Shape responses in a macaque frontal area connected to posterior parietal cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Processing

Background:

• The dorsal visual stream in primates processes object shape for action guidance.
• Information flow from the posterior parietal cortex to the frontal cortex is not well understood.

Purpose of the Study:

• To investigate the connectivity and information processing between the posterior part of the Anterior Intraparietal area (pAIP) and prefrontal cortex (area 45B).
• To clarify the transmission of shape information beyond the posterior parietal cortex.

Main Methods:

• Electrical microstimulation of a shape-selective region in pAIP during functional Magnetic Resonance Imaging (fMRI).
• Recording single-unit responses in fMRI-identified prefrontal cortex (area 45B) following pAIP stimulation.

Main Results:

• pAIP stimulation activated area 45B in the prefrontal cortex.
• Neurons in area 45B responded selectively to shape contours and small fragments at short latencies.
• Area 45B neurons showed preferences for smaller shape fragments and had smaller receptive fields than pAIP neurons, contrary to hierarchical processing expectations.

Conclusions:

• Provides the first evidence for ultra-fast shape processing in the prefrontal cortex.
• Suggests the pAIP to area 45B pathway may not be primarily involved in object grasping.
• Challenges the traditional hierarchical model of visual information processing.