Biology subjects

Caprara, I.

Publications and source records attributed to Caprara, I..

3 recordsLinked to original sources

bioRxiv2020

Temporal dynamics of neural activity in macaque frontal cortex assessed with large-scale recordings

We make eye movements to objects before grasping these objects, and the gaze direction generally indicates where the object will be grasped. Hence, the brain has to coordinate eye-, arm- and hand movements. We performed large-scale recordings (more than 2000 responsive sites) in frontal cortex of monkeys during a saccade-reach-grasp task. When an object appeared in peripheral vision, the first burst of activity emerged in prearcuate areas (the FEF and area 45B), followed by dorsal and ventral premotor cortex, and a buildup of activity in primary motor cortex. After the saccade, prearcuate activity remained elevated while primary motor and premotor activity rose in anticipation of the upcoming arm and hand movement. Some premotor and prearcuate sites were equally active when the object appeared in peripheral vision and at the fovea, suggesting a role in eye-hand coordination. Thus, a large part of lateral frontal cortex is active during a saccade-reach-grasp task.

neuroscience↗

bioRxiv2020

The causal role of three frontal cortical areas in grasping

Efficient object grasping requires the continuous control of arm and hand movements based on visual information. Previous studies have identified a network of parietal and frontal areas that is crucial for the visual control of prehension movements. Electrical microstimulation of 3D shape-selective clusters in AIP during fMRI activates areas F5a and 45B, suggesting that these frontal areas may represent important downstream areas for object processing during grasping, but the role of area F5a and 45B in grasping is unknown. To assess their causal role in the frontal grasping network, we reversibly inactivated 45B, F5a and F5p during visually-guided grasping in macaque monkeys. First, we recorded single neuron activity in 45B, F5a and F5p to identify sites with object responses during grasping. Then, we injected muscimol or saline to measure the grasping deficit induced by the temporary disruption of each of these three nodes in the grasping network. The inactivation of all three areas resulted in a significant increase in the grasping time in both animals, with the strongest effect observed in area F5p. These results not only confirm a clear involvement of F5p, but also indicate causal contributions of area F5a and 45B in visually-guided object grasping.

neuroscience↗

bioRxiv2020

Effect of viewing distance on object responses in macaque areas 45B, F5a and F5p

To perform real-world tasks like grasping, the primate brain has to process visual object information so that the grip aperture can be adjusted before contact with the object is made. Previous studies have demonstrated that the posterior subsector of the Anterior Intraparietal area (pAIP) is connected to frontal area 45B, and the anterior subsector of AIP (aAIP) to F5a (Premereur et al., 2015). However, the role of area 45B and F5a in visually-guided object grasping is poorly understood. Here, we investigated the role of area 45B, F5a and F5p in visually-guided grasping. If a neuronal response to an object during passive fixation represents the activation of a motor command related to the preshaping of the hand, such neurons should prefer objects presented within reachable distance. Conversely, neurons encoding a pure visual representation of an object should be less affected by viewing distance. Contrary to our expectations, we found that the majority of neurons in area 45B were object- and viewing distance selective, with a clear preference for the near viewing distance. Area F5a showed much weaker object selectivity compared to 45B, with a similar preference for objects presented at the Near position emerging mainly in the late epoch. Finally, F5p neurons were less object selective and frequently preferred objects presented at the Far position. Therefore, contrary to our expectations, neurons in area 45B - but not F5p neurons - prefer objects presented in peripersonal space. Significance statementThe current experiment provides the first evidence on the neural representation of distance in frontal areas that are active during visually-guided grasping. Area 45B and F5a neurons were object- and distance-selective, and preferred the near viewing distance even for objects with identical retinal size. In area F5p we observed strong visual responses with an unexpected preference for the Far viewing distance, suggesting that the motor-related object representation was still active during the presentation of objects outside reaching distance.

neuroscience↗