The Functional Morphology and Motor Innervation of the Buccal Mass of Tritonia Hombergi

1979 ◽  
Vol 79 (1) ◽  
pp. 7-22
Author(s):  
A.G. M. BULLOCH ◽  
D. A. DORSETT
Keyword(s):  
Muscle Activity ◽  
Posterior Border ◽  
Motor Innervation ◽  
Fourth Group ◽  
Buccal Mass ◽  
Buccal Ganglia ◽  
Feeding Cycle ◽  
F Cells ◽  
Sequential Activation ◽  
Muscle Groups

The anatomy of the buccal mass and the function of nine principal muscle groups involved in the feeding movements, are described for the mollusc Tritonia hombergi. Anatomical and physiological studies on some 40 neurones along the posterior border of the buccal ganglia indicates that many are primary motoneurones to the muscles of the buccal mass. The feeding cycle may be divided into three phases of muscle activity termed Protraction, Retraction and Flattening, which are correlated with the patterned bursting observed in P, R and F motoneurone groups within the motoneurone population. A fourth group of motoneurones are thought to innervate muscles to the outer lips which are active during protraction. The patterned output of impulses in the buccal nerves during feeding cycles confirms that the motor control of the muscle groups may be explained in terms of the sequential activation of the P, R and F cells.

The Integration of the Patterned Output of Buccal Motoneurones During Feeding in Tritonia Hombergi

1979 ◽  
Vol 79 (1) ◽  
pp. 23-40
Author(s):  
A.G. M. BULLOCH ◽  
D. A. DORSETT
Keyword(s):  
Feeding Activity ◽  
Electrical Coupling ◽  
Cell Activity ◽  
Giant Cells ◽  
Posterior Border ◽  
Buccal Ganglion ◽  
Synaptic Inputs ◽  
Proprioceptive Input ◽  
Buccal Ganglia ◽  
Feeding Cycle

Three phases of activity may be recognized in the buccal mass of Tritonia hombergi during the feeding cycle. These have been termed Protraction, Retraction and Flattening. Each phase is driven by a group of motoneurones along the posterior border of the buccal ganglia. The patterned bursting observed in the motoneurone groups during feeding activity is phased by synaptic inputs which are common to two or more groups. Evidence is presented which indicates these inputs are derived from three unidentified multi-action interneurone sources within each buccal ganglion, and whose action primarily determines the patterned output of the motoneurones. Electrical coupling between between synergistic motoneurones and, in one case, post-inhibitory rebound, contribute to the synchronization of group activity. Proprioceptive input to the motoneurones was not identified, but may project to the interneurones. Some small neurones having synaptic inputs on the motoneurones appropriate to two of the interneurones were found, but require confirmation in this role. The cerebral giant cells synapse on representatives of three motoneurone groups, and also activate the buccal interneurones driving the feeding cycle. The patterned activity of the motoneurones can occur in the absence of cerebral cell activity.

The Morphology and Physiological Properties of the Small White Neurones in the Buccal Ganglia of Tritonia Hombergi

1986 ◽  
Vol 122 (1) ◽  
pp. 237-256
Author(s):  
D. A. DORSETT
Keyword(s):  
Phase I ◽  
Feeding Activity ◽  
The Other ◽  
Inhibitory Input ◽  
Cyclic Activity ◽  
Buccal Ganglia ◽  
Physiological Properties ◽  
Feeding Cycle ◽  
F Cells ◽  
P Cells

The two small white (W) cells in the buccal ganglia of Tritonia hombergi can initiate and modulate cyclic activity in the pattern generating neurones which drive feeding activity in the buccal mass. They also make extensive monosynaptic connections with the buccal motoneurones, generating EPSPs on protractor (P) cells, IPSPs on retractor (R) cells, and EIPSPs on the small radula flattener (F) cells. Two F motoneurones receive a chemically mediated, facilitating EPSP from the W cells. Inactive W cells receive weak excitatory feedback from the pattern generating network interneurones (FPG) in phase I of the feeding cycle and also from some F cells. Prolonged depolarization of one W cell recruits the other. When both are active they adopt a patterned burst mode with a common inhibitory input in phase I.

Sequential Activation of Muscle Synergies During Locomotion in the Intact Cat as Revealed by Cluster Analysis and Direct Decomposition

2006 ◽  
Vol 96 (4) ◽  
pp. 1991-2010 ◽  
Author(s):  
Nedialko Krouchev ◽  
John F. Kalaska ◽  
Trevor Drew
Keyword(s):  
Cluster Analysis ◽  
Muscle Activity ◽  
Decomposition Methods ◽  
Electromyographic Activity ◽  
Flexible Control ◽  
Co Activation ◽  
Spinal Interneuron ◽  
Sequential Activation ◽  
Synergistic Muscles ◽  
Muscle Groups

During goal-directed locomotion, descending signals from supraspinal structures act through spinal interneuron pathways to effect modifications of muscle activity that are appropriate to the task requirements. Recent studies using decomposition methods suggest that this control might be facilitated by activating synergies organized at the level of the spinal cord. However, it is difficult to directly relate these mathematically defined synergies to the patterns of electromyographic activity observed in the original recordings. To address this issue, we have used a novel cluster analysis to make a detailed study of the organization of the synergistic patterns of muscle activity observed in the fore- and hindlimb during treadmill locomotion. The results show that the activity of a large number of forelimb muscles (26 bursts of activity from 18 muscles) can be grouped into 11 clusters on the basis of synchronous co-activation. Nine (9/11) of these clusters defined muscle activity during the swing phase of locomotion; these clusters were distributed in a sequential manner and were related to discrete behavioral events. A comparison with the synergies identified by linear decomposition methods showed some striking similarities between the synergies identified by the different methods. In the hindlimb, a simpler organization was observed, and a sequential activation of muscles similar to that observed in the forelimb during swing was less clear. We suggest that this organization of synergistic muscles provides a means by which descending signals could provide the detailed control of different muscle groups that is necessary for the flexible control of multi-articular movements.

Myoelectric Activity Differences in Three Learning Sessions

2002 ◽  
Vol 16 (2) ◽  
pp. 92-96
Author(s):  
Tiina Ritvanen ◽  
Reijo Koskelo ◽  
Osmo H„nninen
Keyword(s):  
High School Students ◽  
Muscle Activity ◽  
Muscle Tension ◽  
Emg Activity ◽  
Traditional Learning ◽  
Myoelectric Activity ◽  
School Students ◽  
Language Laboratory ◽  
Upper Trapezius ◽  
Muscle Groups

Abstract This study follows muscle activity in three different learning sessions (computer, language laboratory, and normal classroom) while students were studying foreign languages. Myoelectric activity was measured in 21 high school students (10 girls, 11 boys, age range 17-20 years) by surface electromyography (sEMG) from the upper trapezius and frontalis muscles during three 45-min sessions. Root mean square (RMS) average from both investigated muscles was calculated. The EMG activity was highest in both muscle groups in the computer-aided session and lowest in the language laboratory. The girls had higher EMG activity in both investigated muscle groups in all three learning situations. The measured blood pressure was highest at the beginning of the sessions, decreased within 10 min, but increased again toward the end of the sessions. Our results indicate that the use of a computer as a teaching-aid evokes more constant muscle activity than the traditional learning situations. Since muscle tension can have adverse health consequences, more research is needed to determine optimal classroom conditions, especially when technical aids are used in teaching.

Simulate and sense force exertions during virtual patient transfer tasks

2020 ◽  
Vol 64 (1) ◽  
pp. 2092-2096
Author(s):  
Ken Chen ◽  
Rebecca Widmayer ◽  
Karen B. Chen
Keyword(s):  
Muscle Activity ◽  
Fine Tuning ◽  
Activity Levels ◽  
Patient Lifting ◽  
Perceived Workload ◽  
Specific Muscle ◽  
Muscle Groups ◽  
Forceful Exertion ◽  
Lifting Task ◽  
Transfer Tasks

Virtual reality (VR) is commonplace for training, yet simulated physical activities in VR do not require trainees to engage and contract the muscle groups normally engaged in physical lifting. This paper presents a muscle activity-driven interface to elicit the sensation of forceful, physical exertions when lifting virtual objects. Users contracted and attained predefined muscle activity levels that were calibrated to user-specific muscle activity when lifting the physical counterpart. The overarching goal is to engage the appropriate muscles, and thereby encourage and elicit behaviors normally seen in the physical environment. Activities of 12 key muscles were monitored using electromyography (EMG) sensors while they performed a three-part patient lifting task in a Cave Automatic Virtual Environment. Participants reported higher task mental loads and less physical loads for the virtual lift than the physical lift. Findings suggest the potential to elicit sensation of forceful exertion via EMG feedback but needed fine-tuning to offset perceived workload.

Upper extremity muscle activity during household floor vacuuming with upright cleaners

2018 ◽  
Vol 62 (1) ◽  
pp. 1018-1021
Author(s):  
Haerim Bak ◽  
Clive D’Souza ◽  
Gwanseob Shin
Keyword(s):  
Upper Extremity ◽  
Muscle Activity ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Activity Levels ◽  
Physical Demands ◽  
Study Results ◽  
Musculoskeletal Problems ◽  
Muscle Groups ◽  
Intensive Work

Physical demands of household carpet vacuuming and associated risks for musculoskeletal problems have received little attention although the level of muscle exertions is often assumed to be similar to that of occupational vacuuming. The aim of this study was to quantitatively assess the level of muscle activities of the upper extremity during carpeted floor vacuuming with household upright vacuum cleaners. Eighteen participants conducted four different carpet vacuuming tasks with two different cleaner models. Electromyography data from seven upper extremity muscles were collected. Median muscle activity ranged from 4.5% to 47.5% of the maximum voluntary contraction capacity for female participants and from 2.7% to 23.6% for male participants. Normalized muscle activity levels were significantly higher in women compared to men across tasks and muscle groups. Study results suggest that home vacuuming with upright vacuum cleaners is physically intensive work, especially for female users who are less physically capable.

Motor patterns of labriform locomotion: kinematic and electromyographic analysis of pectoral fin swimming in the labrid fish Gomphosus varius

1997 ◽  
Vol 200 (13) ◽  
pp. 1881-1893 ◽  
Author(s):  
M Westneat ◽  
J Walker
Keyword(s):  
Muscle Activity ◽  
Motor Pattern ◽  
Onset Time ◽  
Total Body Length ◽  
Adductor Muscle ◽  
Pectoral Fin ◽  
Motor Patterns ◽  
Emg Patterns ◽  
Muscle Groups ◽  
Electromyographic Analysis

Labriform locomotion is a widespread swimming mechanism in fishes during which propulsive forces are generated by oscillating the pectoral fins. We examined the activity of the six major muscles that power the pectoral fin of the bird wrasse Gomphosus varius (Labridae: Perciformes). The muscles studied included the fin abductors (arrector ventralis, abductor superficialis and abductor profundus) and the fin adductors (arrector dorsalis, adductor superficialis and adductor profundus). Our goals were to determine the pattern of muscle activity that drives the fins in abduction and adduction cycles during pectoral fin locomotion, to examine changes in the timing and amplitude of electromyographic (EMG) patterns with increases in swimming speed and to correlate EMG patterns with the kinematics of pectoral fin propulsion. EMG data were recorded from three individuals over a range of swimming speeds from 15 to 70 cm s-1 (1­4.8 TL s-1, where TL is total body length). The basic motor pattern of pectoral propulsion is alternating activity of the antagonist abductor and adductor groups. The downstroke is characterized by activity of the arrector ventralis muscle before the other abductors, whereas the upstroke involves nearly synchronous activity of the three adductors. Most EMG variables (duration, onset time, amplitude and integrated area) showed significant correlations with swimming speeds. However, the timing and duration of muscle activity are relatively constant across speeds when expressed as a fraction of the stride period, which decreases with increased velocity. Synchronous recordings of kinematic data (maximal abduction and adduction) with EMG data revealed that activity in the abductors began after maximal adduction and that activity in the adductors began nearly synchronously with maximal abduction. Thus, the pectoral fin mechanism of G. varius is activated by positive work from both abductor and adductor muscle groups over most of the range of swimming speeds. The adductors produce some negative work only at the highest swimming velocities. We combine information from pectoral fin morphology, swimming kinematics and motor patterns to interpret the musculoskeletal mechanism of pectoral propulsion in labrid fishes.

Synaptic Actions of Oesophageal Proprioceptors in the Mollusc, Philine

1981 ◽  
Vol 94 (1) ◽  
pp. 95-104
Author(s):  
J. N. SIGGER ◽  
D. A. DORSETT
Keyword(s):  
Receptive Fields ◽  
Large Cell ◽  
The Other ◽  
Small Cells ◽  
Sensory Cells ◽  
Periodic Activity ◽  
Buccal Ganglia ◽  
Excitatory Synaptic Input ◽  
Feeding Cycle ◽  
Protraction Phase

The buccal ganglia of Philine each contain a group of mechanoreceptors, consisting of 1 large and 3 small cells, with receptive fields in the oesophagus. Synaptic contacts occur between the receptors; the large cell providing an EIPSP input to its contralateral partner and to the two groups of smaller receptors. The small receptors make weak excitatory contacts with both the large receptors. The sensory cells synapse with other buccal motoneurones and interneurones, some of which show periodic activity associated with the feeding movements. Protraction phase neurones are divisible into two groups, one of which receives EPSPs from the receptors, while the other group receives IPSPs. Retraction phase neurones receive a biphasic EIPSP. The receptors provide excitatory synaptic input to a pair of interneurones which ‘gate’ the feeding cycle. A third class of neurones which are not rhythmically active during feeding receive a predominantly inhibitory EIPSP.

Control of extrinsic feeding muscles in Aplysia

1983 ◽  
Vol 49 (6) ◽  
pp. 1481-1503 ◽  
Author(s):  
B. Jahan-Parwar ◽  
S. M. Fredman
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Synaptic Input ◽  
Cerebral Ganglion ◽  
Cyclic Activity ◽  
Buccal Mass ◽  
Buccal Ganglia ◽  
Identified Neuron ◽  
Single Oscillator ◽  
Extrinsic Muscles

The extrinsic buccal muscles in Aplysia are responsible for the overall protraction and retraction of the buccal mass during feeding. The six pairs of extrinsic muscles are organized into two groups, consisting of three protractors and three retractors. Insights into how the extrinsic muscles are controlled were obtained by examining the organization of the motor neurons that innervated them. The extrinsic buccal muscles are innervated by cerebral ganglion nerves and neurons. All the muscles examined appear to be multiply innervated. Identified neurons in the cerebral B, E, and G clusters were found to be motor neurons for individual extrinsic muscles. Some extrinsic muscles had both excitatory and inhibitory innervation. Two synergistic muscles, the extrinsic ventrolateral protractor (ExVLP) and the extrinsic dorsal protractor (ExDP), had common excitatory innervation by identified neuron E5. Two antagonistic muscles, the ExVLP and the extrinsic ventral retractor (ExVR), also had common innervation. Identified neuron E1 appeared to be an inhibitory motor neuron for the ExVLP but an excitatory motor neuron for the ExVR. Common innervation provides a simple mechanism for coordinating synergistic and antagonistic extrinsic muscles. On the basis of these data, a model for the control of buccal mass protraction and retraction is proposed. Bursting by extrinsic buccal muscles was coordinated with cyclic activity in the intrinsic muscles of the buccal mass. Antagonistic extrinsic muscles burst antiphasically and synergistic extrinsic muscles burst in phase when the buccal mass was fully protracted and exhibited a series of rhythmic contractions. Additionally, cerebral E cluster neurons burst in phase with stereotyped rhythmic buccal motor neuron discharges recorded from buccal nerves. The cerebral E cluster motor neurons were coordinated by common synaptic input. No monosynaptic connections were observed; homologous neurons in each E cluster received synaptic input with similar but not identical timing, indicating that the interneurons that coordinate the homologous motor neurons are synchronized. The source of the rhythm that drives synaptically mediated cerebral extrinsic muscle motor neuron bursting was in the buccal ganglia. Cutting one cerebral-buccal connective eliminated E neuron bursting on that side but had no effect on homologous neurons on the intact side. This suggests that a single oscillator in the buccal ganglia may coordinate both the extrinsic and intrinsic buccal muscles during feeding.

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