Neonatal cortical ablation disrupts multisensory development in superior colliculus

Area of Science:

• Neuroscience
• Sensory Integration
• Developmental Neurobiology

Background:

• The superior colliculus (SC) integrates visual, auditory, and somatosensory information.
• Cortical areas, specifically the anterior ectosylvian sulcus (AES) and rostral lateral suprasylvian sulcus (rLS), provide crucial input for SC multisensory processing.
• Early developmental disruption of these inputs impacts SC neuron function and behavior.

Purpose of the Study:

• To investigate the impact of neonatal removal of AES and rLS on the development of multisensory neurons in the cat superior colliculus (SC).
• To determine if the neonatal brain can compensate for the loss of both AES and rLS, or either individually, on SC multisensory development.

Main Methods:

• Neonatal cats underwent surgical removal of specific cortical areas (AES, rLS, or both).
• At maturity, electrophysiological recordings were used to characterize the receptive fields and multisensory integration properties of SC neurons.
• The incidence and functional properties of multisensory neurons were quantified and compared to controls.

Main Results:

• Neonatal removal of both AES and rLS resulted in a significant reduction in multisensory SC neurons, with remaining neurons exhibiting abnormal receptive fields and integration.
• Surprisingly, neonatal removal of either AES or rLS alone did not prevent the normal development of multisensory SC neurons.
• SC neurons in animals with single-area neonatal removal showed normal spatial register and adult-like multisensory integration.

Conclusions:

• Early loss of both AES and rLS severely disrupts the development of multisensory processing in the SC, indicating limited compensatory capacity for combined cortical input loss.
• Neonatal removal of either AES or rLS individually does not impede normal SC multisensory development, suggesting functional redundancy or compensatory mechanisms between these areas during early development.
• These findings highlight the critical role of combined cortico-collicular influences during a specific developmental window for establishing normal SC multisensory function.