Comparison of motoneuron properties and twitch contraction among different species
| Species | Rin, MΩ | AHPd, ms | Fmin | Fmax | f–I slope, Hz/nA | Twitch Contraction Time, ms | Twitch Duration, ms | MN ∅, μm |
|---|---|---|---|---|---|---|---|---|
| Human | NA | 148 (a) | 5.4 (b) | NA | 56 (a) | 131 (a) | 62 (c) | |
| 132 (b) | 8.4 (d) | 61 (b) | 104 (b) | |||||
| 7.8 (e) | 112 (f) | 288 (f) | ||||||
| 70 (g) | 180 (g) | |||||||
| 70 (h) | 200 (h) | |||||||
| Cat | 0.9 (j) | 83 (j) | 15.0 (o) | 54–218 (o) | 1.9 (n) | 35 (k) | 80 (p) | 53 (c) |
| 1.1 (k) | 79 (k) | 31 (l) | 100 (i) | |||||
| 1.2 (l) | 52 (l) | 30 (p) | 158 (r) | |||||
| 105 (m) | 43 (q) | |||||||
| 77 (n) | 21 (i) | |||||||
| 82 (dd) | 41 (r) | |||||||
| 43 (y) | ||||||||
| Rat | 2.2 (x) | 59 (x) | 24.0 (t) | 104 (v) | 2.7 (w) | 17 (x) | 63 (x) | 35 (c) |
| 2.2 (t) | 50 (u) | 35.0 (v) | 6.5 (v) | 14 (s) | 56 (s) | |||
| 49 (s) | 16.0 (t) | 16 (u) | 63 (s) | |||||
| 13 (z) | 42 (z) | |||||||
| Mouse | 3.1 (ee) | 32 (aa) | 24 (ff) | >300 (ff) | 13.0 (ff) | 8.7 (bb) | 32 (cc) | 27 (c) |
| 2.4 (ff) | 46 (ee) | 6.9 (cc) | 47 (ff) | |||||
| 55 (ff) | 12.0 (ff) |
-
All values are obtained for mixed lower limb muscles (with slow and fast units; values from the soleus muscle are not quoted), with the exception of the first interosseous muscle in humans (Gossen et al. 2003; Spiegel et al. 1996). Numbers in italics reflect that they are estimated from records or graphs in the cited reference, rather than specifically given in the text or in tables. The letters in parentheses refer to the references listed later in this footnote. Boldface entries (numbers and letters) refer to this study. The duration of the AHP in humans was estimated from the “interval death rate transform” of motor unit discharge ISI histograms (MacDonell et al. 2007; Matthews 1996; Powers and Binder 2000). The Fmax is usually not given with absolute numbers, but are extrapolated from the text or illustrations in the cited reference. No references are given for Fmax values in humans; the range from a large number of publications is large, partly depending on the difficulties in following single motor units during maximal contraction. Usually the cited estimates range from 20 to 40 Hz. The size of the motoneurons has been measured/estimated in many ways. Here we have given only a single reference, with the strength that all estimates (for all species summarized here and many others as well) were obtained in the same way (Hardesty 1902). Cited references: (a) Gossen et al. (2003); (b) MacDonell et al. (2008); (c) Hardesty (1902); (d) Van Cutsem et al. (1997); (e) Spiegel et al. (1996); (f) Oda et al. (2007a); (g) Oda et al. (2007b); (h) Vandervoort et al. (1983); (i) Gordon and Phillips (1953); (j) Zengel et al. (1985); (k) Hultborn et al. (1988); (l) Dum and Kennedy (1980); (m) Hammarberg and Kellerth (1975); (n) Kernell (1965a); (o) Kernell (1965c); (p) Burke (1967); (q) Emonet-Denand et al. (1988); (r) Denny-Brown (1929); (s) Bakels and Kernell (1993a); (t) Button et al. (2006); (u) Gardiner and Kernell (1990); (v) Button et al. (2008); (w) Granit et al. (1963); (x) Bakels and Kernell (1993b); (y) McPhedran et al. (1965); (z) Close (1967); (aa) Huizar et al. (1975); (bb) Bateson and Parry (1983); (cc) Luff (1981); (dd) Eccles et al. (1958); (ee) Manual et al. (2009); (ff) present study; values are the same as those given in Table 1.