Orientation column

About: Orientation column is a research topic. Over the lifetime, 1142 publications have been published within this topic receiving 130169 citations.

Circuit Mechanisms Governing Local vs. Global Motion Processing in Mouse Visual Cortex.

Abstract: A withstanding question in neuroscience is how neural circuits encode representations and perceptions of the external world. A particularly well-defined visual computation is the representation of global object motion by pattern direction-selective (PDS) cells from convergence of motion of local components represented by component direction-selective (CDS) cells. However, how PDS and CDS cells develop their distinct response properties is still unresolved. The visual cortex of the mouse is an attractive model for experimentally solving this issue due to the large molecular and genetic toolbox available. Although mouse visual cortex lacks the highly ordered orientation columns of primates, it is organized in functional sub-networks and contains striate- and extrastriate areas like its primate counterparts. In this Perspective article, we provide an overview of the experimental and theoretical literature on global motion processing based on works in primates and mice. Lastly, we propose what types of experiments could illuminate what circuit mechanisms are governing cortical global visual motion processing. We propose that PDS cells in mouse visual cortex appear as the perfect arena for delineating and solving how individual sensory features extracted by neural circuits in peripheral brain areas are integrated to build our rich cohesive sensory experiences.

The Role of Striate Cortex

Abstract: Much of what is known about the role of human striate cortex in vision comes from the study of dysfunction in patients with specific lesions of visual pathways, from the retina to the occipital lobe and the adjoining temporal and parietal regions. That evidence depends on neuro-ophthalmological, neuropsychological, and psychophysical techniques. The neuroanatomy is provided, in vivo, by modern neuroimaging techniques such as magnetic resonance imaging (MRI) (Damasio and Damasio, 1989; Damasio and Frank, 1992), and (less often) at autopsy. Positron emission tomography (PET) studies offer another window on regional localization and visual function. Comparative anatomical studies on the functional organization of the visual system, particularly in the monkey, also provide insights into the corresponding organization in the human. This chapter examines these converging lines of evidence in the context of what they tell us about the role of human striate cortex [which is also referred to as the primary visual cortex, the calcarine cortex, area 17 of Brodmann (1909), and more recently as area V1] (see Fig. 1). The emphasis in this chapter is on human brain lesion studies. In the introductory section, we start with a definition of human visual areas and deficits, and follow with comments on the human brain lesion method applied to vision, on human—monkey homologies, and on subcortical inputs to V1.

Unit Responses to Moving Visual Stimuli in the Motor Cortex of the Cat

Abstract: Neurons in the pericruciate cortex of the cat were tested with moving visual stimuli for responses to specific properties of the visual receptive field. Specific response patterns were shown by cells of origin of the pyramidal tract as well as by other cells.

Spatial Receptive Fields of Single Neurons of Primary Auditory Cortex of the Cat

Abstract: Neurons in the primary auditory cortical field (AI) have been shown to be sensitive to the direction of a sound when the source is either in an anechoic free field (Middle- brooks et al, 1980; Rajan et al, 1990; Imig et al, 1990) or in anechoic virtual acoustic space (Brugge et al, 1994; 1996a,b) The spatial receptive fields obtained under these stimulus conditions are typically large in size at suprathreshold levels, often exceeding an acoustic hemifield; close to threshold their centers tend to lie on or near the acoustic axis How large receptive fields centered around the acoustic axis enable AI neurons to encode information about sound direction is not well understood, although it would appear that the time structure of the neuronal discharge within the receptive field plays a role (Mid- dlebrooks et al, 1994; Brugge et al, 1996) In this paper we review and extend our findings on directional sensitivity of isolated AI neurons to transient sound, employing conventional extracellular recording methods (Brugge et al, 1994,1996a) and a technique by which synthesized signals that mimic sounds coming from particular directions in space are delivered at the eardrums of Nembutal-anesthetized cats through a sealed and calibrated sound delivery system (Chan et al, 1993; Reale et al, 1996)

The representation of the horizontal meridian in the primary visual cortex.

Abstract: The authors report the findings of two patients that confirm the location of the horizontal meridian in the human visual cortex. The first patient had an inferior quadrant defect with a band of horizontal meridian sparing. Magnetic resonance imaging showed a lesion concentrated along the medial striate cortex. The second patient had a homonymous horizontal defect that resulted from removal of an arteriovenous malformation located in the lateral striate cortex. The findings of these two patients demonstrate that the horizontal meridian is represented at the calcarine fissure base in the primary visual cortex.