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The brainstem is a hub for sensorimotor integration, which mediates crucial innate behaviors. This brain region is characterized by a rich population of GABAergic inhibitory neurons, required for the proper expression of these innate behaviors. However, what roles these inhibitory neurons play in innate behaviors and how they function are still not fully understood. Here, we show that inhibitory neurons in the nucleus of the optic tract and dorsal-terminal nuclei (NOT-DTN) of the mouse can modulate the innate eye movement optokinetic reflex (OKR) by shaping the tuning properties of excitatory NOT-DTN neurons. Specifically, we demonstrate that although these inhibitory neurons do not directly induce OKR, they enhance the visual feature selectivity of OKR behavior, which is mediated by the activity of excitatory NOT-DTN neurons. Moreover, consistent with the sharpening role of inhibitory neurons in OKR behavior, they have broader tuning relative to excitatory neurons. Last, we demonstrate that inhibitory NOT-DTN neurons directly provide synaptic inhibition to nearby excitatory neurons and sharpen their tuning in a sustained manner, accounting for the enhanced feature selectivity of OKR behavior. In summary, our findings uncover a fundamental principle underlying the computational role of inhibitory neurons in brainstem sensorimotor circuits.

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To better understand the function of cholinergic projection neurons in the ventral pallidum (VP), we examined behavioral responses to appetitive (APP) and aversive (AV) odors that elicited approach or avoidance, respectively. Exposure to each odor increased cFos expression and calcium signaling in VP cholinergic neurons. Activity and Cre-dependent viral vectors selectively labeled VP cholinergic neurons that were activated and reactivated in response to either APP or AV odors, but not both, identifying two non-overlapping populations of VP cholinergic neurons differentially activated by the valence of olfactory stimuli. These two subpopulations showed differences in electrophysiological properties, morphology, and projections to the basolateral amygdala. Although VP neurons are engaged in both approach and avoidance behavioral responses, cholinergic signaling is only required for approach behavior. Thus, two distinct subpopulations of VP cholinergic neurons differentially encode valence of olfactory stimuli and play distinct roles in approach and avoidance behaviors.

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The ventral pallidum (VP) mediates motivated behaviors largely via the action of VP GABA and glutamatergic neurons. In addition to these neuronal subtypes, there is a population of cholinergic projection neurons in the VP, whose functional significance remains unclear. To understand the functional role of VP cholinergic neurons, we first examined behavioral responses to an appetitive (APP) odor that elicited approach, and an aversive (AV) odor that led to avoidance. To examine how VP cholinergic neurons were engaged in APP vs. AV responses, we used an immediate early gene marker and in-vivo fiber photometry, examining the activation profile of VP cholinergic neurons in response to each odor. Exposure to each odor led to an increase in the number of cFos counts and increased calcium signaling of VP cholinergic neurons. Activity and cre-dependent viral vectors were designed to label engaged VP cholinergic neurons in two distinct contexts: (1) exposure to the APP odor, (2) followed by subsequent exposure to the AV odor, and vice versa. These studies revealed two distinct, non-overlapping subpopulations of VP cholinergic neurons: one activated in response to the APP odor, and a second distinct population activated in response to the AV odor. These two subpopulations of VP cholinergic neurons are spatially intermingled within the VP, but show differences in electrophysiological properties, neuronal morphology, and projections to the basolateral amygdala. Although VP cholinergic neurons are engaged in behavioral responses to each odor, VP cholinergic signaling is only required for approach behavior. Indeed, inhibition of VP cholinergic neurons not only blocks approach to the APP odor, but reverses the behavior, leading to active avoidance. Our results highlight the functional heterogeneity of cholinergic projection neurons within the VP. These two subpopulations of VP cholinergic neurons differentially encode valence of olfactory stimuli and play unique roles in approach and avoidance behaviors.

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Animals continuously weigh hunger and thirst against competing needs, such as social contact and mating, according to state and opportunity. Yet neuronal mechanisms of sensing and ranking nutritional needs remain poorly understood. Here, combining calcium imaging in freely behaving mice, optogenetics, and chemogenetics, we show that two neuronal populations of the lateral hypothalamus (LH) guide increasingly hungry animals through behavioral choices between nutritional and social rewards. While increased food consumption was marked by increasing inhibition of a leptin receptor-expressing (LepRLH) subpopulation at a fast timescale, LepRLH neurons limited feeding or drinking and promoted social interaction despite hunger or thirst. Conversely, neurotensin-expressing LH neurons preferentially encoded water despite hunger pressure and promoted water seeking, while relegating social needs. Thus, hunger and thirst gate both LH populations in a complementary manner to enable the flexible fulfillment of multiple essential needs.

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In nature, parasitoid wasp infections are a major cause of insect mortality. Parasitoid wasps attack a vast range of insect species to lay their eggs. As a defense, insects evolved survival strategies to protect themselves from parasitoid infection. While a growing number of studies reported both host defensive tactics and parasitoid counter-offensives, we emphasize that this parasite-host relationship presents a unique ecological and evolutionary relevant model that is often challenging to replicate in a laboratory. Although maintaining parasitoid wasp cultures in the laboratory requires meticulous planning and can be labor intensive, a diverse set of wasp species that target many different insect types can be maintained in similar culture conditions. Here, we describe the protocol for culturing parasitoid wasp species on Drosophila larvae and pupae in laboratory conditions. We also detail an egg-laying assay to assess the reproductive modification of Drosophila females in response to parasitoid wasps. This behavioral study is relatively simple and easily adaptable to study environmental or genetic influences on egg-laying, a readout for female germline development. Neither the parasitoid culture conditions or the behavioral assay require special supplies or equipment, making them a powerful and versatile approach in research or teaching laboratory settings. Graphical abstract.

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The superior colliculus (SC), one of the most well-characterized midbrain sensorimotor structures where visual, auditory, and somatosensory information are integrated to initiate motor commands, is highly conserved across vertebrate evolution. Moreover, cell-type-specific SC neurons integrate afferent signals within local networks to generate defined output related to innate and cognitive behaviors. This review focuses on the recent progress in understanding of phenotypic diversity amongst SC neurons and their intrinsic circuits and long-projection targets. We further describe relevant neural circuits and specific cell types in relation to behavioral outputs and cognitive functions. The systematic delineation of SC organization, cell types, and neural connections is further put into context across species as these depend upon laminar architecture. Moreover, we focus on SC neural circuitry involving saccadic eye movement, and cognitive and innate behaviors. Overall, the review provides insight into SC functioning and represents a basis for further understanding of the pathology associated with SC dysfunction.

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In animals, neuropeptidergic signaling is essential for the regulation of survival and reproduction. In insects, Orcokinins are poorly studied, despite their high level of conservation among different orders. In particular, there are currently no reports on the role of Orcokinins in the experimental insect model, the fruit fly, Drosophila melanogaster. In the present work, we made use of the genetic tools available in this species to investigate the role of Orcokinins in the regulation of different innate behaviors including ecdysis, sleep, locomotor activity, oviposition, and courtship. We found that RNAi-mediated knockdown of the orcokinin gene caused a disinhibition of male courtship behavior, including the occurrence of male to male courtship, which is rarely seen in wildtype flies. In addition, orcokinin gene silencing caused a reduction in egg production. Orcokinin is emerging as an important neuropeptide family in the regulation of the physiology of insects from different orders. In the case of the fruit fly, our results suggest an important role in reproductive success.

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Neuronal cell types are arranged in brain-wide circuits that guide behavior. In mice, the superior colliculus innervates a set of targets that direct orienting and defensive actions. We combined functional ultrasound imaging (fUSI) with optogenetics to reveal the network of brain regions functionally activated by four collicular cell types. Stimulating each neuronal group triggered different behaviors and activated distinct sets of brain nuclei. This included regions not previously thought to mediate defensive behaviors, for example, the posterior paralaminar nuclei of the thalamus (PPnT), which we show to play a role in suppressing habituation. Neuronal recordings with Neuropixels probes show that (1) patterns of spiking activity and fUSI signals correlate well in space and (2) neurons in downstream nuclei preferentially respond to innately threatening visual stimuli. This work provides insight into the functional organization of the networks governing innate behaviors and demonstrates an experimental approach to explore the whole-brain neuronal activity downstream of targeted cell types.

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All animals can perform certain survival behaviors without prior experience, suggesting a "hard wiring" of underlying neural circuits. Experience, however, can alter the expression of innate behaviors. Where in the brain and how such plasticity occurs remains largely unknown. Previous studies have established the phenomenon of "aggression training," in which the repeated experience of winning successive aggressive encounters across multiple days leads to increased aggressiveness. Here, we show that this procedure also leads to long-term potentiation (LTP) at an excitatory synapse, derived from the posteromedial part of the amygdalohippocampal area (AHiPM), onto estrogen receptor 1-expressing (Esr1+) neurons in the ventrolateral subdivision of the ventromedial hypothalamus (VMHvl). We demonstrate further that the optogenetic induction of such LTP in vivo facilitates, while optogenetic long-term depression (LTD) diminishes, the behavioral effect of aggression training, implying a causal role for potentiation at AHiPM→VMHvlEsr1 synapses in mediating the effect of this training. Interestingly, ∼25% of inbred C57BL/6 mice fail to respond to aggression training. We show that these individual differences are correlated both with lower levels of testosterone, relative to mice that respond to such training, and with a failure to exhibit LTP after aggression training. Administration of exogenous testosterone to such nonaggressive mice restores both behavioral and physiological plasticity. Together, these findings reveal that LTP at a hypothalamic circuit node mediates a form of experience-dependent plasticity in an innate social behavior, and a potential hormone-dependent basis for individual differences in such plasticity among genetically identical mice.

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The ability to sense sour provides an important sensory signal to prevent the ingestion of unripe, spoiled, or fermented foods. Taste and somatosensory receptors in the oral cavity trigger aversive behaviors in response to acid stimuli. Here, we show that the ion channel Otopetrin-1, a proton-selective channel normally involved in the sensation of gravity in the vestibular system, is essential for sour sensing in the taste system. We demonstrate that knockout of Otop1 eliminates acid responses from sour-sensing taste receptor cells (TRCs). In addition, we show that mice engineered to express otopetrin-1 in sweet TRCs have sweet cells that also respond to sour stimuli. Next, we genetically identified the taste ganglion neurons mediating each of the five basic taste qualities and demonstrate that sour taste uses its own dedicated labeled line from TRCs in the tongue to finely tuned taste neurons in the brain to trigger aversive behaviors.

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The medial subnucleus of the amygdala (MeA) plays a central role in processing sensory cues required for innate behaviors. However, whether there is a link between developmental programs and the emergence of inborn behaviors remains unknown. Our previous studies revealed that the telencephalic preoptic area (POA) embryonic niche is a novel source of MeA destined progenitors. Here, we show that the POA is comprised of distinct progenitor pools complementarily marked by the transcription factors Dbx1 and Foxp2. As determined by molecular and electrophysiological criteria this embryonic parcellation predicts postnatal MeA inhibitory neuronal subtype identity. We further find that Dbx1-derived and Foxp2+ cells in the MeA are differentially activated in response to innate behavioral cues in a sex-specific manner. Thus, developmental transcription factor expression is predictive of MeA neuronal identity and sex-specific neuronal responses, providing a potential developmental logic for how innate behaviors could be processed by different MeA neuronal subtypes.

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Many complex behaviors that do not require learning are displayed and are termed innate. Although traditionally the subject matter of ethology, innate behaviors offer a unique entry point for neuroscientists to dissect the physiological mechanisms governing complex behaviors. Since the last century, converging evidence has implicated the hypothalamus as the central brain area that controls innate behaviors. Recent studies using cutting-edge tools have revealed that genetically-defined populations of neurons residing in distinct hypothalamic nuclei and their associated neural pathways regulate the initiation and maintenance of diverse behaviors including feeding, sleep, aggression, and parental care. Here, we review the newly-defined hypothalamic pathways that regulate each innate behavior. In addition, emerging general principles of the neural control of complex behaviors are discussed.

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Introduction The study of the early neonatal and infant behavior has called the attention of several researchers with the purpose of establishing an early diagnostic of neurological damage. Ferenc Katona identifies, from the 28th week of gestation to the third month of extrauterine life, a group of locomotion and verticalization innate behaviors which are called Complex Elementary Movements (CEM). These sequences of generalized motor activity of central origin, with automatic movements, generate sensory impulses to the spinal cord, brainstem and superior systems in response to gravitational and acceleration stimulus. These impulses cause continuous and repetitive movements of the head, trunk and limbs, and lead to verticalization and locomotion. They also prefigure the human behavior by organizing structures and cerebral functions ontogenetically mature at birth and with greater resistance to damage. In normal European neonates and infants, the constancy and stability has allowed for the diagnose of early Nervous System dysfunction (SN). European researchers have applied procedures that include CEM for neurohabilitation. Katona explains that when CEM are induced, they stimulate the vestibular system performance. The repetitive and/or sustained muscular contractions of trunk and extremities during the attempts of verticalize or locomotion, transmit new stimulus that strengthen the initial stimulation. During the time that the infant maintains the pattern activation, the thalamus, basal ganglia and cerebral cortex are stimulated, simultaneously and proportionally, occurring changes in the muscular tone, the movement dynamics and posture within a critical period of cerebral plasticity. The movements of head, trunk and extremities are refined or reorganized as in normal child maturity (development). This prevents and avoids risks and altered functions. In Mexico, according to the information sources reviewed, there are no studies describing the normal postnatal development variations. It is important to differentiate normal movements from the pathological ones to make early diagnosis of neurological damage in Mexican populations. Material and methods The Tlalpan outpatient family medicine clinic of the Institute of Security and Social Services for State Employees (ISSSTE) referred 25 infants, considered with low perinatal biological risk, residents of Mexico City. The Heinz Prechtl neurological sieve was applied to each infant to confirm an adequate neurological maturity. Fifteen infants fulfilled the inclusion criteria, the parents of nine infants agreed on their child participation in four evaluations, scheduled monthly, according to the day of birth. The parents signed the informed consent letter. In each evaluation, the ten maneuvers of activation were applied twice. They were distributed 6 at the first month, 9 at 2 and 3 months, and 8 at 4 months. Five maneuvers were applied to activate locomotion: Mcgraw, Bauer, reinforced Bauer, crawling on an inclinate slide and assisted crawling. Also five maneuvers were put into practice for verticalization: carry sitting, antigravity verticalization, stand up reaction, elementary walking and sitting in the air. Five behaviors and movements were described: crying, visual behavior (eyes closed or open with or without visual fixation), limbs, trunk and head movements. The evaluations were recorded in 8mm digital format and reviewed instantly during the evaluation. The camera's timer was used to measure the time they took to activate movements of locomotion or verticalization. To calculate frequencies and central tendency measures, the SAS statistical software JMP, version 7.0 was used. Results 320 activating maneuvers were used, 82.5% activated locomotion and 58% verticalization. The children awoked spontaneously with rude movements and cried, in 63% of the evaluations including the five locomotion patterns: 58.7% in the Alternating Cross Pattern (ACP), 10% for the Incomplete Simultaneous Pattern (ISP), 10% in the Lower Limb Alternating Pattern (LLAP), 1.25% on Complete Simultaneous Pattern (CSP) 2.5% and Homolateral Pattern (HP). The most frequent pattern observed was the Alternate Cross Pattern (PAC) 58.7% and the less frequent was the Homolateral Pattern (PH) 1.25%. In verticalization two patterns were observed: 58% with complete trunk and head alignment, 42% with incomplete alignment. The latencies to enable MEC were from 0-120 seconds, with M 27.7, DE ±48.8 for locomotion and M 9.43, DE ±20.7 for verticalization. Opening the eyes and visual fixation in the locomotion maneuvers occurred in the 43%, 20% in the first month, 31% in the 2nd month, 42% in the 3rd month and 75% in the 4th month. Verticalization maneuvers occurred in 64%, 47% in the first month, 49% in the second month, 64% in the 3rd month and 95% in the 4th month. As the children grew, the open eye and visual fixation conducts increased in presence. Locomotion appeared in the 43% of the children and verticalization in 64%. Discussion Katona reports that the MEC activation is given from birth to three months, with exception in two maneuvers: crawling on an inclined slide that appears until two months and on the four month the manifestation of elementary march. In this research, the locomotion and ver-ticalization patterns appeared sometimes until the fourth month, with frequencies that change in 12% to 100% of the cases according to the maneuvers form. Two patterns were identified but not described, the PH with a case frecuency of 1.25% and the PSC with 2.5%. Katona suggested that infants up to three months old are able to activate several seconds to complete verticalization, due to vestibular activity. In our experience, until two months they are mainly short and incomplete patterns of vertical integration then completed and sustained during the third and fourth month. Concerning the time required to activate MEC, Katona reported latencies of 5-100 sec. with absence of responses until the 4th month. Except for elementary walking, we observed that the latency time varies with age. In this investigation the locomotion time was 27.7 sec average, founding 0-120 sec intervals. In verticalization, latencies were faster than the average latency time of 9.43 sec. With intervals of latency in the first two months of age of 0-19 sec. elementary walking and the stand up reaction with age took but in activating and to the fourth month in several cases no longer they appeared. Katona reported that the newborn is capable of a brief visual fixation with the presentation of the face or with a flashing object 20cm away. The results of the locomotion and verticalization maneuvers showed that the behavior was present in the first month, in less of the 50% locomotion assessments and in less of 70% in verticalization. When the maneuver allowed controlling the head or maintaining the face to face line sight, the infant opened and fixed visually. Conclusions In the nine Mexican infants explored, variations were reported in the postnatal MEC evolution, with respect to the age of appearing, patterns type, trunk and limbs movements, time required for activation (latencies), visual activity and crying presence were not observed. If these variations are confirmed we could establish more accurate reference parameters and analyze their relationship with biological and environmental factors. Thus, to strengthen a prevention method in neurohabilitation/neurorehabilitation for high-risk population benefit.

Introducción Con el propósito de diagnosticar tempranamente el daño neurológico, Ferenc Katona identifica desde la semana 28 de gestación hasta los tres meses de vida extrauterina un grupo de comportamientos innatos de locomoción y verticalización, a los cuales se les denomina Movimientos Elementales Complejos (MEC). Son secuencias de actividad motora generalizada automática de origen central provocadas por estímulos gravitacionales y de aceleración. Su activación genera impulsos sensoriales al cordón espinal, al tallo cerebral y a los sistemas superiores, lo que resulta en movimientos continuos y repetidos de la cabeza, del tronco y de las extremidades dirigidos a la verticalización y a la locomoción. La constancia y estabilidad en la normalidad de los MEC en neonatos y lactantes europeos ha permitido diagnosticar la disfunción temprana del Sistema Nervioso (SN) y utilizarlos como procedimientos de neurohabilitación. En México, con base en las fuentes de información revisadas, no hay estudios que describan las variaciones del desarrollo normal postnatal por lo que es importante conocerlas y tener un referente para diferenciar las normales de las patológicas. Material y métodos La consulta externa de la Clínica de Medicina Familiar Tlalpan, del Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (ISSSTE), refirió 25 lactantes considerados de bajo riesgo perinatal, a quienes se les aplicó el Tamiz neurológico de Heinz Prechtl para confirmar una adecuada madurez neurológica. Quince de los lactantes cumplieron con los criterios de inclusión. Los padres de nueve lactantes aceptaron llevar a sus hijos a las cuatro evaluaciones programadas mensualmente de acuerdo al día en que nacieron y firmaron la carta de consentimiento informado. En cada evaluación se aplicaron dos veces las diez maniobras de activación (cuadro 1). Las variables de estudio son: presencia de llanto, comportamiento visual, movimientos de extremidades, tronco y cabeza. Las valoraciones se filmaron en formato digital de 8mm. El cronómetro de la cámara midió el tiempo que tomaba cada maniobra en activar los movimientos (latencia). Se utilizó el programa estadístico JMP de SAS, versión 7.0, para el cálculo de frecuencias y medidas de tendencia central. Resultados Se provocaron 320 maniobras, de las cuales se activaron 82.5% en locomoción y 58% en verticalización. El 63% de los niños estuvieron despiertos con movimientos groseros y llanto. De los patrones de locomoción, el de mayor frecuencia fue el Patrón Alterno Cruzado (PAC), con 58.7%, y el de menor frecuencia fue el Patrón Homolateral (PH), con 1.25%. En la verticalización, su presencia fue de 58%, con alineación completa del tronco y la cabeza, y 42% con alineación incompleta. Se obtuvieron latencias de activación, para la locomoción, entre 0-120 segundos, con una media de 27.7±48.8 y para la verticalización una media de 9.43±20.7. El comportamiento visual, abrir ojos y fijación visual aumentó conforme el niño crecía. Discusión Katona reporta que la activación de los MEC se presenta al nacimiento y hasta los tres meses, con excepción de dos maniobras: gateo en plano inclinado, presente hasta los dos meses, y marcha elemental que se observa hasta el cuarto mes. En esta investigación, los patrones para locomoción y verticalización pudieron provocarse hasta el cuarto mes con frecuencias que variaron de un 12% a un 100%, de acuerdo al tipo de maniobra. Se identificaron dos patrones no descritos: el PH, con 1.25%, y el Patrón Simultáneo Completo (PSC), con 2.5%. La verticalización completa apareció y aumentó en frecuencia con la edad en nuestra población. En cuanto a la locomoción se obtuvieron variaciones en el movimiento de las extremidades, el tronco y el tiempo de latencia. Cuando la maniobra permitió controlar la cabeza o mantener la línea de la mirada frente a frente, el lactante abrió los ojos y fijó visualmente. Conclusiones Se documento la variabilidad de los MEC en niños mexicanos de bajo riesgo, mostrando que éstos evolucionan desde patrones de menor verticalización, con llanto frecuente y escasa fijación visual al nacimiento a patrones de verticalización completa, mayor fijación y disminución del llanto, lo cual comprende una modificación al criterio de calificación propuesto por los autores para niños europeos. Los ajustes al procedimiento tienen implicación en la detección temprana de riesgos para la discapacidad motriz.