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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 93 (1993), S. 37-45 
    ISSN: 1432-1106
    Keywords: Jaw muscle spindles ; Fusimotor control ; Midbrain ; Succinylcholine ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of electrical stimulation within the midbrain on fusimotor output to the jaw elevator muscles were studied in anaesthetized cats. Muscle spindle afferents recorded in the mesencephalic trigeminal nucleus were categorised as primary or secondary by their responses to succinylcholine during sinusoidal or rampand-hold stretches. Changes in their stretch responses during midbrain stimulation were then assessed by changes in bias and in dynamic sensitivity. Problems were encountered in interpreting changes in sine wave stretch responses of primary afferents, in some of which a very small change in firing pattern produced large changes in estimates of the reponse amplitude. Sine wave testing also sometimes over-estimated static effects and under-estimated dynamic effects relative to ramp responses. On other occasions a small amount of static fusimotor activity caused a marked increase in sine response amplitude, which could be wrongly interpreted as a dynamic effect. Consequently, ramp responses only were used for diagnosing fusimotor changes. The most effective region for producing pure dynamic fusimotor excitation was directly rostral to the red nucleus, extending dorsally and ventrally approximately in the course of the retroflex bundle. Stimulation of regions caudal and dorso-caudal to the red nucleus, previously designated as the mesencephalic area for dynamic fusimotor control of leg muscles, gave static or mixed static and dynamic effects on jaw spindles. The use of midbrain stimulation to identify fusimotor neurones of jaw muscles as static or dynamic would be most reliable with stimulation just rostral to the red nucleus and would require spindle afferent behaviour to be monitored at the same time with ramp stretches.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 133 (1979), S. 131-139 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The functional properties, localization and connections of neurons with a respiratory-rhythmic firing pattern in the mesencephalon, diencephalon and cerebellum of the carp were studied. Some neurons acquire respiratory rhythm only as a side effect of respiration via sensory stimulation by movements or water current. In other neurons, however, the rhythm is the result of nervous input from the respiratory center. These were studied in more detail. Three categories were distinguished: 1. Plain respiratory neurons. None of the stimuli used could influence the firing pattern of these neurons. 2. Respiratory-optical neurons, which receive both respiratory and visual input. 3. Respiratory-movement-sensitive neurons, the firing pattern of which is sensitive to stimuli influencing the respiratory movements. The respiratory-optical neurons are argued to be components of a system correcting the visual image for respiration-induced displacements of the eyes. The movement sensitive neurons appear to process proprioceptive information at a level, where the demands on the cranial muscles of respiratory and other movements are integrated. The plain respiratory neurons, at least partly, can be regarded as interneurons between the respiratory center and the systems mentioned above.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 141 (1981), S. 157-162 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microelectrode studies were performed on neurons of the mesencephalic trigeminal nucleus in the carp. All units in normal respiring animals showed respiratory-rhythmic activity during respiratory movements. The units can be activated by forced abductions of the lower jaw, and deactivated by adductions. According to their reaction to abduction two categories can be distinguished: 1. Slowly adapting units. Abduction of jaw resulted in a continuous activity with slowly decreasing firing frequency. 2. Fast adapting units. Initially these units become strongly activated but after about two respiratory cycles complete adaptation is established. Both types of units exclusively process mechanoreceptor information from the jaw region.
    Type of Medium: Electronic Resource
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