Effects of angiotensin II on visual neurons in the superficial laminae of the hamster's superior colliculus

1994 ◽  
Vol 11 (6) ◽  
pp. 1163-1173 ◽  
Author(s):  
Richard D. Mooney ◽  
Yi Zhang ◽  
Robert W. Rhoades
Keyword(s):  
Electrical Stimulation ◽  
Angiotensin Ii ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Optic Chiasm ◽  
Superficial Layer ◽  
Receptor Subtypes ◽  
Visual Responses ◽  
Visual Neurons ◽  
Stimulation Of

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.

Effects of neurotensin on visual neurons in the superficial laminae of the hamster's superior colliculus

1996 ◽  
Vol 13 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Yi Zhang ◽  
Richard D. ◽  
Carol A. Bennett-Clarke ◽  
Robert W. Rhoades
Keyword(s):  
Electrical Stimulation ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Optic Chiasm ◽  
Superficial Layer ◽  
Visual Responses ◽  
Unit Recording ◽  
Visual Neurons ◽  
Standard Deviation Range ◽  
Stimulation Of

AbstractAutoradiography with 125I-neurotensin in normal and enucleated hamsters was used to define the distribution of receptors for this peptide in the superficial layers of the superior colliculus (SC). Neurotensin binding sites were densely distributed in the stratum griseum superficiale (SGS), and results from the enucleated animals indicated that they were not located on retinal axons. The effects of neurotensin on individual superficial layer cells were tested in single-unit recording experiments. Neurotensin was delivered via micropressure ejection during visual stimulation (n = 75 cells), or during electrical stimulation of either the optic chiasm (OX; n = 47 cells) or visual cortex (CTX; n = 29 cells). In comparison with control values, application of neurotensin decreased visual responses of all SC cells tested to 54.1 ± 34.9% (mean ± standard deviation; range of decrement 7.5 to 100%; nine cells showed no effect or an increase in visual activity, which for four of these was ≥30%). Neurotensin application also reduced responses to electrical stimulation of either OX or CTX, respectively, to 65.8 ± 36.5% of control values (range of decrement 2.6 to 97.4%; 12 neurons showed a weak increment ≤ 30%) and 68.0 ± 38.5% (range of decrement 3.3 to 100%; five cells showed no effect or an increment, in one case ≥ 30%). Of the 25 neurons tested with both OX and CTX stimulation, the correlation of evoked response suppression by neurotensin was highly significant (r = 0.70; P < 0.001). This suggests that the suppressive effects of neurotensin were common to both pathways. To test whether the inhibitory effects of neurotensin were presynaptic or postsynaptic, Mg2+ ions were ejected iontophoretically to abolish synaptic responses, and the neurons (n = 16) were activated by iontophoresis of glutamate and then tested with neurotensin. Neurotensin reduced the glutamate-evoked responses to an average 59.3 ± 37.9% of control values (range 2.3 to 92.5%; one cell showed an increment >30%). This result suggests that the site of action of neurotensin is most likely postsynaptic.

Effects of norepinephrine on the activity of visual neurons in the superior colliculus of the hamster

1999 ◽  
Vol 16 (3) ◽  
pp. 541-555 ◽  
Author(s):  
YI ZHANG ◽  
RICHARD D. MOONEY ◽  
ROBERT W. RHOADES
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Optic Chiasm ◽  
Evoked Responses ◽  
Visual Responses ◽  
Signal To Noise ◽  
Direct Stimulation ◽  
Stimulation Of

Single-unit recording and micropressure ejection techniques were used to test the effects of norepinephrine (NE) on the responses of neurons in the superficial layers (the stratum griseum superficiale and stratum opticum) of the hamster's superior colliculus (SC). Application of NE suppressed visually evoked responses by ≥30% in 75% of 40 neurons tested and produced ≥30% augmentation of responses in only 5%. The decrement in response strength was mimicked by application of the α2 adrenoceptor agonist, p-aminoclonidine, the nonspecific β agonist, isoproterenol, and the β1 agonist, dobutamine. These agents had similar effects on responses evoked by electrical stimulation of the optic chiasm and visual cortex. The α1 agonist, methoxamine, augmented the light-evoked responses of 53% of 49 SC cells by ≥30%, but had little effect on responses evoked by electrical stimulation of optic chiasm or visual cortex. The effects of adrenergic agonists upon the glutamate-evoked responses of SC cells that were synaptically “isolated” by concurrent application of Mg2+ were similar to those obtained during visual stimulation. Analysis of effects of NE on visually evoked and background activity indicated that application of this amine did not significantly enhance signal-to-noise ratios for most superficial layer SC neurons, and signal-to-noise ratios were in some cases reduced. These results indicate that NE acts primarily through α2 and β1 receptors to suppress the visual responses of SC neurons. Activation of either of these receptors reduces the responses of SC neurons to either of their two major visual inputs as well as to direct stimulation by glutamate, and it would thus appear that these effects are primarily postsynaptic.

Effects of serotonin on retinotectal-, corticotectal-, and glutamate-induced activity in the superior colliculus of the hamster

1993 ◽  
Vol 70 (2) ◽  
pp. 723-732 ◽  
Author(s):  
X. Huang ◽  
R. D. Mooney ◽  
R. W. Rhoades
Keyword(s):  
Superior Colliculus ◽  
Optic Chiasm ◽  
Superficial Layer ◽  
Response Suppression ◽  
Visual Response ◽  
Evoked Responses ◽  
Average Response ◽  
Visual Responses ◽  
Unit Recording ◽  
Visual Cortical

1. Single-unit recording and iontophoretic techniques were used to test the effects of serotonin (5-HT) on the responses of neurons in the superficial layers (the stratum griseum superficiale and stratum opticum) of the hamster's superior colliculus (SC). 2. Iontophoresis of 5-HT produced a visual response suppression of 40% or greater in 78.1% (n = 50) of 64 neurons tested. 5-HT did not augment the visual responses of any of the cells tested. The average response suppression was 75.3 +/- 21.2% (mean +/- S.D.). 3. Iontophoresis of 5-HT had significantly different effects on activation of SC cells by optic chiasm (OX) and visual cortical (CTX) stimulation. Application of 5-HT suppressed the OX-evoked responses of 96.9% (n = 31) of the 32 SC cells tested by at least 40%, and the average response suppression for all 32 neurons tested was 87.1 +/- 22.5%. Application of 5-HT suppressed the responses of only 35.7% (n = 10) of the 28 cells tested with CTX stimulation by at least 40%. The average response suppression for all 28 cells was 35.3 +/- 38.8%. 4. The effects of 5-HT on the glutamate-evoked responses of SC cells that were synaptically "isolated" by concurrent application of Mg2+ were also evaluated. Application of 5-HT produced a response suppression > or = 40% in 29.7% (n = 19) of the 64 neurons tested under these conditions. The average response suppression for all of the cells tested was 28.4 +/- 35.7%. This effect of 5-HT was significantly weaker than that on visually evoked responses of these neurons. 5. The present results demonstrate that 5-HT markedly depresses the visual responses of most superficial layer SC neurons. They suggest further that much of this effect is mediated by presynaptic inhibition of retinotectal transmission.

scholarly journals Frontal Eye Field Neurons Orthodromically Activated From the Superior Colliculus

1998 ◽  
Vol 80 (6) ◽  
pp. 3331-3335 ◽  
Author(s):  
Marc A. Sommer ◽  
Robert H. Wurtz
Keyword(s):  
Electrical Stimulation ◽  
Superior Colliculus ◽  
Direct Evidence ◽  
Visual Stimulation ◽  
Saccadic Eye Movements ◽  
Frontal Eye Field ◽  
Anatomical Studies ◽  
Eye Field ◽  
To Receive ◽  
Stimulation Of

Sommer, Marc A. and Robert H. Wurtz. Frontal eye field neurons orthodromically activated from the superior colliculus. J. Neurophysiol. 80: 3331–3333, 1998. Anatomical studies have shown that the frontal eye field (FEF) and superior colliculus (SC) of monkeys are reciprocally connected, and a physiological study described the signals sent from the FEF to the SC. Nothing is known, however, about the signals sent from the SC to the FEF. We physiologically identified and characterized FEF neurons that are likely to receive input from the SC. Fifty-two FEF neurons were found that were orthodromically activated by electrical stimulation of the intermediate or deeper layers of the SC. All the neurons that we tested ( n = 34) discharged in response to visual stimulation. One-half also discharged when saccadic eye movements were made. This provides the first direct evidence that the ascending pathway from SC to FEF might carry visual- and saccade-related signals. Our findings support a hypothesis that the SC and the FEF interact bidirectionally during the events leading up to saccade generation.

scholarly journals Decoding network-mediated retinal response to electrical stimulation: implications for fidelity of prosthetic vision

2020 ◽  
Author(s):  
Elton Ho ◽  
Alex Shmakov ◽  
Daniel Palanker
Keyword(s):  
Electrical Stimulation ◽  
Visual Stimulation ◽  
Ganglion Cells ◽  
Signal To Noise Ratio ◽  
Population Level ◽  
Sufficient Information ◽  
Visual Responses ◽  
Natural Vision ◽  
Retinal Response ◽  
Stimulation Of

AbstractObjectivePatients with the photovoltaic subretinal implant PRIMA demonstrated letter acuity by ~0.1 logMAR worse than the sampling limit for 100μm pixels (1.3 logMAR) and performed slower than healthy subjects, which exceeded the sampling limit at equivalently pixelated images by ~0.2 logMAR. To explore the underlying differences between the natural and prosthetic vision, we compare the fidelity of the retinal response to visual and subretinal electrical stimulation through single-cell modeling and ensemble decoding.ApproachResponses of the retinal ganglion cells (RGC) to optical or electrical (1mm diameter arrays, 75μm pixels) white noise stimulation in healthy and degenerate rat retinas were recorded via MEA. Each RGC was fit with linear-non-linear (LN) and convolutional neural network (CNN) models. To characterize RGC noise level, we compared statistics of the spike-triggered average (STA) in RGCs responding to electrical or visual stimulation of healthy and degenerate retinas. At the population level, we constructed a linear decoder to determine the certainty with which the ensemble of RGCs can support the N-way discrimination tasks.Main resultsAlthough LN and CNN models can match the natural visual responses pretty well (correlation ~0.6), they fit significantly worse to spike timings elicited by electrical stimulation of the healthy retina (correlation ~0.15). In the degenerate retina, response to electrical stimulation is equally bad. The signal-to-noise ratio of electrical STAs in degenerate retinas matched that of the natural responses when 78±6.5% of the spikes were replaced with random timing. However, the noise in RGC responses contributed minimally to errors in the ensemble decoding. The determining factor in accuracy of decoding was the number of responding cells. To compensate for fewer responding cells under electrical stimulation than in natural vision, larger number of presentations of the same stimulus are required to deliver sufficient information for image decoding.SignificanceSlower than natural pattern identification by patients with the PRIMA implant may be explained by the lower number of electrically activated cells than in natural vision, which is compensated by a larger number of the stimulus presentations.

Activity of monkey frontal eye field neurons projecting to oculomotor regions of the pons

1992 ◽  
Vol 68 (6) ◽  
pp. 1967-1985 ◽  
Author(s):  
M. A. Segraves
Keyword(s):  
Electrical Stimulation ◽  
Visual Stimulation ◽  
Saccadic Eye Movements ◽  
Frontal Eye Field ◽  
Related Activity ◽  
Burst Neurons ◽  
Eye Field ◽  
Movement Field ◽  
Omnipause Neurons ◽  
Stimulation Of

1. This study identified neurons in the rhesus monkey's frontal eye field that projected to oculomotor regions of the pons and characterized the signals sent by these neurons from frontal eye field to pons. 2. In two behaving rhesus monkeys, frontal eye field neurons projecting to the pons were identified via antidromic excitation by a stimulating microelectrode whose tip was centered in or near the omnipause region of the pontine raphe. This stimulation site corresponded to the nucleus raphe interpositus (RIP). In addition, electrical stimulation of the frontal eye field was used to demonstrate the effects of frontal eye field input on neurons in the omnipause region and surrounding paramedian pontine reticular formation (PPRF). 3. Twenty-five corticopontine neurons were identified and characterized. Most frontal eye field neurons projecting to the pons were either movement neurons, firing in association with saccadic eye movements (48%), or foveal neurons responsive to visual stimulation of the fovea combined with activity related to fixation (28%). Corticopontine movement neurons fired before, during, and after saccades made within a restricted movement field. 4. The activity of identified corticopontine neurons was very similar to the activity of neurons antidromically excited from the superior colliculus where 59% had movement related activity, and 22% had foveal and fixation related activity. 5. High-intensity, short-duration electrical stimulation of the frontal eye field caused omnipause neurons to stop firing. The cessation in firing appeared to be immediate, within < or = 5 ms. The time that the omnipause neuron remained quiet depended on the intensity of the cortical stimulus and lasted up to 30 ms after a train of three stimulus pulses lasting a total of 6 ms at an intensity of 1,000 microA. Low-intensity, longer duration electrical stimuli (24 pulses, 75 microA, 70 ms) traditionally used to evoke saccades from the frontal eye field were also followed by a cessation in omnipause neuron firing, but only after a delay of approximately 30 ms. For these stimuli, the omnipause neuron resumed firing when the stimulus was turned off. 6. The same stimuli that caused omnipause neurons to stop firing excited burst neurons in the PPRF. The latency to excitation ranged from 4.2 to 9.8 ms, suggesting that there is at least one additional neuron between frontal eye field neurons and burst neurons in the PPRF. 7. The present study confirms and extends the results of previous work, with the use of retrograde and anterograde tracers, demonstrating direct projections from the frontal eye field to the pons.(ABSTRACT TRUNCATED AT 400 WORDS)

Visual responses of pulvinar and collicular neurons during eye movements of awake, trained macaques

1991 ◽  
Vol 66 (2) ◽  
pp. 485-496 ◽  
Author(s):  
D. L. Robinson ◽  
J. W. McClurkin ◽  
C. Kertzman ◽  
S. E. Petersen
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Receptive Fields ◽  
Visual Responses ◽  
Stimulus Motion ◽  
Stimulus Movement ◽  
Pursuit Eye Movements ◽  
Extraretinal Signal ◽  
Wide Range

1. We recorded from single neurons in awake, trained rhesus monkeys in a lighted environment and compared responses to stimulus movement during periods of fixation with those to motion caused by saccadic or pursuit eye movements. Neurons in the inferior pulvinar (PI), lateral pulvinar (PL), and superior colliculus were tested. 2. Cells in PI and PL respond to stimulus movement over a wide range of speeds. Some of these cells do not respond to comparable stimulus motion, or discharge only weakly, when it is generated by saccadic or pursuit eye movements. Other neurons respond equivalently to both types of motion. Cells in the superficial layers of the superior colliculus have similar properties to those in PI and PL. 3. When tested in the dark to reduce visual stimulation from the background, cells in PI and PL still do not respond to motion generated by eye movements. Some of these cells have a suppression of activity after saccadic eye movements made in total darkness. These data suggest that an extraretinal signal suppresses responses to visual stimuli during eye movements. 4. The suppression of responses to stimuli during eye movements is not an absolute effect. Images brighter than 2.0 log units above background illumination evoke responses from cells in PI and PL. The suppression appears stronger in the superior colliculus than in PI and PL. 5. These experiments demonstrate that many cells in PI and PL have a suppression of their responses to stimuli that cross their receptive fields during eye movements. These cells are probably suppressed by an extraretinal signal. Comparable effects are present in the superficial layers of the superior colliculus. These properties in PI and PL may reflect the function of the ascending tectopulvinar system.

scholarly journals Characterization of Prejunctional Muscarinic Receptors: Effects on the Release of VIP and Functional Responses and Receptor Expression in the Ovine Submandibular Gland

2009 ◽  
Vol 2009 ◽  
pp. 1-6
Author(s):  
Anders T. Ryberg ◽  
Ondrej Soukup ◽  
Gunnar Tobin
Keyword(s):  
Electrical Stimulation ◽  
Submandibular Gland ◽  
Muscarinic Receptor ◽  
Muscarinic Receptors ◽  
Receptor Expression ◽  
Receptor Subtypes ◽  
Chorda Tympani Nerve ◽  
Functional Responses ◽  
Stimulation Of

In the in vivo experiments on anaesthetized sheep, it was presently examined whether muscarinic receptor antagonists with diverse selectivity affect the release of VIP in response to electrical stimulation of the parasympathetic chorda tympanic nerve differently, and if the changes in the release could be associated to altered secretory and vasodilator responses. The location of the muscarinic receptor subtypes was examined also. In the experiments, blood was collected out of the submandibular venous drainage before and during electrical stimulation of chorda tympani nerve in the absence and presence either of pirenzepine or methoctramine. While metchoctramine increased the output of protein, pirenzepine inhibited flow of saliva and increased protein output, vasodilatation, and VIP output. In morphological examinations, the inhibitory muscarinic M4 receptor occurred interacinarily in the gland. It is concluded that prejunctional muscarinic receptors, most likely of the M4 subtype, exert inhibitory modulation of the parasympathetic release of VIP in the ovine submandibular gland.

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