Postsynaptic mechanism of withdrawal reflex sensitization in the snail

1983 ◽  
Vol 14 (5) ◽  
pp. 365-375 ◽  
Author(s):  
P. M. Balaban
Keyword(s):  
Withdrawal Reflex ◽  
Postsynaptic Mechanism

Reexamination of the gill withdrawal reflex of Aplysia californica cooper (Gastropoda; Opisthobranchia).

1989 ◽  
Vol 103 (3) ◽  
pp. 585-604 ◽  
Author(s):  
Janet L. Leonard ◽  
John Edstrom ◽  
Ken Lukowiak
Keyword(s):  
Aplysia Californica ◽  
Withdrawal Reflex

Cellular analysis of long-term habituation of the gill-withdrawal reflex of Aplysia californica

Science ◽  
1978 ◽  
Vol 202 (4374) ◽  
pp. 1306-1308 ◽  
Author(s):  
V. Castellucci ◽  
T. Carew ◽  
E. Kandel
Keyword(s):  
Aplysia Californica ◽  
Withdrawal Reflex ◽  
Cellular Analysis

Optical recording and analysis of short-term habituation learning of Aplysia gill-withdrawal reflex

1991 ◽  
Vol 16 ◽  
pp. 156
Author(s):  
Michio Nakashima ◽  
Satoshi Yamada ◽  
Satoru Shiono ◽  
Kenji Matsumoto
Keyword(s):  
Optical Recording ◽  
Short Term ◽  
Withdrawal Reflex

Effect of Subarachnoid Bupivacaine Block on Anesthetic Requirements for Thiopental in Rats 

1998 ◽  
Vol 88 (4) ◽  
pp. 1036-1042 ◽  
Author(s):  
Sunil Eappen ◽  
Igor Kissin
Keyword(s):  
Local Anesthetic ◽  
Direct Action ◽  
Afferent Input ◽  
Crossover Design ◽  
Hemodynamic Parameters ◽  
Motor Responses ◽  
Withdrawal Reflex ◽  
Corneal Reflex ◽  
To Receive ◽  
The Brain

Background Subarachnoid bupivacaine blockade has been reported to reduce thiopental and midazolam hypnotic requirements in patients. The purpose of this study was to examine if local anesthetically induced lumbar intrathecal blockade would reduce thiopental requirements for blockade of motor responses to noxious and nonnoxious stimuli in rats. Methods After intrathecal and external jugular catheter placement, rats were assigned randomly to two groups in a crossover design study, with each rat to receive either 10 microl of 0.75% bupivacaine or 10 microl of normal saline intrathecally. The doses of intravenously administered thiopental required to ablate the eyelid reflex, to block the withdrawal reflex of a front limb digit, and to block the corneal reflex were compared. In two separate groups of animals, hemodynamic parameters and concentrations of thiopental in the brain were compared between intrathecally administered bupivacaine and saline. Results The thiopental dose required to block the described responses was decreased with intrathecally administered bupivacaine versus intrathecally administered saline from (mean +/- SD) 40 +/- 5 to 24 +/- 4 mg/kg (P < 0.001) for the eyelid reflex, from 51 +/- 6 to 29 +/- 6 mg/kg (P < 0.005) for front limb withdrawal, and from 67 +/- 8 to 46 +/- 8 mg/kg (P < 0.01) for the corneal reflex. The concentration of thiopental in the brain at the time of corneal reflex blockade for the group given bupivacaine was significantly lower than in the group given saline (24.1 vs. 35.8 microg/g, P = 0.02). Conclusion This study demonstrates that lumbar intrathecally administered local anesthetic blockade decreases anesthetic requirements for thiopental for a spectrum of end points tested. This effect is due neither to altered pharmacokinetics nor to a direct action of the local anesthetic on the brain; rather, it is most likely due to decreased afferent input.

Tempo-spatial integration of nociceptive stimuli assessed via the nociceptive withdrawal reflex in healthy humans.

2021 ◽  
Author(s):  
Mauricio Carlos Henrich ◽  
Ken Steffen Frahm ◽  
Ole K. Andersen
Keyword(s):  
Spinal Cord ◽  
Pain Intensity ◽  
Spatial Information ◽  
Reflex Response ◽  
Spatial Integration ◽  
Opposite Pattern ◽  
Simultaneous Stimulation ◽  
Nociceptive Withdrawal Reflex ◽  
Withdrawal Reflex ◽  
Healthy Humans

Spatial information of nociceptive stimuli applied in the skin of healthy humans is integrated in the spinal cord to determine the appropriate withdrawal reflex response. Double-simultaneous stimulus applied in different skin sites are integrated, eliciting a larger reflex response. The temporal characteristics of the stimuli also modulate the reflex e.g. by temporal summation. The primary aim of this study was to investigate how the combined tempo-spatial aspects of two stimuli are integrated in the nociceptive system. This was investigated by delivering single and double simultaneous stimulation, and sequential stimulation with different inter-stimulus intervals (ISIs ranging 30-500 ms.) to the sole of the foot of fifteen healthy subjects. The primary outcome measure was the size of the nociceptive withdrawal reflex (NWR) recorded from the Tibialis Anterior (TA) and Biceps Femoris (BF) muscles. Pain intensity was measured using an NRS scale. Results showed spatial summation in both TA and BF when delivering simultaneous stimulation. Simultaneous stimulation provoked larger reflexes than sequential stimulation in TA, but not in BF. Larger ISIs elicited significantly larger reflexes in TA, while the opposite pattern occurred in BF. This differential modulation between proximal and distal muscles suggests the presence of spinal circuits eliciting a functional reflex response based on the specific tempo-spatial characteristics of a noxious stimulus. No modulation was observed in pain intensity ratings across ISIs. Absence of modulation in the pain intensity ratings argues for an integrative mechanism located within the spinal cord governed by a need for efficient withdrawal from a potentially harmful stimulus.

The role of interneurons in controlling the tail-withdrawal reflex in Aplysia: a network model

1993 ◽  
Vol 70 (5) ◽  
pp. 1777-1786 ◽  
Author(s):  
J. A. White ◽  
I. Ziv ◽  
L. J. Cleary ◽  
D. A. Baxter ◽  
J. H. Byrne
Keyword(s):  
Synaptic Plasticity ◽  
Sensory Neurons ◽  
Network Model ◽  
Motor Neurons ◽  
Excitatory Postsynaptic Potential ◽  
Layer Model ◽  
Neural Network Models ◽  
Plastic Properties ◽  
Withdrawal Reflex ◽  
Long Duration

1. The contributions of monosynaptic and polysynaptic circuitry to the tail-withdrawal reflex in the marine mollusk Aplysia californica were assessed by the use of physiologically based neural network models. Effects of monosynaptic circuitry were examined by the use of a two-layer network model with four sensory neurons in the input layer and one motor neuron in the output layer. Results of these simulations indicated that the monosynaptic circuit could not account fully for long-duration responses of tail motor neurons elicited by tail stimulation. 2. A three-layer network model was constructed by interposing a layer of two excitatory interneurons between the input and output layers of the two-layer network model. These interneurons had properties mimicking those of the recently described interneuron LP117, receiving excitatory input from pleural sensory neurons and evoking a biphasic excitatory postsynaptic potential (EPSP) in pedal motor neurons (Cleary and Byrne 1993). The three-layer model could account for long-duration responses in motor neurons. 3. Sensory neurons are a known site of plasticity in Aplysia. Synaptic plasticity was incorporated into the three-layer model by altering the magnitudes of conductance changes evoked in motor neurons and interneurons by presynaptic sensory neurons. In these simulations the excitatory interneurons converted an amplitude-coded input into an amplitude- and duration-coded output, allowing the three-layer network to support a large range of output amplitudes and durations. 4. Synaptic plasticity at more than one locus modified dramatically the input-output relationship of the three-layer network model. This feature gave the model redundancy in its plastic properties and points to the possibility of distributed memory in the circuitry mediating withdrawal reflexes in Aplysia. Multiple sites of control over the response of the network would likely allow a more diverse repertoire of responses.

The effects of focal stimulation in nucleus raphe magnus and periaqueductal gray on intracellularly recorded neurons in spinal laminae I and II

1986 ◽  
Vol 56 (3) ◽  
pp. 555-571 ◽  
Author(s):  
A. R. Light ◽  
E. J. Casale ◽  
D. M. Menetrey
Keyword(s):  
Brain Stem ◽  
Periaqueductal Gray ◽  
The Other ◽  
Descending Pathways ◽  
Nucleus Raphe Magnus ◽  
Raphe Magnus ◽  
Low Threshold ◽  
Conductance Increase ◽  
Small Conductance ◽  
Postsynaptic Mechanism

Single neurons in spinal laminae I and II of cats were recorded intracellularly while stimulating in nucleus raphe magnus (NRM) and periaqueductal gray (PAG) with monopolar tungsten microelectrodes. Brain stem stimulation inhibited about one-half of the nociceptive-specific neurons, whereas the other half was unaffected. Brain stem stimulation inhibited about one-half of the multireceptive neurons, but the other half was excited and then inhibited. Brain stem stimulation inhibited about one-third of the low-threshold neurons, one-half was excited then inhibited, and one-fifth showed no effect. In all classes of neurons, the inhibition was produced by an inhibitory postsynaptic potential (IPSP) that began with a latency of approximately 25 ms and lasted approximately 400 ms following a single stimulus. The IPSP occurred with a small conductance increase and was reversed by hyperpolarizing currents applied to the cell. These data indicate that NRM and PAG modulated laminae I and II neurons via a postsynaptic mechanism. The conduction velocity of this descending pathway was calculated to range from 6.1 to 66.6 m/s with an average of 13.8 m/s. These data also indicate heterogeneity in the pathway, since some neurons were inhibited, whereas other neurons were excited then inhibited by descending stimulation. Finally, these data indicate specificity in these descending pathways since nearly one-half of neurons that had low-threshold inputs were excited by brain stem stimulation, whereas nearly all nociceptive-specific neurons were either inhibited or unaffected.

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