A sensory map based on velocity threshold of sensory neurones from a chordotonal organ in the tailfan of the crayfish

1993 ◽  
Vol 172 (1) ◽  
pp. 7-15 ◽  
Author(s):  
T. Nagayama ◽  
P.L. Newland
Keyword(s):  
Chordotonal Organ ◽  
Sensory Neurones ◽  
Velocity Threshold ◽  
Sensory Map

Octopamine modulates the responses and presynaptic inhibition of proprioceptive sensory neurones in the locust Schistocerca gregaria

1997 ◽  
Vol 200 (9) ◽  
pp. 1317-1325 ◽  
Author(s):  
T Matheson
Keyword(s):  
Presynaptic Inhibition ◽  
Schistocerca Gregaria ◽  
Chordotonal Organ ◽  
Mechanical Stimuli ◽  
Sensory Neurone ◽  
Tonic Component ◽  
Sensory Neurones ◽  
Phasic Component ◽  
Bath Application ◽  
Motor Neurones

A multineuronal proprioceptor, the femoral chordotonal organ (feCO), monitors the position and movements of the tibia of an insect leg. Superfusing the locust metathoracic feCO with the neuromodulator octopamine, or the octopamine agonist synephrine, affects the position (tonic) component of the organ's response, but not the movement (phasic) component. Both octopamine and synephrine act with the same threshold (10(-6) mol l-1). Individual sensory neurones that respond tonically at flexed tibial angles show increased tonic spike activity following application of octopamine, but those that respond at extended angles do not. Tonic spiking of phaso-tonic flexion-sensitive neurones is enhanced but their phasic spiking is unaffected. Bath application of octopamine to the feCO increases the tonic component of presynaptic inhibition recorded in the sensory terminals, but not the phasic component. This inhibition should at least partially counteract the increased sensory spiking and reduce its effect on postsynaptic targets such as motor neurones. Furthermore, some phasic sensory neurones whose spiking is not affected by octopamine nevertheless show enhanced tonic synaptic inputs. The chordotonal organ is not known to be under direct efferent control, but its output is modified by octopamine acting on its sensory neurones to alter their responsiveness to mechanical stimuli and by presynaptic inhibition acting on their central branches. The effects of this neuromodulator acting peripherally on sensory neurones are therefore further complicated by indirect interactions between the sensory neurones within the central nervous system. Increases of sensory neurone spiking caused by neuromodulators may not necessarily lead to parallel increases in the responses of postsynaptic target neurones.

scholarly journals THE PHYSIOLOGY OF SENSORY CELLS IN THE VENTRAL SCOLOPARIUM OF THE STICK INSECT FEMORAL CHORDOTONAL ORGAN

1994 ◽  
Vol 189 (1) ◽  
pp. 285-292 ◽  
Author(s):  
A Büschges
Keyword(s):  
Sensory Feedback ◽  
Neural Control ◽  
Sensory Information ◽  
Stick Insect ◽  
Sensory Cells ◽  
Chordotonal Organ ◽  
Joint Movement ◽  
Control Loop ◽  
Sensory Neurones ◽  
Control Loops

The leg joints of invertebrates are governed by neural control loops that control their position and velocity during movements (for reviews, see Bassler, 1983, 1993). These neural control loops rely on sensory feedback about the position and velocity of the controlled leg joint. In invertebrates, this sensory feedback is provided by external (e.g. hair fields, hair rows) and/or internal sense organs (e.g. chordotonal organs). The femoral chordotonal organ (fCO) serves as the main proprioceptor in the control loop governing the femur-tibia (FT) joint of the insect leg. The fCO measures the position and movement of this joint (e.g. Bassler, 1965, 1993; Burns, 1974; Usherwood et al. 1968; Zill, 1985). Previous investigations have described the physiology of sensory cells within femoral chordotonal organs (e.g. stick insect, Hofmann et al. 1985; Hofmann and Koch, 1985; locust, Matheson, 1990; Matheson and Field, 1990). Numerous investigations have been undertaken into the central processing of sensory information provided by the fCO to gain an insight into the control of FT joint movement during different behavioural tasks, for example during resistance reflexes in the standing animal (locust, Burrows, 1987, 1988; Burrows et al. 1988; stick insect, Bassler, 1988; Buschges, 1989, 1990; Driesang and Buschges, 1993) or during active movements (stick insect, Bassler, 1988; Bassler and Buschges, 1990). Most previous studies have not, however, taken into account the morphological separation of the fCO into two distinct scoloparia in the legs of some species (stick insect, Fuller and Ernst, 1973; Hofmann et al. 1985; Hofmann and Koch, 1985; locust middle leg, Burns, 1974). It has been inferred that the whole fCO supplies position and velocity information about the FT joint. In contrast, recent studies of leg reflexes have shown that only its smaller scoloparium (Fig. 1A), containing approximately one-sixth of the total number of sensory neurones, provides the sensory information that is used by the FT control loop (locust, Field and Pfluger, 1989; stick insect, Kittmann and Schmitz, 1992). These studies did not show what types of sensory neurones are located in the ventral part of the fCO and thus contribute to the FT control loop. We have therefore investigated the physiology of sensory neurones that are located in the ventral scoloparium of the fCO.

scholarly journals Prediction of One Repetition Maximum Using Reference Minimum Velocity Threshold Values in Young and Middle-Aged Resistance-Trained Males

2021 ◽  
Vol 11 (5) ◽  
pp. 71
Author(s):  
John F. T. Fernandes ◽  
Amelia F. Dingley ◽  
Amador Garcia-Ramos ◽  
Alejandro Perez-Castilla ◽  
James J. Tufano ◽  
...  
Keyword(s):  
Bench Press ◽  
Absolute Error ◽  
Young Group ◽  
Middle Aged ◽  
Repetition Maximum ◽  
Back Squat ◽  
Velocity Threshold ◽  
Low Load ◽  
The Absolute ◽  
Minimum Velocity

Background: This study determined the accuracy of different velocity-based methods when predicting one-repetition maximum (1RM) in young and middle-aged resistance-trained males. Methods: Two days after maximal strength testing, 20 young (age 21.0 ± 1.6 years) and 20 middle-aged (age 42.6 ± 6.7 years) resistance-trained males completed three repetitions of bench press, back squat, and bent-over-row at loads corresponding to 20–80% 1RM. Using reference minimum velocity threshold (MVT) values, the 1RM was estimated from the load-velocity relationships through multiple (20, 30, 40, 50, 60, 70, and 80% 1RM), two-point (20 and 80% 1RM), high-load (60 and 80% 1RM) and low-load (20 and 40% 1RM) methods for each group. Results: Despite most prediction methods demonstrating acceptable correlations (r = 0.55 to 0.96), the absolute errors for young and middle-aged groups were generally moderate to high for bench press (absolute errors = 8.2 to 14.2% and 8.6 to 20.4%, respectively) and bent-over-row (absolute error = 14.9 to 19.9% and 8.6 to 18.2%, respectively). For squats, the absolute errors were lower in the young group (5.7 to 13.4%) than the middle-aged group (13.2 to 17.0%) but still unacceptable. Conclusion: These findings suggest that reference MVTs cannot accurately predict the 1RM in these populations. Therefore, practitioners need to directly assess 1RM.

scholarly journals Modulation of Ca2+-dependent currents in metabolically stressed cultured sensory neurones by intracellular photorelease of ATP

1995 ◽  
Vol 114 (2) ◽  
pp. 544-550 ◽  
Author(s):  
S.R. Stapleton ◽  
B.A. Bell ◽  
J.F. Wootton ◽  
R.H. Scott
Keyword(s):  
Sensory Neurones

scholarly journals A New Critical Period for Sensory Map Plasticity

Neuron ◽  
2001 ◽  
Vol 31 (2) ◽  
pp. 171-173 ◽  
Author(s):  
Daniel E Feldman
Keyword(s):  
Critical Period ◽  
Sensory Map
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