Terminal arbors of individual ?Feedback? axons projecting from area V2 to V1 in the macaque monkey: A study using immunohistochemistry of anterogradely transportedPhaseolus vulgaris-leucoagglutinin

We recorded responses in 107 cells in the primary visual area V1 and 113 cells in the extrastriate visual area V2 while presenting a kinetically defined edge or a luminance contrast edge. Cells meeting statistical criteria for responsiveness and orientation selectivity were classified as selective for the orientation of the kinetic edge if the preferred orientation for a kinetic boundary stimulus remained essentially the same even when the directions of the two motion components defining that boundary were changed by 90°. In area V2, 13 of the 113 cells met all three requirements, whereas in V1, only 4 cells met the criteria of 107 that were tested, and even these demonstrated relatively weak selectivity. Correlation analysis showed that V1 and V2 populations differed greatly ( P < 1.0 × 10−6, Student's t-test) in their selectively for specific orientations of kinetic edge stimuli. Neurons in V2 that were selective for the orientation of a kinetic boundary were further distinguished from their counterparts in V1 in displaying a strong, sharply tuned response to a luminance edge of the same orientation. We concluded that selectivity for the orientation of kinetically defined boundaries first emerges in area V2 rather than in primary visual cortex. An analysis of response onset latencies in V2 revealed that cells selective for the orientation of the motion-defined boundary responded about 40 ms more slowly, on average, to the kinetic edge stimulus than to a luminance edge. In nonselective cells, that is, those presumably responding only to the local motion in the stimulus, this difference was only about 20 ms. Response latencies for the luminance edge were indistinguishable in KE-selective and -nonselective neurons. We infer that while responses to luminance edges or local motion are indigenous to V2, KE-selective responses may involve feedback entering the ventral stream at a point downstream with respect to V2.

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Organization of individual cortical axons projecting from area V1 (area 17) to V2 (area 18) in the macaque monkey

Visual Neuroscience ◽

10.1017/s095252380000273x ◽

1990 ◽

Vol 4 (1) ◽

pp. 11-28 ◽

Cited By ~ 60

Author(s):

Kathleen S. Rockland ◽

Agnes Virga

Keyword(s):

Small Groups ◽

Macaque Monkey ◽

Area 17 ◽

Area V2 ◽

Laminar Distribution ◽

Layer 4 ◽

Single Field ◽

Morphological Differences ◽

Anterograde Tracer ◽

Anterior Posterior

AbstractThe present study uses the anterograde tracer, Phaseolus vulgaris-leucoagglutinin (PHA-L), to investigate the detailed morphology of individual axons projecting from area V1 to prestriate area V2. Observations are derived from serial reconstructions of 45 axons. Axons are found to differ both in laminar distribution and in arbor size. The majority (25/45; 56%) terminate in the upper half of layer 4 and the lower part of layer 3. Terminal clusters typically measure about 200 μm in diameter (dimensions are uncorrected for shrinkage), and are either in one, two, or occasionally three patches. Patches are separated by 200−500 μm. Of these 25 axons, four also have minor collaterals to layer 5. Of the remaining 20 axons in our sample, eight have one or two terminal arbors (about 200 μm in diameter) mainly in layer 3; another eight have terminations, organized as a single field (about 350 μm in diameter), within layer 4; and four axons have much larger terminal fields (1.0−1.2 mm × 0.3 mm), in layers 3 nd 4. These morphological differences might constitute a gradient or, alternately, indicate distinct subgroups within the striate efferent population. Large terminal fields are asymmetrical, with their long axis oriented in an anterior-posterior fashion toward the depth of the lunate sulcus. Axons with two terminal arbors have a similar bias. As this arrangement is approximately perpendicular to the border of V1, we suggest that striate axons may be extended preferentially along the length of the stripelike compartments in V2. These compartments are also arrayed perpendicular to the border between areas V1 and V2. Reconstruction of small groups of 2–4 convergent axons demonstrates that axons with different morphology (i.e. large or small terminal fields) can occur within the same projection focus. Terminal arbors belonging to different axons can overlap, but tend not to be superimposed exactly.

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Projection of the lateral geniculate nucleus onto cortical area V2 in the macaque monkey

Experimental Brain Research ◽

10.1007/bf00239409 ◽

1983 ◽

Vol 53 (1) ◽

Cited By ~ 105

Author(s):

J. Bullier ◽

H. Kennedy

Keyword(s):

Lateral Geniculate Nucleus ◽

Cortical Area ◽

Macaque Monkey ◽

Lateral Geniculate ◽

Area V2

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Response Modulations by Static Texture Surround in Area V1 of the Macaque Monkey Do Not Depend on Feedback Connections From V2

Journal of Neurophysiology ◽

10.1152/jn.2001.85.1.146 ◽

2001 ◽

Vol 85 (1) ◽

pp. 146-163 ◽

Cited By ~ 89

Author(s):

Jean-Michel Hupé ◽

Andrew C. James ◽

Pascal Girard ◽

Jean Bullier

Keyword(s):

Visual Information ◽

Macaque Monkey ◽

V1 Neurons ◽

Orientation Contrast ◽

Area V2 ◽

Classical Receptive Field ◽

Main Effect ◽

Oriented Line ◽

Response Onset ◽

Feedback Connections

We analyzed the extracellular responses of 70 V1 neurons (recorded in 3 anesthetized macaque monkeys) to a single oriented line segment (or bar) placed within the cell classical receptive field (RF), or center of the RF. These responses could be modulated when rings of bars were placed entirely outside, but around the RF (the “near” surround region), as described in previous studies. Suppression was the main effect. The response was enhanced for 12 neurons when orthogonal bars in the surround were presented instead of bars having the same orientation as the center bar. This orientation contrast property is possibly involved in the mediation of perceptual pop-out. The enhancement was delayed compared with the onset of the response by about 40 ms. We also observed a suppression originating specifically from the flanks of the surround. This “side-inhibition,” significant for nine neurons, was delayed by about 20 ms. We tested whether these center/surround interactions in V1 depend on feedback connections from area V2. V2 was inactivated by GABA injections. We used devices made of six micropipettes to inactivate the convergent zone from V2 to V1. We could reliably inactivate a 2- to 4-mm-wide region of V2. Inactivation of V2 had no effect on the center/surround interactions of V1 neurons, even those that were delayed. Therefore the center/surround interactions of V1 neurons that might be involved in pop-out do not appear to depend on feedback connections from V2, at least in the anesthetized monkey. We conclude that these properties are probably shaped by long-range connections within V1 or depend on other feedback connections. The main effect of V2 inactivation was a decrease of the response to the single bar for about 10% of V1 neurons. The decrease was delayed by <20 ms after the response onset. Even the earliest neurons to respond could be affected by the feedback from V2. Together with the results on feedback connections from MT (previous paper), these findings show that feedback connections potentiate the responses to stimulation of the RF center and are recruited very early for the treatment of visual information.

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Responses of Spectrally Selective Cells in Macaque Area V2 to Wavelengths and Colors

Journal of Neurophysiology ◽

10.1152/jn.00248.2001 ◽

2002 ◽

Vol 87 (4) ◽

pp. 2104-2112 ◽

Cited By ~ 30

Author(s):

K. Moutoussis ◽

S. Zeki

Keyword(s):

Spatial Configuration ◽

Receptive Fields ◽

Macaque Monkey ◽

Short Wave ◽

Spectrally Selective ◽

Area V2 ◽

Color Constant ◽

Different Color ◽

Determining Factor

We have recorded from wavelength-selective cells in macaque monkey visual area V2, interposed between areas V1 and V4 of the color-specialized pathway, to learn whether their responses correlate with perceived colors or are determined by the wavelength composition of light reflected from their receptive fields. All the cells we recorded from were unselective for the orientation and direction of motion of the stimulus, and all were histologically identified to be in the thin cytochrome oxidase stripes. Using multi-colored “Mondrian” scenes of the appropriate spatial configuration, areas of different color were placed in the receptive field of each cell and the entire scene illuminated by three projectors, passing long-, middle-, and short-wave light, respectively, in various combinations. Our results show that wavelength-selective cells in V2 respond to an area of any color depending on whether or not it reflects a sufficient amount of light of their preferred wavelength. In addition, the responses of a third of the cells tested were also influenced by the wavelength composition of their immediate surrounds, thus signaling the result of a local spatial comparison with respect to the amount of their preferred wavelength present. The responses of all also depended on the sequence with which their receptive fields were illuminated with light of the three different wavebands: cells were activated when there was an increase (and inhibited when there was a decrease) in the amount of their preferred wavelength with respect to the other two; the temporal route taken was therefore a determining factor, and, depending on it, cells would either respond or not to a particular combination of wavelengths. We conclude that although spatiotemporal wavelength comparisons are taking place in the color-specialized subdivisions of area V2, the determination of complete color-constant behavior at the neuronal level requires further processing, in other areas.

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