Biomedical subjects

S Treue

Publications and source records attributed to S Treue.

20 records · Page 2Linked to original sources

PubMedDate not supplied

The effect of transiency on perceived velocity of visual patterns: a case of "temporal capture".

We measured the points of subjective equality of velocity for dynamic unidirectionally moving random-dot patterns with different amounts of transiency. The transiency was changed by varying the time a dot would move before being randomly replotted within the stimulus. The perceived velocity of patterns moving at intermediate velocities (4 or 6 deg/sec) was increased by decreasing the point lifetime while no speedup was observed at high velocities (12 deg/sec). A speedup was also observed when a few stationary points of short lifetime were introduced into a stimulus. The non-directional transiency generated by these flickering points seems to be captured by the moving pattern and biases the velocity estimate. We term this phenomenon "temporal capture". The results are in agreement with models that determine velocity by comparing the activity in lower and higher temporal frequency channels. Our stimuli would selectively increase activity in high temporal frequency channels and thus lead to an increase in perceived velocity.

Humans↗

PubMedDate not supplied

Neural responses to velocity gradients in macaque cortical area MT.

Visual motion, i.e. the pattern of changes on the retinae caused by the motion of objects or the observer through the environment, contains important cues for the accurate perception of the three-dimensional layout of the visual scene. In this study, we investigate if neurons in the visual system, specifically in area MT of the macaque monkey, are able to differentiate between various velocity gradients. Our stimuli were random dot patterns designed to eliminate stimulus variables other than the orientation of a velocity gradient. We develop a stimulus space ("deformation space") that allows us to easily parameterize our stimuli. We demonstrate that a substantial proportion of MT cells show tuned responses to our various velocity gradients, often exceeding the response evoked by an optimized flat velocity profile. This suggests that MT cells are able to represent complex aspects of the visual environment and that their properties make them well suited as building blocks for the complex receptive field properties encountered in higher areas, such as area MST to which many cells in area MT project.

Animals↗