Frank Bremmer

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In monkeys, posterior parietal and premotor cortex play an important integrative role in polymodal motion processing. In contrast, our understanding of the convergence of senses in humans is only at its beginning. To test for equivalencies between macaque and human polymodal motion processing, we used functional MRI in normals while presenting moving(More)
Spatial information is conveyed to the primary visual cortex in retinal coordinates. Movement trajectory programming, however, requires a transformation from this sensory frame of reference into a frame appropriate for the selected part of the body, such as the eye, head or arms. To achieve this transformation, visual information must be combined with(More)
The representation of the visual field in the primate lateral intraparietal area (LIP) was examined, using a rapid, computer-driven receptive field (RF) mapping procedure. RF characteristics of single LIP neurons could thus be measured repeatedly under different behavioral conditions. Here we report data obtained using a standard ocular fixation task during(More)
How does the brain process visual information about self-motion? In monkey cortex, the analysis of visual motion is performed by successive areas specialized in different aspects of motion processing. Whereas neurons in the middle temporal (MT) area are direction-selective for local motion, neurons in the medial superior temporal (MST) area respond to(More)
We studied the effect of eye position on visual and pursuit-related activity in neurons in the superior temporal sulcus of the macaque monkey. Altogether, 109 neurons from the middle temporal area (area MT) and the medial superior temporal area (area MST) were tested for influence of eye position on their stimulus-driven response in a fixation paradigm. In(More)
Animals can use different sensory signals to localize objects in the environment. Depending on the situation, the brain either integrates information from multiple sensory sources or it chooses the modality conveying the most reliable information to direct behavior. This suggests that somehow, the brain has access to a modality-invariant representation of(More)
We studied the effect of eye position on pursuit-related discharges and activity during fixation in darkness for neurons of monkey visual cortical areas (lateral intraparietal area) LIP and 7A. In a first step, neurons were tested for direction-specific activity related to pursuit eye movements while the monkey tracked a moving target. In consecutive trials(More)
Self-motion detection requires the interaction of a number of sensory systems for correct perceptual interpretation of a given movement and an eventual motor response. Parietal cortical areas are thought to play an important role in this function, and we have thus studied the encoding of multimodal signals and their spatiotemporal interactions in the(More)
Visual inputs to the brain are mapped in a retinocentric reference frame, but the motor system plans movements in a body-centered frame. This basic observation implies that the brain must transform target coordinates from one reference frame to another. Physiological studies revealed that the posterior parietal cortex may contribute a large part of such a(More)
We make fast, ballistic eye movements called saccades more often than our heart beats. Although every saccade causes a large movement of the image of the environment on our retina, we never perceive this motion. This aspect of perceptual stability is often referred to as saccadic suppression: a reduction of visual sensitivity around the time of saccades.(More)