Anatomical distribution of arm-movement-related neurons in the primate superior colliculus and underlying reticular formation in comparison with visual and saccadic cells

1997 ◽  
Vol 115 (2) ◽  
pp. 206-216 ◽  
Author(s):  
W. Werner ◽  
Klaus-Peter Hoffmann ◽  
Sabine Dannenberg
Keyword(s):  
Superior Colliculus ◽  
Reticular Formation ◽  
Arm Movement ◽  
Anatomical Distribution

scholarly journals On your mark, get set: Brainstem circuitry underlying saccadic initiation

2000 ◽  
Vol 78 (11) ◽  
pp. 934-944 ◽  
Author(s):  
D P Munoz ◽  
M C Dorris ◽  
M Paré ◽  
S Everling
Keyword(s):  
Motor Control ◽  
Visual Field ◽  
Superior Colliculus ◽  
Reticular Formation ◽  
Motor Preparation ◽  
Motor Behaviour ◽  
Visual Axis ◽  
Brainstem Reticular Formation ◽  
Behavioural Performance ◽  
Situational Experience

Saccades are rapid eye movements that are used to move the visual axis toward targets of interest in the visual field. The time to initiate a saccade is dependent upon many factors. Here we review some of the recent advances in our understanding of the these processes in primates. Neurons in the superior colliculus and brainstem reticular formation are organised into a network to control saccades. Some neurons are active during visual fixation, while others are active during the preparation and execution of saccades. Several factors can influence the excitability levels of these neurons prior to the appearance of a new saccadic target. These pre-target changes in excitability are correlated to subsequent changes in behavioural performance. Our results show how neuronal signals in the superior colliculus and brainstem reticular formation can be shaped by contextual factors and demonstrate how situational experience can expedite motor behaviour via the advanced preparation of motor programs.Key words: superior colliculus, reticular formation, eye movement, saccade, motor preparation, motor control.

Suppression of Visually and Memory-Guided Saccades Induced by Electrical Stimulation of the Monkey Frontal Eye Field. II. Suppression of Bilateral Saccades

2004 ◽  
Vol 92 (4) ◽  
pp. 2261-2273 ◽  
Author(s):  
Yoshiko Izawa ◽  
Hisao Suzuki ◽  
Yoshikazu Shinoda
Keyword(s):  
Electrical Stimulation ◽  
Superior Colliculus ◽  
Reticular Formation ◽  
Neural Mechanism ◽  
Frontal Eye Field ◽  
Pontine Reticular Formation ◽  
Visually Guided ◽  
Saccade Onset ◽  
Eye Field ◽  
Stimulation Of

To understand the neural mechanism of fixation, we investigated effects of electrical stimulation of the frontal eye field (FEF) and its vicinity on visually guided (Vsacs) and memory-guided saccades (Msacs) in trained monkeys and found that there were two types of suppression induced by the electrical stimulation: suppression of ipsilateral saccades and suppression of bilateral saccades. In this report, we characterized the properties of the suppression of bilateral Vsacs and Msacs. Stimulation of the bilateral suppression sites suppressed the initiation of both Vsacs and Msacs in all directions during and ∼50 ms after stimulation but did not affect the vector of these saccades. The suppression was stronger for ipsiversive larger saccades and contraversive smaller saccades, and saccades with initial eye positions shifted more in the saccadic direction. The most effective stimulation timing for the suppression of ipsilateral and contralateral Vsacs was ∼40–50 ms before saccade onset, indicating that the suppression occurred most likely in the superior colliculus and/or the paramedian pontine reticular formation. Suppression sites of bilateral saccades were located in the prearcuate gyrus facing the inferior arcuate sulcus where stimulation induced suppression at ≤40 μA but usually did not evoke any saccades at 80 μA and were different from those of ipsilateral saccades where stimulation evoked saccades at ≤50 μA. The bilateral suppression sites contained fixation neurons. The results suggest that fixation neurons in the bilateral suppression area of the FEF may play roles in maintaining fixation by suppressing saccades in all directions.

Anatomy and physiology of saccadic long-lead burst neurons recorded in the alert squirrel monkey. II. Pontine neurons

1996 ◽  
Vol 76 (1) ◽  
pp. 353-370 ◽  
Author(s):  
C. A. Scudder ◽  
A. K. Moschovakis ◽  
A. B. Karabelas ◽  
S. M. Highstein
Keyword(s):  
Superior Colliculus ◽  
Brain Stem ◽  
Reticular Formation ◽  
Reticulospinal Neurons ◽  
Burst Neurons ◽  
Nucleus Reticularis ◽  
Discharge Patterns ◽  
The Brain ◽  
Saccade Generation

1. The discharge patterns and axonal projections of saccadic long-lead burst neurons (LLBNs) with somata in the pontine reticular formation were studied in alert squirrel monkeys with the use of the method of intraaxonal recording and horseradish peroxidase injection. 2. The largest population of stained neurons were afferents to the cerebellum. They originated in the dorsomedial nucleus reticularis tegmenti pontis (NRTP) including its dorsal cell group (N = 5), the preabducens intrafascicular nucleus (N = 5), and the raphe pontis (N = 1). Axons of all neurons coursed under NRTP and entered brachium pontis without having synapsed in the brain stem. Three axons sent collaterals to the floccular lobe, but other more distant targets of these and the other cerebellar afferents could not be determined. Movement fields of these neurons were intermediate between vectorial and directional types. 3. Four neurons had their somata in nucleus reticularis pontis oralis and terminations in the brain stem reticular formation. Each neuron was different, but all terminated in the region containing excitatory burst neurons, and most terminated in the region containing inhibitory burst neurons. Other targets include nucleus reticularis pontis oralis and caudalis, NRTP, raphe interpositus, and the spinal cord. Discharge patterns included both vectorial and directional types. 4. Two reticulospinal neurons had large multipolar somata either just rostral or ventral to the abducens nucleus. These neurons also projected to the medullary reticular formation, caudal nucleus prepositus hypoglossi, and dorsal and ventral paramedian reticular nucleus. 5. The functional implications of the connections of these LLBNs and those reported in the companion paper are extensively discussed. The fact that the efferents of the superior colliculus target the regions containing medium-lead saccadic burst neurons confirms the role of the colliculus in saccade generation. However, the finding that many other neurons project to these regions and the finding that superior colliculus efferents project more heavily to areas containing reticulospinal neurons argue for a diminished role of the superior colliculus in saccade generation but an augmented role in head movement control.

Role of the Rostral Superior Colliculus in Gaze Anchoring During Reach Movements

2010 ◽  
Vol 103 (6) ◽  
pp. 3153-3166 ◽  
Author(s):  
Vicente Reyes-Puerta ◽  
Roland Philipp ◽  
Werner Lindner ◽  
Klaus-Peter Hoffmann
Keyword(s):  
Superior Colliculus ◽  
Target Location ◽  
Arm Movement ◽  
Neural System ◽  
Reaching Movements ◽  
Neural Substrate ◽  
Gaze Anchoring ◽  
Hand Coordination ◽  
Reach Movements

When reaching for an object, primates usually look at their target before touching it with the hand. This gaze movement prior to the arm movement allows target fixation, which is usually prolonged until the target is reached. In this manner, a stable image of the object is provided on the fovea during the reach, which is crucial for guiding the final part of the hand trajectory by visual feedback. Here we investigated a neural substrate possibly responsible for this behavior. In particular we tested the influence of reaching movements on neurons recorded at the rostral pole of the superior colliculus (rSC), an area classically related to fixation. Most rSC neurons showed a significant increase in their activity during reaching. Moreover, this increase was particularly high when the reaching movements were preceded by corresponding saccades to the targets to be reached, probably revealing a stronger coupling of the oculo-manual neural system during such a natural task. However, none of the parameters tested—including movement kinematics and target location—was found to be closely related to the observed increase in neural activity. Thus the increase in activity during reaching was found to be rather nonspecific except for its dependence on whether the reach was produced in isolation or in combination with a gaze movement. These results identify the rSC as a neural substrate sufficient for gaze anchoring during natural reaching movements, placing its activity at the core of the neural system dedicated to eye-hand coordination.

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