Cortical maps as a fundamental neural substrate for visual representation.

Visual perception is the product of serial hierarchical processing, parallel processing, and remapping on a dynamic network involving several topographically organized cortical visual areas. Here, we will focus on the topographical organization of cortical areas and the different kinds of visual maps found in the primate brain. We will interpret our findings in light of a broader representational framework for perception.

Architecture of the inferior parietal cortex in capuchin monkey.

We studied the organization of the inferior parietal cortex (IPC) in five capuchin monkey (6 hemispheres) using cytoarchitectonic (Nissl), myeloarchitectonic (Gallyas), and immune-architectonic (SMI-32 monoclonal antibody) techniques. We partitioned the IPC into five distinct areas: PFG, PG, Opt, PFop, and PGop. Since we used parasagittal sections, we were not able to study area PF due to its far lateral position, which yielded slices that were tangential to the pial surface.

Time course of dorsolateral geniculate nucleus plasticity in adult monkeys with laser-induced retinal lesions.

We studied changes in the expression of growth-associated protein 43 (GAP43), glial fibrillary acidic protein (GFAP), and calcium-binding proteins (calbindin [Cb] and parvalbumin [Pv]) in the dorsal lateral geniculate nucleus (dLGN) of four capuchin monkeys with laser-induced retinal lesions. The lesions were generated with the aid of a neodymium-YAG dual-frequency laser with shots of different intensity and at different survival time in each animal. The expression of these proteins in the layers of the dLGN was evaluated by performing histodensitometry of coronal sections throughout the nucleus.

Effects of MT lesions on visuomotor performance in macaques.

Monkeys with selective bilateral lesions of area MT were trained on tasks designed to examine visuomotor function. They were required to: 1- retrieve a small food pellet from a narrow slot; 2- locate and retrieve a loose peanut mounted on a background of fixed peanuts; and 3- retrieve an erratically moving food pellet from a spinning bowl. After the lesions, these monkeys were behaviorally impaired relative to their own preoperative performances and also relative to the postoperative performances of the control monkeys with lesions in optic radiation fibers (OR) under MT or lesions in the posterior parietal cortex (PP).

Genetic variability of the sws1 cone opsin gene among New World monkeys.

Vision is a major sense for Primates and the ability to perceive colors has great importance for the species ecology and behavior. Visual processing begins with the activation of the visual opsins in the retina, and the spectral absorption peaks are highly variable among species. In most Primates, LWS/MWS opsins are responsible for sensitivity to long/middle wavelengths within the visible light spectrum, and SWS1 opsins provide sensitivity to short wavelengths, in the violet region of the spectrum.

Tangential distribution of cell type and direction selectivity in monkey area MT.

We studied the multiunit responses to moving and static stimuli from 585 cell clusters in area MT using multi-electrode arrays. Our aim was to explore if MT columns exhibit any larger-scale tangential organization or clustering based on their response properties. Neurons showing both motion and orientation selectivity were classified into four categories: 1- Type I (orientation selectivity orthogonal to the axis of motion); 2- Type II (orientation selectivity coaxial to the axis of motion); 3- Type DS (significant response to moving stimuli, but non-significant response to static stimuli); and 4- Type OS (significant orientation selectivity, but non-significant direction selectivity).

Neuronal response properties across cytochrome oxidase stripes in primate V2.

Cytochrome oxidase histochemistry reveals large-scale cortical modules in area V2 of primates known as thick, thin, and interstripes. Anatomical, electrophysiological, and tracing studies suggest that V2 cytochrome oxidase stripes participate in functionally distinct streams of visual information processing. However, there is controversy whether the different V2 compartments indeed correlate with specialized neuronal response properties.

Cortical Afferents of Area 10 in Cebus Monkeys: Implications for the Evolution of the Frontal Pole.

Area 10, located in the frontal pole, is a unique specialization of the primate cortex. We studied the cortical connections of area 10 in the New World Cebus monkey, using injections of retrograde tracers in different parts of this area. We found that injections throughout area 10 labeled neurons in a consistent set of areas in the dorsolateral, ventrolateral, orbital, and medial parts of the frontal cortex, superior temporal association cortex, and posterior cingulate/retrosplenial region.

Partitioning of the primate intraparietal cortex based on connectivity pattern and immunohistochemistry for Cat-301 and SMI-32.

We propose a partitioning of the primate intraparietal sulcus (IPS) using immunoarchitectural and connectivity criteria. We studied the immunoarchitecture of the IPS areas in the capuchin monkey using Cat-301 and SMI-32 immunohistochemistry. In addition, we investigated the IPS projections to areas V4, TEO, PO, and MT using retrograde tracer injections in nine hemispheres of seven animals.

Time course of cytochrome oxidase blob plasticity in the primary visual cortex of adult monkeys after retinal laser lesions.

We studied the time course of changes of cytochrome oxidase (CytOx) blob spatial density and blob cross-sectional area of deprived (D) and nondeprived (ND) portions of V1 in four capuchin monkeys after massive and restricted retinal laser lesions. Laser shots at the border of the optic disc produced massive retinal lesions, while low power laser shots in the retina produced restricted retinal lesions. These massive and restricted retinal lesions were intended to simulate glaucoma and diabetic retinopathy, respectively.

The Role of the Pulvinar in Spatial Visual Attention.

This chapter deals with the role of the pulvinar in spatial visual attention. There are at least two aspects in which the pulvinar seems to be instrumental for selective visual processes. The first aspect concerns pulvinar connectivity pattern.

GABA Inactivation of the Pulvinar.

In this chapter, we discuss the effects of GABA (gamma-aminobutyric acid) inactivation of the pulvinar on the electrophysiological responses to visual stimuli. A direct way to access the pulvinar-cortical interaction is to pharmacologically inactivate the pulvinar and measure the impact on cortical activity. To this aim, we have focused our efforts on recording in cortical visual area V2 while inactivating the topographically corresponding region of the pulvinar.

Modulation of Pulvinar Neuronal Activity by Arousal.

In this chapter, we discuss the modulation of pulvinar neuronal activity by arousal. In contrast to electrophysiological recordings in the early visual cortex, neuronal activity in the pulvinar is particularly sensitive to anesthesia. In the absence of sensory stimulation, pulvinar neurons can be characterized by spontaneous low-frequency rhythmic bursts of spiking activity.

Response Properties of Pulvinar Neurons Studied with Single-Unit Electrophysiological Recordings.

In this chapter, we discuss the types of visual receptive fields revealed by single-unit electrophysiological recordings in the pulvinar. Nearly all neurons with identifiable receptive fields responded to visual stimulation presented on the contralateral hemifield, within 25° of the fovea. The majority of the visual neurons responded to some form of moving stimulus, and some additionally exhibited direction or orientation selectivity.

Comparative Pulvinar Organization Across Different Primate Species.

In this chapter, we compare the pattern of pulvinar immunohistochemical staining for the calcium-binding proteins calbindin and parvalbumin and for the neurofilament protein SMI-32 in macaque, capuchin, and squirrel monkeys. This group of New and Old World primates shares five similar pulvinar subdivisions: PI, PI, PI, PI, and PI. In the Old World macaque monkey, the inferior-lateral pulvinar can be subdivided into the P1 and P2 fields based on its connectivity with visual area V1.

Visual Topography of the Pulvinar Projection Zones.

In this chapter, we describe the visuotopy of the pulvinar subdivisions P1, P2, and P4. In all primates, P1 colocalizes with the chemoarchitecturally defined PI and a small portion of PL. The peripheral visual field is represented anteriorly in the medial portion of PI, while central vision is represented more posteriorly in the medial portion of PL.

Reestablishing the Chemoarchitectural Borders Based on Electrophysiological and Connectivity Data.

In this chapter, we discuss the poor agreement between visuotopic maps described using electrophysiological and connectivity data and the subdivisions of the pulvinar based on chemoarchitecture. We focus on the differences and similarities between New and Old World monkeys to evaluate how this agreement evolved during evolution. There is some agreement in the localization of P1, described using electrophysiological and connectivity data, and the lateral and central portions of the nucleus pulvinaris inferior (PI), defined based on chemoarchitectural criteria.

Connectivity of the Pulvinar.

Pulvinar connectivity has been studied using a variety of neuroanatomical tracing techniques in both New and Old World monkeys. Connectivity studies have revealed additional maps of the visual field other than those described using electrophysiological techniques, such as P3 in the capuchin monkey and P3/P4 in the macaque monkey. In this chapter, we argue that with increasing cortical size, the pulvinar developed new functional subdivisions in order to effectively interconnect and interact with the cortex.

Visual Map Representations in the Primate Pulvinar.

The pulvinar receives direct visual information from the retina and indirect visual information from several cortical and subcortical areas. In this chapter, we discuss the visuotopic organization of the primate pulvinar. Electrophysiological techniques have been systematically employed to study pulvinar visuotopy in the owl, capuchin, and macaque monkeys.

Chemoarchitecture of the Pulvinar.

Cytochemical and immunocytochemical methods reveal details of the pulvinar architecture that are not apparent from Nissl and myelin staining. The results of these techniques have been interpreted in different ways by different investigators, each adopting different sets of nomenclature for the various pulvinar subdivisions. In this chapter, we discuss the notion that the differentiation of the pulvinar along primate evolution took place upon a relatively rigid chemoarchitectonic scaffold.

Cytoarchitecture and Myeloarchitecture of the Pulvinar.

In this chapter, we discuss the different ways in which the primate pulvinar has been subdivided, based on cytoarchitectural and myeloarchitectural criteria. One original criterion, based on cytoarchitecture, subdivided the pulvinar into nucleus pulvinaris medialis (PM), nucleus pulvinaris lateralis (PL), and nucleus pulvinaris inferior (PI). Later, the anterior limits of the pulvinar were extended and a subdivision was added to this nucleus, named pulvinar oralis (PO).

Introduction.

The pulvinar can be subdivided into well-delimitated regions based on chemoarchitectural, cytoarchitectural, myeloarchitectural, connectivity, and electrophysiological criteria. Subdivisions of the pulvinar based on its chemoarchitectural features are the most consistently preserved across species of New and Old World monkeys. It is reasonable to speculate that the occurrence and distribution of calcium-binding proteins in the pulvinar, such as calbindin and parvalbumin, have been preserved along evolution.

Controversies about the visual areas located at the anterior border of area V2 in primates.

Anatomical and electrophysiological studies have provided us with detailed information regarding the extent and topography of the primary (V1) and secondary (V2) visual areas in primates. The consensus about the V1 and V2 maps, however, is in sharp contrast with controversies regarding the organization of the cortical areas lying immediately rostral to V2. In this review, we address the contentious issue of the extent of the third visual area (V3).

Precise visuotopic organization of the blind spot representation in primate V1.

The optic disk is a region of the retina consisting mainly of ganglion cell axons and blood vessels, which generates a visual scotoma known as the blind spot (BS). Information present in the surroundings of the BS can be used to complete the missing information. However, the neuronal mechanisms underlying these perceptual phenomena are poorly understood.

Claustrum projections to prefrontal cortex in the capuchin monkey (Cebus apella).

We examined the pattern of retrograde tracer distribution in the claustrum following intracortical injections into the frontal pole (area 10), and in dorsal (area 9), and ventral lateral (area 12) regions of the rostral prefrontal cortex in the tufted capuchin monkey (Cebus apella). The resulting pattern of labeled cells was assessed in relation to the three-dimensional geometry of the claustrum, as well as recent reports of claustrum-prefrontal connections in other primates. Claustrum-prefrontal projections were extensive, and largely concentrated in the ventral half of the claustrum, especially in the rostral 2/3 of the nucleus.