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Using noninvasive functional magnetic resonance imaging (fMRI) technique, we analyzed the responses in human area MT with regard to visual motion, color, and luminance contrast sensitivity, and retinotopy. As in previous PET studies, we found that area MT responded selectively to moving (compared to stationary) stimuli. The location of human MT in the(More)
A critical step in the interpretation of the visual world is the integration of the various local motion signals generated by moving objects. This process is complicated by the fact that local velocity measurements can differ depending on contour orientation and spatial position. Specifically, any local motion detector can measure only the component of(More)
The small visual area known as MT or V5 has played a major role in our understanding of the primate cerebral cortex. This area has been historically important in the concept of cortical processing streams and the idea that different visual areas constitute highly specialized representations of visual information. MT has also proven to be a fertile culture(More)
To generate behavioral responses based on sensory input, motor areas of the brain must interpret, or "read out," signals from sensory maps. Our experiments tested several algorithms for how the motor systems for smooth pursuit and saccadic eye movements might extract a usable signal of target velocity from the distributed representation of velocity in the(More)
The early stages of primate visual processing appear to be divided up into several component parts so that, for example, colour, form and motion are analysed by anatomically distinct streams. We have found that further subspecialization occurs within the motion processing stream. Neurons representing two different kinds of information about visual motion(More)
Microelectrode recording and 2-deoxyglucose (2dg) labeling were used to investigate center-surround interactions in the middle temporal visual area (MT) of the owl monkey. These techniques revealed columnar groups of neurons whose receptive fields had opposite types of center-surround interaction with respect to moving visual stimuli. In one type of column,(More)
Visual neurons are often characterized in terms of their tuning for various stimulus properties, such as shape, color, and velocity. Generally, these tuning curves are further modulated by the overall intensity of the stimulus, such that increasing the contrast increases the firing rate, up to some maximum. In this paper, we describe the tuning of neurons(More)
The contribution of sensory neurons to perceptual decisions about external stimulus events has received much attention, but it is less clear how sensory responses are integrated over time to produce decisions that are both rapid and reliable. To address this issue, we recorded from middle temporal area and medial superior temporal area neurons in rhesus(More)
The integration of visual information is a critical task that is performed by neurons in the extrastriate cortex of the primate brain. For motion signals, integration is complicated by the geometry of the visual world, which renders some velocity measurements ambiguous and others incorrect. The ambiguity arises because neurons in the early stages of visual(More)
To track a moving object, its motion must first be distinguished from that of the background. The center-surround properties of neurons in the middle temporal visual area (MT) may be important for signaling the relative motion between object and background. To test this, we microstimulated within MT and measured the effects on monkeys' eye movements to(More)