Medium-lead burst neurons related to vertical saccades in cat Forel's field H: input from vestibular nucleus

The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of saccades toward a visual target. On the basis of the organization of their efferences to the premotor burst neurons and the bilateral control of saccades, the hypothesis was proposed that the same unbalanced activity accounts for the dysmetria of all saccades during cFN unilateral inactivation, regardless of whether the saccade is horizontal, oblique, or vertical. We further tested this hypothesis by studying, in two head-restrained macaques, the effects of unilaterally inactivating the caudal fastigial nucleus on saccades toward a target moving vertically with a constant, increasing or decreasing speed. After local muscimol injection, vertical saccades were deviated horizontally toward the injected side with a magnitude that increased with saccade size. The ipsipulsion indeed depended upon the tested target speed, but not its instantaneous value because it did not increase (decrease) when the target accelerated (decelerated). By subtracting the effect on contralesional horizontal saccades from the effect on ipsilesional ones, we found that the net bilateral effect on horizontal saccades was strongly correlated with the effect on vertical saccades. We explain how this correlation corroborates the bilateral hypothesis and provide arguments against the suggestion that instantaneous saccade velocity would somehow be "encoded" by the discharge of Purkinje cells in the oculomotor vermis.

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Activity of Mesencephalic Vertical Burst Neurons During Saccades and Smooth Pursuit

Journal of Neurophysiology ◽

10.1152/jn.2000.83.4.2080 ◽

2000 ◽

Vol 83 (4) ◽

pp. 2080-2092 ◽

Cited By ~ 26

Author(s):

M. Missal ◽

S. de Brouwer ◽

P. Lefèvre ◽

E. Olivier

Keyword(s):

Vertical Velocity ◽

Smooth Pursuit ◽

Medial Longitudinal Fasciculus ◽

Eye Position ◽

Interstitial Nucleus Of Cajal ◽

Burst Neurons ◽

Preferred Direction ◽

Saccade Onset ◽

Vertical Saccades ◽

Eye Velocity

The activity of vertical burst neurons (BNs) was recorded in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF-BNs) and in the interstitial nucleus of Cajal (NIC-BNs) in head-restrained cats while performing saccades or smooth pursuit. BNs emitted a high-frequency burst of action potentials before and during vertical saccades. On average, these bursts led saccade onset by 14 ± 4 ms (mean ± SD, n = 23), and this value was in the range of latencies (∼5–15 ms) of medium-lead burst neurons (MLBNs). All NIC-BNs ( n = 15) had a downward preferred direction, whereas riMLF-BNs showed either a downward ( n = 3) or an upward ( n = 5) preferred direction. We found significant correlations between saccade and burst parameters in all BNs: vertical amplitude was correlated with the number of spikes, maximum vertical velocity with maximum of the spike density, and saccade duration with burst duration. A correlation was also found between instantaneous vertical velocity and neuronal activity during saccades. During fixation, all riMLF-BNs and ∼50% of NIC-BNs (7/15) were silent. Among NIC-BNs active during fixation (8/15), only two cells had an activity correlated with the eye position in the orbit. During smooth pursuit, most riMLF-BNs were silent (7/8), but all NIC-BNs showed an activity that was significantly correlated with the eye velocity. This activity was unaltered during temporary disappearance of the visual target, demonstrating that it was not visual in origin. For a given neuron, its on-direction during smooth pursuit and saccades remained identical. The activity of NIC-BNs during both saccades and smooth pursuit can be described by a nonlinear exponential function using the velocity of the eye as independent variable. We suggest that riMLF-BNs, which were not active during smooth pursuit, are vertical MLBNs responsible for the generation of vertical saccades. Because NIC-BNs discharged during both saccades and pursuit, they cannot be regarded as MLBNs as usually defined. NIC-BNs could, however, be the site of convergence of both the saccadic and smooth pursuit signals at the premotoneuronal level. Alternatively, NIC-BNs could participate in the integration of eye velocity to eye position signals and represent input neurons to a common integrator.

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Direct inhibitory projection of pontine omnipause neurons to vertical eye movement-related burst neurons in forel's field H

Neuroscience Research Supplements ◽

10.1016/0921-8696(88)90193-4 ◽

1988 ◽

Vol 7 ◽

pp. S91

Author(s):

Shozo Nakao ◽

Yoshimitsu Shiraishi ◽

Hirohisa Oda ◽

Masumi Inagaki ◽

Toshihiko Oikawa

Keyword(s):

Eye Movement ◽

Burst Neurons ◽

Forel's Field H ◽

Omnipause Neurons

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Excitatory inputs from superior colliculus to burst neurons in the Forel's field H participate in genesis of vertical eye movements

Neuroscience Research Supplements ◽

10.1016/0921-8696(89)90725-1 ◽

1989 ◽

Vol 9 ◽

pp. 93

Author(s):

Yoshimitsu Shiraishi ◽

Shozo Nakao ◽

Toshihiko Oikawa

Keyword(s):

Eye Movements ◽

Superior Colliculus ◽

Burst Neurons ◽

Forel's Field H

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Direct inhibitory projection of pontine omnipause neurons to burst neurons in the Forel's field H controlling vertical eye movement-related motoneurons in the cat

Experimental Brain Research ◽

10.1007/bf00247612 ◽

1988 ◽

Vol 70 (3) ◽

Cited By ~ 28

Author(s):

S. Nakao ◽

Y. Shiraishi ◽

H. Oda ◽

M. Inagaki

Keyword(s):

Eye Movement ◽

Burst Neurons ◽

Forel's Field H ◽

Omnipause Neurons

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Input-output organization of inhibitory neurons in the interstitial nucleus of Cajal projecting to the contralateral trochlear and oculomotor nucleus

Journal of Neurophysiology ◽

10.1152/jn.01045.2012 ◽

2013 ◽

Vol 110 (3) ◽

pp. 640-657 ◽

Cited By ~ 9

Author(s):

Y. Sugiuchi ◽

M. Takahashi ◽

Y. Shinoda

Keyword(s):

Head Movements ◽

Input Output ◽

Oculomotor Nucleus ◽

Inferior Rectus ◽

Interstitial Nucleus Of Cajal ◽

Vertical Saccades ◽

Disynaptic Inhibition ◽

Forel's Field H ◽

Trochlear Nucleus ◽

Monosynaptic Excitation

Neurons in the interstitial nucleus of Cajal (INC) that are known to be involved in eye and head movements are excitatory. We investigated the input-output organization of inhibitory INC neurons involved in controlling vertical saccades. Intracellular recordings were made in INC neurons activated antidromically by stimulation of the contralateral trochlear or oculomotor nucleus, and their synaptic input properties from the superior colliculi (SCs) and the contralateral INC were analyzed in anesthetized cats. Many INC neurons projected to the contralateral trochlear nucleus, Forel's field H, INC, and oculomotor nucleus, and mainly received monosynaptic excitation followed by disynaptic inhibition from the ipsi- and contralateral SCs. After sectioning the commissural connections between the SCs, these neurons received monosynaptic excitation from the ipsilateral medial SC and disynaptic inhibition via the INC from the contralateral lateral SC. Another group of INC neurons were antidromically activated from the contralateral oculomotor nucleus, INC and Forel's field H, but not from the trochlear nucleus, and received monosynaptic excitation from the ipsilateral lateral SC and disynaptic inhibition from the contralateral medial SC. The former group was considered to inhibit contralateral trochlear and inferior rectus motoneurons in upward saccades, whereas the latter was considered to inhibit contralateral superior rectus and inferior oblique motoneurons in downward saccades. The mutual inhibition existed between these two groups of INC neurons for upward saccades on one side and downward saccades on the other. This pattern of input-output organization of inhibitory INC neurons suggests that the basic neural circuits for horizontal and vertical saccades are similar.

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