Pharmacological inactivation of pretectal nuclei reveals different modulatory effects on retino-geniculate transmission by X and Y cells in the cat

1995 ◽  
Vol 12 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Klaus Funke ◽  
Ulf T. Eysel

AbstractThe modulatory influence of pretectal neurons on retino-geniculate transmission in the cat was studied by cross-correlation analysis of single-unit activity simultaneously recorded from the dorsal lateral geniculate nucleus (dLGN) and the pretectum (PT) and with reversible inactivation of the PT by GABA microiontophoresis during simultaneous visual stimulation of PT and dLGN neurons. Visually induced population activity in PT nuclei was achieved by a moving (or counterphasing) grating which was presented in the background of the light spot used to stimulate the dLGN neuron. As a control, the light spot was presented on a stationary grating to avoid stimulation of PT neurons but to yield the same illumination of the background. Extracellularly recorded dLGN relay cells of the X- and Y-type were found to be differentially affected by the PT-dLGN projection. During visual stimulation of PT cells, X cells were strongly inhibited and this effect was significantly reduced during PT inactivation. By contrast, the visual responses of most Y cells were affected neither by PT stimulation nor by PT inactivation. In addition, the temporal structure of spike patterns during the light response was examined with autocorrelograms and spike-interval distributions. X-on cells often exhibited a multimodal interval distribution and oscillatory type of activity. During stimulation of the PT interval distributions changed in a characteristic manner and oscillations disappeared. Both effects could be almost totally cancelled by PT inactivation. By contrast, the temporal structure of Y-cell responses was not affected. Our results demonstrate for the first time a pretectal modulation of retino-geniculate transmission in cat dLGN which is clearly different for X and Y cells. This influence seems to be mediated via (inhibitory) interneurons, since we found no indication for a direct coupling between PT and dLGN units. This projection might contribute to the well-known phenomenon of saccadic suppression.

1998 ◽  
Vol 15 (4) ◽  
pp. 711-729 ◽  
Author(s):  
KLAUS FUNKE ◽  
ULF T. EYSEL

Action potentials of single perigeniculate (PGN) cells and relay cells of the dorsal lateral geniculate nucleus (dLGN) with topographically matched or at least partially overlapping receptive fields (RF) were simultaneously recorded in the anesthetized and paralyzed cat during visual stimulation with moving gratings or flashing light spots of different size. In many cases, PGN cells showed an activity pattern which appeared like a mirror image of distinct periods of dLGN activity. Flashing spots evoked transient volleys of activity in PGN cells which increased in strength and shortened in latency with increasing size of the stimulus. These responses were temporally matched with inhibitory phases in the early part of visual responses in the dLGN. The spatio-temporal properties of the RFs were established by reverse correlation of the spike activity with the spatially random presentation of bright and dark spots within an array of 20 × 20 positions. Anticorrelated firing patterns of such kind could also be elicited as interocular inhibition with stimulation of the perigeniculate RF in the nondominant eye. Inversely correlated changes in spontaneous and visually induced activity were also visible during spontaneous changes in EEG pattern. With increasing synchronization of the EEG (predominance of delta-waves) the strength of geniculate visual responses declined while maintained perigeniculate activity increased. A weakened interocular and monocular inhibition of dLGN relay cells during visual stimulation of PGN RFs could be achieved with local reversible inactivation of PGN areas topographically matched with the dLGN recording sites. The results indicate that the PGN contributes to the state-dependent control of retino-geniculate transmission and to the monocular and interocular inhibitory processes that shape the visual responses in the dLGN.


1990 ◽  
Vol 63 (2) ◽  
pp. 347-355 ◽  
Author(s):  
A. M. Sillito ◽  
P. C. Murphy ◽  
T. E. Salt ◽  
C. I. Moody

1. We have examined the possibility that N-methyl-D-aspartate (NMDA) receptors may be involved in the visual response of relay cells in the cat dorsal lateral geniculate nucleus (dLGN). The selective NMDA receptor antagonists D-2-amino-5-phosphonovalerate (APV) and 3-[(+/-)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid (CPP) have been iontophoretically applied to X and Y cells in the dLGN and their effects on the visual response to a light spot flashed within the receptive field center determined. 2. The antagonist effects were assessed at ejection current levels producing a selective blockade of the responses to iontophoretically applied NMDA with respect to those elicited by the non-NMDA receptor agonists quisqualate and kainate. These selective effects were determined in an experimental paradigm where the visual response and responses to NMDA and the non-NMDA receptor agonists were compared in the same test run. The data refer to a total population of 52 cells (28 X, 24 Y). 3. Application of APV abolished or greatly reduced the visual responses of both X and Y cells. The mean percentage reduction in the visual response for the X cells studied was 59 +/- 10% (SE; n = 7) and for the Y cells 66 +/- 8% (SE; n = 11). Both the early onset transient and the sustained component of the visual response to the flashed stimulus were equally affected. 4. The antagonist CPP produced a similar pattern of effect to APV, substantially reducing or abolishing the visual response in both X and Y cells.(ABSTRACT TRUNCATED AT 250 WORDS)


1995 ◽  
Vol 73 (4) ◽  
pp. 1414-1421 ◽  
Author(s):  
T. Shou ◽  
A. G. Leventhal ◽  
K. G. Thompson ◽  
Y. Zhou

1. It has been reported that in the cat only a specialized group of retinal ganglion cells constituting approximately 1% of the overall population are direction sensitive. Two major groups of retinal ganglion cells, the X and Y cells, have been reported not to be sensitive to the direction of stimulus motion. 2. We recorded action potentials of retinal ganglion cells intraocularly. We studied quantitatively the visual responses elicited by drifting sinusoidal gratings of various spatial frequencies, bars, and spots. 3. The results confirm previous reports that most cat retinal ganglion cells exhibit orientation biases when tested with gratings of relatively high spatial frequency. 4. Additionally, we find that 22% of X and 34% of Y type retinal ganglion cells exhibit direction biases. Overall, Y cells displayed significantly stronger direction biases than did X cells. 5. In general, direction biases are clearest when the test gratings are of relatively low spatial frequency. 6. The direction biases of X and Y cells subserving the central 15 degrees of retina were weaker than those of cells subserving more peripheral regions. 7. The direction-biased responses of cat ganglion cells were similar to those of X and Y type relay cells in the cat dorsal lateral geniculate nucleus (LGNd). Thus we suggest that the direction biases of LGNd cells are a reflection of their retinal inputs.


1998 ◽  
Vol 15 (2) ◽  
pp. 197-210 ◽  
Author(s):  
W.H. FISCHER ◽  
M. SCHMIDT ◽  
K.-P. HOFFMANN

The influence of neurons projecting from the pretectal nuclear complex to the ipsilateral dorsal lateral geniculate nucleus (LGNd) was investigated in awake cats. Responses from relay cells in the A-laminae of the LGNd were extracellularly recorded and analyzed during saccadic eye movements and visual stimulation in association with reversible inactivation of the ipsilateral pretectum with the GABA agonist, muscimol. Pretectal inactivation (PTI) resulted in spontaneous nystagmic eye movements in the dark with slow phases directed away from the injected side. In the control situation, all Y-cells and about two thirds of X-cells were excited during saccades or saccade-like visual stimulation but one third of X-cells were inhibited. During PTI all recorded X-cells were inhibited, either during saccades or saccade-like visual stimulation. The PTI-associated inhibition was stronger than in inhibited X-cells in control experiments only during saccades but not during stimulation with a moving pattern while the eyes were stationary. In Y-cells a reduction in the response peak width at half-height was seen during PTI, again only during saccades but not during stimulation with a moving pattern. These results indicate that during saccades the pretecto-geniculate pathway has a stronger influence on X LGNd relay cells than on Y-cells. The findings are discussed in terms of saccadic suppression and postsaccadic facilitation.


1986 ◽  
Vol 56 (2) ◽  
pp. 523-541 ◽  
Author(s):  
J. S. Tootle ◽  
M. J. Friedlander

We recorded the responses to visual stimulation of single neurons in the A-layers of the dorsal lateral geniculate nucleus (LGNd) of 4- to 5-wk-old kittens and adult cats. Visual stimuli were generated on a cathode-ray tube (CRT) display and consisted of circular spots and annuli whose contrast was twice the threshold for each neuron and was modulated about a background luminance of 28 cd/m2 at 0.5 Hz. Neural responses were collected as interspike intervals and displayed as instantaneous firing rates for individual trials. From the responses to a series of sizes of spot stimuli, area-response functions were constructed and used to derive a quantitative measure of the strength of the receptive field (RF) surround inhibition of each neuron, the spatial density minimum ([SDmin[). To separate neural from optical factors that affect measurements of surround inhibition, published values for the posterior nodal distances of the kitten and adult eye were used to scale stimuli in terms of the retinal area subtended. Of 153 kitten and 95 adult LGNd neurons studied, the responses to a complete series of spot stimuli of different sizes (areas) were obtained for 52 kitten neurons [44 with linear spatial summation (L) and 8 with nonlinear spatial summation (NL)] and 45 adult (24 X-and 21 Y-) neurons. In addition, intracellular recordings were made from 30 of the kitten neurons that were filled iontophoretically with horseradish peroxidase (HRP) and were evaluated structurally. In the adult, neurons were classified as X-or Y-cells on the basis of a battery of physiological properties, including linearity of spatial summation, latency to electrical stimulation of the optic chiasm, and ability to respond reliably to rapidly moving stimuli. Kitten neuronal responses allowed them to be clearly identified as exhibiting linear or nonlinear spatial summation, but application of additional criteria produced ambiguous results for classification into X-or Y-categories. Kitten L or NL neurons showed differences typical of adult X-and Y-cells on some [e.g., RF center size (P less than 0.01)] but not other [e.g., latency to stimulation of optic chiasm (P greater than 0.40)] properties. In addition, by direct comparison of morphological features with these physiological responses, some kitten cells with adult X-cell physiological properties on these tests were found to have typical adult Y-cell somadendritic structure.(ABSTRACT TRUNCATED AT 400 WORDS)


1983 ◽  
Vol 50 (1) ◽  
pp. 240-264 ◽  
Author(s):  
S. C. Mangel ◽  
J. R. Wilson ◽  
S. M. Sherman

We measured response properties of X- and Y-cells from laminae A and A1 of the dorsal lateral geniculate nucleus of monocularly lid-sutured cats at 8, 12, 16, 24, and 52-60 wk of age. Visual stimuli consisted of small spots of light and vertically oriented sine-wave gratings counterphased at a rate of 2 cycles/s. In cats as young as 8 wk of age, nondeprived and deprived neurons could be clearly identified as X-cells or Y-cells with criteria previously established for adult animals. Nonlinear responses of Y-cells from 8- and 12-wk-old cats were often temporally labile; that is, the amplitude of the nonlinear response of nondeprived and deprived cells increased or decreased suddenly. A similar lability was not noted for the linear response component. This phenomenon rarely occurred in older cats. At 8 wk of age, Y-cell proportions (number of Y-cells/total number of cells) in nondeprived and deprived A-laminae were approximately equal. By 12 wk of age and thereafter, the proportion of Y-cells in deprived laminae was significantly lower than that in nondeprived laminae. At no age was there a systematic difference in response properties (spatial resolution, latency to optic chiasm stimulation, etc.) for Y-cells between deprived and nondeprived laminae. Spatial resolution, defined as the highest spatial frequency to which a cell would respond at a contrast of 0.6, was similar for nondeprived and deprived X-cells until 24 wk of age. In these and older cats, the mean spatial resolution of deprived X-cells was lower than that of nondeprived X-cells. This difference was noted first for lamina A1 at 24 wk of age and later for lamina A at 52-60 wk of age. The average latency of X-cells to optic chiasm stimulation was slightly greater in deprived laminae than in nondeprived laminae. No such difference was seen for Y-cells. Cells with poor and inconsistent responses were encountered infrequently but were observed far more often in deprived laminae than in nondeprived laminae. Lid suture appears to affect the development of geniculate X- and Y-cells in very different ways. Not only is the final pattern of abnormalities quite different between these cell groups, but the developmental dynamics of these abnormalities also differ.


1994 ◽  
Vol 11 (6) ◽  
pp. 1163-1173 ◽  
Author(s):  
Richard D. Mooney ◽  
Yi Zhang ◽  
Robert W. Rhoades

AbstractSuperficial layer superior colliculus (SC) neurons were recorded extracellularly with multibarreled recording/ejecting micropipettes. Angiotensin II was delivered via micropressure ejection during visual stimulation (n = 215 cells), or during electrical stimulation of either the optic chiasm (OX; n = 150 cells) or visual cortex (CTX; n = 42 cells). Application of angiotensin II decreased visual responses of SC cells to 43.8% ± 30.7% (mean ± S.D.) and reduced responses to electrical stimulation of the OX and CTX to 58.6% ± 34.1% and 43.8% ± 30.7% of control values, respectively. Angiotensin II enhanced responses by at least 30% in only 6 cells (1.5%). Of the 35 neurons tested with both OX and CTX stimulation, the correlation of evoked response suppression by angiotensin II was highly significant (r = 0.69; P < 0.001). This suggests that the suppressive effects of angiotensin II were common to both pathways. To test whether the inhibitory effects of angiotensin II were presynaptic or postsynaptic, Mg2+ ions were ejected iontophoretically to abolish synaptic responses, and the neurons were activated by iontophoresis of glutamate and then tested with angiotensin II. Angiotensin II reduced the glutamate-evoked responses to an average 29.1% ± 21.1% of control values (n = 9 cells). This suggests that the site of action of angiotensin II is most likely postsynaptic. To identify which receptors were involved in these effects, angiotensin II was ejected concurrently with the AT1 antagonist Losartan (DUP753) or with either of two AT2 antagonists, CGP42112A or PD123177. Losartan antagonized the action of angiotensin II in 65.6% of the cells tested (n = 99) and CGP42112A and PD123177 had antagonistic effects in 58% (n = 65) and 60% (n = 5), respectively. Both classes of antagonists were tested in 29 cells; and there was no significant correlation between their effectiveness. These results suggest that both AT1, and AT2 receptors may independently mediate the suppressive effects of angiotensin II, and that collicular neurons may have either or both receptor subtypes.


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