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R Eckmiller

Publications and source records attributed to R Eckmiller.

30 records · Page 2Linked to original sources
PubMed1978

Pursuit eye movements and their neural control in the monkey.

1. Single units in the 3. and 6. nerve nuclei were recorded, together with the stimulus and eye movements in trained macaques during pursuit eye movements. 2. The relationship between the impulse rate of an oculomotor motoneuron and the corresponding eye movements can be described by a first order differential equation only, if distinctions are made between the modes of the oculomotor system (e.g., fixation or pursuit) and between the agonist phase and the antagonist phase of the corresponding eye muscle. 3. The trained monkeys showed a frequency response during pursuit eye movements, which was comparable to that of humans and which clearly indicates the existence of a predictor mechanism. 4. After sudden stimulus disappearance in the pursuit mode, both the neural impulse rate and the eye movement performed smooth changes for more than 1s. These slow post-pursuit eye movements were related to the time course before stimulus disappearance. 5. Our findings lead to the hypothesis, that pursuit eye movements in primates, if elicited by small moving visual stimuli, are generated by means of a feedback system consisting of a predictor mechanism, the parameters of which are continuously corrected by an updating process in the afferent visual system.

Animals↗
PubMed1976

Functional changes in the oculomotor system of the monkey at various stages of barbiturate anesthesia and alertness.

1. Single units in the III. and VI. nerve nuclei were continuously recorded together with vestibular stimuli and eye movements in macaques before, during, and after administration of barbiturate. 2. The visual input was functionally detached from the oculomotor system during the deeper stages of anesthesia, whereas some kind of vestibulo-ocular response could always be elicited. 3. The finding of various phase values between the maximum impulse rate IRmax of oculomotor units and the maximum stimulus velocity vmax during 1 Hz sinusoidal vestibular stimulation ranging from about 65 deg phase lead to 65 deg phase lag is suggested as important for the explanation of the phase shifts between head rotation and eye movement during anesthesia. 4. The phase relationship between IRmax and vmax was found to be unchanged, whereas the characteristic of IRmax versus vmax was highly sensitive to arousal stimuli for some oculomotor neurons. This sensitivity was represented exclusively by activation rather than inhibition.

Anesthesia↗
PubMed1975

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

Single units in the regions of the III, IV and VI nuclei were recorded together with EOG's for horizontal and vertical eye positions in alert macaques. The sequential analysis for several dynamic parameters of the activity patterns in correlation to the saccade velocity for saccades in the on-direction leads to the results that: 1. eye position coded neurons can clearly be separated into two main classes [early peak (EP) and late peak (LP] by means of their activity patterns during saccades in the on-direction; 2. the maximum impulse rate of EP neurons shows a better correlation with saccade velocity than the difference between maximum and initial impulse rate while the opposite is valid for LP neurons. EP neurons are likely to be motoneurons which initiate saccadic eye movements whereas LP neurons are too slow for this task because they reach their maximum impulse rate after half the saccadic time. The dynamic properties of LP neurons have several features similar to those of primary stretch receptors during ramp-like stretches. The possible influence of fusimotor activity on the oculomotor system is discussed. The fact that the relationship between dynamic index and saccade velocity shows subgroups of data supports the assumption that the state of alertness changes instantaneously in untrained monkeys.

Animals↗
PubMed1975

A digital instantaneous impulse rate meter for neural activity.

An instantaneous impulse rate meter is described, which can be used fro the precise instantaneous conversion of neural or heart activity trains in real time. The device is designed in digital technology to meet various requirements which are important for physiological reserach laboratories.

Action Potentials↗