Connected neurons in multiple neocortical areas, comprising parallel circuits, encode essential information for...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Neocortical areas utilize complex neuronal circuits for advanced cognitive functions.
• Synaptic plasticity research suggests specific neurons and circuits process distinct information.
• The precise structure of circuits and key neurons for tasks like visual discrimination remains unclear.

Purpose of the Study:

• To investigate the role of postsynaptic neurons in the perirhinal cortex and ventral temporal association areas in visual shape discrimination learning.
• To elucidate the specific neuronal circuits involved in learning and recalling visual shapes.

Main Methods:

• Constitutively active Protein Kinase C (PKC) was delivered to rat postrhinal cortex neurons.
• Silencing small interfering RNA (siRNA) was introduced to postsynaptic neurons in perirhinal cortex or ventral temporal areas using novel gene transfer technology.
• Activity-dependent gene imaging was employed to monitor neuronal activity and assess the impact of siRNA.

Main Results:

• siRNA-induced silencing of postsynaptic neurons in perirhinal cortex or ventral temporal areas led to deficits in visual shape discrimination performance.
• Neuronal activity was blocked, hindering the activation of specific signaling pathways crucial for learning.
• Dendritic protein synthesis and CREB activation were subsequently obstructed.

Conclusions:

• Two distinct parallel circuits, involving the perirhinal cortex and ventral temporal association areas, are necessary for visual shape discrimination learning.
• These circuits are critical for encoding and potentially recalling learned visual information.
• The findings underscore the importance of specific neuronal pathways in complex cognitive tasks.