Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 76 (1989), S. 510-518 
    ISSN: 1432-1106
    Keywords: Heteronymous Ia facilitation ; Presynaptic inhibition ; Reciprocal inhibition ; Monosynaptic reflex ; Voluntary movement ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Variations of presynaptic inhibition in heteronymous Ia fibres projecting to soleus motoneurones were studied during the first 250 ms of phasic voluntary isometric contractions of the antagonist tibialis anterior muscle in human subjects. During the first 60–80 ms of TA e.m.g activity, presynaptic inhibition was often more marked than at rest, but not in all experimental sessions. After 60–80 ms, presynaptic inhibition was always increased compared to rest and to the onset of TA e.m.g. activity. A “rebound” in femoral nerve induced Ia facilitation was often observed between 90–150 ms. The early increase in presynaptic inhibition was widespread and non specific since it was observed at the onset of extensor carpi radialis contractions of maximal strength. The “rebound” in heteronymous Ia facilitation was interpreted as a relative decrease in presynaptic inhibition to which nonspecific suprasegmental and cutaneous effects contributed. The late increase in presynaptic inhibition in Ia fibers to soleus motoneurones was considered as reciprocally inhibiting the Sol H-reflex, thus counteracting the phasic stretch of the antagonist muscle during TA contraction.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 119 (1998), S. 415-426 
    ISSN: 1432-1106
    Keywords: Key words Cortical stimulation ; Ia afferents ; Presynaptic inhibition ; Spinal interneurones ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effect of transcranial magnetic stimulation was investigated on presynaptic inhibition of Ia terminals in the human upper and lower limb. Presynaptic inhibition of Ia afferents was assessed by three different and independent methods: (1) heteronymous Ia facilitation of the H-reflex (assessing ongoing presynaptic inhibition of Ia afferents in the conditioning volley); (2) long-lasting inhibition of the H-reflex by a group I volley (D1 inhibition, assessing presynaptic inhibition on Ia afferents in the test volley); (3) measurement of the monosynaptic Ia peak evoked in single motor units by a homonymous or heteronymous volley (post stimulus time histogram method). The first two methods were used on the lower limb; the last two on the upper limb. Provided that the corticospinal volley and the explored Ia volley were directed to the same target motoneurones, cortical stimulation evoked significant and congruent changes: (1) In the lower limb, transcranial stimulation provided increased heteronymous Ia facilitation and decreased D1 inhibition, both of which suggest a decrease in presynaptic inhibition of Ia afferents; (2) in the upper limb, transcranial stimulation provided an increase in the radial-induced inhibition of the wrist flexor H-reflex and a decrease in the peak of monosynaptic Ia excitation in single units, both of which suggest an increase in presynaptic inhibition. Selectivity of corticospinal effects was explored by testing presynaptic inhibition of Ia afferents to soleus motoneurones and focusing the transcranial stimulation to excite preferentially different motor nuclei (soleus, quadriceps and tibialis anterior). A cortical-induced decrease in presynaptic inhibition of Ia afferents was seen when, and only when, cortical and peripheral Ia volleys were directed to the same motor nucleus.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...