The central mesencephalic reticular formation (cMRF) was electrically stimulated in the alert monkey. Saccadic eye movements were induced to the contralateral side in the horizontal plane at latencies of 18-35 ms. Smooth or slow eye deviations were not produced by cMRF stimulation. If the stimulus was given during slow phases of nystagmus, rapid eye movements were elicited, and the velocity of the slow phases was not affected. The function of cMRF neurons and/or of pathways that lie within it appear primarily related to generation of rapid eye movements in the horizontal plane. The amplitude of induced saccadic eye movements depended solely on the region of cMRF that was activated. When the stimulation frequency was lower, the latency was longer, but the size and characteristics of the induced movement were the same. The product of latency and stimulus frequency was approximately constant, suggesting that saccades had been triggered after a fixed number of pulses had been given. Stimulation of cMRF at frequencies that were too low to elicit rapid eye movements had a tonic effect on saccade generation. When the animal was having optokinetic nystagmus (OKN), stimulation modulated beat frequency according to the direction of the nystagmus: contralateral quick phases were facilitated and ipsilateral quick phases were suppressed. The frequencies of stimulation necessary to suppress ipsilateral quick phases increased as slow phase eye velocity increased. This demonstrates that both cMRF activity and slow phase velocity affect quick phase triggering. When the cMRF on both sides were simultaneously stimulated, the eyes were fixed in place, and no further rapid movements occurred until the stimulus had ended. Thus, activity in pathways and/or cells in cMRF is not only able to trigger saccades, but can also change the excitability of saccade generating mechanisms and promote fixation by suppressing eye movements. Two types of rapid eye movements were elicited from cMRF. From dorsal portions of cMRF saccades were induced whose size was relatively constant and not dependent on the initial position of the eyes in the orbit. The size of saccades increased from small to large as the stimulating electrode was advanced through cMRF from dorsal to ventral. This suggests that the tecto-bulbo-spinal efferents coursing through cMRF and/or cMRF neurons related to this input, are organized in a topographic fashion, with cells and fibers related to eye movements of increasing size being layered one beneath another.(ABSTRACT TRUNCATED AT 400 WORDS)

ObjectivesUltrasonography (US) is sensitive for detecting echostructural abnormalities of the major salivary glands (SGs) in primary Sjögren’s syndrome (pSS). Our objectives were to define selected US-SG echostructural abnormalities in pSS, set up a preliminary atlas of these definitions and evaluate the consensual definitions reliability in both static and acquisition US-SG images.MethodsInternational experts in SG US in pSS participated in consensus meetings to select and define echostructural abnormalities in pSS. The US reliability of detecting these abnormalities was assessed using a two-step method. First 12 experts used a web-based standardised form to evaluate 60 static US-SG images. Intra observer and interobserver reliabilities were expressed in κ values. Second, five experts, who participated all throughout the study, evaluated US-SG acquisition interobserver reliability in pSS patients.ResultsParotid glands (PGs) and submandibular glands (SMGs) intra observer US reliability on static images was substantial (κ > 0.60) for the two main reliable items (echogenicity and homogeneity) and for the advised pSS diagnosis. PG inter observer reliability was substantial for homogeneity. SMGs interobserver reliability was moderate for homogeneity (κ = 0.46) and fair for echogenicity (κ = 0.38). On acquisition images, PGs interobserver reliability was substantial (κ = 0.62) for echogenicity and moderate (κ = 0.52) for homogeneity. The advised pSS diagnosis reliability was substantial (κ = 0.66). SMGs interobserver reliability was fair (0.20< κ ≤ 0.40) for echogenicity and homogeneity and either slight or poor for all other US core items.ConclusionThis work identified two most reliable US-SG items (echogenicity and homogeneity) to be used by US-SG trained experts. US-PG interobserver reliability result for echogenicity is in line with diagnosis of pSS.

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