Visuotopic organisation of striate cortex in the marmoset monkey (Callithrix jacchus)

Fritsches, Kerstin A.; Rosa, Marcello G. P.

doi:10.1002/(sici)1096-9861(19960819)372:2<264::aid-cne8>3.0.co;2-1

Cited by 91 publications

(50 citation statements)

References 67 publications

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“…This resulted in no responses along some parts of the perimeter of the lesion, indicating that, as in other monkeys (Cowey, 1964;Girard and Bullier, 1989), the visual responses of cells in marmoset V2 depend on inputs from V1. In these cases, the corresponding parts of the perimeter of the scotoma were estimated as the vertical meridian, which is normally represented along the outer boundary of V1 (Fritsches and Rosa, 1996). Based on a comparison between myelin-stained sections through V2 in normal and lesioned hemispheres, the maximum invasion of V2 was estimated to be ϳ1.5 mm dorsally and 1 mm ventrally, in case 2.…”

Section: Methodsmentioning

confidence: 73%

“…The horizontal meridian (HM) of the visual field was defined as a line connecting the centers of the left eye fovea and blind spot (Troilo et al, 1993), and the vertical meridian (V M) was defined as perpendicular to the HM through the center of the fovea. As described previously , the doses of pancuronium used resulted in no residual eye movements being detectable in these experiments, as evaluated by repeated examination of the position of the fovea (i.e., the variation between consecutive estimates was within the error afforded by the reversible ophthalmoscope, which is 0.5-1°) (Fritsches and Rosa, 1996).…”

Section: Methodsmentioning

confidence: 97%

“…Under sterile conditions, a craniot-omy was made over the occipital pole of the right hemisphere, allowing access to V1. After removal of the dura mater, a suction probe was used to destroy V1, using previously published stereotaxic coordinates and visuotopic maps of this area as guides (Fritsches and Rosa, 1996). As illustrated in Figure 1, the topography of the marmoset cortex is such that a vertical ablation at an appropriate anteroposterior level results in a lesion nearly restricted to V1, affecting mostly the central representation and leaving the far peripheral representation untouched.…”

Section: Methodsmentioning

confidence: 99%

“…The gray pattern also covered a strip of the visual field that included the approximate borders of the scotoma, estimated as explained above. The width of this strip was 2°centrally but increased toward the periphery according to the known relationship between receptive field size and eccentricity in V1 (Fritsches and Rosa, 1996). Histolog y.…”

Section: Methodsmentioning

confidence: 99%

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Visual Responses of Neurons in the Middle Temporal Area of New World Monkeys after Lesions of Striate Cortex

2000

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In primates, lesions of striate cortex (V1) result in scotomas in which only rudimentary visual abilities remain. These aspects of vision that survive V1 lesions have been attributed to direct thalamic pathways to extrastriate areas, including the middle temporal area (MT). However, studies in New World monkeys and humans have questioned this interpretation, suggesting that remnants of V1 are responsible for both the activation of MT and residual vision. We studied the visual responses of neurons in area MT in New World marmoset monkeys in the weeks after lesions of V1. The extent of the scotoma in each case was estimated by mapping the receptive fields of cells located near the lesion border and by histological reconstruction. Two response types were observed among the cells located in the part of MT that corresponds, in visuotopic coordinates, to the lesioned part of V1. Many neurons (62%) had receptive fields that were displaced relative to their expected location, so that they represented the visual field immediately surrounding the scotoma. This may be a consequence of a process analogous to the reorganization of the V1 map after retinal lesions. However, another 20% of the cells had receptive fields centered inside the scotoma. Most of these neurons were strongly directionselective, similar to normal MT cells. These results show that MT cells differ in their responses to lesioning of V1 and that only a subpopulation of MT neurons can be reasonably linked to residual vision and blindsight.

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Section: Methodsmentioning

confidence: 73%

Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Visual Responses of Neurons in the Middle Temporal Area of New World Monkeys after Lesions of Striate Cortex

2000

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“…Moreover, cells in the gPFC of humans were 70% more spinous than those in the next closest species (macaque monkey), three times more spinous than Rosa et al (1997a). b Fritsches and Rosa (1996). c Tootell et al (1985).…”

Section: Resultsmentioning

confidence: 97%

Specializations of the granular prefrontal cortex of primates: Implications for cognitive processing

et al. 2005

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The biological underpinnings of human intelligence remain enigmatic. There remains the greatest confusion and controversy regarding mechanisms that enable humans to conceptualize, plan, and prioritize, and why they are set apart from other animals in their cognitive abilities. Here we demonstrate that the basic neuronal building block of the cerebral cortex, the pyramidal cell, is characterized by marked differences in structure among primate species. Moreover, comparison of the complexity of neuron structure with the size of the cortical area/region in which the cells are located revealed that trends in the granular prefrontal cortex (gPFC) were dramatically different to those in visual cortex. More specifically, pyramidal cells in the gPFC of humans had a disproportionately high number of spines. As neuron structure determines both its biophysical properties and connectivity, differences in the complexity in dendritic structure observed here endow neurons with different computational abilities. Furthermore, cortical circuits composed of neurons with distinguishable morphologies will likely be characterized by different functional capabilities. We propose that 1. circuitry in V1, V2, and gPFC within any given species differs in its functional capabilities and 2. there are dramatic differences in the functional capabilities of gPFC circuitry in different species, which are central to the different cognitive styles of primates. In particular, the highly branched, spinous neurons in the human gPFC may be a key component of human intelligence.

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The second visual area in the marmoset monkey: Visuotopic organisation, magnification factors, architectonical boundaries, and modularity

1997

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The organisation of the second visual area (V2) in marmoset monkeys was studied by means of extracellular recordings of responses to visual stimulation and examination of myelin- and cytochrome oxidase-stained sections. Area V2 forms a continuous cortical belt of variable width (1-2 mm adjacent to the foveal representation of V1, and 3-3.5 mm near the midline and on the tentorial surface) bordering V1 on the lateral, dorsal, medial, and tentorial surfaces of the occipital lobe. The total surface area of V2 is approximately 100 mm2, or about 50% of the surface area of V1 in the same individuals. In each hemisphere, the receptive fields of V2 neurones cover the entire contralateral visual hemifield, forming an ordered visuotopic representation. As in other simians, the dorsal and ventral halves of V2 represent the lower and upper contralateral quadrants, respectively, with little invasion of the ipsilateral hemifield. The representation of the vertical meridian forms the caudal border of V2, with V1, whereas a field discontinuity approximately coincident with the horizontal meridian forms the rostral border of V2, with other visually responsive areas. The bridge of cortex connecting dorsal and ventral V2 contains neurones with receptive fields centred within 1 degree of the centre of the fovea. The visuotopy, size, shape and location of V2 show little variation among individuals. Analysis of cortical magnification factor (CMF) revealed that the V2 map of the visual field is highly anisotropic: for any given eccentricity, the CMF is approximately twice as large in the dimension parallel to the V1/V2 border as it is perpendicular to this border. Moreover, comparison of V2 and V1 in the same individuals demonstrated that the representation of the central visual field is emphasised in V2, relative to V1. Approximately half of the surface area of V2 is dedicated to the representation of the central 5 degrees of the visual field. Calculations based on the CMF, receptive field scatter, and receptive field size revealed that the point-image size measured parallel to the V1/V2 border (2-3 mm) equals the width of a full cycle of cytochrome oxidase stripes in V2, suggesting a close correspondence between physiological and anatomical estimates of the dimensions of modular components in this area.

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Visuotopic organisation of striate cortex in the marmoset monkey (Callithrix jacchus)

Cited by 91 publications

References 67 publications

Visual Responses of Neurons in the Middle Temporal Area of New World Monkeys after Lesions of Striate Cortex

Visual Responses of Neurons in the Middle Temporal Area of New World Monkeys after Lesions of Striate Cortex

Specializations of the granular prefrontal cortex of primates: Implications for cognitive processing

The second visual area in the marmoset monkey: Visuotopic organisation, magnification factors, architectonical boundaries, and modularity

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