Response variability of single cells in the dorsal lateral geniculate nucleus of the cat. Comparison with retinal input and effect of brain stem stimulation

1994 ◽  
Vol 72 (3) ◽  
pp. 1278-1289 ◽  
Author(s):  
E. Hartveit ◽  
P. Heggelund
Keyword(s):  
Firing Rate ◽  
Brain Stem ◽  
Signal To Noise Ratio ◽  
Single Cells ◽  
Response Variability ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Signal To Noise ◽  
Retinal Input ◽  
Dorsal Lateral Geniculate ◽  
The Brain

1. We studied the degree and source of response variability in different classes of cell in the dorsal lateral geniculate nucleus (dLGN). The response of single cells to a series of contrasts of a stationary flashing light spot was measured. The variability analyses were based on the mean and SD of the response to a number of repeated stimulus presentations. The relative variability was expressed by the coefficient of variation (Cv; SD/mean). 2. At a given contrast, the Cv for lagged cells was larger than for nonlagged cells. No difference was found between the Cv of X and Y cells. The magnitude of the Cv was about the same as previously found for cells in striate cortex. Accordingly, little variability is added at the cortical level. The Cv decreased with increasing contrast showing that the reliability of response and the signal-to-noise ratio was improved with increasing contrast. 3. For some cells, the retinal input was determined by recording S potentials in addition to action potentials. The Cv of the retinal input was smaller than the Cv of the dLGN cells at a given contrast. Thus in the paralyzed and anesthetized preparation, variability was added at the geniculate relay. 4. The additional variability was related to modulatory input from the brain stem. This was shown by comparing Cv versus contrast curves for the dLGN cells obtained during electrical stimulation of the peribrachial region of the brain stem (PBR) with corresponding curves obtained without PBR stimulation. During PBR stimulation, which presumably mimics the effects of arousal on the dLGN cell, the Cv at a given contrast was reduced toward the value for the retinal input to the cell. Furthermore PBR stimulation increased the signal-to-noise-ratio of the cell to the level of the retinal input. 5. When Cv was plotted against response rather than against contrast, approximately the same function was found for the various dLGN cell classes. This indicated that the variability basically depended on firing rate rather than on stimulus contrast. No difference of Cv was seen between lagged and nonlagged cells at a given level of response. The difference found at a given level of contrast reflected differences in firing rate of the two cell classes. During PBR stimulation, there was no clear difference between the Cvs of the dLGN cell and its retinal input at a given level of response.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain stem modulation of spatial receptive field properties of single cells in the dorsal lateral geniculate nucleus of the cat

1993 ◽  
Vol 70 (4) ◽  
pp. 1644-1655 ◽  
Author(s):  
E. Hartveit ◽  
S. I. Ramberg ◽  
P. Heggelund
Keyword(s):  
Receptive Field ◽  
Brain Stem ◽  
Single Cells ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Visual Response ◽  
Field Profile ◽  
Field Center ◽  
Retinal Input ◽  
Dorsal Lateral Geniculate ◽  
Receptive Field Center

1. We studied the effect of electrical stimulation of the peribrachial region (PBR) in the brain stem on the visual response of single cells in the dorsal lateral geniculate nucleus (dLGN) to a light slit presented in a series of positions across the receptive field. The response was plotted against slit position, giving a spatial receptive field profile. 2. PBR stimulation markedly increased the visual response. In the middle of the receptive field center, the absolute response increase was considerably larger than in the peripheral parts of the receptive field or than the increase of spontaneous activity. The PBR stimulation also led to a small increase of the diameter of the receptive field center. 3. The maximum steepness of the receptive field profile for the dLGN cells increased by PBR stimulation. We suggest that the visual resolution in the dLGN cell is directly related to this maximal slope of the receptive field profile rather than to the width of the receptive field center. This would mean that increased input from the PBR, as presumably occurs during arousal, increases the visual resolution of the dLGN cells. 4. For some of the cells we could record S-potentials (slow potentials) in addition to action potentials. This allowed us to directly compared the receptive field center size of a dLGN cell with that of its retinal input. For these cells, the center size was considerably reduced by the geniculate relay. During PBR stimulation, the center size of these cells also increased slightly, but even in this condition it was reduced compared with the retinal input. The maximal slope of the receptive field profile in the dLGN cell during PBR stimulation was larger than for the retinal input. 5. We also examined the effect of ionophoretical application of acetylcholine (ACh) and bicuculline methchloride (BMC) on the spatial receptive field properties of dLGN cells. The effects of ACh were similar to those of PBR stimulation. Application of BMC, on the other hand, made the receptive field profile more similar to that of retinal ganglion cells.

An Autoradiographic Study of Visual Pathways of the Australian Rodents Notomys Alexis, Pseudomys Australis and Rattus Villosissimus.

1980 ◽  
Vol 28 (3) ◽  
pp. 381 ◽  
Author(s):  
L Mayner ◽  
LJ Pearson ◽  
KJ Sanderson
Keyword(s):  
Autoradiographic Study ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Optic System ◽  
Accessory Optic System ◽  
Lateral Geniculate ◽  
Retinal Input ◽  
Parabigeminal Nucleus ◽  
Transneuronal Transport ◽  
Dorsal Lateral Geniculate ◽  
The Brain

In three species of Australian rodents, Notomys alexis, Pseudomys australis and Rattus villosissimus, primary optic centres were mapped by observing the distribution of autoradiographic label in the brain following injection of one eye with 3*H-proline or 3*H-leucine. Five regions receive a primary optic input in the three species: the lateral geniculate complex, the pretectum, the superior colliculus, the hypothalamus and the three terminal nuclei of the accessory optic system. The retinal projections are generally similar in the three species, except that in N. alexis and P. australis the dorsal lateral geniculate nucleus (LGNd) is subdivided into two, and the pattern of ipsilateral retinal input to it is similar; but in R. villosissimus the LGNd is not apparently subdivided, and the pattern is slightly different. It is concluded that the pattern of primary optic inputs is likely to be similar in other Australian rodents. Two secondary optic centres were shown in Notomys alexis, using the method of transneuronal transport of 3*H-proline. Autoradiographic label was observed in the visual cortex and in the parabigeminal nucleus 20-25 days after eye injection.

Neural basis for motor learning in the vestibuloocular reflex of primates. I. Changes in the responses of brain stem neurons

1994 ◽  
Vol 72 (2) ◽  
pp. 928-953 ◽  
Author(s):  
S. G. Lisberger ◽  
T. A. Pavelko ◽  
D. M. Broussard
Keyword(s):  
Eye Movements ◽  
Motor Learning ◽  
Firing Rate ◽  
Brain Stem ◽  
Head Rotation ◽  
Head Motion ◽  
Vestibuloocular Reflex ◽  
Neural Basis ◽  
Ventral Paraflocculus ◽  
The Brain

1. We recorded from neurons in the brain stem of monkeys before and after they had worn magnifying or miniaturizing spectacles to cause changes in the gain of the vestibuloocular reflex (VOR). The gain of the VOR was estimated as eye speed divided by head speed during passive horizontal head rotation in darkness. Electrical stimulation in the cerebellum was used to identify neurons that receive inhibition at monosynaptic latencies from the flocculus and ventral paraflocculus (flocculus target neurons or FTNs). Cells were studied during smooth pursuit eye movements with the head stationary, fixation of different positions, cancellation of the VOR, and the VOR evoked by rapid changes in head velocity. 2. FTNs were divided into two populations according to their responses during pursuit with the head stationary. The two groups showed increased firing during smooth eye motion toward the side of recording (Eye-ipsiversive or E-i) or away from the side of recording (Eye-contraversive or E-c). A higher percentage of FTNs showed increased firing rate for contraversive pursuit when the gain of the VOR was high (> or = 1.6) than when the gain of the VOR was low (< or = 0.4). 3. Changes in the gain of the VOR had a striking effect on the responses during the VOR for the FTNs that were E-c during pursuit with the head stationary. Firing rate increased during contraversive VOR eye movements when the gain of the VOR was high or normal and decreased during contraversive VOR eye movements when the gain of the VOR was low. Changes in the gain of the VOR caused smaller changes in the responses during the VOR of FTNs that were E-i during pursuit with the head stationary. We argue that motor learning in the VOR is the result of changes in the responses of individual FTNs. 4. The responses of E-i and E-c FTNS during cancellation of the VOR depended on the gain of the VOR. Responses tended to be in phase with contraversive head motion when the gain of the VOR was low and in phase with ipsiversive head motion when the gain of the VOR was high. Comparison of the effect of motor learning on the responses of FTNs during cancellation of the VOR with the results of similar experiments on horizontal-gaze velocity Purkinje cells in the flocculus and ventral paraflocculus suggests that the brain stem vestibular inputs to FTNs are one site of motor learning in the VOR.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Crossed activation of thoracic trunk motoneurons by medullary reticulospinal neurons

2019 ◽  
Vol 122 (6) ◽  
pp. 2601-2613
Author(s):  
Brandon K. LaPallo ◽  
Andrea Giorgi ◽  
Marie-Claude Perreault
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Brain Stem ◽  
Neural Circuits ◽  
Single Cells ◽  
The Other ◽  
Medullary Reticular Formation ◽  
Functional Connections ◽  
Cord Injury ◽  
The Brain

Activation of contralateral muscles by supraspinal neurons, or crossed activation, is critical for bilateral coordination. Studies in mammals have focused on the neural circuits that mediate cross activation of limb muscles, but the neural circuits involved in crossed activation of trunk muscles are still poorly understood. In this study, we characterized functional connections between reticulospinal (RS) neurons in the medial and lateral regions of the medullary reticular formation (medMRF and latMRF) and contralateral trunk motoneurons (MNs) in the thoracic cord (T7 and T10 segments). To do this, we combined electrical microstimulation of the medMRF and latMRF and calcium imaging from single cells in an ex vivo brain stem-spinal cord preparation of neonatal mice. Our findings substantiate two spatially distinct RS pathways to contralateral trunk MNs. Both pathways originate in the latMRF and are midline crossing, one at the level of the spinal cord via excitatory descending commissural interneurons (reticulo-commissural pathway) and the other at the level of the brain stem (crossed RS pathway). Activation of these RS pathways may enable different patterns of bilateral trunk coordination. Possible implications for recovery of trunk function after stroke or spinal cord injury are discussed. NEW & NOTEWORTHY We identify two spatially distinct reticulospinal pathways for crossed activation of trunk motoneurons. Both pathways cross the midline, one at the level of the brain stem and the other at the level of the spinal cord via excitatory commissural interneurons. Jointly, these pathways provide new opportunities for repair interventions aimed at recovering trunk functions after stroke or spinal cord injury.

Spatial summation and center-surround antagonism in the receptive field of single units in the dorsal lateral geniculate nucleus of cat: Comparison with retinal input

2000 ◽  
Vol 17 (6) ◽  
pp. 855-870 ◽  
Author(s):  
O. RUKSENAS ◽  
I.T. FJELD ◽  
P. HEGGELUND
Keyword(s):  
Receptive Field ◽  
Lateral Geniculate Nucleus ◽  
Cell Response ◽  
Spatial Summation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Relay Cell ◽  
Transfer Ratio ◽  
Retinal Input ◽  
X Cells ◽  
Dorsal Lateral Geniculate

Spatial summation and degree of center-surround antagonism were examined in the receptive field of nonlagged cells in the dorsal lateral geniculate nucleus (dLGN). We recorded responses to stationary light or dark circular spots that were stepwise varied in width. The spots were centered on the receptive field. For a sample of nonlagged X-cells, we made simultaneous recordings of action potentials and S-potentials, and could thereby compare spatial summation in the dLGN cell and in the retinal input to the cell. Plots of response versus spot diameter showed that the response for a dLGN cell was consistently below the response in the retinal input at all spot sizes. There was a marked increase of antagonism at the retinogeniculate relay. The difference between the retinal input and dLGN cell response suggested that the direct retinal input to a relay cell is counteracted in dLGN by an inhibitory field that has an antagonistic center-surround organization. The inhibitory field seems to have the same center sign (ON- or OFF-center), but a wider receptive-field center than the direct retinal input to the relay cell. The broader center of the inhibitory field can explain the increased center-surround antagonism at the retinogeniculate relay. The ratio between the response of a dLGN cell and its retinal input (transfer ratio) varied with spot width. This variation did not necessarily reflect a nonlinearity at the retinogeniculate relay. Plots of dLGN cell response against retinal input were piecewise linear, suggesting that both excitatory and inhibitory transmission in dLGN are close to linear. The variation in transfer ratio could be explained by sustained suppression evoked by the background stimulation, because such suppression has relatively stronger effect on the response to a spot evoking weak response than to a spot evoking a strong response. A simple model for the spatial receptive-field organization of nonlagged X-cells, that is consistent with our findings, is presented.

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