Quantal Organization of Reflex and Conditioned Eyelid Responses

1997 ◽  
Vol 78 (5) ◽  
pp. 2518-2530 ◽  
Author(s):  
José A. Domingo ◽  
Agnes Gruart ◽  
José M. Delgado-García
Keyword(s):  
Conditioned Stimulus ◽  
Unconditioned Stimulus ◽  
Conditioned Response ◽  
Total Duration ◽  
Maximum Amplitude ◽  
Dominant Frequency ◽  
Time Interval ◽  
Electromyographic Activity ◽  
Conditioned Eyelid ◽  
Reflex Blinks

Domingo, José A., Agnes Gruart, and José M. Delgado-Garcı́a. Quantal organization of reflex and conditioned eyelid responses. J. Neurophysiol. 78: 2518–2530, 1997. Upper lid movements and the electromyographic activity of the orbicularis oculi muscle were recorded in behaving cats during spontaneous and experimentally evoked reflex blinks, and conditioned eyelid responses. Reflex blinks evoked by the presentation of air puffs, flashes, or tones consisted of a fast downward lid movement followed by late, small downward waves, recurring at ≈50-ms intervals. The latency, maximum amplitude, peak velocity, and number of late waves depended on the modality, intensity, and duration of the evoking stimulus. The power spectra of acceleration records indicated a dominant frequency of ≈20 Hz for air puff–evoked blinks. Flashes and tones usually evoked small and easily fatigable reflex responses of lower dominant frequencies (14–17 and 9–11 Hz, respectively). A basic ≈20-Hz oscillation was also noticed during lid fixation, and ramplike lid displacements evoked by optokinetic stimuli. Five classical conditioning paradigms were used to analyze the frequency-domain properties of conditioned eyelid responses. These learned lid movements differed in latency, maximum amplitude, and profile smoothness depending on the modality (air puff, tone), intensity (weak, strong), and presentation site (ipsi-, contralateral to the unconditioned stimulus) of the conditioned stimulus. It was found that the characteristic ramplike profile of a conditioned response was not smooth, but appeared to be formed by a succession of small waves at a dominant frequency of ≈20 Hz. The amplitude (and number) of the constituting waves depended on the characteristics of the conditioned stimulus and on the time interval until unconditioned stimulus presentation. Thus conditioned responses seemed to be formed from lid displacements of 2–6° in amplitude and ≈50 ms in duration, which increased in number throughout conditioning sessions, until a complete (i.e., lid closing) conditioned response was reached. It is suggested that a ≈20-Hz oscillator underlies the generation of reflex and conditioned eyelid responses. The oscillator is susceptible to being neurally modulated to modify the velocity of a given quantum of movement, and the total duration of the lid response. Learned eyelid movements are probably the result of a successively longer release of the oscillator as a function of the temporal-spatial needs of the motor response.

Effects of Pentobarbital and Isoflurane on Conditioned Learning after Transient Global Cerebral Ischemia in Rabbits

2000 ◽  
Vol 92 (1) ◽  
pp. 171-171 ◽  
Author(s):  
Jae Young Kwon ◽  
Andreas Bacher ◽  
Donald J. Deyo ◽  
John F. Disterhoft ◽  
Tatsuo Uchida ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Conditioned Stimulus ◽  
Unconditioned Stimulus ◽  
Conditioned Response ◽  
Global Cerebral Ischemia ◽  
Eyeblink Response ◽  
Trace Interval ◽  
Transient Global Cerebral Ischemia ◽  
Isoflurane Group ◽  
Conditioned Responses

Background The acquisition of a conditioned eyeblink response has been used extensively to study the neurologic substrates of learning and memory. We examined the effects of the anesthetics isoflurane and pentobarbital, or hypothermia (30 degrees C), on the ability of rabbits to acquire an eyeblink conditioned response after 6.5 min of cerebral ischemia. Methods New Zealand white rabbits (n = 48) were randomly assigned to sham, normothermic, hypothermic, isoflurane, or pentobarbital groups. In the normothermic, hypothermic, isoflurane, and pentobarbital groups, 6.5 min of global cerebral ischemia was produced. In animals randomized to the isoflurane and pentobarbital groups, a pattern of burst suppression was achieved on the electroencephalogram before the start of the ischemic episode. Animals in the hypothermia group were cooled to 30 degrees C before ischemia. Seven days after ischemia, eyeblink training was started using an audible tone presented for 100 ms as the conditioned stimulus. The unconditioned stimulus was an air puff directed at the cornea. The delay between the end of conditioned stimulus and the start of the unconditioned stimulus (the trace interval) was 300 ms in duration. A conditioned response was defined as an eyeblink that was initiated during the trace interval. Eighty trials per day and 15 days of training were delivered. Results Neurologic deficits were greatest in the normothermia group, and these animals also had fewer conditioned responses than those in the sham, hypothermia, or pentobarbital groups. Animals in the isoflurane group had an intermediate number of conditioned responses that was not significantly different from the normothermia group. Conclusions This study demonstrates that a brief episode of cerebral ischemia results in the impairment of associative learning. Hypothermia and burst-suppressive doses of pentobarbital were able to improve neurobehavioral outcome as measured by ability to acquire a trace conditioned response.

Kinetic and Frequency-Domain Properties of Reflex and Conditioned Eyelid Responses in the Rabbit

2000 ◽  
Vol 83 (2) ◽  
pp. 836-852 ◽  
Author(s):  
Agnès Gruart ◽  
Bernard G. Schreurs ◽  
Eduardo Domínguez del Toro ◽  
JoséMaría Delgado-García
Keyword(s):  
Power Spectrum ◽  
Peak Velocity ◽  
Maximum Amplitude ◽  
Reflex Response ◽  
Neural Oscillator ◽  
Electromyographic Activity ◽  
Onset Latency ◽  
Stimulus Interval ◽  
Time To Peak ◽  
Reflex Blinks

Eyelid position and the electromyographic activity of the orbicularis oculi muscle were recorded unilaterally in rabbits during reflex and conditioned blinks. Air-puff–evoked blinks consisted of a fast downward phase followed sometimes by successive downward sags. The reopening phase had a much longer duration and slower peak velocity. Onset latency, maximum amplitude, peak velocity, and rise time of reflex blinks depended on the intensity and duration of the air puff–evoking stimulus. A flashlight focused on the eye also evoked reflex blinks, but not flashes of light, or tones. Both delayed and trace classical conditioning paradigms were used. For delayed conditioning, animals were presented with a 350-ms, 90-dB, 600-Hz tone, as conditioned stimulus (CS). For trace conditioning, animals were presented with a 10-ms, 1-k/cm2 air puff, as CS. The unconditioned stimulus (US) consisted of a 100-ms, 3-k/cm2 air puff. The stimulus interval between CS and US onsets was 250 ms. Conditioned responses (CRs) to tones were composed of downward sags that increased in number through the successive conditioning sessions. The onset latency of the CR decreased across conditioning at the same time as its maximum amplitude and its peak velocity increased, but the time-to-peak of the CR remained unaltered. The topography of CRs evoked by short, weak air puffs as the CS showed three different components: the alpha response to the CS, the CR, and the reflex response to the US. Through conditioning, CRs showed a decrease in onset latency, and an increase in maximum amplitude and peak velocity. The time-to-peak of the CR remained unchanged. A power spectrum analysis of reflex and conditioned blink acceleration profiles showed a significant ≈8-Hz oscillation within a broadband of frequencies between 4 and 15 Hz. Nose and mandible movements presented power spectrum profiles different from those characterizing reflex and conditioned blinks. It is concluded that eyelid reflex responses in the rabbit present significant differences from CRs in their profiles and metric properties, suggesting different neural origins, but that a common ≈8-Hz neural oscillator underlies lid motor performance. According to available data, the frequency of this putative oscillator seems to be related to the species size.

scholarly journals Time, Trials, and Extinction

2020 ◽  
Author(s):  
Justin Harris ◽  
Benjamin Andrew
Keyword(s):  
Conditioned Stimulus ◽  
Unconditioned Stimulus ◽  
Pavlovian Conditioning ◽  
Total Duration

Four experiments investigated the effect of number of trials and total duration of non-reinforced exposure to the conditioned stimulus (CS) on extinction of Pavlovian conditioning. Rats were first trained in a magazine approach paradigm with multiple CSs, each paired with the unconditioned stimulus (US) on a variable CS-US interval. During subsequent extinction, CSs would differ in the number and length of their extinction trials but would be matched for the total duration of exposure (e.g., one CS would have 20 trials per session with a mean length of 5 s, another CS would have 5 trials per session with a mean length of 20 s). In each case, extinction proceeded more quickly for the CS given more trials per session. Indeed, there was no difference in rate of extinction between CSs that were matched on number of trials but differed on the duration of each trial, indicating that duration of exposure has no effect on extinction. We discuss the implications of these findings for trial-based and time-based theories of conditioning.

EEG-correlates of work efficiency level among young persons with stress-induced bruxism

2021 ◽  
pp. 25-29
Author(s):  
A. E. Barulin ◽  
S. V. Klauchek ◽  
A. E. Klauchek
Keyword(s):  
Regression Models ◽  
Alpha Rhythm ◽  
Negative Relationship ◽  
Maximum Amplitude ◽  
Dominant Frequency ◽  
Regression Equations ◽  
Microsoft Excel ◽  
The Subject ◽  
Males And Females ◽  
The Relationship

Purpose of the study. To establish the relationship between neurophysiological status and the level of efficiency in young people with bruxism.Materials and methods. Two groups of 64 and 53 subjects (males and females) aged 20–35 years old with bruxism and non-bruxers were formed according to questionnaire results and physical examination. The level of efficiency was assessed by the results of sensorimotor tracking of a moving object (the ‘Smile’ model). Spectral analysis was performed for evaluation of the baseline electroencephalograms. Microsoft Excel and Statistica 10.0 programs were used for statistical data processing.Results. The level of efficiency was statistically significantly lower in the hardest test of Smile model among the individuals with bruxism (p < 0.05). The bruxers also demonstrated a significantly lower dominant frequency and maximum amplitude of alpha-rhythm (p < 0.05), and significantly higher dominant frequency of beta2 rhythm (p < 0.05). The dominant frequency and the maximum amplitude of the alpha-rhythm are parameters corresponding to significant coefficients of the regression analysis. A negative relationship was found between the degree of error during sensorimotor tracking and the frequency and amplitude of alpha-rhythm.Conclusion. Regression models present the relationship between the level of efficiency and the alpha-rhythm severity. The regression equations make it possible to determine the functional state of the subject using an electroencephalogram.

Selective serotonin reuptake inhibition increases noise burst-induced unconditioned and context-conditioned freezing

2018 ◽  
Vol 31 (1) ◽  
pp. 46-51
Author(s):  
S. Melker Hagsäter ◽  
Johan Thorén ◽  
Robert Pettersson ◽  
Elias Eriksson
Keyword(s):  
Unconditioned Stimulus ◽  
Serotonin Reuptake ◽  
Conditioned Response ◽  
Selective Serotonin Reuptake Inhibitors ◽  
Conditioned Fear ◽  
Noise Burst ◽  
Selective Serotonin ◽  
Unconditioned Response ◽  
Acute Administration ◽  
Sprague Dawley

AbstractObjectiveWhereas long-term administration of selective serotonin reuptake inhibitors (SSRIs) is effective for the treatment of anxiety disorders, acute administration of these drugs may exert a paradoxical anxiogenic effect. The aim of the present study was to explore the possible effect of an SSRI in situations of unconditioned or limited conditioned fear.MethodsMale Sprague Dawley rats were administered a single dose of an SSRI, escitalopram, before acquisition or expression of context conditioned fear, where noise bursts were used as the unconditioned stimulus. Freezing was assessed as a measure of unconditioned fear (=the acute response to noise bursts) or conditioned fear (=the response to the context), respectively.ResultsNoise bursts elicited an acute increase in freezing but no robust conditioned response 7 days after exposure. Administration of escitalopram before testing exacerbated the freezing response during presentation of the unconditioned stimulus and also unmasked a conditioned response; in contrast, administration of escitalopram prior to acquisition did not influence the conditioned response.ConclusionThe data suggest that freezing in rats exposed to a stimulus inducing relatively mild fear may be enhanced by acute pretreatment with an SSRI regardless of whether the freezing displayed by the animals is an acute unconditioned response to the stimulus in question or a conditioned response to the same stimulus.

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