial emotion recognition and cognitive impairment in presbycusis.

OBJECTIVES: Facial emotion recognition (FER) is impaired in people with dementia and with severe to profound hearing loss, probably reflecting common neural changes. Here, we aim to study the association between brain structures and FER impairment in mild to moderate age-related hearing loss participants. METHODS: We evaluated FER in a cross-sectional cohort of 111 Chilean nondemented elderly participants. They were assessed for FER in seven different categories using 35 facial stimuli. We collected pure-tone average (PTA) audiometric thresholds, cognitive and neuropsychiatric assessments, and morphometric brain imaging using a 3-Tesla MRI. RESULTS: According to PTA threshold levels, participants were classified as controls (≤25 dB, n = 56) or presbycusis (>25 dB, n = 55), with an average PTA of 17.08 ± 4.8 dB HL and 36.27 ± 9.5 dB HL respectively. Poorer total FER score was correlated with worse hearing thresholds (r = -0.23, p < 0.05) in participants with presbycusis. Multiple regression models explained 57 % of the variability of FER in presbycusis and 10% in controls. In both groups, the main determinant of FER was cognitive performance. In the brain structure of presbycusis participants, FER was correlated with the atrophy of the right insula, right hippocampus, bilateral cingulate cortex and multiple areas of the temporal cortex. In controls, FER was only associated with bilateral middle temporal cortex volume. CONCLUSIONS: FER impairment in presbycusis is distinctively associated with atrophy of neural structures engaged in the perceptual and conceptual level of face emotion processing.

The Energy Homeostasis Principle: A Naturalistic Approach to Explain the Emergence of Behavior.

It is still elusive to explain the emergence of behavior and understanding based on its neural mechanisms. One renowned proposal is the Free Energy Principle (FEP), which uses an information-theoretic framework derived from thermodynamic considerations to describe how behavior and understanding emerge. FEP starts from a whole-organism approach, based on mental states and phenomena, mapping them into the neuronal substrate. An alternative approach, the Energy Homeostasis Principle (EHP), initiates a similar explanatory effort but starts from single-neuron phenomena and builds up to whole-organism behavior and understanding. In this work, we further develop the EHP as a distinct but complementary vision to FEP and try to explain how behavior and understanding would emerge from the local requirements of the neurons. Based on EHP and a strict naturalist approach that sees living beings as physical and deterministic systems, we explain scenarios where learning would emerge without the need for volition or goals. Given these starting points, we state several considerations of how we see the nervous system, particularly the role of the function, purpose, and conception of goal-oriented behavior. We problematize these conceptions, giving an alternative teleology-free framework in which behavior and, ultimately, understanding would still emerge. We reinterpret neural processing by explaining basic learning scenarios up to simple anticipatory behavior. Finally, we end the article with an evolutionary perspective of how this non-goal-oriented behavior appeared. We acknowledge that our proposal, in its current form, is still far from explaining the emergence of understanding. Nonetheless, we set the ground for an alternative neuron-based framework to ultimately explain understanding.

Corrigendum: The Energy Homeostasis Principle: Neuronal Energy Regulation Drives Local Network Dynamics Generating Behavior.

[This corrects the article DOI: 10.3389/fncom.2019.00049.].

Reduced suprathreshold auditory nerve responses are associated with slower processing speed and thinner temporal and parietal cortex in presbycusis.

Epidemiological evidence shows an association between hearing loss and dementia in elderly people. However, the mechanisms that connect hearing impairments and cognitive decline are still unknown. Here we propose that a suprathreshold auditory-nerve impairment is associated with cognitive decline and brain atrophy. METHODS: audiological, neuropsychological, and brain structural 3-Tesla MRI data were obtained from elders with different levels of hearing loss recruited in the ANDES cohort. The amplitude of waves I (auditory nerve) and V (midbrain) from auditory brainstem responses were measured at 80 dB nHL. We also calculated the ratio between wave V and I as a proxy of suprathreshold brainstem function. RESULTS: we included a total of 101 subjects (age: 73.5 ± 5.2 years (mean ± SD), mean education: 9.5 ± 4.2 years, and mean audiogram thresholds (0.5-4 kHz): 25.5 ± 12.0 dB HL). We obtained reliable suprathreshold waves V in all subjects (n = 101), while replicable waves I were obtained in 92 subjects (91.1%). Partial Spearman correlations (corrected by age, gender, education and hearing thresholds) showed that reduced suprathreshold wave I responses were associated with thinner temporal and parietal cortices, and with slower processing speed as evidenced by the Trail-Making Test-A and digit symbol performance. Non-significant correlations were obtained between wave I amplitudes and other cognitive domains. CONCLUSIONS: These results evidence that reduced suprathreshold auditory nerve responses in presbycusis are associated with slower processing speed and brain structural changes in temporal and parietal regions.

Insula and Amygdala Atrophy Are Associated With Functional Impairment in Subjects With Presbycusis.

Hearing loss is an important risk factor for dementia. However, the mechanisms that relate these disorders are still unknown. As a proxy of this relationship, we studied the structural brain changes associated with functional impairment in activities of daily living in subjects with age related hearing loss, or presbycusis. One hundred eleven independent, non-demented subjects older than 65 years recruited in the ANDES cohort were evaluated using a combined approach including (i) audiological tests: hearing thresholds and cochlear function measured by pure tone averages and the distortion product otoacoustic emissions respectively; (ii) behavioral variables: cognitive, neuropsychiatric, and functional impairment in activities of daily living measured by validated questionnaires; and (iii) structural brain imaging-assessed by magnetic resonance imaging at 3 Tesla. The mean age of the recruited subjects (69 females) was 73.95 ± 5.47 years (mean ± SD) with an average educational level of 9.44 ± 4.2 years of schooling. According to the audiometric hearing thresholds and presence of otoacoustic emissions, we studied three groups: controls with normal hearing (n = 36), presbycusis with preserved cochlear function (n = 33), and presbycusis with cochlear dysfunction (n = 38). We found a significant association (R 2 D = 0.17) between the number of detected otoacoustic emissions and apathy symptoms. The presbycusis with cochlear dysfunction group had worse performance than controls in global cognition, language and executive functions, and severe apathy symptoms than the other groups. The neuropsychiatric symptoms and language deficits were the main determinants of functional impairment in both groups of subjects with presbycusis. Atrophy of insula, amygdala, and other temporal areas were related with functional impairment, apathy, and language deficits in the presbycusis with cochlear dysfunction group. We conclude that (i) the neuropsychiatric symptoms had a major effect on functional loss in subjects with presbycusis, (ii) cochlear dysfunction is relevant for the association between hearing loss and behavioral impairment, and (iii) atrophy of the insula and amygdala among other temporal areas are related with hearing loss and behavioral impairment.

The Energy Homeostasis Principle: Neuronal Energy Regulation Drives Local Network Dynamics Generating Behavior.

A major goal of neuroscience is understanding how neurons arrange themselves into neural networks that result in behavior. Most theoretical and experimental efforts have focused on a top-down approach which seeks to identify neuronal correlates of behaviors. This has been accomplished by effectively mapping specific behaviors to distinct neural patterns, or by creating computational models that produce a desired behavioral outcome. Nonetheless, these approaches have only implicitly considered the fact that neural tissue, like any other physical system, is subjected to several restrictions and boundaries of operations. Here, we proposed a new, bottom-up conceptual paradigm: The Energy Homeostasis Principle, where the balance between energy income, expenditure, and availability are the key parameters in determining the dynamics of neuronal phenomena found from molecular to behavioral levels. Neurons display high energy consumption relative to other cells, with metabolic consumption of the brain representing 20% of the whole-body oxygen uptake, contrasting with this organ representing only 2% of the body weight. Also, neurons have specialized surrounding tissue providing the necessary energy which, in the case of the brain, is provided by astrocytes. Moreover, and unlike other cell types with high energy demands such as muscle cells, neurons have strict aerobic metabolism. These facts indicate that neurons are highly sensitive to energy limitations, with Gibb's free energy dictating the direction of all cellular metabolic processes. From this activity, the largest energy, by far, is expended by action potentials and post-synaptic potentials; therefore, plasticity can be reinterpreted in terms of their energy context. Consequently, neurons, through their synapses, impose energy demands over post-synaptic neurons in a close loop-manner, modulating the dynamics of local circuits. Subsequently, the energy dynamics end up impacting the homeostatic mechanisms of neuronal networks. Furthermore, local energy management also emerges as a neural population property, where most of the energy expenses are triggered by sensory or other modulatory inputs. Local energy management in neurons may be sufficient to explain the emergence of behavior, enabling the assessment of which properties arise in neural circuits and how. Essentially, the proposal of the Energy Homeostasis Principle is also readily testable for simple neuronal networks.

Cingulate Cortex Atrophy Is Associated With Hearing Loss in Presbycusis With Cochlear Amplifier Dysfunction.

Age-related hearing loss is associated with cognitive decline and has been proposed as a risk factor for dementia. However, the mechanisms that relate hearing loss to cognitive decline remain elusive. Here, we propose that the impairment of the cochlear amplifier mechanism is associated with structural brain changes and cognitive impairment. Ninety-six subjects aged over 65 years old (63 female and 33 male) were evaluated using brain magnetic resonance imaging, neuropsychological and audiological assessments, including distortion product otoacoustic emissions as a measure of the cochlear amplifier function. All the analyses were adjusted by age, gender and education. The group with cochlear amplifier dysfunction showed greater brain atrophy in the cingulate cortex and in the parahippocampus. In addition, the atrophy of the cingulate cortex was associated with cognitive impairment in episodic and working memories and in language and visuoconstructive abilities. We conclude that the neural abnormalities observed in presbycusis subjects with cochlear amplifier dysfunction extend beyond core auditory network and are associated with cognitive decline in multiple domains. These results suggest that a cochlear amplifier dysfunction in presbycusis is an important mechanism relating hearing impairments to brain atrophy in the extended network of effortful hearing.