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1.
PLoS Biol ; 22(5): e3002614, 2024 May.
Article En | MEDLINE | ID: mdl-38743775

The processing of sensory information, even at early stages, is influenced by the internal state of the animal. Internal states, such as arousal, are often characterized by relating neural activity to a single "level" of arousal, defined by a behavioral indicator such as pupil size. In this study, we expand the understanding of arousal-related modulations in sensory systems by uncovering multiple timescales of pupil dynamics and their relationship to neural activity. Specifically, we observed a robust coupling between spiking activity in the mouse dorsolateral geniculate nucleus (dLGN) of the thalamus and pupil dynamics across timescales spanning a few seconds to several minutes. Throughout all these timescales, 2 distinct spiking modes-individual tonic spikes and tightly clustered bursts of spikes-preferred opposite phases of pupil dynamics. This multi-scale coupling reveals modulations distinct from those captured by pupil size per se, locomotion, and eye movements. Furthermore, coupling persisted even during viewing of a naturalistic movie, where it contributed to differences in the encoding of visual information. We conclude that dLGN spiking activity is under the simultaneous influence of multiple arousal-related processes associated with pupil dynamics occurring over a broad range of timescales.


Action Potentials , Arousal , Geniculate Bodies , Pupil , Animals , Pupil/physiology , Geniculate Bodies/physiology , Mice , Action Potentials/physiology , Arousal/physiology , Male , Mice, Inbred C57BL , Photic Stimulation/methods , Neurons/physiology , Thalamus/physiology , Eye Movements/physiology , Time Factors , Visual Pathways/physiology
2.
Nat Commun ; 15(1): 4005, 2024 May 13.
Article En | MEDLINE | ID: mdl-38740786

The neocortex comprises six cortical layers that play a crucial role in information processing; however, it remains unclear whether laminar processing is consistent across all regions within a single cortex. In this study, we demonstrate diverse laminar response patterns in the primary visual cortex (V1) of three male macaque monkeys when exposed to visual stimuli at different spatial frequencies (SFs). These response patterns can be categorized into two groups. One group exhibit suppressed responses in the output layers for all SFs, while the other type shows amplified responses specifically at high SFs. Further analysis suggests that both magnocellular (M) and parvocellular (P) pathways contribute to the suppressive effect through feedforward mechanisms, whereas amplification is specific to local recurrent mechanisms within the parvocellular pathway. These findings highlight the non-uniform distribution of neural mechanisms involved in laminar processing and emphasize how pathway-specific amplification selectively enhances representations of high-SF information in primate V1.


Photic Stimulation , Primary Visual Cortex , Visual Pathways , Animals , Male , Primary Visual Cortex/physiology , Visual Pathways/physiology , Visual Perception/physiology , Visual Cortex/physiology , Macaca mulatta
3.
Nat Commun ; 15(1): 3746, 2024 May 03.
Article En | MEDLINE | ID: mdl-38702319

The neural basis of fear of heights remains largely unknown. In this study, we investigated the fear response to heights in male mice and observed characteristic aversive behaviors resembling human height vertigo. We identified visual input as a critical factor in mouse reactions to heights, while peripheral vestibular input was found to be nonessential for fear of heights. Unexpectedly, we found that fear of heights in naïve mice does not rely on image-forming visual processing by the primary visual cortex. Instead, a subset of neurons in the ventral lateral geniculate nucleus (vLGN), which connects to the lateral/ventrolateral periaqueductal gray (l/vlPAG), drives the expression of fear associated with heights. Additionally, we observed that a subcortical visual pathway linking the superior colliculus to the lateral posterior thalamic nucleus inhibits the defensive response to height threats. These findings highlight a rapid fear response to height threats through a subcortical visual and defensive pathway from the vLGN to the l/vlPAG.


Fear , Geniculate Bodies , Mice, Inbred C57BL , Superior Colliculi , Visual Pathways , Animals , Male , Fear/physiology , Mice , Geniculate Bodies/physiology , Superior Colliculi/physiology , Visual Pathways/physiology , Periaqueductal Gray/physiology , Neurons/physiology , Primary Visual Cortex/physiology , Visual Perception/physiology , Behavior, Animal/physiology
4.
Sci Rep ; 14(1): 8447, 2024 04 11.
Article En | MEDLINE | ID: mdl-38600121

Amniotes feature two principal visual processing systems: the tectofugal and thalamofugal pathways. In most mammals, the thalamofugal pathway predominates, routing retinal afferents through the dorsolateral geniculate complex to the visual cortex. In most birds, the thalamofugal pathway often plays the lesser role with retinal afferents projecting to the principal optic thalami, a complex of several nuclei that resides in the dorsal thalamus. This thalamic complex sends projections to a forebrain structure called the Wulst, the terminus of the thalamofugal visual system. The thalamofugal pathway in birds serves many functions such as pattern discrimination, spatial memory, and navigation/migration. A comprehensive analysis of avian species has unveiled diverse subdivisions within the thalamic and forebrain structures, contingent on species, age, and techniques utilized. In this study, we documented the thalamofugal system in three dimensions by integrating histological and contrast-enhanced computed tomography imaging of the avian brain. Sections of two-week-old chick brains were cut in either coronal, sagittal, or horizontal planes and stained with Nissl and either Gallyas silver or Luxol Fast Blue. The thalamic principal optic complex and pallial Wulst were subdivided on the basis of cell and fiber density. Additionally, we utilized the technique of diffusible iodine-based contrast-enhanced computed tomography (diceCT) on a 5-week-old chick brain, and right eyeball. By merging diceCT data, stained histological sections, and information from the existing literature, a comprehensive three-dimensional model of the avian thalamofugal pathway was constructed. The use of a 3D model provides a clearer understanding of the structural and spatial organization of the thalamofugal system. The ability to integrate histochemical sections with diceCT 3D modeling is critical to better understanding the anatomical and physiologic organization of complex pathways such as the thalamofugal visual system.


Imaging, Three-Dimensional , Visual Pathways , Animals , Visual Pathways/physiology , Thalamus/physiology , Prosencephalon/physiology , Chickens/physiology , Mammals
5.
J Neurosci Res ; 102(4): e25331, 2024 Apr.
Article En | MEDLINE | ID: mdl-38651314

Circadian rhythms synchronize to light through the retinohypothalamic tract (RHT), which is a bundle of axons coming from melanopsin retinal ganglion cells, whose synaptic terminals release glutamate to the ventral suprachiasmatic nucleus (SCN). Activation of AMPA-kainate and NMDA postsynaptic receptors elicits the increase in intracellular calcium required for triggering the signaling cascade that ends in phase shifts. During aging, there is a decline in the synchronization of circadian rhythms to light. With electrophysiological (whole-cell patch-clamp) and immunohistochemical assays, in this work, we studied pre- and postsynaptic properties between the RHT and ventral SCN neurons in young adult (P90-120) and old (P540-650) C57BL/6J mice. Incremental stimulation intensities (applied on the optic chiasm) induced much lesser AMPA-kainate postsynaptic responses in old animals, implying a lower recruitment of RHT fibers. Conversely, a higher proportion of old SCN neurons exhibited synaptic facilitation, and variance-mean analysis indicated an increase in the probability of release in RHT terminals. Moreover, both spontaneous and miniature postsynaptic events displayed larger amplitudes in neurons from aged mice, whereas analysis of the NMDA and AMPA-kainate components (evoked by RHT electrical stimulation) disclosed no difference between the two ages studied. Immunohistochemistry revealed a bigger size in the puncta of vGluT2, GluN2B, and GluN2A of elderly animals, and the number of immunopositive particles was increased, but that of PSD-95 was reduced. All these synaptic adaptations could be part of compensatory mechanisms in the glutamatergic signaling to ameliorate the loss of RHT terminals in old animals.


Aging , Glutamic Acid , Mice, Inbred C57BL , Suprachiasmatic Nucleus , Synaptic Transmission , Animals , Mice , Suprachiasmatic Nucleus/physiology , Suprachiasmatic Nucleus/metabolism , Synaptic Transmission/physiology , Aging/physiology , Glutamic Acid/metabolism , Male , Excitatory Postsynaptic Potentials/physiology , Visual Pathways/physiology , Vesicular Glutamate Transport Protein 2/metabolism , Patch-Clamp Techniques , Receptors, N-Methyl-D-Aspartate/metabolism , Disks Large Homolog 4 Protein/metabolism
6.
Neurosci Lett ; 830: 137777, 2024 May 01.
Article En | MEDLINE | ID: mdl-38621505

Omitted stimulus potentials (OSPs) are elicited in response to the omission of expected stimuli and are thought to reflect prediction errors. If prediction errors are signaled in the sensory cortex, OSPs are expected to be generated in the sensory cortex. The present study investigated the involvement of the early visual cortex in the generation of OSPs by testing whether omitted visual stimuli elicit brain responses in a spatially specific manner. Checkerboard pattern stimuli were presented alternately in the upper and lower visual fields, and the stimuli were omitted in 10 % of the trials. Event-related potentials were recorded from 33 participants. While a retinotopic C1 component was evoked by real visual stimuli, omitted stimuli did not produce any response reflecting retinotopy but did elicit a visual mismatch negativity, which was larger for omitted stimuli expected in the lower visual field than for those in the upper visual field. These results suggest that omitted visual stimuli are processed in a different pathway than actual stimuli.


Evoked Potentials, Visual , Photic Stimulation , Visual Cortex , Visual Fields , Humans , Male , Female , Young Adult , Photic Stimulation/methods , Evoked Potentials, Visual/physiology , Adult , Visual Fields/physiology , Visual Cortex/physiology , Electroencephalography/methods , Visual Perception/physiology , Visual Pathways/physiology , Retina/physiology
7.
Neural Comput ; 36(6): 1041-1083, 2024 May 10.
Article En | MEDLINE | ID: mdl-38669693

We consider a model of basic inner retinal connectivity where bipolar and amacrine cells interconnect and both cell types project onto ganglion cells, modulating their response output to the brain visual areas. We derive an analytical formula for the spatiotemporal response of retinal ganglion cells to stimuli, taking into account the effects of amacrine cells inhibition. This analysis reveals two important functional parameters of the network: (1) the intensity of the interactions between bipolar and amacrine cells and (2) the characteristic timescale of these responses. Both parameters have a profound combined impact on the spatiotemporal features of retinal ganglion cells' responses to light. The validity of the model is confirmed by faithfully reproducing pharmacogenetic experimental results obtained by stimulating excitatory DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) expressed on ganglion cells and amacrine cells' subclasses, thereby modifying the inner retinal network activity to visual stimuli in a complex, entangled manner. Our mathematical model allows us to explore and decipher these complex effects in a manner that would not be feasible experimentally and provides novel insights in retinal dynamics.


Retina , Retinal Ganglion Cells , Retinal Ganglion Cells/physiology , Retina/physiology , Animals , Models, Neurological , Amacrine Cells/physiology , Computer Simulation , Humans , Visual Pathways/physiology , Photic Stimulation/methods , Nerve Net/physiology , Visual Fields/physiology , Retinal Bipolar Cells/physiology
8.
Atten Percept Psychophys ; 86(4): 1303-1317, 2024 May.
Article En | MEDLINE | ID: mdl-38468024

Proximity and feature similarity are two important determinants of perceptual grouping in vision. When viewing visual scenes conveying both grouping options simultaneously, people most usually detect proximity groups faster than similarity groups. This article demonstrates that perceptual judgments of grouping orientation guided by either proximity or contrast similarity are indicative of a sequential organization of grouping operations in the visual pathway, which lends a temporal processing advantage to proximity grouping (Experiment 1). Invoking the double-factorial paradigm, latent cognitive architecture for perceptual grouping is also investigated in a task with redundant signals (Experiment 2). Reaction time data from this task is assessed in terms of the race model inequality, workload capacity analysis, and interaction contrasts of means and survivor functions. Again, empirical benchmarks indicate serial processing of proximity groups and similarity groups, with a self-terminating stopping rule for processing. A subset of participants exhibit atypical performance metrics, hinting at possible individual differences in configural visual processing.


Pattern Recognition, Visual , Reaction Time , Humans , Male , Female , Attention , Young Adult , Orientation , Adult , Judgment , Contrast Sensitivity , Visual Pathways/physiology
9.
J Neurosci ; 44(19)2024 May 08.
Article En | MEDLINE | ID: mdl-38538145

A classic example of experience-dependent plasticity is ocular dominance (OD) shift, in which the responsiveness of neurons in the visual cortex is profoundly altered following monocular deprivation (MD). It has been postulated that OD shifts also modify global neural networks, but such effects have never been demonstrated. Here, we use wide-field fluorescence optical imaging (WFOI) to characterize calcium-based resting-state functional connectivity during acute (3 d) MD in female and male mice with genetically encoded calcium indicators (Thy1-GCaMP6f). We first establish the fundamental performance of WFOI by computing signal to noise properties throughout our data processing pipeline. Following MD, we found that Δ band (0.4-4 Hz) GCaMP6 activity in the deprived visual cortex decreased, suggesting that excitatory activity in this region was reduced by MD. In addition, interhemispheric visual homotopic functional connectivity decreased following MD, which was accompanied by a reduction in parietal and motor homotopic connectivity. Finally, we observed enhanced internetwork connectivity between the visual and parietal cortex that peaked 2 d after MD. Together, these findings support the hypothesis that early MD induces dynamic reorganization of disparate functional networks including the association cortices.


Mice, Inbred C57BL , Nerve Net , Sensory Deprivation , Visual Cortex , Animals , Mice , Male , Female , Sensory Deprivation/physiology , Visual Cortex/physiology , Nerve Net/physiology , Neuronal Plasticity/physiology , Dominance, Ocular/physiology , Critical Period, Psychological , Visual Pathways/physiology
10.
Brain Struct Funct ; 229(4): 937-946, 2024 May.
Article En | MEDLINE | ID: mdl-38492041

KEY MESSAGE: The Riddoch syndrome is thought to be caused by damage to the primary visual cortex (V1), usually following a vascular event. This study shows that damage to the anatomical input to V1, i.e., the optic radiations, can result in selective visual deficits that mimic the Riddoch syndrome. The results also highlight the differential susceptibility of the magnocellular and parvocellular visual systems to injury. Overall, this study offers new insights that will improve our understanding of the impact of brain injury and neurosurgery on the visual pathways. The Riddoch syndrome, characterised by the ability to perceive, consciously, moving visual stimuli but not static ones, has been associated with lesions of primary visual cortex (V1). We present here the case of patient YL who, after a tumour resection surgery that spared his V1, nevertheless showed symptoms of the Riddoch syndrome. Based on our testing, we postulated that the magnocellular (M) and parvocellular (P) inputs to his V1 may be differentially affected. In a first experiment, YL was presented with static and moving checkerboards in his blind field while undergoing multimodal magnetic resonance imaging (MRI), including structural, functional, and diffusion, acquired at 3 T. In a second experiment, we assessed YL's neural responses to M and P visual stimuli using psychophysics and high-resolution fMRI acquired at 7 T. YL's optic radiations were partially damaged but not severed. We found extensive activity in his visual cortex for moving, but not static, visual stimuli, while our psychophysical tests revealed that only low-spatial frequency moving checkerboards were perceived. High-resolution fMRI revealed strong responses in YL's V1 to M stimuli and very weak ones to P stimuli, indicating a functional P lesion affecting V1. In addition, YL frequently reported seeing moving stimuli and discriminating their direction of motion in the absence of visual stimulation, suggesting that he was experiencing visual hallucinations. Overall, this study highlights the possibility of a selective loss of P inputs to V1 resulting in the Riddoch syndrome and in hallucinations of visual motion.


Motion Perception , Visual Cortex , Humans , Male , Hallucinations , Magnetic Resonance Imaging , Motion Perception/physiology , Photic Stimulation/methods , Vision, Ocular , Visual Cortex/physiology , Visual Pathways/physiology
11.
Neuropsychologia ; 198: 108864, 2024 Jun 06.
Article En | MEDLINE | ID: mdl-38521150

Early visual cortex (V1-V3) is believed to be critical for normal visual awareness by providing the necessary feedforward input. However, it remains unclear whether visual awareness can occur without further involvement of early visual cortex, such as re-entrant feedback. It has been challenging to determine the importance of feedback activity to these areas because of the difficulties in dissociating this activity from the initial feedforward activity. Here, we applied single-pulse transcranial magnetic stimulation (TMS) over the left posterior parietal cortex to elicit phosphenes in the absence of direct visual input to early visual cortex. Immediate neural activity after the TMS pulse was assessed using the event-related optical signal (EROS), which can measure activity under the TMS coil without artifacts. Our results show that: 1) The activity in posterior parietal cortex 50 ms after TMS was related to phosphene awareness, and 2) Activity related to awareness was observed in a small portion of V1 140 ms after TMS, but in contrast (3) Activity in V2 was a more robust correlate of awareness. Together, these results are consistent with interactive models proposing that sustained and recurrent loops of activity between cortical areas are necessary for visual awareness to emerge. In addition, we observed phosphene-related activations of the anteromedial cuneus and lateral occipital cortex, suggesting a functional network subserving awareness comprising these regions, the parietal cortex and early visual cortex.


Awareness , Phosphenes , Transcranial Magnetic Stimulation , Visual Cortex , Humans , Male , Female , Awareness/physiology , Adult , Visual Cortex/physiology , Young Adult , Phosphenes/physiology , Visual Perception/physiology , Photic Stimulation , Parietal Lobe/physiology , Brain Mapping , Visual Pathways/physiology
12.
Glia ; 72(7): 1217-1235, 2024 Jul.
Article En | MEDLINE | ID: mdl-38511347

Brain function is critically dependent on correct circuit assembly. Microglia are well-known for their important roles in immunological defense and neural plasticity, but whether they can also mediate experience-induced correction of miswired circuitry is unclear. Ten-m3 knockout (KO) mice display a pronounced and stereotyped visuotopic mismapping of ipsilateral retinal inputs in their visual thalamus, providing a useful model to probe circuit correction mechanisms. Environmental enrichment (EE) commenced around birth, but not later in life, can drive a partial correction of the most mismapped retinal inputs in Ten-m3 KO mice. Here, we assess whether enrichment unlocks the capacity for microglia to selectively engulf and remove miswired circuitry, and the timing of this effect. Expression of the microglial-associated lysosomal protein CD68 showed a clear enrichment-driven, spatially restricted change which had not commenced at postnatal day (P)18, was evident at P21, more robust at P25, and had ceased by P30. This was observed specifically at the corrective pruning site and was absent at a control site. An engulfment assay at the corrective pruning site in P25 mice showed EE-driven microglial-uptake of the mismapped axon terminals. This was temporally and spatially specific, as no enrichment-driven microglial engulfment was seen in P18 KO mice, nor the control locus. The timecourse of the EE-driven corrective pruning as determined anatomically, aligned with this pattern of microglia reactivity and engulfment. Collectively, these findings show experience can drive targeted microglial engulfment of miswired neural circuitry during a restricted postnatal window. This may have important therapeutic implications for neurodevelopmental conditions involving aberrant neural connectivity.


Animals, Newborn , Mice, Knockout , Microglia , Animals , Microglia/metabolism , Microglia/physiology , Mice, Inbred C57BL , Mice , Neuronal Plasticity/physiology , Antigens, CD/metabolism , Visual Pathways/physiology , Antigens, Differentiation, Myelomonocytic/metabolism , Retina/physiology , Retina/cytology , Retina/metabolism , Environment , Nerve Tissue Proteins/metabolism , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/deficiency , CD68 Molecule
13.
Elife ; 132024 Mar 15.
Article En | MEDLINE | ID: mdl-38489224

How neural representations preserve information about multiple stimuli is mysterious. Because tuning of individual neurons is coarse (e.g., visual receptive field diameters can exceed perceptual resolution), the populations of neurons potentially responsive to each individual stimulus can overlap, raising the question of how information about each item might be segregated and preserved in the population. We recently reported evidence for a potential solution to this problem: when two stimuli were present, some neurons in the macaque visual cortical areas V1 and V4 exhibited fluctuating firing patterns, as if they responded to only one individual stimulus at a time (Jun et al., 2022). However, whether such an information encoding strategy is ubiquitous in the visual pathway and thus could constitute a general phenomenon remains unknown. Here, we provide new evidence that such fluctuating activity is also evoked by multiple stimuli in visual areas responsible for processing visual motion (middle temporal visual area, MT), and faces (middle fundus and anterolateral face patches in inferotemporal cortex - areas MF and AL), thus extending the scope of circumstances in which fluctuating activity is observed. Furthermore, consistent with our previous results in the early visual area V1, MT exhibits fluctuations between the representations of two stimuli when these form distinguishable objects but not when they fuse into one perceived object, suggesting that fluctuating activity patterns may underlie visual object formation. Taken together, these findings point toward an updated model of how the brain preserves sensory information about multiple stimuli for subsequent processing and behavioral action.


Visual Cortex , Visual Pathways , Visual Pathways/physiology , Visual Cortex/physiology , Visual Fields , Neurons/physiology , Photic Stimulation
14.
Nat Commun ; 15(1): 2466, 2024 Mar 19.
Article En | MEDLINE | ID: mdl-38503746

How the activity of neurons gives rise to natural vision remains a matter of intense investigation. The mid-level visual areas along the ventral stream are selective to a common class of natural images-textures-but a circuit-level understanding of this selectivity and its link to perception remains unclear. We addressed these questions in mice, first showing that they can perceptually discriminate between textures and statistically simpler spectrally matched stimuli, and between texture types. Then, at the neural level, we found that the secondary visual area (LM) exhibited a higher degree of selectivity for textures compared to the primary visual area (V1). Furthermore, textures were represented in distinct neural activity subspaces whose relative distances were found to correlate with the statistical similarity of the images and the mice's ability to discriminate between them. Notably, these dependencies were more pronounced in LM, where the texture-related subspaces were smaller than in V1, resulting in superior stimulus decoding capabilities. Together, our results demonstrate texture vision in mice, finding a linking framework between stimulus statistics, neural representations, and perceptual sensitivity-a distinct hallmark of efficient coding computations.


Visual Cortex , Visual Pathways , Animals , Mice , Photic Stimulation/methods , Visual Pathways/physiology , Visual Cortex/physiology , Neurons/physiology , Visual Perception/physiology
15.
eNeuro ; 11(3)2024 Mar.
Article En | MEDLINE | ID: mdl-38479809

First-order thalamic nuclei receive feedforward signals from peripheral receptors and relay these signals to primary sensory cortex. Primary sensory cortex, in turn, provides reciprocal feedback to first-order thalamus. Because the vast majority of sensory thalamocortical inputs target primary sensory cortex, their complementary corticothalamic neurons are assumed to be similarly restricted to primary sensory cortex. We upend this assumption by characterizing morphologically diverse neurons in multiple mid-level visual cortical areas of the primate (Macaca mulatta) brain that provide direct feedback to the primary visual thalamus, the dorsal lateral geniculate nucleus (LGN). Although the majority of geniculocortical neurons project to primary visual cortex (V1), a minority, located mainly in the koniocellular LGN layers, provide direct input to extrastriate visual cortex. These "V1-bypassing" projections may be implicated in blindsight. We hypothesized that geniculocortical inputs directly targeting extrastriate cortex should be complemented by reciprocal corticogeniculate circuits. Using virus-mediated circuit tracing, we discovered corticogeniculate neurons throughout three mid-level extrastriate areas: MT, MST, and V4. Quantitative morphological analyses revealed nonuniform distributions of unique cell types across areas. Many extrastriate corticogeniculate neurons had spiny stellate morphology, suggesting possible targeting of koniocellular LGN layers. Importantly though, multiple morphological types were observed across areas. Such morphological diversity could suggest parallel streams of V1-bypassing corticogeniculate feedback at multiple stages of the visual processing hierarchy. Furthermore, the presence of corticogeniculate neurons across visual cortex necessitates a reevaluation of the LGN as a hub for visual information rather than a simple relay.


Visual Cortex , Visual Pathways , Animals , Feedback , Visual Pathways/physiology , Thalamus/physiology , Macaca mulatta , Visual Cortex/physiology
16.
Proc Natl Acad Sci U S A ; 121(12): e2317218121, 2024 Mar 19.
Article En | MEDLINE | ID: mdl-38483997

Across the animal kingdom, visual predation relies on motion-sensing neurons in the superior colliculus (SC) and its orthologs. These neurons exhibit complex stimulus preferences, including direction selectivity, which is thought to be critical for tracking the unpredictable escape routes of prey. The source of direction selectivity in the SC is contested, and its contributions to predation have not been tested experimentally. Here, we use type-specific cell removal to show that narrow-field (NF) neurons in the mouse SC guide predation. In vivo recordings demonstrate that direction-selective responses of NF cells are independent of recently reported stimulus-edge effects. Monosynaptic retrograde tracing reveals that NF cells receive synaptic input from direction-selective ganglion cells. When we eliminate direction selectivity in the retina of adult mice, direction-selective responses in the SC, including in NF cells, are lost. However, eliminating retinal direction selectivity does not affect the hunting success or strategies of mice, even when direction selectivity is removed after mice have learned to hunt, and despite abolishing the gaze-stabilizing optokinetic reflex. Thus, our results identify the retinal source of direction selectivity in the SC. They show that NF cells in the SC guide predation, an essential spatial orienting task, independent of their direction selectivity, revealing behavioral multiplexing of complex neural feature preferences and highlighting the importance of feature-selective manipulations for neuroethology.


Neurons , Predatory Behavior , Mice , Animals , Neurons/physiology , Superior Colliculi/physiology , Retina , Visual Pathways/physiology
17.
J Neurosci ; 44(19)2024 May 08.
Article En | MEDLINE | ID: mdl-38485258

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.


Neurons , Synapses , Thalamus , Visual Cortex , Visual Pathways , Wakefulness , Animals , Rabbits , Male , Female , Visual Pathways/physiology , Wakefulness/physiology , Visual Cortex/physiology , Visual Cortex/cytology , Synapses/physiology , Neurons/physiology , Thalamus/physiology , Thalamus/cytology , Photic Stimulation/methods , Visual Fields/physiology , Action Potentials/physiology , Superior Colliculi/physiology , Superior Colliculi/cytology
18.
J Neurosci ; 44(18)2024 May 01.
Article En | MEDLINE | ID: mdl-38514178

An organizational feature of neural circuits is the specificity of synaptic connections. A striking example is the direction-selective (DS) circuit of the retina. There are multiple subtypes of DS retinal ganglion cells (DSGCs) that prefer motion along one of four preferred directions. This computation is mediated by selective wiring of a single inhibitory interneuron, the starburst amacrine cell (SAC), with each DSGC subtype preferentially receiving input from a subset of SAC processes. We hypothesize that the molecular basis of this wiring is mediated in part by unique expression profiles of DSGC subtypes. To test this, we first performed paired recordings from isolated mouse retinas of both sexes to determine that postnatal day 10 (P10) represents the age at which asymmetric synapses form. Second, we performed RNA sequencing and differential expression analysis on isolated P10 ON-OFF DSGCs tuned for either nasal or ventral motion and identified candidates which may promote direction-specific wiring. We then used a conditional knock-out strategy to test the role of one candidate, the secreted synaptic organizer cerebellin-4 (Cbln4), in the development of DS tuning. Using two-photon calcium imaging, we observed a small deficit in directional tuning among ventral-preferring DSGCs lacking Cbln4, though whole-cell voltage-clamp recordings did not identify a significant change in inhibitory inputs. This suggests that Cbln4 does not function primarily via a cell-autonomous mechanism to instruct wiring of DS circuits. Nevertheless, our transcriptomic analysis identified unique candidate factors for gaining insights into the molecular mechanisms that instruct wiring specificity in the DS circuit.


Mice, Inbred C57BL , Retina , Retinal Ganglion Cells , Synapses , Animals , Mice , Retina/metabolism , Retina/physiology , Male , Synapses/physiology , Synapses/metabolism , Female , Retinal Ganglion Cells/metabolism , Retinal Ganglion Cells/physiology , Amacrine Cells/physiology , Amacrine Cells/metabolism , Motion Perception/physiology , Nerve Net/physiology , Nerve Net/metabolism , Visual Pathways/physiology , Visual Pathways/metabolism
19.
Neuroscience ; 545: 86-110, 2024 May 03.
Article En | MEDLINE | ID: mdl-38484836

Volitional signals for gaze control are provided by multiple parallel pathways converging on the midbrain superior colliculus (SC), whose deeper layers output to the brainstem gaze circuits. In the first of two papers (Takahashi and Veale, 2023), we described the properties of gaze behavior of several species under both laboratory and natural conditions, as well as the current understanding of the brainstem and spinal cord circuits implementing gaze control in primate. In this paper, we review the parallel pathways by which sensory and task information reaches SC and how these sensory and task signals interact within SC's multilayered structure. This includes both bottom-up (world statistics) signals mediated by sensory cortex, association cortex, and subcortical structures, as well as top-down (goal and task) influences which arrive via either direct excitatory pathways from cerebral cortex, or via indirect basal ganglia relays resulting in inhibition or dis-inhibition as appropriate for alternative behaviors. Models of attention such as saliency maps serve as convenient frameworks to organize our understanding of both the separate computations of each neural pathway, as well as the interaction between the multiple parallel pathways influencing gaze. While the spatial interactions between gaze's neural pathways are relatively well understood, the temporal interactions between and within pathways will be an important area of future study, requiring both improved technical methods for measurement and improvement of our understanding of how temporal dynamics results in the observed spatiotemporal allocation of gaze.


Primates , Superior Colliculi , Superior Colliculi/physiology , Animals , Primates/physiology , Humans , Visual Pathways/physiology , Attention/physiology , Fixation, Ocular/physiology
20.
Prog Neurobiol ; 234: 102584, 2024 Mar.
Article En | MEDLINE | ID: mdl-38309458

In human and nonhuman primate brains, columnar (mesoscale) organization has been demonstrated to underlie both lower and higher order aspects of visual information processing. Previous studies have focused on identifying functional preferences of mesoscale domains in specific areas; but there has been little understanding of how mesoscale domains may cooperatively respond to single visual stimuli across dorsal and ventral pathways. Here, we have developed ultrahigh-field 7 T fMRI methods to enable simultaneous mapping, in individual macaque monkeys, of response in both dorsal and ventral pathways to single simple color and motion stimuli. We provide the first evidence that anatomical V2 cytochrome oxidase-stained stripes are well aligned with fMRI maps of V2 stripes, settling a long-standing controversy. In the ventral pathway, a systematic array of paired color and luminance processing domains across V4 was revealed, suggesting a novel organization for surface information processing. In the dorsal pathway, in addition to high quality motion direction maps of MT, MST and V3A, alternating color and motion direction domains in V3 are revealed. As well, submillimeter motion domains were observed in peripheral LIPd and LIPv. In sum, our study provides a novel global snapshot of how mesoscale networks in the ventral and dorsal visual pathways form the organizational basis of visual objection recognition and vision for action.


Macaca , Visual Cortex , Animals , Humans , Visual Pathways/diagnostic imaging , Visual Pathways/physiology , Magnetic Resonance Imaging/methods , Visual Cortex/diagnostic imaging , Visual Cortex/physiology , Brain Mapping
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