RESUMO
The execution of goal-oriented behaviours requires a spatially coherent alignment between sensory and motor maps. The current model for sensorimotor transformation in the superior colliculus relies on the topographic mapping of static spatial receptive fields onto movement endpoints1-6. Here, to experimentally assess the validity of this canonical static model of alignment, we dissected the visuo-motor network in the superior colliculus and performed in vivo intracellular and extracellular recordings across layers, in restrained and unrestrained conditions, to assess both the motor and the visual tuning of individual motor and premotor neurons. We found that collicular motor units have poorly defined visual static spatial receptive fields and respond instead to kinetic visual features, revealing the existence of a direct alignment in vectorial space between sensory and movement vectors, rather than between spatial receptive fields and movement endpoints as canonically hypothesized. We show that a neural network built according to these kinetic alignment principles is ideally placed to sustain ethological behaviours such as the rapid interception of moving and static targets. These findings reveal a novel dimension of the sensorimotor alignment process. By extending the alignment from the static to the kinetic domain this work provides a novel conceptual framework for understanding the nature of sensorimotor convergence and its relevance in guiding goal-directed behaviours.
Assuntos
Modelos Neurológicos , Movimento , Colículos Superiores , Percepção Visual , Animais , Feminino , Masculino , Objetivos , Cinética , Neurônios Motores/fisiologia , Movimento/fisiologia , Rede Nervosa/citologia , Rede Nervosa/fisiologia , Estimulação Luminosa , Desempenho Psicomotor/fisiologia , Reprodutibilidade dos Testes , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Percepção Visual/fisiologiaRESUMO
When faced with predatory threats, escape towards shelter is an adaptive action that offers long-term protection against the attacker. Animals rely on knowledge of safe locations in the environment to instinctively execute rapid shelter-directed escape actions1,2. Although previous work has identified neural mechanisms of escape initiation3,4, it is not known how the escape circuit incorporates spatial information to execute rapid flights along the most efficient route to shelter. Here we show that the mouse retrosplenial cortex (RSP) and superior colliculus (SC) form a circuit that encodes the shelter-direction vector and is specifically required for accurately orienting to shelter during escape. Shelter direction is encoded in RSP and SC neurons in egocentric coordinates and SC shelter-direction tuning depends on RSP activity. Inactivation of the RSP-SC pathway disrupts the orientation to shelter and causes escapes away from the optimal shelter-directed route, but does not lead to generic deficits in orientation or spatial navigation. We find that the RSP and SC are monosynaptically connected and form a feedforward lateral inhibition microcircuit that strongly drives the inhibitory collicular network because of higher RSP input convergence and synaptic integration efficiency in inhibitory SC neurons. This results in broad shelter-direction tuning in inhibitory SC neurons and sharply tuned excitatory SC neurons. These findings are recapitulated by a biologically constrained spiking network model in which RSP input to the local SC recurrent ring architecture generates a circular shelter-direction map. We propose that this RSP-SC circuit might be specialized for generating collicular representations of memorized spatial goals that are readily accessible to the motor system during escape, or more broadly, during navigation when the goal must be reached as fast as possible.
Assuntos
Reação de Fuga , Giro do Cíngulo , Vias Neurais , Neurônios , Navegação Espacial , Colículos Superiores , Animais , Camundongos , Reação de Fuga/fisiologia , Neurônios/fisiologia , Comportamento Predatório , Memória Espacial , Navegação Espacial/fisiologia , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Giro do Cíngulo/citologia , Giro do Cíngulo/fisiologia , Fatores de Tempo , ObjetivosRESUMO
Social affiliation emerges from individual-level behavioural rules that are driven by conspecific signals1-5. Long-distance attraction and short-distance repulsion, for example, are rules that jointly set a preferred interanimal distance in swarms6-8. However, little is known about their perceptual mechanisms and executive neural circuits3. Here we trace the neuronal response to self-like biological motion9,10, a visual trigger for affiliation in developing zebrafish2,11. Unbiased activity mapping and targeted volumetric two-photon calcium imaging revealed 21 activity hotspots distributed throughout the brain as well as clustered biological-motion-tuned neurons in a multimodal, socially activated nucleus of the dorsal thalamus. Individual dorsal thalamus neurons encode local acceleration of visual stimuli mimicking typical fish kinetics but are insensitive to global or continuous motion. Electron microscopic reconstruction of dorsal thalamus neurons revealed synaptic input from the optic tectum and projections into hypothalamic areas with conserved social function12-14. Ablation of the optic tectum or dorsal thalamus selectively disrupted social attraction without affecting short-distance repulsion. This tectothalamic pathway thus serves visual recognition of conspecifics, and dissociates neuronal control of attraction from repulsion during social affiliation, revealing a circuit underpinning collective behaviour.
Assuntos
Aglomeração , Neurônios , Comportamento Social , Colículos Superiores , Tálamo , Vias Visuais , Peixe-Zebra , Animais , Mapeamento Encefálico , Cálcio/análise , Hipotálamo/citologia , Hipotálamo/fisiologia , Locomoção , Microscopia Eletrônica , Neurônios/citologia , Neurônios/fisiologia , Neurônios/ultraestrutura , Reconhecimento Visual de Modelos , Estimulação Luminosa , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Tálamo/citologia , Tálamo/fisiologia , Vias Visuais/citologia , Vias Visuais/fisiologia , Vias Visuais/ultraestrutura , Peixe-Zebra/fisiologiaRESUMO
The ability to suppress actions that lead to a negative outcome and explore alternative actions is necessary for optimal decision making. Although the basal ganglia have been implicated in these processes1-5, the circuit mechanisms underlying action selection and exploration remain unclear. Here, using a simple lateralized licking task, we show that indirect striatal projection neurons (iSPN) in the basal ganglia contribute to these processes through modulation of the superior colliculus (SC). Optogenetic activation of iSPNs suppresses contraversive licking and promotes ipsiversive licking. Activity in lateral superior colliculus (lSC), a region downstream of the basal ganglia, is necessary for task performance and predicts lick direction. Furthermore, iSPN activation suppresses ipsilateral lSC, but surprisingly excites contralateral lSC, explaining the emergence of ipsiversive licking. Optogenetic inactivation reveals inter-collicular competition whereby each hemisphere of the superior colliculus inhibits the other, thus allowing the indirect pathway to disinhibit the contralateral lSC and trigger licking. Finally, inactivating iSPNs impairs suppression of devalued but previously rewarded licking and reduces exploratory licking. Our results reveal that iSPNs engage the competitive interaction between lSC hemispheres to trigger a motor action and suggest a general circuit mechanism for exploration during action selection.
Assuntos
Gânglios da Base/citologia , Gânglios da Base/fisiologia , Corpo Estriado/fisiologia , Comportamento Exploratório/fisiologia , Inibição Neural/fisiologia , Vias Neurais/fisiologia , Colículos Superiores/fisiologia , Animais , Comportamento Animal/fisiologia , Corpo Estriado/citologia , Tomada de Decisões , Feminino , Masculino , Camundongos , Neurônios/fisiologia , Optogenética , Recompensa , Colículos Superiores/citologiaRESUMO
The superior colliculus receives a direct projection from retinal ganglion cells. In primates, it remains unknown if the same ganglion cells also supply the lateral geniculate nucleus. To address this issue, a double-label experiment was performed in two male macaques. The animals fixated a target while injection sites were scouted in the superior colliculus by recording and stimulating with a tetrode. Once suitable sites were identified, cholera toxin subunit B-Alexa Fluor 488 was injected via an adjacent micropipette. In a subsequent acute experiment, cholera toxin subunit B-Alexa Fluor 555 was injected into the lateral geniculate nucleus at matching retinotopic locations. After a brief survival period, ganglion cells were examined in retinal flatmounts. The percentage of double-labeled cells varied locally, depending on the relative efficiency of retrograde transport by each tracer and the precision of retinotopic overlap of injection sites in each target nucleus. In counting boxes with extensive overlap, 76-98% of ganglion cells projecting to the superior colliculus were double labeled. Cells projecting to the superior colliculus constituted 4.0-6.7% of the labeled ganglion cell population. In one particularly large zone, there were 5,746 cells labeled only by CTB-AF555, 561cells double labeled by CTB-AF555 and CTB-AF488, but no cell labeled only by CTB-AF488. These data indicate that retinal input to the macaque superior colliculus arises from a collateral axonal branch supplied by â¼5% of the ganglion cells that project to the lateral geniculate nucleus. Surprisingly, there exist no ganglion cells that project exclusively to the SC.
Assuntos
Axônios , Corpos Geniculados , Retina , Colículos Superiores , Vias Visuais , Animais , Colículos Superiores/fisiologia , Colículos Superiores/citologia , Masculino , Corpos Geniculados/fisiologia , Corpos Geniculados/citologia , Vias Visuais/fisiologia , Axônios/fisiologia , Retina/fisiologia , Retina/citologia , Células Ganglionares da Retina/fisiologia , Macaca mulatta , Toxina da Cólera/metabolismoRESUMO
The development of the visual system is a complex and multistep process characterized by the precise wiring of retinal ganglion cell (RGC) axon terminals with their corresponding neurons in the visual nuclei of the brain. Upon reaching primary image-forming nuclei (IFN), such as the superior colliculus and the lateral geniculate nucleus, RGC axons undergo extensive arborization that refines over the first few postnatal weeks. The molecular mechanisms driving this activity-dependent remodeling process, which is influenced by waves of spontaneous activity in the developing retina, are still not well understood. In this study, by manipulating the activity of RGCs in mice from either sex and analyzing their transcriptomic profiles before eye-opening, we identified the Type I membrane protein synaptotagmin 13 (Syt13) as involved in spontaneous activity-dependent remodeling. Using these mice, we also explored the impact of spontaneous retinal activity on the development of other RGC recipient targets such as nonimage-forming (NIF) nuclei and demonstrated that proper frequency and duration of retinal waves occurring prior to visual experience are essential for shaping the connectivity of the NIF circuit. Together, these findings contribute to a deeper understanding of the molecular and physiological mechanisms governing activity-dependent axon refinement during the assembly of the visual circuit.
Assuntos
Axônios , Retina , Células Ganglionares da Retina , Vias Visuais , Animais , Células Ganglionares da Retina/fisiologia , Camundongos , Axônios/fisiologia , Vias Visuais/fisiologia , Vias Visuais/crescimento & desenvolvimento , Feminino , Masculino , Retina/crescimento & desenvolvimento , Retina/fisiologia , Colículos Superiores/fisiologia , Colículos Superiores/crescimento & desenvolvimento , Colículos Superiores/citologia , Camundongos Endogâmicos C57BL , Corpos Geniculados/fisiologia , Corpos Geniculados/crescimento & desenvolvimento , Animais Recém-NascidosRESUMO
The superior colliculus receives powerful synaptic inputs from corticotectal neurons in the visual cortex. The function of these corticotectal neurons remains largely unknown due to a limited understanding of their response properties and connectivity. Here, we use antidromic methods to identify corticotectal neurons in awake male and female rabbits, and measure their axonal conduction times, thalamic inputs and receptive field properties. All corticotectal neurons responded to sinusoidal drifting gratings with a nonlinear (nonsinusoidal) increase in mean firing rate but showed pronounced differences in their ON-OFF receptive field structures that we classified into three groups, Cx, S2, and S1. Cx receptive fields had highly overlapping ON and OFF subfields as classical complex cells, S2 had largely separated ON and OFF subfields as classical simple cells, and S1 had a single ON or OFF subfield. Thus, all corticotectal neurons are homogeneous in their nonlinear spatial summation but very heterogeneous in their spatial integration of ON and OFF inputs. The Cx type had the fastest conducting axons, the highest spontaneous activity, and the strongest and fastest visual responses. The S2 type had the highest orientation selectivity, and the S1 type had the slowest conducting axons. Moreover, our cross-correlation analyses found that a subpopulation of corticotectal neurons with very fast conducting axons and high spontaneous firing rates (largely "Cx" type) receives monosynaptic input from retinotopically aligned thalamic neurons. This previously unrecognized fast-conducting thalamic-mediated corticotectal pathway may provide specialized information to superior colliculus and prime recipient neurons for subsequent corticotectal or retinal synaptic input.
Assuntos
Neurônios , Sinapses , Tálamo , Córtex Visual , Vias Visuais , Vigília , Animais , Coelhos , Masculino , Feminino , Vias Visuais/fisiologia , Vigília/fisiologia , Córtex Visual/fisiologia , Córtex Visual/citologia , Sinapses/fisiologia , Neurônios/fisiologia , Tálamo/fisiologia , Tálamo/citologia , Estimulação Luminosa/métodos , Campos Visuais/fisiologia , Potenciais de Ação/fisiologia , Colículos Superiores/fisiologia , Colículos Superiores/citologiaRESUMO
A psychotherapeutic regimen that uses alternating bilateral sensory stimulation (ABS) has been used to treat post-traumatic stress disorder. However, the neural basis that underlies the long-lasting effect of this treatment-described as eye movement desensitization and reprocessing-has not been identified. Here we describe a neuronal pathway driven by the superior colliculus (SC) that mediates persistent attenuation of fear. We successfully induced a lasting reduction in fear in mice by pairing visual ABS with conditioned stimuli during fear extinction. Among the types of visual stimulation tested, ABS provided the strongest fear-reducing effect and yielded sustained increases in the activities of the SC and mediodorsal thalamus (MD). Optogenetic manipulation revealed that the SC-MD circuit was necessary and sufficient to prevent the return of fear. ABS suppressed the activity of fear-encoding cells and stabilized inhibitory neurotransmission in the basolateral amygdala through a feedforward inhibitory circuit from the MD. Together, these results reveal the neural circuit that underlies an effective strategy for sustainably attenuating traumatic memories.
Assuntos
Ansiedade/psicologia , Ansiedade/terapia , Extinção Psicológica/fisiologia , Medo/fisiologia , Medo/psicologia , Vias Neurais/fisiologia , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Animais , Ansiedade/fisiopatologia , Complexo Nuclear Basolateral da Amígdala/citologia , Complexo Nuclear Basolateral da Amígdala/fisiologia , Condicionamento Clássico/fisiologia , Retroalimentação Fisiológica , Masculino , Núcleo Mediodorsal do Tálamo/citologia , Núcleo Mediodorsal do Tálamo/fisiologia , Camundongos , Inibição Neural , Optogenética , Estimulação Luminosa , Transtornos de Estresse Pós-Traumáticos , Fatores de TempoRESUMO
Information about features in the visual world is parsed by circuits in the retina and is then transmitted to the brain by distinct subtypes of retinal ganglion cells (RGCs). Axons from RGC subtypes are stratified in retinorecipient brain nuclei, such as the superior colliculus (SC), to provide a segregated relay of parallel and feature-specific visual streams. Here, we sought to identify the molecular mechanisms that direct the stereotyped laminar targeting of these axons. We focused on ipsilateral-projecting subtypes of RGCs (ipsiRGCs) whose axons target a deep SC sublamina. We identified an extracellular glycoprotein, Nephronectin (NPNT), whose expression is restricted to this ipsiRGC-targeted sublamina. SC-derived NPNT and integrin receptors expressed by ipsiRGCs are both required for the targeting of ipsiRGC axons to the deep sublamina of SC. Thus, a cell-extracellular matrix (ECM) recognition mechanism specifies precise laminar targeting of ipsiRGC axons and the assembly of eye-specific parallel visual pathways.
Assuntos
Encéfalo/fisiologia , Matriz Extracelular/fisiologia , Células Ganglionares da Retina/fisiologia , Vias Visuais , Animais , Axônios/fisiologia , Integrinas/metabolismo , Camundongos , Transdução de Sinais , Colículos Superiores/citologia , Colículos Superiores/metabolismo , Colículos Superiores/fisiologiaRESUMO
Neurons in the visual system can be spatially organized according to their response properties such as receptive field location and feature selectivity. For example, the visual cortex of many mammalian species contains orientation and direction columns where neurons with similar preferences are clustered. Here, we examine whether such a columnar structure exists in the mouse superior colliculus (SC), a prominent visual center for motion processing. By performing large-scale physiological recording and two-photon calcium imaging in adult male and female mice, we show that direction-selective neurons in the mouse SC are not organized into stereotypical columns as a function of their preferred directions, although clusters of similarly tuned neurons are seen in a minority of mice. Nearby neurons can prefer similar or opposite directions in a largely position-independent manner. This finding holds true regardless of animal state (anesthetized vs awake, running vs stationary), SC depth (most superficial lamina vs deeper in the SC), research technique (calcium imaging vs electrophysiology), and stimulus type (drifting gratings vs moving dots, full field vs small patch). Together, these results challenge recent reports of region-specific organizations in the mouse SC and reveal how motion direction is represented in this important visual center.
Assuntos
Colículos Superiores/fisiologia , Vias Visuais/fisiologia , Anestesia , Animais , Fenômenos Eletrofisiológicos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Percepção de Movimento , Neuroimagem , Estimulação Luminosa , Corrida/fisiologia , Colículos Superiores/citologia , Colículos Superiores/diagnóstico por imagem , Vias Visuais/diagnóstico por imagem , VigíliaRESUMO
Sensory information from different modalities is processed in parallel, and then integrated in associative brain areas to improve object identification and the interpretation of sensory experiences. The Superior Colliculus (SC) is a midbrain structure that plays a critical role in integrating visual, auditory, and somatosensory input to assess saliency and promote action. Although the response properties of the individual SC neurons to visuoauditory stimuli have been characterized, little is known about the spatial and temporal dynamics of the integration at the population level. Here we recorded the response properties of SC neurons to spatially restricted visual and auditory stimuli using large-scale electrophysiology. We then created a general, population-level model that explains the spatial, temporal, and intensity requirements of stimuli needed for sensory integration. We found that the mouse SC contains topographically organized visual and auditory neurons that exhibit nonlinear multisensory integration. We show that nonlinear integration depends on properties of auditory but not visual stimuli. We also find that a heuristically derived nonlinear modulation function reveals conditions required for sensory integration that are consistent with previously proposed models of sensory integration such as spatial matching and the principle of inverse effectiveness.
Assuntos
Modelos Neurológicos , Colículos Superiores/fisiologia , Estimulação Acústica , Animais , Percepção Auditiva/fisiologia , Mapeamento Encefálico/estatística & dados numéricos , Biologia Computacional , Fenômenos Eletrofisiológicos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos CBA , Modelos Psicológicos , Neurônios/fisiologia , Dinâmica não Linear , Estimulação Luminosa , Sensação/fisiologia , Colículos Superiores/citologia , Percepção Visual/fisiologiaRESUMO
In the brain of teleost fish, radial glial cells are the major type of astroglial cells. To answer the question as to how radial glia structures adapt to the continuous growth of the brain, which is characteristic of salmonids, it is necessary to study various types of cells (neuronal precursors, astroglial cells, and cells in a state of neuronal differentiation) in the major integrative centers of the salmon brain (telencephalon and tectum opticum), using rainbow trout, Oncorhynchus mykiss, as a model. A study of the distribution of several molecular markers in the telencephalon and tectum with the identification of neural stem/progenitor cells, neuroblasts, and radial glia was carried out on juvenile (three-year-old) O. mykiss. The presence of all of these cell types provides specific conditions for the adult neurogenesis processes in the trout telencephalon and tectum. The distribution of glutamine synthetase, a molecular marker of neural stem cells, in the trout telencephalon revealed a large population of radial glia (RG) corresponding to adult-type neural stem cells (NSCs). RG dominated the pallial region of the telencephalon, while, in the subpallial region, RG was found in the lateral and ventral zones. In the optic tectum, RG fibers were widespread and localized both in the marginal layer and in the periventricular gray layer. Doublecortin (DC) immunolabeling revealed a large population of neuroblasts formed in the postembryonic period, which is indicative of intense adult neurogenesis in the trout brain. The pallial and subpallial regions of the telencephalon contained numerous DC+ cells and their clusters. In the tectum, DC+ cells were found not only in the stratum griseum periventriculare (SGP) and longitudinal torus (TL) containing proliferating cells, but also in the layers containing differentiated neurons: the central gray layer, the periventricular gray and white layers, and the superficial white layer. A study of the localization patterns of vimentin and nestin in the trout telencephalon and tectum showed the presence of neuroepithelial neural stem cells (eNSCs) and ependymoglial cells in the periventricular matrix zones of the brain. The presence of vimentin and nestin in the functionally heterogeneous cell types of adult trout indicates new functional properties of these proteins and their heterogeneous involvement in intracellular motility and adult neurogenesis. Investigation into the later stages of neuronal development in various regions of the fish brain can substantially elucidate the major mechanisms of adult neurogenesis, but it can also contribute to understanding the patterns of formation of certain brain regions and the involvement of RG in the construction of the definite brain structure.
Assuntos
Biomarcadores/metabolismo , Células-Tronco Neurais/citologia , Neurogênese , Neurônios/citologia , Oncorhynchus mykiss/crescimento & desenvolvimento , Colículos Superiores/citologia , Telencéfalo/citologia , Animais , Proliferação de Células , Células-Tronco Neurais/metabolismo , Neurônios/metabolismo , Oncorhynchus mykiss/metabolismo , Colículos Superiores/metabolismo , Telencéfalo/metabolismoRESUMO
Humans and animals maintain accurate sound discrimination in the presence of loud sources of background noise. It is commonly assumed that this ability relies on the robustness of auditory cortex responses. However, only a few attempts have been made to characterize neural discrimination of communication sounds masked by noise at each stage of the auditory system and to quantify the noise effects on the neuronal discrimination in terms of alterations in amplitude modulations. Here, we measured neural discrimination between communication sounds masked by a vocalization-shaped stationary noise from multiunit responses recorded in the cochlear nucleus, inferior colliculus, auditory thalamus, and primary and secondary auditory cortex at several signal-to-noise ratios (SNRs) in anesthetized male or female guinea pigs. Masking noise decreased sound discrimination of neuronal populations in each auditory structure, but collicular and thalamic populations showed better performance than cortical populations at each SNR. In contrast, in each auditory structure, discrimination by neuronal populations was slightly decreased when tone-vocoded vocalizations were tested. These results shed new light on the specific contributions of subcortical structures to robust sound encoding, and suggest that the distortion of slow amplitude modulation cues conveyed by communication sounds is one of the factors constraining the neuronal discrimination in subcortical and cortical levels.SIGNIFICANCE STATEMENT Dissecting how auditory neurons discriminate communication sounds in noise is a major goal in auditory neuroscience. Robust sound coding in noise is often viewed as a specific property of cortical networks, although this remains to be demonstrated. Here, we tested the discrimination performance of neuronal populations at five levels of the auditory system in response to conspecific vocalizations masked by noise. In each acoustic condition, subcortical neurons better discriminated target vocalizations than cortical ones and in each structure, the reduction in discrimination performance was related to the reduction in slow amplitude modulation cues.
Assuntos
Comunicação Animal , Percepção Auditiva/fisiologia , Discriminação Psicológica/fisiologia , Ruído , Vocalização Animal/fisiologia , Estimulação Acústica , Algoritmos , Animais , Córtex Auditivo/citologia , Córtex Auditivo/fisiologia , Feminino , Cobaias , Masculino , Mascaramento Perceptivo , Razão Sinal-Ruído , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Tálamo/citologia , Tálamo/fisiologiaRESUMO
The operation of our multiple and distinct sensory systems has long captured the interest of researchers from multiple disciplines. When the Society was founded 50 years ago to bring neuroscience research under a common banner, sensory research was largely divided along modality-specific lines. At the time, there were only a few physiological and anatomical observations of the multisensory interactions that powerfully influence our everyday perception. Since then, the neuroscientific study of multisensory integration has increased exponentially in both volume and diversity. From initial studies identifying the overlapping receptive fields of multisensory neurons, to subsequent studies of the spatial and temporal principles that govern the integration of multiple sensory cues, our understanding of this phenomenon at the single-neuron level has expanded to include a variety of dimensions. We now can appreciate how multisensory integration can alter patterns of neural activity in time, and even coordinate activity among populations of neurons across different brain areas. There is now a growing battery of sophisticated empirical and computational techniques that are being used to study this process in a number of models. These advancements have not only enhanced our understanding of this remarkable process in the normal adult brain, but also its underlying circuitry, requirements for development, susceptibility to malfunction, and how its principles may be used to mitigate malfunction.
Assuntos
Comportamento Animal/fisiologia , Mapeamento Encefálico/história , Neurociências/história , Percepção/fisiologia , Sensação/fisiologia , Sociedades Científicas/história , Colículos Superiores/fisiologia , Envelhecimento/fisiologia , Animais , Cegueira Cortical/fisiopatologia , Gatos , História do Século XX , História do Século XXI , Humanos , Disseminação de Informação , Modelos Neurológicos , Movimento/fisiologia , Rede Nervosa/fisiologia , Redes Neurais de Computação , Plasticidade Neuronal , Prêmio Nobel , Limiar Sensorial , Comportamento Espacial/fisiologia , Colículos Superiores/citologia , Percepção do Tempo/fisiologiaRESUMO
The pattern of neural activity evoked by a stimulus can be substantially affected by ongoing spontaneous activity. Separating these two types of activity is particularly important for calcium imaging data given the slow temporal dynamics of calcium indicators. Here we present a statistical model that decouples stimulus-driven activity from low dimensional spontaneous activity in this case. The model identifies hidden factors giving rise to spontaneous activity while jointly estimating stimulus tuning properties that account for the confounding effects that these factors introduce. By applying our model to data from zebrafish optic tectum and mouse visual cortex, we obtain quantitative measurements of the extent that neurons in each case are driven by evoked activity, spontaneous activity, and their interaction. By not averaging away potentially important information encoded in spontaneous activity, this broadly applicable model brings new insight into population-level neural activity within single trials.
Assuntos
Cálcio/fisiologia , Potenciais Evocados Visuais , Neurônios/fisiologia , Animais , Fluorescência , Camundongos , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Córtex Visual/citologia , Córtex Visual/fisiologia , Peixe-ZebraRESUMO
More than twenty types of retinal ganglion cells conduct visual information from the eye to the rest of the brain. Each retinal ganglion cell type tessellates the retina in a regular mosaic, so that every point in visual space is processed for visual primitives such as contrast and motion. This information flows to two principal brain centres: the visual cortex and the superior colliculus. The superior colliculus plays an evolutionarily conserved role in visual behaviours, but its functional architecture is poorly understood. Here we report on population recordings of visual responses from neurons in the mouse superior colliculus. Many neurons respond preferentially to lines of a certain orientation or movement axis. We show that cells with similar orientation preferences form large patches that span the vertical thickness of the retinorecipient layers. This organization is strikingly different from the randomly interspersed orientation preferences in the mouse's visual cortex; instead, it resembles the orientation columns observed in the visual cortices of large mammals. Notably, adjacent superior colliculus orientation columns have only limited receptive field overlap. This is in contrast to the organization of visual cortex, where each point in the visual field activates neurons with all preferred orientations. Instead, the superior colliculus favours specific contour orientations within â¼30° regions of the visual field, a finding with implications for behavioural responses mediated by this brain centre.
Assuntos
Orientação/fisiologia , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Animais , Mapeamento Encefálico , Cálcio/análise , Cálcio/metabolismo , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Movimento (Física) , Neurônios/fisiologia , Estimulação Luminosa , Colículos Superiores/anatomia & histologia , Córtex Visual/anatomia & histologia , Córtex Visual/citologia , Córtex Visual/fisiologia , Campos Visuais/fisiologia , VigíliaRESUMO
The optic tectum (TeO), or superior colliculus, is a multisensory midbrain center that organizes spatially orienting responses to relevant stimuli. To define the stimulus with the highest priority at each moment, a network of reciprocal connections between the TeO and the isthmi promotes competition between concurrent tectal inputs. In the avian midbrain, the neurons mediating enhancement and suppression of tectal inputs are located in separate isthmic nuclei, facilitating the analysis of the neural processes that mediate competition. A specific subset of radial neurons in the intermediate tectal layers relay retinal inputs to the isthmi, but at present it is unclear whether separate neurons innervate individual nuclei or a single neural type sends a common input to several of them. In this study, we used in vitro neural tracing and cell-filling experiments in chickens to show that single neurons innervate, via axon collaterals, the three nuclei that comprise the isthmotectal network. This demonstrates that the input signals representing the strength of the incoming stimuli are simultaneously relayed to the mechanisms promoting both enhancement and suppression of the input signals. By performing in vivo recordings in anesthetized chicks, we also show that this common input generates synchrony between both antagonistic mechanisms, demonstrating that activity enhancement and suppression are closely coordinated. From a computational point of view, these results suggest that these tectal neurons constitute integrative nodes that combine inputs from different sources to drive in parallel several concurrent neural processes, each performing complementary functions within the network through different firing patterns and connectivity.
Assuntos
Comportamento Animal/fisiologia , Galinhas/fisiologia , Neurônios/fisiologia , Colículos Superiores/fisiologia , Vias Visuais/fisiologia , Animais , Técnicas de Rastreamento Neuroanatômico/métodos , Estimulação Luminosa , Colículos Superiores/citologiaRESUMO
Spatial attention enables us to focus visual processing toward specific locations or stimuli before the next fixation. Recent evidence has suggested that local luminance at the spatial locus of attention or saccade preparation influences pupil size independent of global luminance levels. However, it remains to be determined which neural pathways produce this location-specific modulation of pupil size. The intermediate layers of the midbrain superior colliculus (SC) form part of the network of brain areas involved in spatial attention and modulation of pupil size. Here, we demonstrated that pupil size was altered according to local luminance level at the spatial location corresponding to a microstimulated location in the intermediate SC (SCi) map of monkeys. Moreover, local SCi inactivation through injection of lidocaine reversed this local luminance modulation. Our findings reveal a causal role of the SCi in preparing pupil size for local luminance conditions at the next saccadic goal.
Assuntos
Rede Nervosa , Vias Neurais , Neurônios/fisiologia , Pupila/fisiologia , Movimentos Sacádicos/fisiologia , Colículos Superiores/fisiologia , Potenciais de Ação , Animais , Macaca mulatta , Masculino , Neurônios/citologia , Estimulação Luminosa , Colículos Superiores/citologiaRESUMO
An innocuous sensory stimulus that reliably signals an upcoming aversive event can be conditioned to elicit locomotion to a safe location before the aversive outcome ensues. The neural circuits that mediate the expression of this signaled locomotor action, known as signaled active avoidance, have not been identified. While exploring sensorimotor midbrain circuits in mice of either sex, we found that excitation of GABAergic cells in the substantia nigra pars reticulata blocks signaled active avoidance by inhibiting cells in the pedunculopontine tegmental nucleus (PPT), not by inhibiting cells in the superior colliculus or thalamus. Direct inhibition of putative-glutamatergic PPT cells, excitation of GABAergic PPT cells, or excitation of GABAergic afferents in PPT, abolish signaled active avoidance. Conversely, excitation of putative-glutamatergic PPT cells, or inhibition of GABAergic PPT cells, can be tuned to drive avoidance responses. The PPT is an essential junction for the expression of signaled active avoidance gated by nigral and other synaptic afferents.SIGNIFICANCE STATEMENT When a harmful situation is signaled by a sensory stimulus (e.g., street light), subjects typically learn to respond with active or passive avoidance responses that circumvent the threat. During signaled active avoidance behavior, subjects move away to avoid a threat signaled by a preceding innocuous stimulus. We identified a part of the midbrain essential to process the signal and avoid the threat. Inhibition of neurons in this area eliminates avoidance responses to the signal but preserves escape responses caused by presentation of the threat. The results highlight an essential part of the neural circuits that mediate signaled active avoidance behavior.
Assuntos
Aprendizagem da Esquiva/fisiologia , Reação de Fuga/fisiologia , Neurônios GABAérgicos/fisiologia , Rede Nervosa/fisiologia , Parte Reticular da Substância Negra/fisiologia , Núcleo Tegmental Pedunculopontino/fisiologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Aprendizagem da Esquiva/efeitos da radiação , Mapeamento Encefálico , Proteínas de Transporte/genética , Proteínas de Transporte/efeitos da radiação , Clozapina/análogos & derivados , Clozapina/farmacologia , Condicionamento Clássico , Dependovirus/genética , Comportamento de Ingestão de Líquido , Eletrochoque , Reação de Fuga/efeitos dos fármacos , Reação de Fuga/efeitos da radiação , Mutação com Ganho de Função , Genes Reporter , Vetores Genéticos/administração & dosagem , Luz , Camundongos , Ruído/efeitos adversos , Optogenética , Parte Reticular da Substância Negra/citologia , Tempo de Reação , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/efeitos da radiação , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/efeitos da radiação , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Tálamo/citologia , Tálamo/fisiologiaRESUMO
Adaptation is a ubiquitous feature of sensory processing whereby recent experience shapes future responses. The mouse primary visual cortex (V1) is particularly sensitive to recent experience, where a brief stimulus can suppress subsequent responses for seconds. This rapid adaptation profoundly impacts perception, suggesting that its effects are propagated along the visual hierarchy. To understand how rapid adaptation influences sensory processing, we measured its effects at key nodes in the visual system: in V1, three higher visual areas (HVAs: lateromedial, anterolateral, and posteromedial), and the superior colliculus (SC) in awake mice of both sexes using single-unit recordings. Consistent with the feed-forward propagation of adaptation along the visual hierarchy, we find that neurons in layer 4 adapt less strongly than those in other layers of V1. Furthermore, neurons in the HVAs adapt more strongly, and recover more slowly, than those in V1. The magnitude and time course of adaptation was comparable in each of the HVAs and in the SC, suggesting that adaptation may not linearly accumulate along the feed-forward visual processing hierarchy. Despite the increase in adaptation in the HVAs compared with V1, the effects were similarly orientation specific across all areas. These data reveal that adaptation profoundly shapes cortical processing, with increasing impact at higher levels in the cortical hierarchy, and also strongly influencing computations in the SC. Thus, we find robust, brain-wide effects of rapid adaptation on sensory processing.NEW & NOTEWORTHY Rapid adaptation dynamically alters sensory signals to account for recent experience. To understand how adaptation affects sensory processing and perception, we must determine how it impacts the diverse set of cortical and subcortical areas along the hierarchy of the mouse visual system. We find that rapid adaptation strongly impacts neurons in primary visual cortex, the higher visual areas, and the colliculus, consistent with its profound effects on behavior.