scholarly journals Difference in context-dependency between orienting and defense-like responses induced by the superior colliculus

2019 ◽  
Author(s):  
Kaoru Isa ◽  
Thongchai Sooksawate ◽  
Kenta Kobayashi ◽  
Kazuto Kobayashi ◽  
Peter Redgrave ◽  
...  
Keyword(s):  
Superior Colliculus ◽  
Viral Vector ◽  
Short Latency ◽  
Head Movements ◽  
Context Dependency ◽  
The Novel ◽  
Defense System ◽  
Sensory Inputs ◽  
Cognitive Components ◽  
Stimulation Of

AbstractPrevious electrical stimulation and lesion experiments have suggested that the crossed descending output pathway from the deeper layers (SCd) of superior colliculus (SC) controls orienting responses, while the uncrossed pathway mediates defense-like behavior. Here we extended these investigations by using selective optogenetic activation of each pathway in mice with channelrhodopsin 2 expression by double viral vector techniques. Brief photo-stimulation of the crossed pathway evoked short latency contraversive orienting-like head turns, while extended stimulation induced contraversive circling responses. In contrast, stimulation of uncrossed pathway induced short-latency upward head movements followed by longer-latency defense-like behaviors including retreat and flight. The novel discovery was that the evoked defense-like responses varied depending on the environment, suggesting that uncrossed output can be influenced by top-down modification of the SC or its downstream. This further suggests that the SCd-defense system can be profoundly modulated by non-motor, affective and cognitive components, in addition to direct sensory inputs.

Neck Muscle Responses to Stimulation of Monkey Superior Colliculus. II. Gaze Shift Initiation and Volitional Head Movements

2002 ◽  
Vol 88 (4) ◽  
pp. 2000-2018 ◽  
Author(s):  
Brian D. Corneil ◽  
Etienne Olivier ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Neck Muscles ◽  
Head Movements ◽  
Emg Activity ◽  
Neck Muscle ◽  
Gaze Shift ◽  
Antagonist Muscles ◽  
Agonist And Antagonist ◽  
Agonist And Antagonist Muscles ◽  
Stimulation Of

We report neck muscle activity and head movements evoked by electrical stimulation of the superior colliculus (SC) in head-unrestrained monkeys. Recording neck electromyography (EMG) circumvents complications arising from the head's inertia and the kinetics of muscle force generation and allows precise assessment of the neuromuscular drive to the head plant. This study served two main purposes. First, we sought to test the predictions made in the companion paper of a parallel drive from the SC onto neck muscles. Low-current, long-duration stimulation evoked both neck EMG responses and head movements either without or prior to gaze shifts, testifying to a SC drive to neck muscles that is independent of gaze-shift initiation. However, gaze-shift initiation was linked to a transient additional EMG response and head acceleration, confirming the presence of a SC drive to neck muscles that is dependent on gaze-shift initiation. We forward a conceptual neural architecture and suggest that this parallel drive provides the oculomotor system with the flexibility to orient the eyes and head independently or together, depending on the behavioral context. Second, we compared the EMG responses evoked by SC stimulation to those that accompanied volitional head movements. We found characteristic features in the underlying pattern of evoked neck EMG that were not observed during volitional head movements in spite of the seemingly natural kinematics of evoked head movements. These features included reciprocal patterning of EMG activity on the agonist and antagonist muscles during stimulation, a poststimulation increase in the activity of antagonist muscles, and synchronously evoked responses on agonist and antagonist muscles regardless of initial horizontal head position. These results demonstrate that the electrically evoked SC drive to the head cannot be considered as a neural replicate of the SC drive during volitional head movements and place important new constraints on the interpretation of electrically evoked head movements.

Functional Topography of Converging Visual and Auditory Inputs to Neurons in the Rat Superior Colliculus

2004 ◽  
Vol 92 (5) ◽  
pp. 2933-2946 ◽  
Author(s):  
Irini Skaliora ◽  
Timothy P. Doubell ◽  
Nicholas P. Holmes ◽  
Fernando R. Nodal ◽  
Andrew J. King
Keyword(s):  
Superior Colliculus ◽  
Developmental Plasticity ◽  
Significant Degree ◽  
Sensory Inputs ◽  
Infant Rat ◽  
Synaptic Interactions ◽  
Functional Topography ◽  
Ear Canals ◽  
Auditory Nucleus ◽  
Stimulation Of

We have used a slice preparation of the infant rat midbrain to examine converging inputs onto neurons in the deeper multisensory layers of the superior colliculus (dSC). Electrical stimulation of the superficial visual layers (sSC) and of the auditory nucleus of the brachium of the inferior colliculus (nBIC) evoked robust monosynaptic responses in dSC cells. Furthermore, the inputs from the sSC were found to be topographically organized as early as the second postnatal week and thus before opening of the eyes and ear canals. This precocious topography was found to be sculpted by GABAA-mediated inhibition of a more widespread set of connections. Tracer injections in the nBIC, both in coronal slices as well as in hemisected brains, confirmed a robust projection originating in the nBIC with distinct terminals in the proximity of the cell bodies of dSC neurons. Combined stimulation of the sSC and nBIC sites revealed that the presumptive visual and auditory inputs are summed linearly. Finally, whereas either input on its own could manifest a significant degree of paired-pulse facilitation, temporally offset stimulation of the two sites revealed no synaptic interactions, indicating again that the two inputs function independently. Taken together, these data provide the first detailed intracellular analysis of convergent sensory inputs onto dSC neurons and form the basis for further exploration of multisensory integration and developmental plasticity.

scholarly journals Neck Muscle Responses to Stimulation of Monkey Superior Colliculus. I. Topography and Manipulation of Stimulation Parameters

2002 ◽  
Vol 88 (4) ◽  
pp. 1980-1999 ◽  
Author(s):  
Brian D. Corneil ◽  
Etienne Olivier ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Head Movements ◽  
Emg Activity ◽  
Eye Position ◽  
Neck Muscle ◽  
Evoked Responses ◽  
Inferior Rectus ◽  
Gaze Shifts ◽  
Stimulation Current ◽  
Stimulation Of

The role of the primate superior colliculus (SC) in orienting head movements was studied by recording electromyographic (EMG) activity from multiple neck muscles following electrical stimulation of the SC. Combining SC stimulation with neck EMG recordings provides an objective and sensitive measure of the SC drive onto neck muscle motoneurons, particularly in relation to evoked gaze shifts. In this paper, we address how neck EMG responses to SC stimulation in head-restrained monkeys depend on the rostrocaudal, mediolateral, and dorsoventral location of the stimulating electrode within the SC and vary with manipulations of the eye position prior to stimulation onset and changes in stimulation current and duration. Stimulation predominantly evoked EMG responses on the muscles obliquus capitis inferior, rectus capitis posterior major, and splenius capitis. These responses became larger in magnitude and shorter in onset latency for progressively more caudal stimulation locations, consistent with turning the head. However, evoked responses persisted even for more rostral stimulation locations usually not associated with head movements. Manipulating initial eye position revealed that the magnitude of evoked responses became stronger as the eyes attained positions contralateral to the side of stimulation, consistent with a summation between a generic command evoked by SC stimulation and the influence of eye position on tonic neck EMG. Manipulating stimulation current and duration revealed that the relationship between gaze shifts and evoked EMG responses is not obligatory: short-duration (<20 ms) or low-current stimulation evoked neck EMG responses in the absence of gaze shifts. However, long-duration stimulation (>150 ms) occasionally revealed a transient neck EMG response aligned on the onset of sequential gaze shifts. We conclude that the SC drive to neck muscle motoneurons is far more widespread than traditionally supposed and is relayed through intervening elements which may or may not be activated in association with gaze shifts.

scholarly journals Superior Colliculus Control of Vibrissa Movements

2008 ◽  
Vol 100 (3) ◽  
pp. 1245-1254 ◽  
Author(s):  
Marie E. Hemelt ◽  
Asaf Keller
Keyword(s):  
Motor Cortex ◽  
Superior Colliculus ◽  
Sensory Input ◽  
Field Potential ◽  
Sensory Stimulation ◽  
Set Point ◽  
Sensory Inputs ◽  
Mystacial Vibrissae ◽  
Stimulation Of

This study tested the role of the superior colliculus in generating movements of the mystacial vibrissae—whisking. First, we compared the kinematics of whisking generated by the superior colliculus with those generated by the motor cortex. We found that in anesthetized rats, microstimulation of the colliculus evoked a sustained vibrissa protraction, whereas stimulation of motor cortex produced rhythmic protractions. Movements generated by the superior colliculus are independent of motor cortex and can be evoked at lower thresholds and shorter latencies than those generated by the motor cortex. Next we tested the hypothesis that the colliculus is acting as a simple reflex loop with the neurons that drive vibrissa movement receiving sensory input evoked by vibrissa contacts. We found that most tecto-facial neurons do not receive sensory input. Not only did these neurons not spike in response to sensory stimulation, but field potential analysis revealed that subthreshold sensory inputs do not overlap spatially with tecto-facial neurons. Together these findings suggest that the superior colliculus plays a pivotal role in vibrissa movement—regulating vibrissa set point and whisk amplitude—but does not function as a simple reflex loop. With the motor cortex controlling the whisking frequency, the superior colliculus control of set point and amplitude would account for the main parameters of voluntary whisking.

scholarly journals Evaluation of a System to Screen for Stimulators of Non-Specific DNA Nicking by HIV-1 Integrase: Application to a Library of 50,000 Compounds

2011 ◽  
Vol 22 (2) ◽  
pp. 67-74 ◽  
Author(s):  
Malgorzata Sudol ◽  
Jennifer L Fritz ◽  
Melissa Tran ◽  
Gavin P Robertson ◽  
Julie B Ealy ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Solution Phase ◽  
The Novel ◽  
Endonuclease Activity ◽  
Viral Dna ◽  
Hit Rate ◽  
Dna Nicking ◽  
Hiv 1 ◽  
Stimulation Of

Background: In addition to activities needed to catalyse integration, retroviral integrases exhibit non-specific endonuclease activity that is enhanced by certain small compounds, suggesting that integrase could be stimulated to damage viral DNA before integration occurs. Methods: A non-radioactive, plate-based, solution phase, fluorescence assay was used to screen a library of 50,080 drug-like chemicals for stimulation of non-specific DNA nicking by HIV-1 integrase. Results: A semi-automated workflow was established and primary hits were readily identified from a graphic output. Overall, 0.6% of the chemicals caused a large increase in fluorescence (the primary hit rate) without also having visible colour that could have artifactually caused this result. None of the potential stimulators from this moderate-size library, however, passed a secondary test that included an inactive integrase mutant that assessed whether the increased fluorescence depended on the endonuclease activity of integrase. Conclusions: This first attempt at identifying integrase stimulator compounds establishes the necessary logistics and workflow required. The results from this study should encourage larger scale high-throughput screening to advance the novel antiviral strategy of stimulating integrase to damage retroviral DNA.

scholarly journals CRISPR-Cas System: The Powerful Modulator of Accessory Genomes in Prokaryotes

2021 ◽  
pp. 1-16
Author(s):  
Anca Butiuc-Keul ◽  
Anca Farkas ◽  
Rahela Carpa ◽  
Dumitrana Iordache
Keyword(s):  
Nucleic Acids ◽  
Pathogenic Bacteria ◽  
The Novel ◽  
Defense System ◽  
Guide Rnas ◽  
Crispr Array ◽  
Different Types ◽  
Evolutionary Trajectories ◽  
Novel Coronavirus ◽  
Cas Proteins

Being frequently exposed to foreign nucleic acids, bacteria and archaea have developed an ingenious adaptive defense system, called CRISPR-Cas. The system is composed of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) array, together with CRISPR (<i>cas</i>)-associated genes. This system consists of a complex machinery that integrates fragments of foreign nucleic acids from viruses and mobile genetic elements (MGEs), into CRISPR arrays. The inserted segments (spacers) are transcribed and then used by cas proteins as guide RNAs for recognition and inactivation of the targets. Different types and families of CRISPR-Cas systems consist of distinct adaptation and effector modules with evolutionary trajectories, partially independent. The origin of the effector modules and the mechanism of spacer integration/deletion is far less clear. A review of the most recent data regarding the structure, ecology, and evolution of CRISPR-Cas systems and their role in the modulation of accessory genomes in prokaryotes is proposed in this article. The CRISPR-Cas system&apos;s impact on the physiology and ecology of prokaryotes, modulation of horizontal gene transfer events, is also discussed here. This system gained popularity after it was proposed as a tool for plant and animal embryo editing, in cancer therapy, as antimicrobial against pathogenic bacteria, and even for combating the novel coronavirus – SARS-CoV-2; thus, the newest and promising applications are reviewed as well.

Effects of low-frequency stimulation of the superior colliculus on spontaneous and visually guided saccades

1993 ◽  
Vol 69 (3) ◽  
pp. 953-964 ◽  
Author(s):  
P. W. Glimcher ◽  
D. L. Sparks
Keyword(s):  
Superior Colliculus ◽  
Time Course ◽  
Low Frequency ◽  
Arbitrary Point ◽  
Visually Guided ◽  
Spontaneous Movements ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation ◽  
Stimulation Current ◽  
Stimulation Of

1. The first experiment of this study determined the effects of low-frequency stimulation of the monkey superior colliculus on spontaneous saccades in the dark. Stimulation trains, subthreshold for eliciting short-latency fixed-vector saccades, were highly effective at biasing the metrics (direction and amplitude) of spontaneous movements. During low-frequency stimulation, the distribution of saccade metrics was biased toward the direction and amplitude of movements induced by suprathreshold stimulation of the same collicular location. 2. Low-frequency stimulation biased the distribution of saccade metrics but did not initiate movements. The distribution of intervals between stimulation onset and the onset of the next saccade did not differ significantly from the distribution of intervals between an arbitrary point in time and the onset of the next saccade under unstimulated conditions. 3. Results of our second experiment indicate that low-frequency stimulation also influenced the metrics of visually guided saccades. The magnitude of the stimulation-induced bias increased as stimulation current or frequency was increased. 4. The time course of these effects was analyzed by terminating stimulation immediately before, during, or after visually guided saccades. Stimulation trains terminated at the onset of a movement were as effective as stimulation trains that continued throughout the movement. No effects were observed if stimulation ended 40–60 ms before the movement began. 5. These results show that low-frequency collicular stimulation can influence the direction and amplitude of spontaneous or visually guided saccades without initiating a movement. These data are compatible with the hypothesis that the collicular activity responsible for specifying the horizontal and vertical amplitude of a saccade differs from the type of collicular activity that initiates a saccade.

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