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PubMed1977

Functional linkage between the electrical activity in the vermal cerebellar cortex and saccadic eye movements.

The temporal relation between the onset of electrical activity of Purkinje cells and the occurrence of rapid eye movements was studied. Experiments were performed in unanesthetized animals, the recordings being made under direct vision through the use of a chronically implanted teflon sleeve. The following results were obtained. 1. Correlation between the activity of Purkinje cells and eye movements indicates that Purkinje cell firing in vermal lobules VI and VII precedes eye movement by 11-12 msec, peak activity corresponding to the time of onset of eye movement. 2. This eye movement related activity of Purkinje cells occurred regardless of the direction of the eye movements but some cells showed directional biases. Best correlation between eye movement and Purkinje cell activity was found with fast eye movements toward the right regardless of recording side. 3. Electrical activity of Purkinje cells was mainly related to saccades. Slow eye movement modulation, although probably present, was not studied in detail. 4. In those cells where an extensive set of measurements could be made, Purkinje cell firing was found to be inversely proportional to the amplitude of the eye movement, small movements being preceded by highest Purkinje cell activity. The present results suggest that cerebellar vermis responds prior to the generation of eye movement and may probably serve to control eye movements in a ballistic manner.

Animals↗
PubMed1979

Cerebral potentials preceding unilateral and simultaneous bilateral finger movements.

Cerebral potentials preceding voluntary bilateral simultaneous finger movements were investigated in 19 right-handed young adult subjects, and were compared with unilateral right-sided finger m n the same experiment. With bilateral movements, the Bereitschaftspotential (BP) was not symmetrical or larger over the dominant hemisphere, but surprisingly, it was larger over the minor hemisphere. The BP averaged -3.66 microV (S.D. 1.96) over the left precentral region and -4.82 microV (S.D. 3.73) over the right precentral region in this condition. The difference was significant at 2P less than 0.01. This difference was pronounced in precentral leads but very small and almost missing in parietal leads. The pre-motion positivity (PMP) was well developed and even larger with bilateral than with unilateral (right-sides) movements. At the vertex it averaged +1.33 microV (S.D.4.16) with bilateral movements and only +0.15 microV (S.D. 1.42) with right-sided unilateral movements (2P less than 0.05). With bilateral movements the PMP could be observed in any record, but with unilateral movements it was missing at the left precentral lead, in accordance with previous publications (Deecke et al. 1969, 1976). The motor potential (MP), measured in a bipolar record from left and right precentral leads, was larger with unilateral (-1.25 microV, S.D. 1.33) than with bilateral movements (-0.36 microV, S.D. 0.92). Onset time differences of the BP preceding unilateral and bilateral movements were very small. However, there was a tendency towards earlier onset with unilateral than with bilateral movements (1031 msec, S.D. 358, as compared with 951 msec, S.D. 305). The averaged EMG revealed differences in movement onset. Muscular contraction tended to be earlier in the right than in the left m. flexor indicis in our right-handed subjects, on the average by 16 msec (S.D. 15). With unilateral right-sided movements, the left m. flexor indicis was not silent but showed an abortive mirror activity in the EMG, without visible movement. This activity occurred on the average 50 msec (S.D. 39) later on the non-moving side.

Adult↗
PubMed1978

Movement discrimination capacities in the cat.

Cats were trained to discriminate moving from nonmoving targets or one direction of movement from another. Various stimulus changes, e.g., size, direction, and rate, were then introduced as a test for generalization of the dimension of movement. Thresholds for detection for minimal movement were also determined. The results showed that (a) for cats, discrimination of movement is more difficult than discriminations based on brightness; (b) the dimension of movement is completely generalized across stimulus configuration but incompletely generalized for direction of movement; (c) the mean movement detection threshold was found to be 3.3 degrees/sec; (d) the thresholds for minimal movement and direction of movement were essentially identical; and (e) stimulus-viewing strategies were found to play an important role in the threshold determinations. The results of the generalization tests are consistent with the physiological properties of neurons found to be sensitive to movement in the cat visual system. The movement threshold values were found to lend support to the view that resolution and slow movement thresholds are correlated.

Animals↗
PubMed1979

Stimulation of breathing movements in fetal sheep by inhibitors of prostaglandin synthesis.

We studied the effects of inhibitors of prostaglandin synthesis on fetal breathing movements on 17 occasions in 11 lambs (gestational age 125-141 days). We gave 12 h infusions of sodium mechlofenamate (8.6-22.2 mg.kg-1) in 13 studies and indomethacin (21.8-38.8 mg.kg-1) in four studies. Results were similar with both agents and did not correlate with drug dosage. There were no changes in fetal arterial blood pressure, pH or blood gas tensions. We assessed fetal breathing movements by measurements of tracheal pressure for a control period of 224 h prior to and 208 h during the infusion of inhibitors of prostaglandin synthesis; their administration caused a marked stimulation of fetal breathing movements judged from the following four variables: (1) incidence of fetal breathing movements increased from 38.4 to 69.2% of the time (P < 0.001); (2) average amplitude of change in tracheal pressure during fetal breathing movements increased from 4.1 to 6.0 torr (P < 0.01); (3) maximal amplitude of change in tracheal pressure during fetal breathing movements increased from 8.8 to 13.4 torr (P < 0.01); and (4) the duration of the longest continuous episode of fetal breathing movements increased from 37 to 229 min (P < 0.05). Two fetuses had electrocorticogram (ECoG) recordings. In control periods, fetal breathing movements occurred only during low voltage, high frequency ECoG activity; however, during infusions of inhibitors of prostaglandin synthesis, fetal breathing movements occurred also during high voltage, low frequency ECoG activity. We conclude that inhibitors of prostaglandin synthesis stimulate fetal breathing movement in fetal sheep. These results suggest that a component of the prostaglandin system is a factor which inhibits breathing movements during fetal life.

Animals↗
PubMed1979

Vestibulo-ocular function during co-ordinated head and eye movements to acquire visual targets.

1. Experiments have been conducted on human subjects in an attempt to establish the role of the vestibulo-ocular reflex in the co-ordination of head and eye movements during visual target acquisition. 2. When the subject moved head and eyes to acquire visual targets in the horizontal plane, the eye movement consisted of an initial saccade in the direction of head movement followed by a slower return towards orbital centre which compensated for remaining head movement. 3. When the head was moved either voluntarily or passively in the dark the pattern of eye movement was very similar to that seen during target acquisition. 4. The mean latency between the start of head acceleration and the onset of the saccadic eye movement was greater in the dark (108 msec, S.D. 85 msec) than for the visually induced responses (14 msec, S.D. 59 msec), in which eye movement often preceded head movement when moving to small ( less than 45 degrees) target offset angles. 5. In all experimental conditions gaze displacement at the end of the initial saccade was normally related in a predictive manner to final head position, but when fixating visual targets offset by more than 60 degrees from the central position there were often large errors, 22% of responses undershooting the target by more than 15 degrees. 6. A highly significant (P less than 0.001) linear relationship was found between gaze displacement and head velocity under all experimental conditions. During target acquisition head velocity was normally positively correlated with amplitude of target offset. The large errors in gaze displacement in response to the larger target offsets occurred at levels of head velocity lower than normally associated with such target offsets. 7. The results have led to the suggestion of a dual mode of control for head-eye co-ordination. In one mode, normally associated with small target offsets (less than 45 degrees), control is mediated by retinal error information. In the other mode, associated with larger target offsets, gaze displacement is generated as an automatic response to head turning. 8. The observation of similar relationships between head and eye movement during passive head turning implicates the vestibulo-ocular reflex in the secondary mode of control, and provides support for the hypothesis that the role of the vestibular saccade is to induce a rapid offset of the eyes in the direction of head movement, thus facilitating rapid search and target location.

Eye Movements↗
PubMed1976

Electrocorticography of waves associated with eye movements in man during wakefulness.

Waves associated with horizontal saccadic eye movements were recorded from cortical occipital areas through multilead intracerebral electrodes implanted for a few days in 6 drug-resistant epileptic patients in order to localize epileptogenic foci. The waves were studied statistically when the EEG activity was not disturbed by interictal discharges. Cortical occipital waves related to free eye movements while scanning complex material started at the end of the eye movement, later in fact than the corresponding scalp parieto-occipital phenomena. The amplitude of the cortical waves increased with the complexity of the external field (contrasts having no marked effect) and was reduced in an unpatterned field and in dim light. Waves persisted in darkness. Their amplitude was independent of the size of the eye movement. The latency of the waves, calculated from the onset of eye movement, increased with the size of the movement, the complexity of the external field and also in darkness. Imposed eye movements induced cortical waves of larger amplitude and shorter latency and anticipatory potential changes beginning before onset of the eye movement. Waves related to eye movements differed from blinks and from responses to several types of light stimulation more strikingly in cortical records than in those from the scalp. These findings are discussed in relation to lambda waves, activation waves and eye movement potentials, expectancy waves and premotor potentials, and to the phenomena of perceptual blanks preceding normal perception after fixation of gaze. The importance of the subject's attention is emphasized.

Adolescent↗
PubMed1978

An evaluation of mandibular border movements: their character and significance.

1. A comparison of protrusive and lateral condylar border movement pathways of 163 subjects revealed considerable similarity when the frequency of 80% of the pathways was compared with the average pathway. 2. A description of the pathways of posterior cusps during lateral contact gliding movement must consider three simultaneously acting guidance factors: (1) the nonworking condyle pathway, (2) the amount of Bennett movement or the working-side condyle displacement, and (3) the anterior guidance or working-side tooth contacts. 3. A Bennett movement of 2.5 to 3.5 mm caused a dramatic flattening of lateral movement pathways of the molar cusp as seen in the frontal plane. The steepness of neither the anterior guidance nor the nonworking condylar pathway had much influence on the molar cusp pathway in the presence of this excessive Bennett movement. 4. Viewed in the horizontal plane, excessive Bennett movement contributed to the greatest potential for collisions of molar cusps during lateral movements. This phenomenon was more pronounced on the nonworking side. 5. When the Bennett movement was 0.75 mm or less the tracing in the frontal plane showed that the 40-degree anterior guidance became the dominant influence over molar cusp lateral movement pathways.

Adult↗
PubMed1979

Ballistic flexion movements of the human thumb.

1. In response to an auditory stimulus normal subjects made ballistic flexion movements of the top joint of the thumb against a lever attached to the spindle of a low-inertia electric motor. 2. Electromyographic (e.m.g.) activity was recorded from pairs of fine wire electrodes inserted into flexor pollicis longus and extensor pollicis longus, respectively the sole flexor and extensor of the joint. 3. Movements of 5 degrees, 10 degrees and 20 degrees were made from initial angles of 10 degrees, 20 degrees and 30 degrees flexion against torques of 0.04, 0.08 and 0.16 Nm. 4. The e.m.g. activity initiating such movements was characterized by a 'triphasic' pattern of sequential bursts of activity in the agonist (flexor pollicis longus), then in the antagonist (extensor pollicis longus), and then in the agonist again. 5. The duration of the first agonist and first antagonist bursts ranged from about 50 to 90 ms and there was no significant change of burst length in the different mechanical conditions. 6. In movements of differing angular distance, the rectified and integrated e.m.g. activity of the first agonist burst could be correlated with the distance moved. The rectified and integrated e.m.g. activity of the first antagonist burst could not be correlated with the distance moved. 7. Responses of the muscles to perturbations either before or during the ballistic movements were studied. Current in the motor could be altered so to extend the thumb ('stretch'), to allow it to accelerate ('release'), or to prevent further movement ('halt'). 8. Suitably timed stretch increased the e.m.g. activity of the first agonist burst while release decreased it. 9. There was a small response of the agonist to stretch or halt timed to act during the interval between the first two agonist bursts; the major response was an augmentation of the second agonist burst. 10. Stretch, timed to act between the first two agonist bursts which released the antagonist, diminished the activity of the first antagonist burst while halt virtually eradicated it in all but one subject. Release, at this time, which stretched the antagonist, increased the activity of the first antagonist burst. 11. It is concluded that the individual components of a ballistic movement are relatively fixed in duration and the amount of e.m.g. activity is altered within this time interval to produce the different forces required for fast movements of different amplitude. 12. Both agonist and antagonist muscles remain under some feed-back control during the entire course of a ballistic movement, but the amount of influence of fedd-back depends on the supraspinal command signal and the changes in the spindle during the course of the movement.

Electromyography↗
PubMed2026

Interaction between CD82 and integrin &#x3b1;V&#x3b2;3 selectively regulates collective movement of tumor cells via endolysosomal trafficking.

Tetraspanin CD82/KAI1 inhibits cell movement and metastasis of malignant tumors, and reduced and lost expressions of CD82 predict worse outcomes of patients with malignant tumors. Here we found that CD82 inhibits both solitary and collective movement of tumor cells. The CD82 YVAA mutation, which affects CD82 trafficking, selectively abrogates CD82-mediated inhibition of collective migration. Cilengitide, at the concentration that specifically inhibits integrin &#x3b1;V&#x3b2;3, also selectively blocks collective movement, underscoring a promotive role of integrin &#x3b1;V&#x3b2;3 in this mode of cell motility. In contrast, integrin &#x3b1;V&#x3b2;5 appears non-essential for collective migration, and both &#x3b1;V&#x3b2;3 and &#x3b1;V&#x3b2;5 are dispensable for solitary movement on fibronectin, highlighting distinct functions of different integrins in different modes of tumor cell movement. CD82 interacts with &#x3b1;V&#x3b2;3 and &#x3b1;V&#x3b2;5 integrins and downregulates their protein levels, while CD82 YVAA mutation relinquishes this downregulation without disrupting CD82 interactions with these integrins. Mechanistically, CD82, but not the YVAA mutant, considerably reduces digitation junction-the structure where integrin &#x3b1;V&#x3b2;3 localizes-and likely directs integrin &#x3b1;V&#x3b2;3 for lysosomal degradation, thereby lowering its level and suppressing collective migration. Thus, our study reveals that i) integrin &#x3b1;V&#x3b2;3 promotes collective movement of tumor cells, ii) CD82 counteracts this by diminishing integrin &#x3b1;V&#x3b2;3 and its presence in microextrusions, and iii) digitation junction likely participates in collective cell movement. Our study further demonstrates that endolysosomal trafficking of CD82 and integrin &#x3b1;V&#x3b2;3 is needed for their collective movement-regulatory activities and that coupling of metastasis suppressor CD82/KAI1 with different partners regulates different modes of cell movement.

Humans↗
PubMed1978

Frontal 'oculomotor" area in alert cat. I. Eye movements and neck activity evoked by stimulation.

(1) Stimulation within cat frontal lobe elicited saccadic eye movements whose maximum velocity was significantly greater than that of normal spontaneous saccades. (2) The majority (90%) of stimulated cortical points yielded eye movements whose directions and amplitudes were independent of the position of the eye in the orbit. The direction of these eye movements depended on the site being stimulated, with a discrete and orderly representation of directions existing within the cortex. (3) A lesser number of cortical points (10%) yielded centering movements whose directions and amplitudes depended on the position of the eye in the orbit, rather than on the site being stimulated. (4) Evoked neck muscle activation frequently preceded evoked eye movements by some 15--30 msec. This timing was compatible with a coordinated head-eye orientating response. (5) On the basis of the directions, and the latencies, of evoked eye movements, the cat frontal oculomotor area could be divided into two subregions, a 'medial' and a 'lateral', (6) The 'medial' area included the mesial wall of the hemisphere with a portion of the lower lip of the cruciate sulcus, and the medial wall of the presylvian sulcus. This area yielded contraversive eye movements with shorter latencies (average 45 msec). (7) The 'lateral' area included primarily the lateral wall of the presylvian sulcus. It yielded predominantly centering eye movements, and ipsiversive movements with longer latencies (65 msec). (8) The functional characteristics of the 'medial' area, as revealed by focal stimulation, resembled those of the monkey frontal eye field.

Animals↗
PubMed1979

Proximal limb movements in response to microstimulation of primate dentate and interpositus nuclei mediated by brain-stem structures.

The cerebellar dentate and interpositus nuclei and the area of their efferent fibres have been stimulated in Cebus monkeys, using a movable microcathode. Responses consisted of eye and face movements and a stereotyped flexion of proximal parts of extremities. Very few distal limb movements were seen. The activation of proximal muscles was studied most closely. It consisted of the limited number of 5 movements: arm flexion and shoulder elevation in the forelimb and hip flexion, knee flexion and dorsiflexion of the ankle in the hindlimb. With currents of up to 100 microamperemeter these movements were elicited more readily from the interpositus and the area of efferent fibres of both nuclei as compared to the dentate nucleus. Responses were more often seen in forelimb than in hindlimb muscles, without apparent somatotopy in either nucleus. Combined forelimb-hindlimb movements were elicited from 42 per cent of effective points. Lesions placed at various locations of cerebellar output pathways demonstrated that the responses were mediated by the descending branch of brachium conjunctivum and did not require the activation of structures anterior to and including the red nucleus. The responses are interpreted to represent adjustments in flexor posture that may serve to modify maintained antigravity tonus during the initiation of volitional movements. This function, mediated by brain-stem structures, is considered to be closely associated with the activity of the lateral and intermediate cerebellum during initiation and conduction of volitional movements, which is mediated mainly through the cerebral cortex. It is stressed that control over both flexor posture and discrete distal movements is inherent in the initiation of voluntary movements.

Animals↗
PubMed1979

Quantitative studies of saccadic and pursuit eye movements in multiple sclerosis.

Ocular movements were studied in 108 patients with established or suspected multiple sclerosis using an on-line computer-based electro-oculographic technique. In one group of patients peak eye movement velocities alone were measured during horizontal refixation saccades. In a second group saccade reaction times and accuracies were measured in addition to velocities, while in a subgroup a quantitative analysis of horizontal pursuit eye movements was also carried out. With the saccade velocity test abnormalities were present in 44 per cent of cases studied and were subclinical in 18 per cent. Abnormalities were found in 57 per cent of cases in whom the detailed saccade analysis was performed, including 48 per cent of patients with clinically normal eye movements. Saccade reaction time and accuracy were more sensitive parameters than saccade velocity, and the highest yield of abnormalities was obtained when all three were taken into consideration. Abnormalities of pursuit movements were found in 71 per cent of cases studied and were frequently subclinical. Abnormalities of saccadic and pursuit movements were not always present together in the same patient, and the overall yield of abnormalities was higher when the results of both types of study were taken into account. The yield of abnormalities with the eye movement studies was somewhat lower than with the pattern-reversal VEP in the clinically definite multiple sclerosis group, but was higher in patients in the other categories. Subclinical abnormalities of eye movement were found in a significant number of patients with normal VEPs. The finding of such an abnormality in patients with spinal cord syndromes allowed reclassification of 14 patients to a category with a higher degree of diagnostic certainty. It is concluded that quantitative electro-oculography is a valuable adjunct to the clinical evaluation of eye movements and has an important role in the investigation of patients suspected of multiple sclerosis.

Adult↗