RESUMO
The thalamus is a deep cerebral structure that is crucial for proper neurological functioning as it transmits signals from nearly all pathways in the body. Insult to the thalamus can, therefore, result in complex syndromes involving sensation, cognition, executive function, fine motor control, emotion, and arousal, to name a few. Specific territories in the thalamus that are supplied by deep cerebral arteries have been shown to correlate with clinical symptoms. The aim of this review is to enhance our understanding of the arterial anatomy of the thalamus and the complications that can arise from lesions to it by considering the functions of known thalamic nuclei supplied by each vascular territory.
Assuntos
Artéria Basilar/anatomia & histologia , Infarto Encefálico/fisiopatologia , Círculo Arterial do Cérebro/anatomia & histologia , Artéria Cerebral Posterior/anatomia & histologia , Tálamo/irrigação sanguínea , Núcleos Anteriores do Tálamo/anatomia & histologia , Núcleos Anteriores do Tálamo/irrigação sanguínea , Núcleos Anteriores do Tálamo/fisiologia , Corpos Geniculados/anatomia & histologia , Corpos Geniculados/irrigação sanguínea , Corpos Geniculados/fisiologia , Humanos , Núcleos Laterais do Tálamo/anatomia & histologia , Núcleos Laterais do Tálamo/irrigação sanguínea , Núcleos Laterais do Tálamo/fisiologia , Núcleo Mediodorsal do Tálamo/anatomia & histologia , Núcleo Mediodorsal do Tálamo/irrigação sanguínea , Núcleo Mediodorsal do Tálamo/fisiologia , Pulvinar/anatomia & histologia , Pulvinar/irrigação sanguínea , Pulvinar/fisiologia , Tálamo/anatomia & histologia , Tálamo/fisiologia , Núcleos Ventrais do Tálamo/anatomia & histologia , Núcleos Ventrais do Tálamo/irrigação sanguínea , Núcleos Ventrais do Tálamo/fisiologiaRESUMO
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. A single map of the visual field has been described in the pulvinar of the owl monkey, while two independent maps have been described in the capuchin and macaque pulvinar.
Assuntos
Mapeamento Encefálico , Primatas , Pulvinar , Vias Visuais , Animais , Aotus trivirgatus , Primatas/fisiologia , Pulvinar/fisiologia , Retina , Campos VisuaisRESUMO
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.
Assuntos
Pulvinar , Córtex Visual , Campos Visuais , Animais , Cebus , Pulvinar/anatomia & histologia , Pulvinar/fisiologia , Córtex Visual/anatomia & histologia , Córtex Visual/fisiologia , Vias VisuaisRESUMO
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. Similarly, there is some colocalization between P3 and the medial portion of PI in both New and Old World monkeys. One difference between primates refers to P2, which is present in the Old World macaque monkey but absent in the New World monkeys. P4, which has not been studied in all primates, shows a partial spatial agreement with the dorsal portion of the chemoarchitecturally defined PL.
Assuntos
Mapeamento Encefálico , Pulvinar , Vias Visuais , Animais , Cercopithecidae , Platirrinos , Pulvinar/anatomia & histologia , Pulvinar/fisiologia , Córtex VisualRESUMO
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. The vertical meridian representation is located on the lateral edge of P1, while the horizontal meridian is represented obliquely from the lateral to the medial extent of P1. The upper visual field is represented ventrally, while the lower field is located dorsally. P2 has only been described in the macaque monkey. It contains a representation of the peripheral visual field, located in its anterior portion, and of the central field, which is located in posterior PL. P4 has a complex topographic arrangement. The representation of the vertical meridian is located on the dorsal edge of P4, while the representation of the horizontal meridian divides P4 into dorsal and ventral portions.
Assuntos
Primatas , Pulvinar , Campos Visuais , Animais , Primatas/anatomia & histologia , Primatas/fisiologia , Pulvinar/anatomia & histologia , Pulvinar/fisiologia , Córtex VisualRESUMO
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: PIP, PIM, PIC, PIL, and PILS. 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. On the other hand, only the P1 field and no P2 was found in the New World capuchin monkey. Notably, the similarities in chemoarchitecture contrast with the distinct connectivity patterns and the different visuotopic organizations found across the species.
Assuntos
Primatas , Pulvinar , Animais , Primatas/anatomia & histologia , Primatas/fisiologia , Pulvinar/anatomia & histologia , Pulvinar/fisiologia , Córtex Visual , Vias VisuaisRESUMO
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. Most units could be driven by monocular stimulation and showed receptive fields of at least 100 square degrees in area. Finally, most of the units recorded exhibited continuous peripheral receptive fields, even though a few of them could be bilaterally activated.
Assuntos
Estimulação Luminosa , Pulvinar , Percepção Visual , Animais , Fenômenos Eletrofisiológicos , Orientação , Pulvinar/fisiologia , Córtex VisualRESUMO
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. However, multisensory stimulation capable of arousing the animal from deeper anesthesia levels is able to reestablish the necessary neuronal dynamics and switch the pulvinar into an active state. Under these conditions, cortical slow-wave activity is substituted by a higher-frequency oscillatory pattern associated with arousal. Here, we describe two types of transitions in pulvinar activity pattern that can be observed when arousing the animal with multisensory stimulation.
Assuntos
Nível de Alerta , Pulvinar , Córtex Visual , Animais , Neurônios , Periodicidade , Estimulação Luminosa , Pulvinar/fisiologia , Córtex Visual/fisiologia , VigíliaRESUMO
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.
Assuntos
Pulvinar , Ácido gama-Aminobutírico , Animais , Pulvinar/fisiologia , Córtex Visual , Ácido gama-Aminobutírico/fisiologiaRESUMO
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. The pulvinar is connected with brain regions known to be playing a role in attentional mechanisms, such as area V4, the superior colliculus (SC), and the inferior parietal cortex (IP). Additionally, the pulvinar is richly interconnected with multiple cortical areas. This enables the pulvinar to serve as a hub for brain communication, potentially gating the flow of information across different regions. The second aspect concerns neuronal circuits intrinsic to the pulvinar. We claim these circuits are subserving three basic steps regarding the allocation of spatial attention: disengaging from the current focus of attention, moving it to a new target, and engaging it at a new position.