Morphology of retinogeniculate X and Y axon arbors in cats raised with binocular lid suture

1988 ◽  
Vol 60 (6) ◽  
pp. 2152-2167 ◽  
Author(s):  
D. Raczkowski ◽  
D. J. Uhlrich ◽  
S. M. Sherman
Keyword(s):  
Optic Tract ◽  
Selective Reduction ◽  
Complete Darkness ◽  
Response Properties ◽  
Qualitative And Quantitative ◽  
Essentially Normal ◽  
Adult Cats ◽  
The Individual ◽  
X Cells ◽  
Y Cells

1. We examined the terminal arbors of single, physiologically identified retinogeniculate X and Y axons in 13 adult cats raised from birth with binocular lid suture. We recorded in the optic tract from 146 retinogeniculate axons. We studied the response properties of each axon encountered and attempted to penetrate it for labeling with horseradish peroxidase. 2. We attempted to classify each retinogeniculate axon as X or Y on a standard battery of tests. We thus identified 46 X and 91 Y axons; 5 axons had unusual response properties, and 4 axons were lost before they could be adequately identified. The X and Y axons had response properties that were completely normal by our criteria. The 5 unusual axons exhibited linear spatial and temporal summation, which is a property of X cells, despite all of their other tested response properties being consistent with those of Y cells. 3. We achieved complete, dark labeling of 13 X and 13 Y axons that form the data base for all of our qualitative and quantitative morphological observations. All of these labeled axons had response properties entirely normal for their X or Y class. Nine of the labeled X axons arise from the contralateral retina and 4 from the ipsilateral retina, whereas the respective numbers for the Y axons are 8 and 5. 4. Each of the individual retinogeniculate X axons form terminal arbors that appeared essentially normal in terms of location within geniculate lamina A or A1, shape, volume, and number of terminal boutons. 5. In contrast, the retinogeniculate Y axons form clearly abnormal arbors with diminished projections, both in terms of bouton numbers and arbor volumes. For Y axons from the contralateral retina, a roughly normal arbor is formed in the C-laminae, despite greatly diminished or absent projections formed in lamina A, something never seen in normal cats. For Y axons from the ipsilateral retina, the projections to lamina A1 are also diminished, and the arbors there are all limited to the ventral half of the lamina, a pattern rarely seen for normal Y axons. 6. The selective reduction in retinogeniculate Y axon arbors in these binocularly lid-sutured cats is consistent with similar observations reported for monocularly lid-sutured and strabismic cats but is quite different from the apparently normal development of retinogeniculate axon arbors in cats raised in complete darkness.(ABSTRACT TRUNCATED AT 400 WORDS)

Response Properties of Pretectal Omnidirectional Pause Neurons in the Behaving Primate

1997 ◽  
Vol 77 (1) ◽  
pp. 116-125 ◽  
Author(s):  
Michael J. Mustari ◽  
Albert F. Fuchs ◽  
Milton Pong
Keyword(s):  
Rhesus Monkeys ◽  
Optic Tract ◽  
Complete Darkness ◽  
Response Properties ◽  
Efferent Connections ◽  
Saccade Onset ◽  
Pretectal Nucleus ◽  
Contingent Response ◽  
Catch Up ◽  
Anterior Posterior

Mustari, Michael J., Albert F. Fuchs, and Milton Pong. Response properties of pretectal omnidirectional pause neurons in the behaving primate. J. Neurophysiol. 77: 116–125, 1997. We have identified a region in the pretectum of rhesus monkeys ( Macaca mulatta) that contains units that evince a complete cessation in firing immediately after saccades. The pause occurs for saccades to target steps and catch up saccades during smooth pursuit, spontaneously in complete darkness or after quick phases of nystagmus. Because the pause in unit firing always follows saccade onset, we call these neurons following omnidirectional pause neurons (FOPNs). Because the pause also occurs with saccades in the dark, it is related to the saccade per se and is not a visually contingent response. The duration of the pause in firing exceeded the duration of all saccades up to 40 deg. For targeting saccades, the start of the pause was locked rather tightly to the beginning of the saccade but began an average of 51 ms after the saccade did. The end of the pause was linked only loosely to either the beginning or end of the saccade. About half (54%) of our 59 FOPNs also discharged a distinct burst of firing that preceded the pause. In different units, the burst preceded saccade onset by from 0 to 20 ms with an average of 11 ms and therefore could signal the occurrence of an impending saccade. The presaccadic burst was not correlated with any parameter of the saccade. Most FOPNs were found 278 μm, on average, dorsal to the direction-selective units characteristic of the pretectal nucleus of the optic tract (NOT) and occasionally slightly beyond the anterior-posterior and medial-lateral borders of the NOT. The FOPN region does not coincide with any known anatomically or functionally delineated pretectal nucleus. Because the characteristics of the FOPN pause are not reflected in the characteristics of the saccade and the FOPN pause occurs well after the saccade is over, it is unlikely that the pause in pretectal FOPNs is involved with saccade generation. On the other hand, the leading burst exhibited by the majority of FOPNs reliably signals that a saccade is occurring but neither its size nor direction. Perhaps this signal indicating the occurrence of all saccades is routed to visual relay neurons to effect saccadic modification of visual pathways. The substantial efferent connections of the FOPN/NOT region to the pregeniculate nucleus and the saccadic discharge of pregeniculate cells are discussed in the context of this suggestion.

Development of neuronal response properties in the cat dorsal lateral geniculate nucleus during monocular deprivation

1983 ◽  
Vol 50 (1) ◽  
pp. 240-264 ◽  
Author(s):  
S. C. Mangel ◽  
J. R. Wilson ◽  
S. M. Sherman
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Spatial Resolution ◽  
Optic Chiasm ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Response Properties ◽  
Lateral Geniculate ◽  
X And Y Cells ◽  
X Cells ◽  
Y Cells ◽  
Dorsal Lateral Geniculate

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.

The retinal dopamine network alters the adaptational properties of retinal ganglion cells in the cat

1994 ◽  
Vol 72 (2) ◽  
pp. 730-741 ◽  
Author(s):  
G. Maguire ◽  
D. I. Hamasaki
Keyword(s):  
Ganglion Cells ◽  
Optic Tract ◽  
Drug Effects ◽  
Amacrine Cells ◽  
Dopamine Antagonists ◽  
Response Curves ◽  
Pathway Activity ◽  
Response Properties ◽  
Cat Retina ◽  
Y Cells

1. Single-unit extracellular recordings of optic tract fibers were used to study ganglion cell (GC) response properties of the intact cat eye before and after the intravitreal injection of haloperidol or SCH23390, dopamine-specific antagonists. Nearly all of the dopaminergic cells in the cat retina are amacrine cells (ACs); thus the dopamine antagonists are thought to primarily block the postsynaptic effects of these dopaminergic amacrine cells. All GCs encountered were subjected to a battery of receptive-field (RF) tests, including classification as X or Y, and as ON or OFF. 2. The effects of haloperidol were greatest in the light-adapted OFF-center pathways and especially in the OFF-center Y-cell. Within 30 min of haloperidol injection, both the spontaneous and light-evoked activity of the OFF-center Y-cell fell to zero, but when the same cell was exposed to lower levels of steady-state background illumination (scotopic levels), the response of the cell once again became robust. 3. OFF-Center Y-cells that had partially recovered from the drug effects and OFF-center X-cells recorded when the drug effect was maximal both possessed intensity-response curves that were shifted to the right of normal. 4. Recovery from the drug effects reflect supranormal responses after the initial response reductions and may be due to haloperidol's action on the dopamine autoreceptor. 5. Of the ON-center cells, only the Y-cells showed response alterations; possessing higher spontaneous activities and slightly reduced amplitudes to RF center (RFC) illumination. 6. The effects of SCH23390 paralleled those of haloperidol except that the onset was faster and the duration of the action of SCH23390 was much shorter, and no supranormal responses followed the initial effects. 7. Dark-adaptation functions of OFF-center GCs revealed a normal rod-cone shift; however, SCH23390 eliminated the rod-cone break, and threshold quickly fell to that of the rod mechanism. 8. The dopaminergic neurons of the cat retina appear to play an important role in regulating the activity of retinal OFF-center pathways in the photopically adapted eye, and one of its functions may be to control the relative contributions of the rod and cone systems to the response properties of light-adapted OFF-center GCs. 9. It is argued that dopamine is released in the light and enhances cone pathway activity, perhaps in the outer retina at bipolar and horizontal cells, and suppresses rod pathway activity, perhaps in the inner retina at amacrine cells.

Response properties in the dorsal lateral geniculate nucleus of the adult cat after interruption of prenatal binocular interactions

1989 ◽  
Vol 62 (5) ◽  
pp. 1039-1051 ◽  
Author(s):  
C. A. White ◽  
L. M. Chalupa ◽  
L. Maffei ◽  
M. A. Kirby ◽  
B. Lia
Keyword(s):  
Spatial Resolution ◽  
Receptive Fields ◽  
Spatial Summation ◽  
Field Size ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Lower Percentage ◽  
Binocular Interactions ◽  
Adult Cats ◽  
X Cells ◽  
Y Cells

1. Single-cell recordings were made in the magnocellular layer of the dorsal lateral genicule nucleus (dLGN) of five adult cats in which prenatal binocular interactions were interrupted by monocular enucleation at known gestational ages. Three cats (early enucleates) had one eye removed on either embryonic day 44.48, or 49, before retinogeniculate inputs are segregated into uniocular layers. Two other (late enucleates) underwent this procedure on embryonic days 55 and 58, when segregation is well advanced. Responses were compared with those obtained from recordings in the A and A1 layers of the dLGN of seven normal adult cats. 2. Cells were classified as ON or OFF by the use of spots of light and as X or Y based on a test of linearity of spatial summation with the use of counterphased sinusoidal gratings. Receptive-field size and spatial resolution were also obtained. 3. The dLGN of prenatally enucleated cats contains a dorsal magnocellular layer and a ventral parvocellular layer. In early enucleates, only an occasional hint of a cell-sparse interlaminar zone was apparent, located between the magnocellular and parvocellular layers. In late enucleates, a prominent cell-sparse band was observed contralateral to the remaining eye, in a region that would most likely correspond to layer A1 in the normal dLGN. No such cell-sparse band was seen ipsilateral to the remaining eye in late enucleates. 4. Eighty-six X cells and 22 Y cells were studied in the enucleates. Both cell types were found at all depths of the magnocellular layer. All but a few neurons had concentric ON-center or OFF-center receptive fields that were normal in size. The topography of receptive fields also appeared normal. In addition, spatial resolution of X and Y cells was similar in experimental and control animals. 5. In early enucleates there was a higher percentage of X cells and a lower percentage of Y cells than normal. The change in X-to-Y ratio was shown to be because of both a gain in cells with X properties and a loss of cells with Y properties. The distribution of dLGN somal sizes in the early enucleates was comparable with controls, so the change in X-to-Y ratio most likely did not result from an electrode sampling bias. It was suggested that the X-to-Y ratio difference could stem from the abnormalities in retinogeniculate terminal arbors that have been shown to follow early eye removal.(ABSTRACT TRUNCATED AT 400 WORDS)

Correlated firing of cat retinal ganglion cells. I. Spontaneously active inputs to X- and Y-cells

1983 ◽  
Vol 49 (2) ◽  
pp. 303-324 ◽  
Author(s):  
D. N. Mastronarde
Keyword(s):  
Receptive Field ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Optic Tract ◽  
Amacrine Cells ◽  
Retinal Ganglion ◽  
X And Y Cells ◽  
X Cells ◽  
Y Cells ◽  
Shared Inputs

1. The shared inputs to cat retinal ganglion cells have been investigated by studying correlations in the maintained firing of neighboring ganglion cells. The firing of one cell was recorded from its axon in the optic tract, while that of a neighboring cell was simultaneously recorded with a second electrode in the retina. The recorded cells were of the X- or Y-type and viewed a uniform screen having a luminance of 10 cd/m2. 2. Ganglion cells with overlapping receptive-field centers showed two basic forms of correlated firing: if they had the same center sign (both on-center or both off-center), then they tended to fire at the same time, as shown by a peak in their cross-correlogram; but if they had opposite center signs (an on- and and off-center cell), they tended not to fire at the same time, as shown by a well, or dip, in their cross-correlogram. 3. Both of these tendencies were strongest for cells that were close together and did not appear for cells with nonoverlapping receptive-field centers. The strongest correlations were between neighboring Y-cells, cells with large fields, and the weakest were between X-cells, cells with small fields. In general, the strength of the correlations depended primarily on the area of the overlap between fields. 4. These correlations in maintained firing appear to be principally or entirely caused by shared inputs to the ganglion cells from more distal retinal neurons. The signals from these distal neurons appear to have strong, brief (4-8 ms), well-defined effects on ganglion cells, which are observed even in the absence of a visual stimulus. The inputs responsible for the correlated firing are thus referred to as spontaneously active inputs or simply as active inputs. 5. An analysis of the features in the various types of cross-correlograms supports the following statements about these spontaneously active inputs. a) There are two types of active inputs: inputs excitatory to on-center cells and simultaneously inhibitory to off-center center cells and inputs excitatory to off-center cells and simultaneously inhibitory to on-center cells. b) The active inputs of each type provide excitation to both X- and Y-cells of one center sign and inhibition to both X- and Y-cells of the other center sign. There is no evidence for a special class of more selective inputs providing input only to X-cells or only to Y-cells. c) Active inputs account for the majority (about 80%) of the spikes in the maintained activity of Y-cells but only a small fraction (about 15%) of the spikes in the maintained activity of X-cells. 6. A likely source of the active input signals appears to be spiking amacrine cells with a low rate of spontaneous activity.

Spatial and temporal response properties of lagged and nonlagged cells in cat lateral geniculate nucleus

1990 ◽  
Vol 64 (1) ◽  
pp. 206-224 ◽  
Author(s):  
A. B. Saul ◽  
A. L. Humphrey
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Temporal Frequency ◽  
Visual Response ◽  
Phase Versus ◽  
Response Properties ◽  
Lateral Geniculate ◽  
X And Y Cells ◽  
Lagged Cells ◽  
X Cells ◽  
Y Cells

1. It has recently been shown that the X- and Y-cell classes in the A-layers of the cat lateral geniculate nucleus (LGN) are divisible into lagged and nonlagged types. We have characterized the visual response properties of 153 cells in the A-layers to 1) reveal response features that are relevant to the X/Y and lagged/nonlagged classification schemes, and 2) provide a systematic description of the properties of lagged and nonlagged cells as a basis for understanding mechanisms that affect these two groups. Responses to flashing spots and drifting gratings were measured as the contrast and spatial and temporal modulation were varied. 2. X- and Y-cells were readily distinguished by their spatial tuning. Y-cells had much lower preferred spatial frequencies and spatial resolution than X-cells. Within each functional class (X or Y), however, lagged and nonlagged cells were similar in their spatial response properties. Thus the lagged/nonlagged distinction is not one related to the spatial domain. 3. In the temporal domain X- and Y-cells showed little difference in temporal tuning, whereas lagged and nonlagged cells showed distinctive response properties. The temporal tuning functions of lagged cells were slightly shifted toward lower frequencies with optimal temporal frequencies of lagged X-cells averaging an octave lower than those of nonlagged X-cells. Temporal resolution was much lower in lagged X- and Y-cells than in their nonlagged counterparts. 4. The most dramatic differences between lagged and nonlagged cells appeared in the timing of their responses, as measured by the phase of the response relative to the sinusoidal luminance modulation of a spot centered in the receptive field. Response phase varied approximately linearly with temporal frequency. The slope of the phase versus frequency line is a measure of total integration time, which we refer to as visual latency. Lagged cells has much longer latencies than nonlagged cells. 5. The intercept of the phase versus frequency line is a measure of when in the stimulus cycle the cell responds: we refer to this as the intrinsic or absolute phase of the cell. This measure of response timing not only distinguished lagged and nonlagged cells well but also covaried with the sustained or transient nature of cells' responses to flashed stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Drowning in negativism, self-hate, doubt, madness: Linguistic insights into Sylvia Plath’s experience of depression

2015 ◽  
Vol 11 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Zsófia Demjén
Keyword(s):  
Lived Experience ◽  
Medical Humanities ◽  
Sylvia Plath ◽  
Individual Experience ◽  
Qualitative And Quantitative ◽  
The World ◽  
The Individual ◽  
Linguistic Methods ◽  
Linguistic Approach

This paper demonstrates how a range of linguistic methods can be harnessed in pursuit of a deeper understanding of the ‘lived experience’ of psychological disorders. It argues that such methods should be applied more in medical contexts, especially in medical humanities. Key extracts from The Unabridged Journals of Sylvia Plath are examined, as a case study of the experience of depression. Combinations of qualitative and quantitative linguistic methods, and inter- and intra-textual comparisons are used to consider distinctive patterns in the use of metaphor, personal pronouns and (the semantics of) verbs, as well as other relevant aspects of language. Qualitative techniques provide in-depth insights, while quantitative corpus methods make the analyses more robust and ensure the breadth necessary to gain insights into the individual experience. Depression emerges as a highly complex and sometimes potentially contradictory experience for Plath, involving both a sense of apathy and inner turmoil. It involves a sense of a split self, trapped in a state that one cannot overcome, and intense self-focus, a turning in on oneself and a view of the world that is both more negative and more polarized than the norm. It is argued that a linguistic approach is useful beyond this specific case.

scholarly journals Leveraging human factors in cybersecurity: an integrated methodological approach

2021 ◽  
Author(s):  
Alessandro Pollini ◽  
Tiziana C. Callari ◽  
Alessandra Tedeschi ◽  
Daniele Ruscio ◽  
Luca Save ◽  
...  
Keyword(s):  
Human Factors ◽  
Cyber Security ◽  
Quantitative Research ◽  
Methodological Approach ◽  
Quantitative Research Methods ◽  
Security Culture ◽  
Technological Factors ◽  
Qualitative And Quantitative ◽  
The Individual ◽  
Technical Solutions

AbstractComputer and Information Security (CIS) is usually approached adopting a technology-centric viewpoint, where the human components of sociotechnical systems are generally considered as their weakest part, with little consideration for the end users’ cognitive characteristics, needs and motivations. This paper presents a holistic/Human Factors (HF) approach, where the individual, organisational and technological factors are investigated in pilot healthcare organisations to show how HF vulnerabilities may impact on cybersecurity risks. An overview of current challenges in relation to cybersecurity is first provided, followed by the presentation of an integrated top–down and bottom–up methodology using qualitative and quantitative research methods to assess the level of maturity of the pilot organisations with respect to their capability to face and tackle cyber threats and attacks. This approach adopts a user-centred perspective, involving both the organisations’ management and employees, The results show that a better cyber-security culture does not always correspond with more rule compliant behaviour. In addition, conflicts among cybersecurity rules and procedures may trigger human vulnerabilities. In conclusion, the integration of traditional technical solutions with guidelines to enhance CIS systems by leveraging HF in cybersecurity may lead to the adoption of non-technical countermeasures (such as user awareness) for a comprehensive and holistic way to manage cyber security in organisations.

scholarly journals Decentralised sweetpotato (Ipomoea batatas) vine multiplication in Lake Zone, Tanzania: Five years later

2020 ◽  
Vol 5 (1) ◽  
pp. 677-689
Author(s):  
Margaret A. McEwan ◽  
Conny J. M. Almekinders ◽  
Moses S. Matui ◽  
Dorothy Lusheshanija ◽  
Mariana Massawe ◽  
...  
Keyword(s):  
Group Dynamics ◽  
Ipomoea Batatas ◽  
Water Access ◽  
Qualitative And Quantitative ◽  
Factors Influencing ◽  
Lake Zone ◽  
Norms And Values ◽  
Group Members ◽  
Market Factors ◽  
The Individual

AbstractFarmer-based seed multiplication is widely promoted by development practitioners, but there is limited understanding of the individual or collective motivations of farmers to engage or disengage in specialised seed production. The objective of this study is to understand the factors influencing the continuity of sweetpotato vine multiplication enterprises in the Lake Zone of Tanzania, five years after support from a project ended. A total of 81 out of 88 trained group or individual decentralised vine multipliers (DVMs) were traced to assess their vine multiplication activities. Qualitative and quantitative data were collected through telephone and field interviews. Our data showed that 40% of the 81 DVMs had sold vines in the year prior to the study and 20% had maintained the improved varieties for their own use. Some group members had continued vine sales as individuals. The DVMs’ reasons for abandoning vine multiplication included climatic and water access issues, market factors and group dynamics. The DVMs did not engage in high volumes of commercial sales. Socio-economic norms and values underpin the transactions of sweetpotato vines. These norms may undermine the emergence of commercially viable enterprises yet seem navigable for a substantial number of the DVMs. Group DVMs seem less commercially successful than individuals.

Effects of strabismus on responsivity, spatial resolution, and contrast sensitivity of cat lateral geniculate neurons

1984 ◽  
Vol 52 (3) ◽  
pp. 538-552 ◽  
Author(s):  
K. R. Jones ◽  
R. E. Kalil ◽  
P. D. Spear
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Resolution ◽  
Striate Cortex ◽  
Receptive Fields ◽  
Orienting Response ◽  
Lateral Geniculate ◽  
Spatial Frequencies ◽  
Area Centralis ◽  
X Cells ◽  
Y Cells

Rearing cats with esotropia is known to cause a number of deficits in visual behavior tested through the deviated eye. These include a loss of orienting response to stimuli presented in the nasal visual field of the deviated eye, a reduction in visual acuity, and a general reduction in contrast sensitivity at all spatial frequencies. To assess the involvement of the lateral geniculate nucleus (LGN) in these deficits, we measured the following: 1) the visual responsiveness of lamina A1 cells with peripheral (more than 10 degrees from area centralis) receptive fields in three esotropic and three normal cats and 2) the spatial resolution and contrast sensitivity of lamina A X-cells with central (within 5 degrees of the area centralis) receptive fields in six esotropic and six normal cats. For comparison, we also measured LGN X-cell spatial resolutions in four exotropic cats and in two cats raised with an esotropia in one eye and the lids of the other eye sutured shut (MD-estropes). Recordings from the lateral portion of lamina A1 in esotropic cats yielded similar numbers of visually responsive cells with far nasal receptive fields as were seen in normal animals. Peak and mean response rates to a flashing spot also were normal. In addition, no differences were found between esotropes and normals in the percentages of X- and Y-cells encountered. These results suggest that the loss of orienting response to stimuli presented in the nasal field (12, 20) is not due to a loss of neural responses in the LGN of esotropic cats. In addition, they suggest that decreases in cell size in lamina A1 of esotropic cats (13, 36; R. E. Kalil, unpublished observations) are not accompanied by marked functional abnormalities of the cells and that cortical abnormalities ipsilateral to the deviated eye (22) are likely to have their origin within striate cortex itself. Recordings from lamina A cells with receptive fields near area centralis revealed that the average X-cell spatial resolution in esotropes (2.1 cycles/deg) was significantly lower than that in normal cats (3.1 cycles/deg). This reduction was seen in all esotropic cats tested and was due both to an increase in the proportion of X-cells with very low spatial resolution and to a loss of X-cells responding to high spatial frequencies (greater than 3.25 cycles/deg). The average spatial resolution of X-cells driven by the deviated eye in MD-esotropes fell midway between those of esotropes and normals. In exotropes, mean X-cell spatial resolution was normal.(ABSTRACT TRUNCATED AT 400 WORDS)

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