Gaze direction influences grasping actions towards unseen, haptically explored, objects.

Area of Science:

• Neuroscience
• Motor Control
• Sensory Integration

Background:

• Haptic exploration generates mental object representations for future actions.
• Haptically-acquired object images (HOIs) involve early visual cortex (EVC), but its causal role is unclear.
• Grasping relies on visual information, requiring frame of reference shifts with eye position.

Purpose of the Study:

• To investigate the causal role of the early visual cortex (EVC) in haptically-acquired object representation.
• To determine if motor control of grasping haptic objects depends on eye position.
• To explore potential resource sharing between haptic and visual/oculomotor systems.

Main Methods:

• Measured 4-finger kinematics in 15 participants grasping unseen, previously haptically explored objects.
• Manipulated participants' gaze direction (3 positions) while object position remained fixed.
• Conducted a control experiment with intransitive hand movements to assess gaze modulation.

Main Results:

• Finger kinematics during reaching for unseen objects significantly varied with gaze position.
• Gaze direction modulated grasping movements, indicating an eye-centered frame of reference influence.
• Intransitive hand movements were not affected by gaze direction, confirming task specificity.

Conclusions:

• The motor system appears to use haptically acquired object information coded in an eye-centered frame of reference within the visual cortex.
• Eye position influences haptic grasping, even without visual input, suggesting shared neural resources.
• This indicates integration between haptic and visual/oculomotor systems for object-directed actions.