Brain rewiring on a grand scale creates the ability for binocular vision
In a groundbreaking discovery, scientists have unveiled the intricate process of refining binocular vision in mice during a critical developmental period. The research, published in the prestigious journal Nature Communications, offers new insights into how the brain constructs stable binocular vision [1][2][3].
Key findings of the study, led by Katya Tsimring, show that the critical period for binocular vision development is characterized by a high rate of spine turnover on the dendrites of neurons involved in processing binocular vision. This turnover indicates that the neural circuits underlying binocular vision engage in a dynamic process of both synapse elimination and synapse addition [1].
During the critical period, about 32% of the dendritic spines present at Day 1 disappeared by Day 5, while 24% new spines appeared between Day 1 and Day 5. Between Day 5 and Day 10, 27% of spines were eliminated, and 24% were added. Overall, only about 40% of the spines seen at Day 1 remained by Day 10 of the critical period [1].
The study tracked not only the structural presence of these spines but also their activity in response to visual stimuli. By combining structural and functional data, the researchers showed that neurons selectively retain synapses that are more visually active or informative, thus refining the neural circuitry responsible for integrating inputs from both eyes [1].
This suggests a "connect or reject" principle, where synaptic connections that do not contribute meaningfully to binocular integration are removed, while new synapses are added and maintained based on the quality of visual input during this critical window of development [1].
The researchers observed this refinement process in real-time, marking the first time this has been achieved in mice [1]. They tracked hundreds of "spine" structures on the dendrite branches of neurons in the visual cortex over 10 days [1].
The refinement occurs via Hebbian plasticity (synaptic property related to volume of activity) and heterosynaptic plasticity (property related to correlation with neighboring spines) [1]. A computer model of a neuron recapitulated the same trends as what was seen in the mice [1].
More active spines are more likely to be retained during development, following the 'use it or lose it' hypothesis [1]. Inputs from the ipsilateral eye begin joining the race to visual cortex neurons during the critical period [1]. Binocular spines are more active than non-binocular ones, making them more likely to survive [1].
The study aimed to uncover the process by which synaptic turnover refines binocular vision [1]. The findings offer a deeper understanding of how the brain constructs stable binocular vision, which is crucial for depth perception and 3D vision [1].
The research was funded by the National Institutes of Health, The Picower Institute for Learning and Memory, and the Freedom Together Foundation [1]. This study represents a significant step forward in understanding the complex process of binocular vision development and could pave the way for future research into neural circuit refinement and plasticity.
[1] Tsimring, K., et al. (2022). Extensive structural remodeling of dendritic spines during the critical period of binocular vision development. Nature Communications. [2] https://www.mit.edu/newsoffice/2022/how-brain-builds-3d-vision-0120 [3] https://www.nature.com/articles/s41467-021-28365-1
- The new insights from the study, led by Katya Tsimring, about binocular vision development could potentially aid in future medical-conditions research related to health and wellness.
- Funding for this groundbreaking research came from the National Institutes of Health, The Picower Institute for Learning and Memory, and the Freedom Together Foundation.
- The research published in Nature Communications details the process of refining binocular vision in mice, which is essential for depth perception and 3D vision.
- The study's findings suggest a "connect or reject" principle, where synaptic connections that do not contribute meaningfully to binocular integration are eliminated, while new connections are added based on the quality of visual input.
- The research not only sheds light on the process by which synaptic turnover refines binocular vision but also could pave the way for future learning about neural circuit refinement and plasticity in the science field.
