Temporal Relation of Population Activity in Visual Areas MT/MST and in Primary Motor Cortex during Visually Guided Tracking Movements

Abstract

There is growing evidence that in primate cerebral cortex the areas along the 'dorsal pathway' are involved in the transformation of visual motion information towards a motor command. To pursue this cortical flow of information from visual motion areas to the motor cortex, single-cell activity was recorded from visual areas MT/MST (middle temporal area/medial superior temporal area) and from primary motor cortex (M1) while monkeys tracked moving targets with their right hand. Spike activity of 353 directionally tuned motor cortex cells was combined to a time-varying population vector, and similarly a time-resolved visual population vector was calculated from 252 MT/MST cells. Both population vectors code faithfully for the direction of the collinear motion of target and hand. For a given direction, the length of the population vectors varied over time during the performance of the task. The temporal evolution of both population responses reflects the different relationship between the early visual responses to the moving target and the directional motor command controlling the hand movement. The results indicate that during the visual tracking task visual and motor populations which code for similar directions of movement are co-activated with considerable temporal overlap. Despite this co-activation in both modalities, we failed to observe any significant synchronization between areas MT/MST and M1.

Adaptations of lateral hand movements to early and late visual occlusion in catching

“…1). However, cross-links exist between the oculomotor and forelimb control systems (e.g., Engel and Soechting 2003;Ilg and Schumann 2007;Lazzari et al 1997; see also Kruse et al 2002) and the present results suggest that the dynamic visuomotor gain control proposed for the former is also employed for the latter.…”

Functional Organization of Parietal Neuronal Responses to Optic-Flow Stimuli

“…Therefore it was reasonable to try to find out whether the latter superordinate aspects of optic flow could be represented at the level of the neuronal population. It should be noted that this analysis was not aimed to reconstruct the visual stimulus from the neuronal responses and has nothing to do with the population vector analysis employed to that end by other researchers in studies of visual motion (Kruse et al 2002;Page and Duffy 1999;Steinmetz et al 1987). The second consideration stems from behavioral aspects, namely the prominence of expansion in daily life due to locomotion.…”

“…In addition to responding to rectilinear motion, cells in MST and area 7a also respond to optic-flow stimuli, including stimulus motion in depth (Duffy and Wurtz 1991;Merchant et al 2001;Siegel and Read 1997;Tanaka and Saito 1989). Finally, the population vector analysis has been successfully applied in several studies to reconstruct the course of a moving visual stimulus from the discharge of cell ensembles in MT (Kruse et al 2002), MST (Page and Duffy 1999), and area 7a (Steinmetz et al 1987).…”

Contributions of the Human Temporoparietal Junction and MT/V5+ to the Timing of Interception Revealed by Transcranial Magnetic Stimulation

“…Best-fitting was 136 and 114 ms in control and TMS-perturbed trials, respectively. After we account for the neuromechanical delay between motor cortex activation and button-press response (ϳ75 ms, see Materials and Methods), we estimate the additional processing time to be ϳ40 -60 ms, compatible with processing delays between visual-motion regions and motor cortex in target tracking or interception (Kruse et al, 2002;Merchant et al, 2004;Senot et al, 2008).…”