Information-theoretic analysis of de-efferented single muscle spindles.
The information transmission properties of single, de-efferented primary muscle-spindle afferents from the hind limb of the cat were investigated. The gastrocnemius medialis muscle was stretched randomly while recording spike trains from several muscle-spindle afferents in the dorsal root. Two classes of input stimuli were used: (i) Gaussian noise with band-limited flat spectrum, and (ii) Gaussian noise with a more "naturalistic" 1/f(n) spectrum. The "reconstruction" method was used to calculate a lower bound to the information rate (in bits per second) between the muscle spindles and the spinal cord. Results show that in response to the flat-spectrum input, primary muscle-spindle afferents transfer information mainly about high frequencies, carrying 2.12 bits/spike. In response to naturalistic-spectrum inputs, primary muscle-spindle afferents transfer information about both low and high frequencies, with "spiking efficiency" increasing to 2.67 bits/spike. A simple muscle-spindle simulation model was analyzed with the same method, emphasizing the important part played by the intrafusal fiber mechanical properties in information transmission.
Tock
Y
Y
Electrical Engineering Department, Technion, Haifa 32000, Israel. ytock@tx.technion.ac.il
Ljubisavljevic
M
M
Thunberg
J
J
Windhorst
U
U
Inbar
G F
GF
Johansson
H
H
D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways / Q000166:cytology / Q000502:physiology*; D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008959:Models, Neurological; D009047:Motor Neurons, Gamma / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009470:Muscle Spindles / Q000166:cytology / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009475:Neurons, Afferent / Q000166:cytology / Q000502:physiology*; D016011:Normal Distribution; D013126:Spinal Nerve Roots / Q000166:cytology / Q000502:physiology