Binocular competition affects the pattern and intensity of ocular activation columns in the visual cortex of cats

1989 ◽  
Vol 2 (4) ◽  
pp. 391-407 ◽  
Author(s):  
N. Tumosa ◽  
S. B. Tieman ◽  
D. G. Tieman
Keyword(s):  
Visual Cortex ◽  
Competitive Advantage ◽  
Monocular Deprivation ◽  
Area 17 ◽  
Large Area ◽  
Cortical Cells ◽  
Areas 17 And 18 ◽  
Binocular Competition ◽  
Video Densitometry ◽  
Average Size

AbstractThe effect of binocular competition on the development of ocular activation columns in areas 17 and 18 of cats was studied using the 14C-2-deoxyglucose (14C-2DG) technique to visualize the regions of cortex activated by one eye in cats reared with equal alternating monocular exposure (equal AME), unequal AME, or monocular deprivation (MD). The average size of the ocular activation columns of the eye stimulated during administration of 2DG was positively correlated with the competitive advantage during rearing. In order of increasing percentage of visual cortex activated, the eyes were (1) deprived eye of MD cats, (2) less experienced eye of unequal AME cats, (3) either eye of equal AME cats, (4) more experienced eye of unequal AME cats, and (5) experienced eye of MD cats. In area 17, the shape of the activation columns also was affected by the relative experience of the eye. The columns of the deprived eye of MD cats were widest in layer IV, where they were about the same width as those of the less experienced eye of the unequal AME cats; in other layers they were narrower, sometimes disappearing altogether. In contrast, the activation columns of the less experienced eye of the unequal AME cats were about the same width in all layers. These results suggest that when one eye is placed at a severe disadvantage and receives no patterned input, as in MD, both geniculocortical connections and intracortical connections may be disrupted, but when the disadvantage is less, as in unequal AME, only the geniculocortical connections are disrupted.Binocular competition also affected the intensity of activation within columns in area 17. We used video densitometry to determine ratios of the amount of label in cortical and thalamic structures. Both the ratio of label in area 17 to that in the lateral geniculate nucleus (LGN) and the ratio of label in the binocular segment of area 17 to that in the monocular segment were significantly less for the deprived eye of MD cats than for any other group. These results suggest that even within the smaller activation columns, deprived geniculocortical afferents are relatively ineffective at driving cortical cells. This finding is consistent with earlier reports that the synapses from the deprived pathway are both morphologically abnormal and reduced in number. The cortical labeling for the less experienced eye of the unequal AME cats and the experienced eye of the MD cats were also significantly less than that in equal AME cats. The decreased labeling for the experienced eye activation columns suggests that, in order to cover an abnormally large area, afferents representing the experienced eye must make fewer synaptic contacts within that area and that there are intrinsic limits on the number of synapses that one axon can make.

Experience-dependent changes in NMDAR1 expression in the visual cortex of an animal model for amblyopia

2004 ◽  
Vol 21 (4) ◽  
pp. 653-670 ◽  
Author(s):  
KATHRYN M. MURPHY ◽  
KEVIN R. DUFFY ◽  
DAVID G. JONES
Keyword(s):  
Visual Cortex ◽  
Neural Plasticity ◽  
Visual Deprivation ◽  
Monocular Deprivation ◽  
Homeostatic Plasticity ◽  
Cortical Circuits ◽  
Central Visual Field ◽  
Binocular Competition ◽  
Binocular Deprivation ◽  
Cortical Representations

When normal binocular visual experience is disrupted during postnatal development, it affects the maturation of cortical circuits and often results in the development of poor visual acuity known as amblyopia. Two main factors contribute to the development of amblyopia: visual deprivation and reduced binocular competition. We investigated the affect of these two amblyogenic factors on the expression of the NMDAR1 subunit in the visual cortex because activation of the NMDA receptor is a key mechanism of developmental neural plasticity. We found that disruption of binocular correlations by monocular deprivation promoted a topographic loss of NMDAR1 expression within the cortical representations of the central visual field and the vertical and horizontal meridians. In contrast, binocular deprivation, which primarily affects visual deprivation, promoted an increase in NMDAR1 expression throughout the visual cortex. These different changes in NMDAR1 expression can be described as topographic and homeostatic plasticity of NMDA expression, respectively. In addition, the changes in NMDA expression in the visual cortex provide a greater understanding of the neural mechanisms that underlie the development of amblyopia and the potential for visual recovery.

Physiological effects of unequal alternating monocular exposure

1983 ◽  
Vol 49 (3) ◽  
pp. 804-818 ◽  
Author(s):  
D. G. Tieman ◽  
M. A. McCall ◽  
H. V. Hirsch
Keyword(s):  
Visual Cortex ◽  
Receptive Field ◽  
Single Cells ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Cortical Cells ◽  
Receptive Field Properties ◽  
Binocular Competition ◽  
Almost All

1. In order to investigate the effects of an imbalance in stimulation to the eyes without the confounding influence of continuous deprivation of one eye, we reared cats with unequal alternating monocular exposure (AME) and, for comparison, cats with equal AME. We recorded extracellularly from single cells in area 17 of visual cortex. 2. For unequal AME cats, a majority of the cells that were visually responsive were dominated by the eye that had received more patterned visual experience. The percentage of cells dominated by the more experienced eye was greater with a large imbalance in stimulation to the two eyes (AME 8/1, 77%) than with a small imbalance (AME 8/4, 62%). 3. For both equal AME cats and unequal AME cats, we obtained evidence for differences in cells activated by the contralateral and by the ipsilateral afferents. a) In equal AME cats receiving only 1 h of exposure per day, we obtained a greater dominance by the contralateral eye (60%) than in equal AME cats receiving 8 h of exposure per day (42%). b) Although a large imbalance in stimulation (AME 8/1) resulted in a shift in ocular dominance in both cortical hemispheres, a moderate imbalance (AME 8/4) resulted in a smaller shift, which was apparent only in the hemisphere ipsilateral to the less-experienced eye. 4. The percentage of cortical cells responsive to each eye was uniform throughout the depth of cortex. Thus, for the unequal AME cats, cells activated by the less-experienced eye were no more frequent in layer IV of visual cortex than in the infragranular and supragranular layers. 5. Although almost all cells recorded from AME cats had relatively normal receptive-field properties, three receptive-field properties of cells in unequal AME cats showed an effect of the rearing. In each case cells dominated by the less-experienced eye and recorded in the cortical hemisphere ipsilateral to it showed the largest changes. These cells a) were more poorly tuned, b) had lower cutoff velocities, and c) had smaller receptive fields. 6. It is suggested that cortical cells that putatively receive Y-cell afferents from the dorsal lateral geniculate nucleus (LGNd) are more affected by an imbalance in stimulation than are cortical cells that putatively receive X-cell afferents. Thus, the decrease in mean receptive-field area and cutoff velocity for the cells dominated by the less-experienced eye is suggested to be due to a greater shift in ocular dominance by the cortical cells receiving Y-cell afferents from the LGNd. 7. The interaction between binocular competition and deprivation of pattern vision may contribute to differences between monocularly deprived cats and unequal AME cats.

Effects of vasoactive intestinal polypeptide on the response properties of cells in area 17 of the cat visual cortex

1993 ◽  
Vol 69 (5) ◽  
pp. 1465-1474 ◽  
Author(s):  
P. C. Murphy ◽  
K. L. Grieve ◽  
A. M. Sillito
Keyword(s):  
Visual Cortex ◽  
Spontaneous Activity ◽  
Vasoactive Intestinal Polypeptide ◽  
Signal To Noise Ratio ◽  
Response Magnitude ◽  
Visual Response ◽  
Area 17 ◽  
Signal To Noise ◽  
Cortical Cells ◽  
Cholinergic Agonist

1. Vasoactive intestinal polypeptide (VIP) was iontophoretically applied to a population of 90 single cells in the primary visual cortex (area 17) of the cat. Response magnitude, response selectivity, spontaneous activity, and the ratio between the visual response and spontaneous activity (signal-to-noise ratio) of the cells were assessed quantitatively before and during drug application. 2. VIP had little effect in the absence of visual stimulation, with only 29/90 (32%) of the cells showing a change of even 1 sp/s in their spontaneous activity. In contrast it had a clear effect on the visual responses of the majority (73/90, 81%) of the cells tested. 3. VIP produced a substantial change (i.e., > or = 40%) in optimal response magnitude for 57 of the affected cells. Of these 65% were facilitated, usually with no change or an improvement in signal-to-noise ratio and direction selectivity. The remaining cells were inhibited, with more variable effects on their visual response characteristics, and were found predominantly in the superficial laminae. 4. The effects of VIP bore a remarkable resemblance to those reported previously for the muscarinic action of acetylcholine (ACh). VIP and a muscarinic cholinergic agonist, either ACh or acetyl-beta-methacholine (MeCh), were therefore applied in turn to a group of 40 cells. In 23 cases VIP and the muscarinic agonist were also applied simultaneously. 5. The effects of VIP and the cholinergic agonist matched in 92% of the cases where both drugs were effective. That is to say, cells that were facilitated by VIP were facilitated also by ACh or MeCh, and vice versa. In many instances there was a clear similarity in the pattern as well as the direction of the effects produced by the two substances. The result of simultaneous application was generally additive. 6. These data suggest that VIP and ACh activate very similar postsynaptic mechanisms, and share a closely related function at the level of individual cortical cells. Thus VIP may facilitate the responses of both the excitatory and the inhibitory components of the cortical circuit, leading to an overall increase in responsiveness and selectivity. In contrast to the cholinergic input from the basal forebrain, however, the VIP-positive cortical cells are likely to exert a very localized influence, over a circumscribed region of the cortex, in response to the presence of an effective visual stimulus.

Degree of interocular synchrony required for maintenance of binocularity in kitten's visual cortex

1979 ◽  
Vol 42 (6) ◽  
pp. 1692-1710 ◽  
Author(s):  
G. G. Blasdel ◽  
J. D. Pettigrew
Keyword(s):  
Visual Cortex ◽  
Substantial Reduction ◽  
Monocular Deprivation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Cortical Cells ◽  
The Third ◽  
Monocular Stimulation ◽  
Cortical Inputs ◽  
Dorsal Lateral Geniculate ◽  
Stimulation Of

1. The importance of synchronous activation in maintaining cortical binocularity was studied physiologically in kittens that had been reared under different regimens of alternating monocular deprivation. 2. Three different techniques were employed to provide alternate monocular stimulation: a) mechanical shutters placed before the animals' eyes; b) goggles fitted with complementary colored cutoff filters, which restricted visual input to one eye at a time; and c) two rotating gratings that were 90 degrees out of phase. In the third technique, the gratings were always orthogonal to one another and viewed separately through cutoff filters. This allowed us to exploit the orientation selectivity of cortical cells and thereby stimulate them alternately through each eye without simultaneously affecting activity in the dorsal lateral geniculate nucleus (dLGN). 3. We based our conclusions on a sample of 691 neurons, which we recorded in 21 animals. Results with all techniques were remarkably consistent. Binocular cortical inputs predominated at normal or nearly normal levels, even when a number of seconds elapsed between successive exposures of each eye. 4. An interonset interval of at least 10 s was required to make a substantial reduction in binocularity. This interval can be separated into two parts--the duration of exclusive monocular stimulation and the time when neither channel receives input. Of these, the latter appeared to be less important. Blanking times of 0.15--1.0 s did not affect binocularity if the interonset interval was 1 or 10 s; and in one experiment where the blanking time was 9 s, the resulting disruption in binocularity was less than that found with shorter blanking times and the same interonset interval. 5. Our results imply that mechanisms responsible for the disappearance of binocular cortical inputs require independent stimulation of each eye for periods of at least a few seconds; this stimulation must be of a kind that is known to excite cortical cells. Our results with the rotating grafting show, in addition, that the mechanisms whose timing we have measured are intrinsic to the cortex.

Role of visual experience in activating critical period in cat visual cortex

1985 ◽  
Vol 53 (2) ◽  
pp. 572-589 ◽  
Author(s):  
G. D. Mower ◽  
W. G. Christen
Keyword(s):  
Visual Cortex ◽  
Visual Experience ◽  
Ocular Dominance ◽  
Orientation Selectivity ◽  
Monocular Deprivation ◽  
Total Darkness ◽  
Cortical Cells ◽  
Visual Cortical ◽  
Dark Rearing ◽  
Made In

Cats were reared in total darkness from birth until 4-5 mo of age (DR cats, n = 7) or with very brief visual experience (1 or 2 days) during an otherwise similar period of dark rearing [DR(1) cats, n = 3; DR(2) cats, n = 7]. Single-cell recordings were made in area 17 of visual cortex at the end of this rearing period and/or after a subsequent prolonged period of monocular deprivation. Control observations were made in normal cats (n = 3), cats reared with monocular deprivation from birth (n = 4), and cats monocularly deprived after being reared normally until 4 mo of age (n = 2). After rearing cats in total darkness, the majority of visual cortical cells were binocularly driven and the overall distribution of ocular dominance was not different from that of normal cats. Orientation-selective cells were very rare in dark-reared cats. Monocular deprivation imposed after dark rearing resulted in selective development of connections from the open eye. Most cells were responsive only to the open eye and the majority of these were orientation selective. These results were similar to, though less severe than, those found in cats reared with monocular deprivation from birth. Monocular deprivation imposed after 4 mo of normal rearing did not produce selective development of connections from the open eye in terms of either ocular dominance or orientation selectivity. In DR(1) cats visual cortical physiology was degraded in comparison to dark-reared cats after the rearing period. Most cells were binocularly driven but there was a higher frequency of unresponsive cells and a reduced frequency of orientation-selective cells. Subsequent monocular deprivation resulted in a further decrease in the number of binocularly driven cells and an increase in unresponsive cells. However, it did not produce a bias in favor of the open eye in terms of either ocular dominance or orientation selectivity. In DR(2) cats there was a high incidence of unresponsive cells and a marked loss of binocularly driven cells after the rearing period. Subsequent monocular deprivation failed to produce any significant changes.(ABSTRACT TRUNCATED AT 400 WORDS)

The period of susceptibility of visual cortical binocularity to unilateral proprioceptive deafferentation of extraocular muscles

1987 ◽  
Vol 58 (4) ◽  
pp. 795-815 ◽  
Author(s):  
Y. Trotter ◽  
Y. Fregnac ◽  
P. Buisseret
Keyword(s):  
Receptive Field ◽  
Ocular Dominance ◽  
Total Sample ◽  
Area 17 ◽  
Large Area ◽  
Cortical Cells ◽  
Similar Reduction ◽  
Adult Cats ◽  
Proprioceptive Afferents ◽  
Visual Cortical

1. The electrophysiological effects of section of extraocular muscle proprioceptive afferents have been investigated in kitten area 17. Extraocular proprioceptive afferents were interrupted by cutting the ophthalmic branch of the fifth trigeminal nerve (V1 nerve) unilaterally in 15 normally reared kittens (NR) between 3 and 12 wk postnatal, in 3 NR adult cats, and in 7 dark-reared (DR) kittens at 6 wk postnatal. Bilateral sections of the V1 nerve were performed in two kittens at 6 wk postnatal. NR kittens were maintained in a normal environment after the section. DR kittens were returned to the darkroom until the recording session. Receptive-field properties of area 17 neurons were studied after a postsurgical delay of 4-7 wk in most NR kittens and of 4 days to 5 wk in DR kittens. In one NR kitten and in the operated adult cats, the delay was 1-2.5 yr. This study is based on a total sample of 1,190 visual cortical units. 2. When performed in NR kittens between 4 and 8 wk of age, the unilateral section of extraocular proprioceptive afferents significantly reduced the proportion of binocular cells: 1 mo after the section of the V1 nerve, half of the visual cortical cells were monocularly activated. A similar reduction in the proportion of binocular cells was also observed in DR kittens operated at 6 wk of age and then maintained in the dark for 5-7 wk. In contrast to the unilateral section, the bilateral section of the V1 nerve performed in 6-wk-old NR kittens did not disrupt cortical binocularity. 3. In 10 of the 22 kittens that had undergone unilateral sections, there was a strong asymmetry in the ocular dominance distribution in favor of one eye. This asymmetry was not related to the side of the section and was the same in both hemispheres for a given kitten. 4. The postsurgical delay played an important role in the appearance of the cortical deficit: binocularity loss was not found within the week following the section but was present 1 mo after the section. This functional impairment appeared to be permanent, since it was still observed 2.5 yr after the section. 5. Cortical cells were classified in two ways on the basis of their receptive-field organization: 1) into S- or C-types (38, 73), and 2) into small area slow (SAS), large area slow (LAS), or Fast (F)-types (42, 57).(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of dark rearing on the volume of visual cortex (areas 17 and 18) and number of visual cortical cells in young kittens

1992 ◽  
Vol 32 (3) ◽  
pp. 449-459 ◽  
Author(s):  
József Takács ◽  
P. Saillour ◽  
M. Imbert ◽  
M. Bogner ◽  
J. Hámori
Keyword(s):  
Visual Cortex ◽  
Cortical Cells ◽  
Areas 17 And 18 ◽  
Visual Cortical ◽  
Dark Rearing

scholarly journals Synaptic Mechanisms of Activity-Dependent Remodeling in Visual Cortex during Monocular Deprivation

2009 ◽  
Vol 2 ◽  
pp. JEN.S2559 ◽  
Author(s):  
Cynthia D. Rittenhouse ◽  
Ania K Majewska
Keyword(s):  
Visual Cortex ◽  
Critical Period ◽  
Ocular Dominance ◽  
Monocular Deprivation ◽  
Neuronal Structure ◽  
Cortical Cells ◽  
Dependent Plasticity ◽  
Cortical Synapses ◽  
Activity Dependent ◽  
Synaptic Mechanisms

It has long been appreciated that in the visual cortex, particularly within a postnatal critical period for experience-dependent plasticity, the closure of one eye results in a shift in the responsiveness of cortical cells toward the experienced eye. While the functional aspects of this ocular dominance shift have been studied for many decades, their cortical substrates and synaptic mechanisms remain elusive. Nonetheless, it is becoming increasingly clear that ocular dominance plasticity is a complex phenomenon that appears to have an early and a late component. Early during monocular deprivation, deprived eye cortical synapses depress, while later during the deprivation open eye synapses potentiate. Here we review current literature on the cortical mechanisms of activity-dependent plasticity in the visual system during the critical period. These studies shed light on the role of activity in shaping neuronal structure and function in general and can lead to insights regarding how learning is acquired and maintained at the neuronal level during normal and pathological brain development.

Stimulus dependence of orientation and direction sensitivity of cat LGNd relay cells without cortical inputs: A comparison with area 17 cells

1994 ◽  
Vol 11 (5) ◽  
pp. 939-951 ◽  
Author(s):  
Kirk G. Thompson ◽  
Audie G. Leventhal ◽  
Yifeng Zhou ◽  
Dan Liu
Keyword(s):  
Visual Cortex ◽  
Spatial Frequency ◽  
Frequency Tuning ◽  
Area 17 ◽  
Cortical Cells ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies ◽  
Direction Sensitivity ◽  
Cortical Inputs ◽  
Direction Tuning

AbstractThe cortical contribution to the orientation and direction sensitivity of LGNd relay cells was investigated by recording the responses of relay cells to drifting sinusoidal gratings of varying spatial frequencies, moving bars, and moving spots in cats in which the visual cortex (areas 17, 18, 19, and LS) was ablated. For comparison, the spatial-frequency dependence of orientation and direction tuning of striate cortical cells was investigated employing the same quantitative techniques used to test LGNd cells. There are no significant differences in the orientation and direction tuning to relay cells in the LGNd of normal and decorticate cats. The orientation and direction sensitivities of cortical cells are dependent on stimulus parameters in a fashion qualitatively similar to that of LGNd cells. The differences in the spatial-frequency bandwidths of LGNd cells and cortical cells may explain many of their differences in orientation and direction tuning. Although factors beyond narrowness of spatial-frequency tuning must exist to account for the much stronger orientation and direction preferences of cells in area 17 when compared to LGNd cells, the evidence suggests that the orientation and direction biases present in the afferents to the visual cortex may contribute to the orientation and direction selectivities found in cortical cells.

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