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Vestibulospinal and Reticulospinal Systems

Victor J. Wilson, Barry W. Peterson

10.1002/cphy.cp010214

Source: Supplement 2: Handbook of Physiology, The Nervous System, Motor Control

Originally published: 1981

Published online: January 2011

Full Article on Wiley Online Library



Abstract

The sections in this article are:

1 Vestibular and Neck Reflexes
1.1 Vestibular Reflexes
1.2 Neck Reflexes
1.3 Interaction of Vestibular and Neck Reflexes
2 Central Pathways for Vestibular Reflexes
2.1 Pathways Linking Vestibular Nuclei to Spinal Cord
2.2 Vestibulospinal Tracts
2.3 Reticulospinal Tracts
2.4 Connections Between Labyrinthine and Spinal Motoneurons
3 Central Pathways for Neck Reflexes
4 Functional Studies of Vestibulospinal Reflexes
4.1 Semicircular Canal Reflexes
4.2 Otolith Reflexes
4.3 Central Pathways for Vestibulospinal Reflexes
4.4 Vestibulospinal Reflexes and γ‐Loop
4.5 Cerebellum and Vestibulospinal Reflexes
5 Conclusion
Figure 1. Figure 1.

Neck and vestibular reflexes in animal with C1 and C2 denervated. Top, rotation of head with axis clamped evokes vestibular reflexes. Bottom, rotation of axis (line shows tilt of spinal process) evokes neck reflexes.

From Roberts 182
Figure 2. Figure 2.

Scheme of combined effects upon limbs produced by tonic neck reflexes and vestibular otolith reflexes. With head normal (b, e, h) only neck reflexes are evoked. With neck normal (d, e, f) only vestibular reflexes are evoked. The 4 corners show combined effects of vestibular and neck reflexes.

From Roberts 183
Figure 3. Figure 3.

Isotonic length changes in medial triceps elicited by combinations of head tilt and neck torsion (given in degrees) in same direction. Decerebrate cat: upper cervical dorsal roots (C1 and C2) cut. A: neck reflex superimposed on labyrinthine reflex. B: labyrinthine reflex superimposed on neck reflex.

From Lindsay et al. 117
Figure 4. Figure 4.

Location of lateral vestibulospinal tract (LVST) and medial vestibulospinal tract (MVST) cells in cat. A, C, and E show spacing of LVST cells on 3 transverse sections of medulla obtained from 3 cats. IV, 4th ventricle; DV, descending vestibular nucleus; LV, Deiters' nucleus; MV, medial vestibular nucleus; RB, restiform body; SA, stria acoustica. Arrows indicate microelectrode tracks, each 0.25 mm apart. Open circles, second‐order LVST cells. Closed circles, non‐second‐order LVST cells. B, D, and F show spacing of MVST cells on same sections as A, C, and E. Open triangles, second‐order MVST cells. No non‐second‐order MVST cells were sampled in these preparations. In both rows most rostral sections are on left.

From Akaike 6
Figure 5. Figure 5.

Monosynaptic and polysynaptic excitatory postsynaptic potentials (EPSPs) evoked from Deiters' nucleus. Upper traces are intracellular potentials, lower traces are cord dorsum potentials. DP, deep peroneal; FDL, flexor digitorum longus; G‐S, gastrocnemius. A: G‐S cell. Photographic superimposition of vestibulospinal EPSPs evoked by 1–5 stimuli applied to Deiters' nucleus. Monosynaptic EPSPs indicated by arrows. B: FDL cell; EPSPs evoked by single, double, and triple shocks to Deiters' nucleus. C: DP cell; same as B. First stimulus was given just before onset of sweep. Arrows in B and C indicate arrival of descending volley (peak of initial positivity in cord dorsum potential). D: another DP cell; polysynaptic EPSPs produced by repetitive stimulation of Deiters' nucleus at different frequencies.

From Grillner et al. 78
Figure 6. Figure 6.

Properties of inhibitory neuron in vestibular nuclei, and unitary inhibitory postsynaptic potentials (IPSPs) evoked by activity of this neuron in 2 neck motoneurons. A1: antidromic spike of neuron evoked by 8‐μA stimulus (arrow) to electrode in C3 dorsal ramus motoneuron pool. A2: monosynaptic response of neuron to stimulation of ipsilateral vestibular nerve at 1.4 times N1 threshold. B: upper trace shows spontaneous activity of neuron as poststimulus time histogram (440 sweeps). Lower trace shows effect of 150‐μA triple shock to contralateral vestibular nerve (150 sweeps). C: unitary IPSP evoked in 1 motoneuron by activity of inhibitory neuron; lower trace, extracellular record. D: unitary IPSP (middle trace) evoked in another motoneuron. IPSP was reversed by injection of 10‐μA hyperpolarizing current; part of this reversed IPSP is shown in upper trace. Downward arrow in middle trace shows divergence between IPSPs recorded with and without current injection. Lower trace, extracellular record. All records in C and D are averages of 600–1,000 sweeps; upward arrows indicate time of discriminator output pulses.

From Rapoport, Wilson, et al. 176
Figure 7. Figure 7.

Locations of reticulospinal neurons in cat. Histologically determined locations of neurons projecting in medial reticulospinal tract (RSTm) and in the ipsilateral (RSTi) and contralateral (RSTc) lateral reticulospinal tracts are shown on drawings of a parasagittal section through pons and medulla. Symbols indicate neurons projecting to different spinal levels (N, neck; C, cervical; T, thoracic; and L, lumbar cord). The L cells found in experiments in which spinal cord was stimulated at 4 levels are shown by large, closed circles in A, B, and C. An additional group of L cells, found in experiments where stimuli were applied at fewer spinal levels, are shown by small, filled circles. These L cells were included only in A. Dashed lines indicate border between 2 reticular regions labeled zone 1 and zone 2 in A. Zone 1 contains primarily medial, and zone 2 primarily lateral, reticulospinal neurons. IO, inferior olivary nucleus; NRTP, nucleus reticularis tegmenti pontis; PH, nucleus prepositus hypoglossi; TB, trapezoid body; VI, abducens nucleus; VII, genu of facial nerve; XII, hypoglossal nucleus.

From Peterson et al. 163
Figure 8. Figure 8.

Localization of reticulospinal axon branches within cervical enlargement. Shaded areas in A, B, and C indicate regions within which stimuli of 20 μA or less produced antidromic activation of 3 reticulospinal neurons found in left nucleus reticularis gigantocellularis. Open ends of shaded profiles indicate points where axon branch extended to edge of region explored and possibly beyond. Arrows indicate part of branch that was closest to parent axon as shown by latency measurements. Neuron in A projected into ipsilateral reticulospinal tract (RST), neuron in B into medial RST, and neuron in C into contralateral RST. Numbers in A indicate spinal laminae.

From Peterson et al. 163
Figure 9. Figure 9.

Locations within medial reticular formation of neurons responding to vestibular nerve stimulation. Histologically determined locations of neurons whose responses were studied with intracellular recording are superimposed on 4 identical schematic parasagittal sections through pons and medulla. Dashed lines indicate rostral and caudal borders of nucleus reticularis gigantocellularis. Symbols indicate whether each neuron was reticulospinal (RS) or nonreticulospinal (N) neuron and whether it exhibited a di‐ or polysynaptic postsynaptic potential (PSP) or had no response to vestibular nerve stimulation. A: locations of neurons that responded with excitatory PSPs to stimulation of ipsilateral vestibular nerve (lower section) and contralateral vestibular nerve (upper section). B: locations of neurons that exhibited inhibitory PSPs or no response following stimulation of ipsilateral vestibular nerve (lower section) or contralateral vestibular nerve (upper section). I.O., inferior olivary nucleus; N.R.T.P, nucleus reticularis tegmenti pontis; T.B., trapezoid body; VI, abducens nucleus; VII, genu of facial nerve; X, dorsal nucleus of vagus.

From Peterson et al. 159
Figure 10. Figure 10.

Responses of reticulospinal neuron evoked antidromically and orthodromically with nerve and adequate stimulation. A–D are antidromic responses to juxtathreshold stimulation of ipsi‐ and contralateral cervical (A and B) and lumbar (C and D) spinal cord (i indicates ipsilateral, c denotes contralateral). E and F are monosynaptic responses to fastigial stimulation. G and H illustrate responses evoked by stimulation of superficial radial (SR) and peroneal (PER) nerves. Specimen records to iSR are shown in G; H displays poststimulus time histograms (PSTHs) and cumulative frequency distributions (CFDs) for responses to iSR and 3 other limb nerves as indicated. In I are PSTHs and CFDs for responses to brief taps (16 ms and 1.6 mm) to indicated foot pads on ipsilateral side: FCP, forelimb central pad; FT2 and FT5, forelimb toes 2 and 5; HCP, hindlimb central pad. In J are PSTHs and CFDs to airjet stimulation applied to hairy skin at indicated sites as defined in text. Same time and voltage scales for A–F. Same time scale for all PSTHs and CFDs. In H, arrows mark onsets of initial inhibition.

From Eccles et al. 43
Figure 11. Figure 11.

Response of neuron in nucleus reticularis gigantocellularis during stimulation of ipsilateral hindpaw at rates of 0.1/s (control rate) and 2/s. A: oscilloscope traces showing firing of neuron during initial control period, during 2/s stimulation, and at end of final control period. Horizontal scale, 10 ms; vertical scale, 0.5 mV. B: raster display showing changes in neuronal firing during transition from 0.1/s to 2/s stimulation and from 2/s back to 0.1/s. Each dot represents an action potential and each row of dots shows neuronal firing in the first 80 ms after stimulus, which was given at point marked by vertical dash. Time scale is given below C. Heavy vertical bars indicate period of 2/s stimulation. First and second groups of responses were separated by 95 responses at 2/s. C: poststimulus time histogram of firing during initial control period. Abscissa is divided into 80 1‐ms bins. Ordinate indicates average number of action potentials per bin per response. Filled and shaded areas show how response was divided into early and late components for further analysis. D: plot of number of action potentials occurring between 10 and 50 ms after each stimulus. Filled bar on base line indicates period of 2/s stimulation. E: plot similar to D of action potentials occurring within early response component (solid area) shown in C. F: plot of action potentials occurring within late response component (shaded area in C).

From Peterson et al. 160
Figure 12. Figure 12.

Amplitude distribution of monosynaptic excitatory postsynaptic potentials (EPSPs) in α‐motoneurons (A) and distribution of monosynaptic EPSPs (B), disynaptic inhibitory PSPs (C) and disynaptic EPSPs (D) evoked by stimulation of medial longitudinal fasciculus (MLF) in different species of α‐motoneurons. A: frequency histogram of amplitude of maximal monosynaptic EPSP evoked by MLF stimulation, from 15 cells sampled in same cat. B–D: percentages of occurrence, indicated by height of columns (left ordinates). Bars in B show mean amplitude of monosynaptic EPSPs (right ordinate). Q, quadriceps; G‐S, gastrocnemius‐soleus; Pl, plantaris; Tib, tibial; FDL, flexor digitorum and hallucis longus; ABSm, anterior biceps‐semimembranosus; PBSt, posterior biceps‐semitendinosus; Grac, gracilis; DP, deep peroneal. (Parentheses indicate that data are based on less than 10 cells.) Motoneurons with spike and resting potentials below 40 mV were discarded.

From Grillner et al. 79
Figure 13. Figure 13.

Reticular regions from which monosynaptic excitation of spinal motoneurons could be evoked. Effectiveness of 100‐μA stimuli (applied at points located 0.5 mm from midline) in evoking monosynaptic excitation of ipsilateral neck (A), forelimb (B), back (C), and hindlimb (D) motoneurons is indicated by shaded areas in each schematic parasagittal section. Light shading indicates regions that contained a few effective points (i.e., points at which 100‐μA stimulus produced monosynaptic excitation in more than 10% of motoneurons tested). Dark shading indicates areas within which more than half of points were effective. Dotted line in D separates zone 1 (which contains primarily medial reticulospinal neurons) and zone 2 (comprised of mainly lateral reticulospinal neurons). IO, inferior olive; NRTP, nucleus reticularis tegmenti pontis; TB, trapezoid body; VI, abducens nucleus; XII, hypoglossal nucleus.

From Peterson 155
Figure 14. Figure 14.

Synaptic potentials evoked in forelimb motoneurons. A: after transection of medial longitudinal fasciculus (MLF), as illustrated in drawing, typical potentials are still evoked in motoneurons of left lateral head of triceps (LAT) or biceps (BIC) by stimulation of either vestibular nerve. After large lateral lesion of brain stem that interrupts right lateral vestibulospinal tract, stimulation of right vestibular nerve is no longer effective, although stimulation of left vestibular nerve still evokes excitatory postsynaptic potentials bilaterally in motoneurons of long head of triceps (LON). IO, inferior olive; NXII, hypoglossal nerve; PT, pyramidal tract.

From Maeda, Maunz, and Wilson 128
Figure 15. Figure 15.

Schematic drawings of semicircular canals and head movements induced in cat by stimulation of ampullary nerves. Arrows show direction of induced head movements. RAC and LAC, right and left anterior canals, respectively; RPC and LPC, right and left posterior canals, respectively; RLC, right lateral (horizontal) canal.

From Suzuki and Cohen 201
Figure 16. Figure 16.

Schematic drawing of connections between ipsilateral and contralateral ampullae and neck motoneurons. A, H, and P are anterior, horizontal, and posterior ampullae, respectively; VN, vestibular nuclei; LVST, lateral vestibulospinal tract; MLF, medial longitudinal fasciculus. Inhibitory neurons and their terminals shown in black, excitatory in white.

From Wilson and Maeda 221
Figure 17. Figure 17.

Early and late excitation evoked from cervical dorsal root ganglion stimulation but only late excitation from combined muscle‐skin stimulation in cat with intact CNS. Intracellular records from gastrocnemius (A and D), flexor digitorum longus (B and E), and posterior biceps‐semitendinosus (C and F) motoneuron (upper beam). Records of extracellular potential on lower beam. Stimulation of ipsilateral C2 dorsal root ganglion (A–C), and contralateral muscle and skin nerves (D–F) with double stimuli; stimuli marked on lower beam.

From Kenins et al. 111
Figure 18. Figure 18.

Monosynaptic excitatory postsynaptic potentials (EPSPs) evoked from cervical primary afferents in propriospinal neurons in 3rd cervical segment (C3). Cell 1 (A–I) projected beyond 3rd lumbar segment (L3 in C). Cell 2 (J–M) was only tested for antidromic invasion from C6 (J). The EPSPs in upper traces of E–H were evoked by bipolar stimulation of dorsal column (DC) in C5. Lower traces recorded from surface of lateral funiculus (LF). Stimulus strengths are given in multiples of threshold. Observe that DC stimulation in 4th thoracic segment (Th4) does not evoke monosynaptic EPSP (I) at a strength giving slight coactivation of LF, from which can be seen a small discharge preceding main volley. Amplification of surface record in H is one‐half of that in E–G. Histogram in D gives distribution of segmental latencies of EPSPs evoked from DC. Monosynaptic EPSP in cell 2 was evoked by stimulation of C3 dorsal rami close to spinal ganglion; graded stimulation in K–M.

From Illert et al. 92
Figure 19. Figure 19.

Response of compound electromyograms (EMGs) to sinusoidal oscillation. A: top, compound EMG activity of right extensor muscles; bottom, position of turntable, downward displacement indicating rightward movement. B: methods of measurement of phase lag and gain. Top, position of turntable, upward displacement indicating rightward rotation. For measurement of phase lag, rectified EMGs were averaged (left); for measurement of gain, rectified EMGs were integrated through low‐pass filter and then averaged (right). S, level of spontaneous activity. C: Bode diagram. Phase lags were plotted from 11 cats; open circles, averaged phase lag of motor units. Gain was obtained from cat whose spontaneous activity was maintained constant during whole period of recording (normalized at 0.25 Hz). Inset: linearity of compound EMG responses, abscissa showing amplitude of oscillation (turntable position).

From Ezure and Sasaki 50
Figure 20. Figure 20.

Averaged phase differences (as function of frequency) between vestibular nucleus neurons and neck motor units. Best‐fit curve is drawn with least‐square methods (broken lines). Inset: upper curve, from data of Shinoda and Yoshida 196 on neurons in vestibular nuclei (VN); lower curve, neck motor unit responses.

From Ezure and Sasaki 50
Figure 21. Figure 21.

Phase relation between excitatory acceleration for horizontal semicircular canals and motor output to forelimb extensor. Comparison between canal afferent activity (Δ) and motor output (X). Phase reference on left ordinate is ipsilateral angular acceleration. Phase reference on right ordinate is contralateral angular acceleration, that is, positive acceleration for horizontal canal afferents of labyrinth opposite each forelimb. Output of this canal was shown to be adequate input that excites triceps muscle of opposite forelimb. Data points for afferent activity were obtained from transfer function for canal afferents given by Fernandez and Goldberg 54. Stippled area is difference in phase introduced by central processing.

From Anderson et al. 16
Figure 22. Figure 22.

Effect of sectioning medial longitudinal fasciculus (MLF) on dynamic characteristics of neck electromyogram (EMG) response. A: typical lesion. Bottom, 2 recordings are compound EMG potentials (from right neck extensor muscles) evoked by stimulation of contralateral horizontal canal nerve (trains of 3 pulses are indicated by dots). Recording taken after MLF cut (below) does not show EMG activity that is seen in control record (above). B: distribution of gain of motor‐unit response at 0.17 Hz. White columns, before cut (means ± SD: −6.75 ± 6.14 dB; n = 65). Filled columns, after cut (means ± SD: −6.26 ± 7.47 dB; n = 27). C: phase characteristics of compound EMG response from 2 cats. Phase lags (ordinate, in degrees) are plotted (open symbols, before cut; filled symbols, after cut) against angular frequency (abscissa).

Modified from Ezure, Wilson, et al. 51
Figure 23. Figure 23.

Effect of dorsal root section on neck extensor motor‐unit response. A: motor units that were examined at more than 3 different frequencies are plotted on Bode diagram. Solid lines, before deafferentation (n = 11). Dotted lines, after deafferentation (n = 10). B: mean and standard deviation at each frequency.

From Ezure, Wilson, et al. 51


Figure 1.

Neck and vestibular reflexes in animal with C1 and C2 denervated. Top, rotation of head with axis clamped evokes vestibular reflexes. Bottom, rotation of axis (line shows tilt of spinal process) evokes neck reflexes.

From Roberts 182


Figure 2.

Scheme of combined effects upon limbs produced by tonic neck reflexes and vestibular otolith reflexes. With head normal (b, e, h) only neck reflexes are evoked. With neck normal (d, e, f) only vestibular reflexes are evoked. The 4 corners show combined effects of vestibular and neck reflexes.

From Roberts 183


Figure 3.

Isotonic length changes in medial triceps elicited by combinations of head tilt and neck torsion (given in degrees) in same direction. Decerebrate cat: upper cervical dorsal roots (C1 and C2) cut. A: neck reflex superimposed on labyrinthine reflex. B: labyrinthine reflex superimposed on neck reflex.

From Lindsay et al. 117


Figure 4.

Location of lateral vestibulospinal tract (LVST) and medial vestibulospinal tract (MVST) cells in cat. A, C, and E show spacing of LVST cells on 3 transverse sections of medulla obtained from 3 cats. IV, 4th ventricle; DV, descending vestibular nucleus; LV, Deiters' nucleus; MV, medial vestibular nucleus; RB, restiform body; SA, stria acoustica. Arrows indicate microelectrode tracks, each 0.25 mm apart. Open circles, second‐order LVST cells. Closed circles, non‐second‐order LVST cells. B, D, and F show spacing of MVST cells on same sections as A, C, and E. Open triangles, second‐order MVST cells. No non‐second‐order MVST cells were sampled in these preparations. In both rows most rostral sections are on left.

From Akaike 6


Figure 5.

Monosynaptic and polysynaptic excitatory postsynaptic potentials (EPSPs) evoked from Deiters' nucleus. Upper traces are intracellular potentials, lower traces are cord dorsum potentials. DP, deep peroneal; FDL, flexor digitorum longus; G‐S, gastrocnemius. A: G‐S cell. Photographic superimposition of vestibulospinal EPSPs evoked by 1–5 stimuli applied to Deiters' nucleus. Monosynaptic EPSPs indicated by arrows. B: FDL cell; EPSPs evoked by single, double, and triple shocks to Deiters' nucleus. C: DP cell; same as B. First stimulus was given just before onset of sweep. Arrows in B and C indicate arrival of descending volley (peak of initial positivity in cord dorsum potential). D: another DP cell; polysynaptic EPSPs produced by repetitive stimulation of Deiters' nucleus at different frequencies.

From Grillner et al. 78


Figure 6.

Properties of inhibitory neuron in vestibular nuclei, and unitary inhibitory postsynaptic potentials (IPSPs) evoked by activity of this neuron in 2 neck motoneurons. A1: antidromic spike of neuron evoked by 8‐μA stimulus (arrow) to electrode in C3 dorsal ramus motoneuron pool. A2: monosynaptic response of neuron to stimulation of ipsilateral vestibular nerve at 1.4 times N1 threshold. B: upper trace shows spontaneous activity of neuron as poststimulus time histogram (440 sweeps). Lower trace shows effect of 150‐μA triple shock to contralateral vestibular nerve (150 sweeps). C: unitary IPSP evoked in 1 motoneuron by activity of inhibitory neuron; lower trace, extracellular record. D: unitary IPSP (middle trace) evoked in another motoneuron. IPSP was reversed by injection of 10‐μA hyperpolarizing current; part of this reversed IPSP is shown in upper trace. Downward arrow in middle trace shows divergence between IPSPs recorded with and without current injection. Lower trace, extracellular record. All records in C and D are averages of 600–1,000 sweeps; upward arrows indicate time of discriminator output pulses.

From Rapoport, Wilson, et al. 176


Figure 7.

Locations of reticulospinal neurons in cat. Histologically determined locations of neurons projecting in medial reticulospinal tract (RSTm) and in the ipsilateral (RSTi) and contralateral (RSTc) lateral reticulospinal tracts are shown on drawings of a parasagittal section through pons and medulla. Symbols indicate neurons projecting to different spinal levels (N, neck; C, cervical; T, thoracic; and L, lumbar cord). The L cells found in experiments in which spinal cord was stimulated at 4 levels are shown by large, closed circles in A, B, and C. An additional group of L cells, found in experiments where stimuli were applied at fewer spinal levels, are shown by small, filled circles. These L cells were included only in A. Dashed lines indicate border between 2 reticular regions labeled zone 1 and zone 2 in A. Zone 1 contains primarily medial, and zone 2 primarily lateral, reticulospinal neurons. IO, inferior olivary nucleus; NRTP, nucleus reticularis tegmenti pontis; PH, nucleus prepositus hypoglossi; TB, trapezoid body; VI, abducens nucleus; VII, genu of facial nerve; XII, hypoglossal nucleus.

From Peterson et al. 163


Figure 8.

Localization of reticulospinal axon branches within cervical enlargement. Shaded areas in A, B, and C indicate regions within which stimuli of 20 μA or less produced antidromic activation of 3 reticulospinal neurons found in left nucleus reticularis gigantocellularis. Open ends of shaded profiles indicate points where axon branch extended to edge of region explored and possibly beyond. Arrows indicate part of branch that was closest to parent axon as shown by latency measurements. Neuron in A projected into ipsilateral reticulospinal tract (RST), neuron in B into medial RST, and neuron in C into contralateral RST. Numbers in A indicate spinal laminae.

From Peterson et al. 163


Figure 9.

Locations within medial reticular formation of neurons responding to vestibular nerve stimulation. Histologically determined locations of neurons whose responses were studied with intracellular recording are superimposed on 4 identical schematic parasagittal sections through pons and medulla. Dashed lines indicate rostral and caudal borders of nucleus reticularis gigantocellularis. Symbols indicate whether each neuron was reticulospinal (RS) or nonreticulospinal (N) neuron and whether it exhibited a di‐ or polysynaptic postsynaptic potential (PSP) or had no response to vestibular nerve stimulation. A: locations of neurons that responded with excitatory PSPs to stimulation of ipsilateral vestibular nerve (lower section) and contralateral vestibular nerve (upper section). B: locations of neurons that exhibited inhibitory PSPs or no response following stimulation of ipsilateral vestibular nerve (lower section) or contralateral vestibular nerve (upper section). I.O., inferior olivary nucleus; N.R.T.P, nucleus reticularis tegmenti pontis; T.B., trapezoid body; VI, abducens nucleus; VII, genu of facial nerve; X, dorsal nucleus of vagus.

From Peterson et al. 159


Figure 10.

Responses of reticulospinal neuron evoked antidromically and orthodromically with nerve and adequate stimulation. A–D are antidromic responses to juxtathreshold stimulation of ipsi‐ and contralateral cervical (A and B) and lumbar (C and D) spinal cord (i indicates ipsilateral, c denotes contralateral). E and F are monosynaptic responses to fastigial stimulation. G and H illustrate responses evoked by stimulation of superficial radial (SR) and peroneal (PER) nerves. Specimen records to iSR are shown in G; H displays poststimulus time histograms (PSTHs) and cumulative frequency distributions (CFDs) for responses to iSR and 3 other limb nerves as indicated. In I are PSTHs and CFDs for responses to brief taps (16 ms and 1.6 mm) to indicated foot pads on ipsilateral side: FCP, forelimb central pad; FT2 and FT5, forelimb toes 2 and 5; HCP, hindlimb central pad. In J are PSTHs and CFDs to airjet stimulation applied to hairy skin at indicated sites as defined in text. Same time and voltage scales for A–F. Same time scale for all PSTHs and CFDs. In H, arrows mark onsets of initial inhibition.

From Eccles et al. 43


Figure 11.

Response of neuron in nucleus reticularis gigantocellularis during stimulation of ipsilateral hindpaw at rates of 0.1/s (control rate) and 2/s. A: oscilloscope traces showing firing of neuron during initial control period, during 2/s stimulation, and at end of final control period. Horizontal scale, 10 ms; vertical scale, 0.5 mV. B: raster display showing changes in neuronal firing during transition from 0.1/s to 2/s stimulation and from 2/s back to 0.1/s. Each dot represents an action potential and each row of dots shows neuronal firing in the first 80 ms after stimulus, which was given at point marked by vertical dash. Time scale is given below C. Heavy vertical bars indicate period of 2/s stimulation. First and second groups of responses were separated by 95 responses at 2/s. C: poststimulus time histogram of firing during initial control period. Abscissa is divided into 80 1‐ms bins. Ordinate indicates average number of action potentials per bin per response. Filled and shaded areas show how response was divided into early and late components for further analysis. D: plot of number of action potentials occurring between 10 and 50 ms after each stimulus. Filled bar on base line indicates period of 2/s stimulation. E: plot similar to D of action potentials occurring within early response component (solid area) shown in C. F: plot of action potentials occurring within late response component (shaded area in C).

From Peterson et al. 160


Figure 12.

Amplitude distribution of monosynaptic excitatory postsynaptic potentials (EPSPs) in α‐motoneurons (A) and distribution of monosynaptic EPSPs (B), disynaptic inhibitory PSPs (C) and disynaptic EPSPs (D) evoked by stimulation of medial longitudinal fasciculus (MLF) in different species of α‐motoneurons. A: frequency histogram of amplitude of maximal monosynaptic EPSP evoked by MLF stimulation, from 15 cells sampled in same cat. B–D: percentages of occurrence, indicated by height of columns (left ordinates). Bars in B show mean amplitude of monosynaptic EPSPs (right ordinate). Q, quadriceps; G‐S, gastrocnemius‐soleus; Pl, plantaris; Tib, tibial; FDL, flexor digitorum and hallucis longus; ABSm, anterior biceps‐semimembranosus; PBSt, posterior biceps‐semitendinosus; Grac, gracilis; DP, deep peroneal. (Parentheses indicate that data are based on less than 10 cells.) Motoneurons with spike and resting potentials below 40 mV were discarded.

From Grillner et al. 79


Figure 13.

Reticular regions from which monosynaptic excitation of spinal motoneurons could be evoked. Effectiveness of 100‐μA stimuli (applied at points located 0.5 mm from midline) in evoking monosynaptic excitation of ipsilateral neck (A), forelimb (B), back (C), and hindlimb (D) motoneurons is indicated by shaded areas in each schematic parasagittal section. Light shading indicates regions that contained a few effective points (i.e., points at which 100‐μA stimulus produced monosynaptic excitation in more than 10% of motoneurons tested). Dark shading indicates areas within which more than half of points were effective. Dotted line in D separates zone 1 (which contains primarily medial reticulospinal neurons) and zone 2 (comprised of mainly lateral reticulospinal neurons). IO, inferior olive; NRTP, nucleus reticularis tegmenti pontis; TB, trapezoid body; VI, abducens nucleus; XII, hypoglossal nucleus.

From Peterson 155


Figure 14.

Synaptic potentials evoked in forelimb motoneurons. A: after transection of medial longitudinal fasciculus (MLF), as illustrated in drawing, typical potentials are still evoked in motoneurons of left lateral head of triceps (LAT) or biceps (BIC) by stimulation of either vestibular nerve. After large lateral lesion of brain stem that interrupts right lateral vestibulospinal tract, stimulation of right vestibular nerve is no longer effective, although stimulation of left vestibular nerve still evokes excitatory postsynaptic potentials bilaterally in motoneurons of long head of triceps (LON). IO, inferior olive; NXII, hypoglossal nerve; PT, pyramidal tract.

From Maeda, Maunz, and Wilson 128


Figure 15.

Schematic drawings of semicircular canals and head movements induced in cat by stimulation of ampullary nerves. Arrows show direction of induced head movements. RAC and LAC, right and left anterior canals, respectively; RPC and LPC, right and left posterior canals, respectively; RLC, right lateral (horizontal) canal.

From Suzuki and Cohen 201


Figure 16.

Schematic drawing of connections between ipsilateral and contralateral ampullae and neck motoneurons. A, H, and P are anterior, horizontal, and posterior ampullae, respectively; VN, vestibular nuclei; LVST, lateral vestibulospinal tract; MLF, medial longitudinal fasciculus. Inhibitory neurons and their terminals shown in black, excitatory in white.

From Wilson and Maeda 221


Figure 17.

Early and late excitation evoked from cervical dorsal root ganglion stimulation but only late excitation from combined muscle‐skin stimulation in cat with intact CNS. Intracellular records from gastrocnemius (A and D), flexor digitorum longus (B and E), and posterior biceps‐semitendinosus (C and F) motoneuron (upper beam). Records of extracellular potential on lower beam. Stimulation of ipsilateral C2 dorsal root ganglion (A–C), and contralateral muscle and skin nerves (D–F) with double stimuli; stimuli marked on lower beam.

From Kenins et al. 111


Figure 18.

Monosynaptic excitatory postsynaptic potentials (EPSPs) evoked from cervical primary afferents in propriospinal neurons in 3rd cervical segment (C3). Cell 1 (A–I) projected beyond 3rd lumbar segment (L3 in C). Cell 2 (J–M) was only tested for antidromic invasion from C6 (J). The EPSPs in upper traces of E–H were evoked by bipolar stimulation of dorsal column (DC) in C5. Lower traces recorded from surface of lateral funiculus (LF). Stimulus strengths are given in multiples of threshold. Observe that DC stimulation in 4th thoracic segment (Th4) does not evoke monosynaptic EPSP (I) at a strength giving slight coactivation of LF, from which can be seen a small discharge preceding main volley. Amplification of surface record in H is one‐half of that in E–G. Histogram in D gives distribution of segmental latencies of EPSPs evoked from DC. Monosynaptic EPSP in cell 2 was evoked by stimulation of C3 dorsal rami close to spinal ganglion; graded stimulation in K–M.

From Illert et al. 92


Figure 19.

Response of compound electromyograms (EMGs) to sinusoidal oscillation. A: top, compound EMG activity of right extensor muscles; bottom, position of turntable, downward displacement indicating rightward movement. B: methods of measurement of phase lag and gain. Top, position of turntable, upward displacement indicating rightward rotation. For measurement of phase lag, rectified EMGs were averaged (left); for measurement of gain, rectified EMGs were integrated through low‐pass filter and then averaged (right). S, level of spontaneous activity. C: Bode diagram. Phase lags were plotted from 11 cats; open circles, averaged phase lag of motor units. Gain was obtained from cat whose spontaneous activity was maintained constant during whole period of recording (normalized at 0.25 Hz). Inset: linearity of compound EMG responses, abscissa showing amplitude of oscillation (turntable position).

From Ezure and Sasaki 50


Figure 20.

Averaged phase differences (as function of frequency) between vestibular nucleus neurons and neck motor units. Best‐fit curve is drawn with least‐square methods (broken lines). Inset: upper curve, from data of Shinoda and Yoshida 196 on neurons in vestibular nuclei (VN); lower curve, neck motor unit responses.

From Ezure and Sasaki 50


Figure 21.

Phase relation between excitatory acceleration for horizontal semicircular canals and motor output to forelimb extensor. Comparison between canal afferent activity (Δ) and motor output (X). Phase reference on left ordinate is ipsilateral angular acceleration. Phase reference on right ordinate is contralateral angular acceleration, that is, positive acceleration for horizontal canal afferents of labyrinth opposite each forelimb. Output of this canal was shown to be adequate input that excites triceps muscle of opposite forelimb. Data points for afferent activity were obtained from transfer function for canal afferents given by Fernandez and Goldberg 54. Stippled area is difference in phase introduced by central processing.

From Anderson et al. 16


Figure 22.

Effect of sectioning medial longitudinal fasciculus (MLF) on dynamic characteristics of neck electromyogram (EMG) response. A: typical lesion. Bottom, 2 recordings are compound EMG potentials (from right neck extensor muscles) evoked by stimulation of contralateral horizontal canal nerve (trains of 3 pulses are indicated by dots). Recording taken after MLF cut (below) does not show EMG activity that is seen in control record (above). B: distribution of gain of motor‐unit response at 0.17 Hz. White columns, before cut (means ± SD: −6.75 ± 6.14 dB; n = 65). Filled columns, after cut (means ± SD: −6.26 ± 7.47 dB; n = 27). C: phase characteristics of compound EMG response from 2 cats. Phase lags (ordinate, in degrees) are plotted (open symbols, before cut; filled symbols, after cut) against angular frequency (abscissa).

Modified from Ezure, Wilson, et al. 51


Figure 23.

Effect of dorsal root section on neck extensor motor‐unit response. A: motor units that were examined at more than 3 different frequencies are plotted on Bode diagram. Solid lines, before deafferentation (n = 11). Dotted lines, after deafferentation (n = 10). B: mean and standard deviation at each frequency.

From Ezure, Wilson, et al. 51
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Article Title: Vestibulospinal and Reticulospinal Systems
 

How to Cite

Victor J. Wilson, Barry W. Peterson. Vestibulospinal and Reticulospinal Systems. Compr Physiol 2011, Supplement 2: Handbook of Physiology, The Nervous System, Motor Control: 667-702. First published in print 1981. doi: 10.1002/cphy.cp010214