Knowledge of amygdalar and hippocampal development as they pertain to sex differences and laterality would help to understand not only brain development but also the relationship between brain volume ...and brain functions. However, few studies investigated development of these two regions, especially during infancy. The purpose of this study was to examine typical volumetric trajectories of amygdala and hippocampus from infancy to early adulthood by predicting sexual dimorphism and laterality. We performed a cross-sectional morphometric MRI study of amygdalar and hippocampal growth from 1 month to 25 years old, using 109 healthy individuals. The findings indicated significant non-linear age-related volume changes, especially during the first few years of life, in both the amygdala and hippocampus regardless of sex. The peak ages of amygdalar and hippocampal volumes came at the timing of preadolescence (9-11 years old). The female amygdala reached its peak age about one year and a half earlier than the male amygdala did. In addition, its rate of growth change decreased earlier in the females. Furthermore, both females and males displayed rightward laterality in the hippocampus, but only the males in the amygdala. The robust growth of the amygdala and hippocampus during infancy highlight the importance of this period for neural and functional development. The sex differences and laterality during development of these two regions suggest that sex-related factors such as sex hormones and functional laterality might affect brain development.
•Chronic widespread pain like fibromyalgia (FM) is a serious medical problem.•Here we examined the spinal mechanisms using a rat model of FM.•Superficial dorsal horn (SDH) neurons were strongly ...sensitized in the model.•Increased excitatory postsynaptic input and decreased inhibitory drive to the SDH neurons were also evident.•These spinal mechanisms may be relevant to the nociceptive hypersensitivity in FM.
Chronic widespread pain is one of the important issues to be solved in medical practice. Impaired spinal descending pain inhibitory system due to decreased monoamine neurotransmitters is assumed to cause nociceptive hypersensitivities in chronic painful conditions like that described in patients with fibromyalgia (FM). However, response behaviors and synaptic transmission of the spinal dorsal horn neurons in response to reserpine remain to be clarified. Here we examined the activities of superficial dorsal horn (SDH) neurons, as well as excitatory and inhibitory postsynaptic inputs to SDH neurons, using a putative rat model of FM that was established by injecting reserpine. Extracellular recordings in vivo revealed that SDH neurons were sensitized to mechanical stimulation applied to the neurons’ receptive fields, and the mechanically sensitized neurons were spontaneously more active. The sensitizing effect was evident 1 day and 3 days after the reserpine treatment, but subsided 5 days after the treatment or later. Using patch-clamp recordings in vivo, spontaneous excitatory postsynaptic currents (sEPSCs) to SDH neurons were found to increase in the pain model, while spontaneous inhibitory postsynaptic currents (sIPSCs) to SDH neurons decreased. These results demonstrate that the SDH neurons were strongly sensitized in response to the reserpine treatment, and that increased excitatory and decreased inhibitory postsynaptic inputs could be responsible for the spinal nociceptive hypersensitivity in the putative FM model.
Animal behaviors can be divided into two states according to their motor activity: the active motor state, which involves significant body movements, and the inactive motor state, which refers to ...when the animal is stationary. The timing and duration of these states are determined by the activity of the neuronal circuits involved in motor control. Among these motor circuits, those that generate locomotion are some of the most studied neuronal networks and are widely distributed from the spinal cord to the cerebral cortex. In this review, we discuss recent discoveries, mainly in rodents using state-of-the-art experimental approaches, of the neuronal mechanisms underlying the initiation and termination of locomotion in the brainstem, basal ganglia, and prefrontal cortex. These findings is discussed with reference to studies on the neuronal mechanism of motor control during sleep and the modulation of cortical states in these structures. Accumulating evidence has unraveled the complex yet highly structured network that controls the transition between motor states.
•Locomotor states are controlled by a widely distributed neuronal network.•The MLR is crucial for the initiation and termination of locomotion.•Neurons in the MLR are involved in regulating motor activity during REM sleep.•The basal ganglia regulate MLR activity to generate appropriate locomotor behavior.•M2 and ACC neurons encode temporal goal-directed locomotor behavior information.
Objective To investigate the longitudinal effects of perinatal exposure to dioxin on neurodevelopment and physical growth of a birth cohort during the first 3 years of life. Study design A total of ...217 mother–infant pairs living in a dioxin-contaminated area in Vietnam were followed up. Perinatal dioxin exposure of infants was estimated by the measurement of dioxin levels in breast milk of nursing mothers. Neurodevelopment of infants and children, including cognitive, language, and motor development, was determined at 4 months, 1 year, and 3 years of age. Physical growth, including weight, height, and head and abdominal circumferences, was measured at birth, 1 and 4 months, and 1 and 3 years of age. Multivariate mixed models were applied for analyzing repeated measures. Results In boys, composite motor and gross motor scores were decreased with increasing exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TetraCDD). The high toxic equivalent of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs-TEQ) group showed a significant decrease in expressive communication score. In girls, there was no decreased score in any neurodevelopment aspects in high-exposure groups. All body size measures in boys were decreased in the high-exposure groups of 2,3,7,8-TetraCDD and PCDDs/PCDFs-TEQ. In girls, high 2,3,7,8-TetraCDD and PCDDs/PCDFs-TEQ exposure was associated with increased head and abdominal circumferences. Conclusions Perinatal dioxin exposure affects physical growth and neurodevelopment of infants and children in the first 3 years of life in a sex-specific manner.
Snakes and their relationships with humans and other primates have attracted broad attention from multiple fields of study, but not, surprisingly, from neuroscience, despite the involvement of the ...visual system and strong behavioral and physiological evidence that humans and other primates can detect snakes faster than innocuous objects. Here, we report the existence of neurons in the primate medial and dorsolateral pulvinar that respond selectively to visual images of snakes. Compared with three other categories of stimuli (monkey faces, monkey hands, and geometrical shapes), snakes elicited the strongest, fastest responses, and the responses were not reduced by low spatial filtering. These findings integrate neuroscience with evolutionary biology, anthropology, psychology, herpetology, and primatology by identifying a neurobiological basis for primates' heightened visual sensitivity to snakes, and adding a crucial component to the growing evolutionary perspective that snakes have long shaped our primate lineage.
Video-based markerless motion capture permits quantification of an animal's pose and motion, with a high spatiotemporal resolution in a naturalistic context, and is a powerful tool for analyzing the ...relationship between the animal's behaviors and its brain functions. Macaque monkeys are excellent non-human primate models, especially for studying neuroscience. Due to the lack of a dataset allowing training of a deep neural network for the macaque's markerless motion capture in the naturalistic context, it has been challenging to apply this technology for macaques-based studies. In this study, we created MacaquePose, a novel open dataset with manually labeled body part positions (keypoints) for macaques in naturalistic scenes, consisting of >13,000 images. We also validated the application of the dataset by training and evaluating an artificial neural network with the dataset. The results indicated that the keypoint estimation performance of the trained network was close to that of a human-level. The dataset will be instrumental to train/test the neural networks for markerless motion capture of the macaques and developments of the algorithms for the networks, contributing establishment of an innovative platform for behavior analysis for non-human primates for neuroscience and medicine, as well as other fields using macaques as a model organism.
The purpose of this review extends beyond the traditional triune brain model, aiming to elucidate the evolutionary aspects of alpha rhythms in vertebrates. The forebrain, comprising the telencephalon ...(pallium) and diencephalon (thalamus, hypothalamus), is a common feature in the brains of all vertebrates. In mammals, evolution has prioritized the development of the forebrain, especially the neocortex, over the midbrain (mesencephalon) optic tectum, which serves as the prototype for the visual brain. This evolution enables mammals to process visual information in the retina-thalamus (lateral geniculate nucleus)-occipital cortex pathway. The origin of posterior-dominant alpha rhythms observed in mammals in quiet and dark environments is not solely attributed to cholinergic pontine nuclei cells functioning as a 10 Hz pacemaker in the brainstem. It also involves the ability of the neocortex's cortical layers to generate traveling waves of alpha rhythms with waxing and waning characteristics. The utilization of alpha rhythms might have facilitated the shift of attention from external visual inputs to internal cognitive processes as an adaptation to thrive in dark environments. The evolution of alpha rhythms might trace back to the dinosaur era, suggesting that enhanced cortical connectivity linked to alpha bands could have facilitated the development of nocturnal awakening in the ancestors of mammals. In fishes, reptiles, and birds, the pallium lacks a cortical layer. However, there is a lack of research clearly observing dominant alpha rhythms in the pallium or organized nuclear structures in fishes, reptiles, or birds. Through convergent evolution, the pallium of birds, which exhibits cortex-like fiber architecture, has not only acquired advanced cognitive and motor abilities but also the capability to generate low-frequency oscillations (4-25 Hz) resembling alpha rhythms. This suggests that the origins of alpha rhythms might lie in the pallium of a common ancestor of birds and mammals.
Neuroligin 3 (NLGN3) and neurexins (NRXNs) constitute a canonical transsynaptic cell-adhesion pair, which has been implicated in autism. In autism spectrum disorder (ASD) development of sociality can ...be impaired. However, the molecular mechanism underlying NLGN3-mediated social development is unclear. Here, we identify non-canonical interactions between NLGN3 and protein tyrosine phosphatase δ (PTPδ) splice variants, competing with NRXN binding. NLGN3-PTPδ complex structure revealed a splicing-dependent interaction mode and competition mechanism between PTPδ and NRXNs. Mice carrying a NLGN3 mutation that selectively impairs NLGN3-NRXN interaction show increased sociability, whereas mice where the NLGN3-PTPδ interaction is impaired exhibit impaired social behavior and enhanced motor learning, with imbalance in excitatory/inhibitory synaptic protein expressions, as reported in the Nlgn3 R451C autism model. At neuronal level, the autism-related Nlgn3 R451C mutation causes selective impairment in the non-canonical pathway. Our findings suggest that canonical and non-canonical NLGN3 pathways compete and regulate the development of sociality.
Vertebrates, including primates, can recognize or respond to specific stimuli that are important for survival, such as specific visual objects (natural enemies, prey animals, foods, etc.), sounds ...(e.g., animal barks), and odors or pheromones, even if they have never previously experienced those stimuli. That is, those stimuli can be recognized immediately after birth without learning (innate recognition), and the neural circuits involved in the detection of these stimuli are supposed to be genetically coded for innate recognition. In primates, the extrageniculate subcortical visual pathway (extrageniculate visual system), consisting of the retina, superior colliculus, pulvinar in the thalamus and amygdala (or association area, etc.), has been suggested to be involved in innate recognition of these stimuli. To investigate neural mechanisms of innate recognition in primates, we have analyzed single neuronal responses to these stimuli in the monkey pulvinar and superior colliculus. The results indicated that pulvinar and collicular neurons responded preferentially to facial patterns and snakes, detection of which is crucial for survival in primates. The response characteristics of these neurons suggest that the extrageniculate visual system is involved in processing visual information of faces and snakes at low resolution for rapid detection. These findings suggest that primate evolution might shape the extrageniculate visual system for innate and automatic (unconscious) detection of these stimuli to survive in the natural environment.
Fifty-five children aged 2 years from a birth cohort in the largest dioxin-contaminated area in Bien Hoa city, Vietnam participated in this survey to examine gaze behavior. Exposure levels were ...indicated by 2,3,7,8-tetrachlorodibenzo-p-dibenzodioxin (TCDD) and toxic equivalent of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (TEQ-PCDD/Fs) levels in maternal breast milk. The percentage of the total fixation duration on the face (% Face), mouth (% Mouth), and eye areas (% Eyes) when viewing silent and conversation scenes was used as gaze behavior indices. When they reached 3-year-old, autistic behavior was assessed using the Autism Spectrum Rating Scale (ASRS). A general linear model adjusted for confounding factors was used to compare gaze indices and ASRS scores between high and low dioxin exposure groups. Effects of perinatal dioxin exposure on gaze behavior were found only when viewing conversation scenes indicated by lower % Face for boys in high TCDD exposure group and lower % Eyes for girls in high TEQ-PCDD/Fs group. Increased autistic traits showed by higher ASRS scores at 3-year-old were found in both gender in the high TCDD exposure group. These findings indicate that perinatal TCDD and TEQ-PCDD/Fs exposure may reduce gaze behavior in 2-year-old children, predicting increased autistic traits at 3-year-old.
PDF
