Human Experimental Studies on Motion Perception


A number of studies have been done and more are in progress.  Each of the published ones is summarized below.

The work below was only possible because of a terrific post-doctoral fellows in my lab (Julio Martinez-Trujillo, Marc Pomplun), research associate Eugene Simine, York colleague Richard Wildes, and a superb set of international collaborators (Hans-Joachim Heinze, Jens-Max Hopf,  Douglas Cheyne, William Gaetz, Stefan Treue).

Martinez-Trujillo, J.C., Cheyne, D., Gaetz, W., Simine, E., Tsotsos, J.K., Activation of area MT/V5 and the right inferior parietal cortex during the discrimination of transient direction changes in translational motion, Cerebral Cortex, 2007 Jul;17(7):1733-9. Epub 2006 Sep 29.

The perception of changes in the direction of objects that translate in space is an important function of our visual system. Here we investigate the brain electrical phenomena underlying such a function by using a combination of magnetoencephalography (MEG) and magnetic resonance imaging. We recorded MEG-evoked responses in 9 healthy human subjects while they discriminated the direction of a transient change in a translationally moving random dot pattern presented either to the right or to the left of a central fixation point. We found that responses reached their maximum in 2 main regions corresponding to motion processing area middle temporal (MT)/V5 contralateral to the stimulated visual field, and to the right inferior parietal lobe (rIPL). The activation latencies were very similar in both regions (~135 ms) following the direction change onset. Our findings suggest that area MT/V5 provides the strongest sensory signal in response to changes in the direction of translational motion, whereas area rIPL may be involved either in the sensory processing of transient motion signals or in the processing of signals related to orienting of attention.

Martinez-Trujillo, J.C., Tsotsos, J.K., Simine, E., Pomplun, M., Wildes, R., Treue, S., Heinze, H.-J., Hopf, J.-M., Selectivity for Speed Gradients in Human Area MT/V5, NeuroReport 16(5):435-438, 2005 Apr 4.

Cortical area MT/V5 in the human occipito-temporal cortex is activated by visual motion. In this study, we use functional imaging to demonstrate that a subregion of MT/V5 is more strongly activated by unidirectional motion with speed gradients than by other motion patterns. Our results suggest that like the monkey homolog middle temporal area (MT), human MT/V5 contains neurons selective for the processing of speed gradients. Such neurons may constitute an intermediate stage of processing between neurons selective for the average speed of unidirectional motion and neurons selective for different combinations of speed gradient and different motion directions such as expanding optical flow patterns.