Saccades to somatosensory targets. II. motor convergence in primate superior colliculus

1996 ◽  
Vol 75 (1) ◽  
pp. 428-438 ◽  
Author(s):  
J. M. Groh ◽  
D. L. Sparks
Keyword(s):  
Motor Activity ◽  
Superior Colliculus ◽  
Large Population ◽  
Reaction Times ◽  
The Body ◽  
Behavioral Characteristics ◽  
Related Activity ◽  
Motor Pathway ◽  
Visual Targets ◽  
Motor Cells

1. We examined cells with saccade-related activity in the superior colliculus (SC) of monkeys performing saccades to both somatosensory and visual targets. Our goals were 1) to determine whether signals from these separate sensory systems have converged onto a common motor pathway by the level of the SC; 2) to determine the frame of reference of somatosensory saccade signals in the SC; and 3) to relate collicular motor activity to the behavioral characteristics of somatosensory saccades. 2. Somatosensory targets consisted of vibrotactile stimuli delivered to the hands, which were held in fixed spatial positions. Saccades of different directions and amplitudes were elicited from different initial eye positions. Of 86 cells with motor-related activity, 85 (99%) discharged for saccades to both visual and somatosensory targets. The remaining cell was active only for visual saccades. 3. Cells with saccade-related activity had movement fields representing the direction and amplitude of saccades to both visual and somatosensory targets. We found no cells that discharged for saccades to a particular somatosensory target regardless of the vector of the saccade. 4. Small modality-dependent differences in the spatial tuning of the movement fields were observed, but these variations formed no clear pattern. Given the large population of cells active in conjunction with each saccade, these small tuning differences may have no net effect. Because the visual and somatosensory movement fields of individual cells were similar to each other, the inaccuracy of somatosensory saccades is likely to be the result of inaccurate signals reaching the SC, rather than an error signal added downstream. 5. The peak discharge frequency of collicular motor cells was lower for somatosensory saccades than for visual saccades, although the number of spikes in the discharge was about the same. 6. The latency of the onset of the prelude of motor activity following the cue to initiate a saccade was about the same for somatosensory and visual trials, even though somatosensory saccades have longer reaction times than visual saccades. However, the peak of the motor activity was delayed on somatosensory trials such that the timing of the peak was the same with respect to the movement on somatosensory and visual trials. 7. We conclude that the same population of saccade-related neurons in the SC that represents saccades to visual targets also represents saccades to somatosensory targets. Somatosensory saccades are encoded by these cells as the change in eye position necessary to bring the target onto the fovea, rather than the location of the stimulus on the body surface. Modality-dependent differences in the frequency and timing of collicular motor activity may contribute to velocity and reaction time differences.

Dependence of Saccade-Related Activity in the Primate Superior Colliculus on Visual Target Presence

2001 ◽  
Vol 86 (2) ◽  
pp. 676-691 ◽  
Author(s):  
Jay A. Edelman ◽  
Michael E. Goldberg
Keyword(s):  
Superior Colliculus ◽  
Visual Target ◽  
Visual Response ◽  
Target Presence ◽  
Related Activity ◽  
Intermediate Layers ◽  
Saccade Velocity ◽  
Trial Basis ◽  
Visual Targets ◽  
Extracellular Activity

Neurons in the intermediate layers of the superior colliculus respond to visual targets and/or discharge immediately before and during saccades. These visual and motor responses have generally been considered independent, with the visual response dependent on the nature of the stimulus, and the saccade-related activity related to the attributes of the saccade, but not to how the saccade was elicited. In these experiments we asked whether saccade-related discharge in the superior colliculus depended on whether the saccade was directed to a visual target. We recorded extracellular activity of neurons in the intermediate layers of the superior colliculus of three rhesus monkeys during saccades in tasks in which we varied the presence or absence of a visual target and the temporal delays between the appearance and disappearance of a target and saccade initiation. Across our sample of neurons ( n = 64), discharge was highest when a saccade was made to a still-present visual target, regardless of whether the target had recently appeared or had been present for several hundred milliseconds. Discharge was intermediate when the target had recently disappeared and lowest when the target had never appeared during that trial. These results are consistent with the hypothesis that saccade-related discharge decreases as the time between the target disappearance and saccade initiation increases. Saccade velocity was also higher for saccades to visual targets, and correlated on a trial-by-trial basis with perisaccadic discharge for many neurons. However, discharge of many neurons was dependent on task but independent of saccade velocity, and across our sample of neurons, saccade velocity was higher for saccades made immediately after target appearance than would be predicted by discharge level. A tighter relationship was found between saccade precision and perisaccadic discharge. These findings suggest that just as the purpose of the saccadic system in primates is to drive the fovea to a visual target, presaccadic motor activity in the superior colliculus is most intense when such a target is actually present. This enhanced activity may, itself, contribute to the enhanced performance of the saccade system when the saccade is made to a real visual target.

scholarly journals Auditory signals evolve from hybrid- to eye-centered coordinates in the primate superior colliculus

2012 ◽  
Vol 108 (1) ◽  
pp. 227-242 ◽  
Author(s):  
Jungah Lee ◽  
Jennifer M. Groh
Keyword(s):  
Superior Colliculus ◽  
Reference Frame ◽  
Reference Frames ◽  
Visual Response ◽  
Response Patterns ◽  
Related Activity ◽  
Visual Spatial ◽  
Auditory Representation ◽  
Auditory Signals ◽  
Visual Targets

Visual and auditory spatial signals initially arise in different reference frames. It has been postulated that auditory signals are translated from a head-centered to an eye-centered frame of reference compatible with the visual spatial maps, but, to date, only various forms of hybrid reference frames for sound have been identified. Here, we show that the auditory representation of space in the superior colliculus involves a hybrid reference frame immediately after the sound onset but evolves to become predominantly eye centered, and more similar to the visual representation, by the time of a saccade to that sound. Specifically, during the first 500 ms after the sound onset, auditory response patterns ( N = 103) were usually neither head nor eye centered: 64% of neurons showed such a hybrid pattern, whereas 29% were more eye centered and 8% were more head centered. This differed from the pattern observed for visual targets ( N = 156): 86% were eye centered, <1% were head centered, and only 13% exhibited a hybrid of both reference frames. For auditory-evoked activity observed within 20 ms of the saccade ( N = 154), the proportion of eye-centered response patterns increased to 69%, whereas the hybrid and head-centered response patterns dropped to 30% and <1%, respectively. This pattern approached, although did not quite reach, that observed for saccade-related activity for visual targets: 89% were eye centered, 11% were hybrid, and <1% were head centered ( N = 162). The plainly eye-centered visual response patterns and predominantly eye-centered auditory motor response patterns lie in marked contrast to our previous study of the intraparietal cortex, where both visual and auditory sensory and motor-related activity used a predominantly hybrid reference frame ( Mullette-Gillman et al. 2005 , 2009 ). Our present findings indicate that auditory signals are ultimately translated into a reference frame roughly similar to that used for vision, but suggest that such signals might emerge only in motor areas responsible for directing gaze to visual and auditory stimuli.

Saccades to somatosensory targets. III. eye-position-dependent somatosensory activity in primate superior colliculus

1996 ◽  
Vol 75 (1) ◽  
pp. 439-453 ◽  
Author(s):  
J. M. Groh ◽  
D. L. Sparks
Keyword(s):  
Motor Activity ◽  
Superior Colliculus ◽  
Body Surface ◽  
Body Position ◽  
Frame Of Reference ◽  
The Body ◽  
Eye Position ◽  
Limited Region ◽  
Somatosensory Responses ◽  
Sensory Responses

1. We recorded from cells with sensory responses to somatosensory stimuli in the superior colliculus (SC) of awake monkeys. Our goal was to determine the frame of reference of collicular somatosensory signals by seeing whether the positions of the eyes influenced the responses of cells to a given tactile stimulus. Somatosensory targets consisted of vibrotactile stimuli delivered to the hands, which were held in fixed spatial positions. Monkeys performed a delayed saccade task from different initial fixation positions to the locations of these tactile stimuli or to visual stimuli at approximately the same location. 2. The responses of a majority of somatosensory cells (25 of 34 or 74%) were significantly affected by eye position. Nearly all somatosensory cells also responded to visual targets (28 of 30, 93%). Cells whose somatosensory responses depended on eye position responded to visual and somatosensory targets located at approximately the same direction in space with respect to the eyes. 3. The activity of these cells exhibited both sensory and motor qualities. The discharge was more closely linked in time to stimulus onset than to the movement. Sensory features of the stimulus were reflected in the responses: the discharge of a number of cells was phase-locked to the pulses of vibration. The sensory responses occurred even if the animal's next saccade was not directed into the response field of the cell. However, two thirds of the cells also exhibited a burst of motor activity in conjunction with the saccade to the somatosensory target. Sensory and motor activity were not always spatially coextensive. When different, the tuning of motor activity was broader. 4. Cells with somatosensory responses to vibratory stimulation of the hands were found in a wide region of the SC, spanning a 40 degrees range of movement amplitudes. 5. These data show that somatosensory signals in the SC are not purely somatotopic but are dependent on eye position. For stimuli at a fixed location, this eye position dependence allows somatosensory and visual signals to be in register and share a premotor circuitry for guiding saccadic eye movements. 6. The dependence of the somatosensory responses on eye position suggests that the somatosensory receptive fields may either shift on the body surface or they may be restricted to a limited region of the body surface but be gated by eye (and body) position. Future experiments varying body position and the location of the stimulus on the body surface are needed to determine which of these alternatives is correct. Cells with either type of receptive field could provide an unambiguous signal of the location of somatosensory saccade targets with respect to the eyes. The transformation of somatosensory signals from a body-centered frame of reference to a frame of reference that depends on the position of the stimulus with respect to the eyes is necessary for the correct activation of collicular neurons with motor activity, because this activity encodes saccades as desired changes in eye position.

Effects of Local Nicotinic Activation of the Superior Colliculus on Saccades in Monkeys

2005 ◽  
Vol 93 (1) ◽  
pp. 519-534 ◽  
Author(s):  
Masayuki Watanabe ◽  
Yasushi Kobayashi ◽  
Yuka Inoue ◽  
Tadashi Isa
Keyword(s):  
Superior Colliculus ◽  
Reaction Times ◽  
Low Frequency ◽  
Visually Guided ◽  
Population Activity ◽  
Affected Area ◽  
Movement Field ◽  
Neural Interactions ◽  
Restricted Region

To examine the role of competitive and cooperative neural interactions within the intermediate layer of superior colliculus (SC), we elevated the basal SC neuronal activity by locally injecting a cholinergic agonist nicotine and analyzed its effects on saccade performance. After microinjection, spontaneous saccades were directed toward the movement field of neurons at the injection site (affected area). For visually guided saccades, reaction times were decreased when targets were presented close to the affected area. However, when visual targets were presented remote from the affected area, reaction times were not increased regardless of the rostrocaudal level of the injection sites. The endpoints of visually guided saccades were biased toward the affected area when targets were presented close to the affected area. After this endpoint effect diminished, the trajectories of visually guided saccades remained modestly curved toward the affected area. Compared with the effects on endpoints, the effects on reaction times were more localized to the targets close to the affected area. These results are consistent with a model that saccades are triggered by the activities of neurons within a restricted region, and the endpoints and trajectories of the saccades are determined by the widespread population activity in the SC. However, because increased reaction times were not observed for saccades toward targets remote from the affected area, inhibitory interactions in the SC may not be strong enough to shape the spatial distribution of the low-frequency preparatory activities in the SC.

Effect of vagotomy on the acid response to gastric distension

1970 ◽  
Vol 48 (10) ◽  
pp. 670-674 ◽  
Author(s):  
R. M. Preshaw
Keyword(s):  
Motor Activity ◽  
Gastric Acid ◽  
Motor Response ◽  
Acid Output ◽  
The Body ◽  
Conscious Dogs ◽  
Truncal Vagotomy ◽  
Gastric Distension ◽  
Gastric Acid Output

Distension of the body of the stomach, in conscious dogs with vagally innervated antral pouches, caused an increase in gastric acid output, and an increase in antral motor activity. Truncal vagotomy inhibited the acid response to distension, but had no effect on the antral motor response. Denervation of the antral pouch by separating it from the main stomach caused little further diminution in the response.

scholarly journals DYNAMICS OF CHANGES IN THE PSYCHOPHYSIOLOGICAL STATE OF TECHNICAL UNIVERSITY STUDENTS

2021 ◽  
Vol 5 ◽  
pp. 91-95
Author(s):  
Elena V. Klimova ◽  
Olga V. Mukhametova ◽  
Nail Sh. Mukhametov
Keyword(s):  
Physical Education ◽  
Motor Activity ◽  
Goal Orientation ◽  
The Body ◽  
State University ◽  
First Year Students ◽  
Motor Abilities ◽  
Functional Capabilities ◽  
Functional Development ◽  
Psychophysiological State

This paper examines the dynamics of changes in the indicators of the psychophysiological state of students of the Siberian State University of Railway Transport. The indicators of motor activity, vital index (ZHI) and respiratory system were considered. The purpose of the study is to identify the physical and functional capabilities of the body of first-year students, as well as to analyze the level of health. The objectives of the study are to determine the level of psychophysiological state of students in dynamics. Research hypothesis: the source of physical education should be on motor activity that is appropriate for development, in order to promote self-efficacy and pleasure, as well as encourage continuous participation in physical activity; through the acquisition of motivational experience by students in physical education and sports, physical and functional development is achieved, as well as self-esteem, goal orientation and tasks; the effectiveness of physical development can be achieved by changing the approaches to the implementation of FC programs, sports facilities, recruitment, as well as the organization of school-university continuity. Research methods: analysis, systematization, generalization. The results of the research showed a decrease in physical fitness and activity in general, as well as the need to develop motor abilities and improve the level of physical health of students.

scholarly journals The Novel Coronavirus 2019 (COVID-19): A Narrative Review

2020 ◽  
Vol 1 (2) ◽  
pp. 15-52
Author(s):  
Baratali Rezapour ◽  
Sayed Jalil Musavi ◽  
Faezeh Shirzadeh Maleki
Keyword(s):  
Food Chain ◽  
Signs And Symptoms ◽  
Viral Disease ◽  
Zoonotic Diseases ◽  
The Body ◽  
Behavioral Characteristics ◽  
The Novel ◽  
Ecological Characteristics ◽  
Novel Coronavirus ◽  
Key Steps

One of the key steps in determining how to prevent the viral disease is to identify the virus. The virus lives in different ways and in different environments. It lives in the air, in the sea, on plants, animals and objects and humans. Some people put humans on the path of developing zoonotic diseases that are specific to animals but also involve people with unhealthy behaviors. In the food chain, each animal is hunted by other animals and feeds on other animals or plants and other objects. Bacteriophages are viruses that kill bacteria. And there are creatures that kill viruses and this is the biological struggle with viruses. When the virus enters the body, it performs a series of activities that lead to a series of symptoms in the patient. These symptoms include the behavior of viruses. These are among the ecological and behavioral characteristics of viruses that need to be fully understood in order to limit viruses and deal with epidemics and pandemics. In this study, we try to reach a conclusion by reviewing the articles that have information about the behavioral (signs and symptoms) and ecological characteristics of viruses and use these findings in order to combat viruses.

scholarly journals Possible mechanisms of anosognosia: a defect in self–awareness

1998 ◽  
Vol 353 (1377) ◽  
pp. 1903-1909 ◽  
Author(s):  
◽  
K. M. Heilman ◽  
A. M. Barrett ◽  
J. C. Adair
Keyword(s):  
Population Study ◽  
Sensory Feedback ◽  
Large Population ◽  
The Body ◽  
Spatial Neglect ◽  
Self Awareness ◽  
Knowledge Of Results ◽  
Present Evidence ◽  
Sensory Deficits ◽  
Parallel Processes

Anosognosia of hemiplegia is of interest for both pragmatic and theoretical reasons. We discuss several neuropsychological theories that have been proposed to explain this deficit. Although for psychological reasons people might deny deficits, the denial hypothesis cannot account for the hemispheric asymmetries associated with this disorder and cannot explain why some patients might deny one deficit and recognize another equally disabling deficit. There is some evidence that faulty feedback from sensory deficits, spatial neglect and asomatognosia might be responsible for anosognosia in some patients. However, these feedback hypotheses cannot account for anosognosia in all patients. Although the hemispheric disconnection hypothesis is appealing, disconnection is probably only a rare cause of this disorder. The feedforward intentional theory of anosognosia suggests that the discovery of weakness is dependent on attempted action and some patients might have anosognosia because they do not attempt to move. We present evidence that supports this theory. The presence of one mechanism of anosognosia, however, does not preclude the possibility that other mechanisms might also be working to produce this disorder. Although a large population study needs to be performed, we suspect that anosognosia might be caused by several of the mechanisms that we have discussed. On the basis of the studies of impaired corporeal self–awareness that we have reviewed, we can infer that normal self–awareness is dependent on several parallel processes. One must have sensory feedback and the ability to attend to both one's body and the space where parts of the body may be positioned or acting. One must develop a representation of the body, and this representation must be continuously modified by expectations (feedforward) and knowledge of results (feedback).

The effect of size on the fast-start performance of rainbow trout Salmo gairdneri, and a consideration of piscivorous predator-prey interactions

1976 ◽  
Vol 65 (1) ◽  
pp. 157-177 ◽  
Author(s):  
P. W. Webb
Keyword(s):  
Rainbow Trout ◽  
Reaction Time ◽  
Reaction Times ◽  
The Body ◽  
Salmo Gairdneri ◽  
Escape Behaviour ◽  
Predator Prey ◽  
Average Value ◽  
Fast Start ◽  
Prey Escape

The fast-start (acceleration) performance of seven groups of rainbow trout from 9-6 to 38-7 cm total length was measured in response to d.c. electric shock stimuli. Two fast-start kinematic patterns, L- and S-start were observed. In L-starts the body was bent into an L or U shape and a recoil turn normally accompanied acceleration. Free manoeuvre was not possible in L-starts without loss of speed. In S-starts the body was bent into an S-shape and fish accelerated without a recoil turn. The frequency of S-starts increased with size from 0 for the smallest fish to 60–65% for the largest fish. Acceleration turns were common. The radius of smallest turn for both fast-start patterns was proportional to length (L) with an overall radius of 0–17 L. The duration of the primary acceleration stages increased with size from 0–07 s for the group of smallest fish to 0–10 s for the group of largest fish. Acceleration rates were independent of size. The overall mean maximum rate was 3438 cm/s2 and the average value to the end of the primary acceleration movements was 1562 cm/s2. The distance covered and velocity attained after a given time for fish accelerating from rest were independent of size. The results are discussed in the context of interactions between a predator and prey fish following initial approach by the predator. It is concluded that the outcome of an interaction is likely to depend on reaction times of interacting fish responding to manoeuvres initiated by the predator or prey. The prey reaction time results in the performance of the predator exceeding that of the prey at any instant. The predator reaction time and predator error in responses to unpredictable prey manoeuvre are required for prey escape. It is predicted that a predator should strike the prey within 0-1 s if the fish are initially 5–15 cm apart as reported in the literature for predator-prey interactions. These distances would be increased for non-optimal prey escape behaviour and when the prey body was more compressed or depressed than the predator.

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