Dynamic properties of eye position coded neurons in the alert monkey during saccades

1975 ◽  
Vol 357 (3-4) ◽  
pp. 253-265
Author(s):  
R. Eckmiller
2010 ◽  
Vol 3 (9) ◽  
pp. 698-698 ◽  
Author(s):  
A. W Przybyszewski ◽  
I. Kagan ◽  
M. D Snodderly
Keyword(s):  

1983 ◽  
Vol 23 (10) ◽  
pp. 1025-1030 ◽  
Author(s):  
J. Schlag ◽  
B. Merker ◽  
M. Schlag-Rey

1996 ◽  
Vol 75 (6) ◽  
pp. 2405-2424 ◽  
Author(s):  
D. E. Angelaki ◽  
B. J. Hess

1. The dynamic properties of otolith-ocular reflexes elicited by sinusoidal linear acceleration along the three cardinal head axes were studied during off-vertical axis rotations in rhesus monkeys. As the head rotates in space at constant velocity about an off-vertical axis, otolith-ocular reflexes are elicited in response to the sinusoidally varying linear acceleration (gravity) components along the interaural, nasooccipital, or vertical head axis. Because the frequency of these sinusoidal stimuli is proportional to the velocity of rotation, rotation at low and moderately fast speeds allows the study of the mid-and low-frequency dynamics of these otolith-ocular reflexes. 2. Animals were rotated in complete darkness in the yaw, pitch, and roll planes at velocities ranging between 7.4 and 184 degrees/s. Accordingly, otolith-ocular reflexes (manifested as sinusoidal modulations in eye position and/or slow-phase eye velocity) were quantitatively studied for stimulus frequencies ranging between 0.02 and 0.51 Hz. During yaw and roll rotation, torsional, vertical, and horizontal slow-phase eye velocity was sinusoidally modulated as a function of head position. The amplitudes of these responses were symmetric for rotations in opposite directions. In contrast, mainly vertical slow-phase eye velocity was modulated during pitch rotation. This modulation was asymmetric for rotations in opposite direction. 3. Each of these response components in a given rotation plane could be associated with an otolith-ocular response vector whose sensitivity, temporal phase, and spatial orientation were estimated on the basis of the amplitude and phase of sinusoidal modulations during both directions of rotation. Based on this analysis, which was performed either for slow-phase eye velocity alone or for total eye excursion (including both slow and fast eye movements), two distinct response patterns were observed: 1) response vectors with pronounced dynamics and spatial/temporal properties that could be characterized as the low-frequency range of “translational” otolith-ocular reflexes; and 2) response vectors associated with an eye position modulation in phase with head position ("tilt" otolith-ocular reflexes). 4. The responses associated with two otolith-ocular vectors with pronounced dynamics consisted of horizontal eye movements evoked as a function of gravity along the interaural axis and vertical eye movements elicited as a function of gravity along the vertical head axis. Both responses were characterized by a slow-phase eye velocity sensitivity that increased three- to five-fold and large phase changes of approximately 100-180 degrees between 0.02 and 0.51 Hz. These dynamic properties could suggest nontraditional temporal processing in utriculoocular and sacculoocular pathways, possibly involving spatiotemporal otolith-ocular interactions. 5. The two otolith-ocular vectors associated with eye position responses in phase with head position (tilt otolith-ocular reflexes) consisted of torsional eye movements in response to gravity along the interaural axis, and vertical eye movements in response to gravity along the nasooccipital head axis. These otolith-ocular responses did not result from an otolithic effect on slow eye movements alone. Particularly at high frequencies (i.e., high speed rotations), saccades were responsible for most of the modulation of torsional and vertical eye position, which was relatively large (on average +/- 8-10 degrees/g) and remained independent of frequency. Such reflex dynamics can be simulated by a direct coupling of primary otolith afferent inputs to the oculomotor plant. (ABSTRACT TRUNCATED)


1984 ◽  
Vol 51 (6) ◽  
pp. 1149-1174 ◽  
Author(s):  
M. Schlag-Rey ◽  
J. Schlag

The region in and around the thalamic internal medullary lamina (IML) in the cat recently has been shown to contain neurons active with ocular saccades and responding to visual stimuli. In the present study, single-unit microelectrode recordings were made in the corresponding thalamic region of the alert monkey in order to determine whether neurons with similar properties existed. Our objective was to specify the functional characteristics of these thalamic cells in the monkey, since 1) cell populations in the central thalamus form an important link between brain stem structures, such as superior colliculus and paramedian pontine reticular formation, and cortical areas, such as frontal eye field and inferior parietal lobule; and 2) most neurophysiological information on these structures with regard to gaze mechanisms has been obtained in primates. In this first part of the study we report observations on 164 thalamic units whose activity was related to the performance of spontaneous eye movements, head fixed. The animals had been trained on a visual discrimination task but photic stimuli were used only for calibrating the eye-position recording and for inducing small saccades and smooth pursuit. The experiments were performed in dim red light and in total darkness. Three types of units were found: 67 saccadic burst units, 58 saccade pause-rebound units, and 39 eye-position units. Sixty-two of the burst units had a directional preference. Most of the on-directions were contraversive, and it was in such units that the lead time of firing before saccades was the longest (up to at least 400 ms). Some of the burst units had a movement field, others fired more intensively and with a longer lead time, depending on the eccentricity of the eye position reached in orbit. The five units with no directional preference were the ones showing the best relation of burst duration with saccade duration. Three types of pause-rebound units were distinguished, depending on whether the saccadic pause or the postsaccadic burst was the most conspicuous event or the pause occurred after saccade offset. The three types were called, respectively, omnipausers, omnirebound cells, and late pausers. Omnipausers and omnirebound cells had no directional preference but their typical firing patterns occurred very consistently with all saccades, even less than 2 degrees. In a few units, the rebound progressively faded away in total darkness. The relation of firing rate of eye-position units with eccentricity of the eyes in orbit was analyzed. Fluctuations in time and a hysteresis effect were found to affect this relation.(ABSTRACT TRUNCATED AT 400 WORDS)


Author(s):  
R.F. Stump ◽  
J.R. Pfeiffer ◽  
JC. Seagrave ◽  
D. Huskisson ◽  
J.M. Oliver

In RBL-2H3 rat basophilic leukemia cells, antigen binding to cell surface IgE-receptor complexes stimulates the release of inflammatory mediators and initiates a series of membrane and cytoskeletal events including a transformation of the cell surface from a microvillous to a lamellar topography. It is likely that dynamic properties of the IgE receptor contribute to the activation of these responses. Fewtrell and Metzger have established that limited crosslinking of IgE-receptor complexes is essential to trigger secretion. In addition, Baird and colleagues have reported that antigen binding causes a rapid immobilization of IgE-receptor complexes, and we have demonstrated an apparent increase with time in the affinity of IgE-receptor complexes for antigen.


2006 ◽  
Vol 73 ◽  
pp. 109-119 ◽  
Author(s):  
Chris Stockdale ◽  
Michael Bruno ◽  
Helder Ferreira ◽  
Elisa Garcia-Wilson ◽  
Nicola Wiechens ◽  
...  

In the 30 years since the discovery of the nucleosome, our picture of it has come into sharp focus. The recent high-resolution structures have provided a wealth of insight into the function of the nucleosome, but they are inherently static. Our current knowledge of how nucleosomes can be reconfigured dynamically is at a much earlier stage. Here, recent advances in the understanding of chromatin structure and dynamics are highlighted. The ways in which different modes of nucleosome reconfiguration are likely to influence each other are discussed, and some of the factors likely to regulate the dynamic properties of nucleosomes are considered.


2019 ◽  
Vol 45 (10) ◽  
pp. 1910-1921 ◽  
Author(s):  
Samuel Salvaggio ◽  
Nicolas Masson ◽  
Michael Andres

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