overview: Studies reveal structural changes in connections to other brain regions in the congenital blind thalamus, providing evidence for brain plasticity. The area of the thalamus that connects with the occipital lobe in the blind is weaker and smaller, with stronger connections in the temporal cortex.
sauce: IDOR
Recently published in a scientific journal mapping the human braina Brazilian study identified for the first time anatomical rearrangements in the brains of congenitally blind individuals.
This study was conducted by the Dole Institute for Research and Education (IDOR), Federal University of Rio de Janeiro (UFRJ), Brazilian Center for Specialized Ophthalmology.
Decades ago, scientific studies showed that when people who were born blind engaged in non-visual activities such as reading in Braille (a tactile language system), the visual processing area of the brain, the occipital cortex, reported an interesting finding that it can activate .
These studies were further evidence of so-called brain plasticity, the brain’s ability to reorganize connections to face adversity. This process may involve a series of structural changes, such as the development of new neural pathways and the reorganization of existing connections.
“From the moment we are born, we are exposed to stimuli captured by the senses that are fundamental to determining the circuitry of our brains.
“Technically, we can think that people who are born blind have a non-functioning occipital lobe, but we know it’s not. was the structural process behind it,” explains Dr. Fernanda Tovar-Moll, corresponding author of the current study and president of IDOR.
In this study, we used magnetic resonance imaging techniques to analyze structural connections in the human brain and explore the possibility of alternative neural connections. Neuroimaging of 10 individuals with congenital blindness and a Braille reader was compared with a control group of 10 individuals with intact vision.
After detailed analysis, scientists observed structural changes in thalamic connectivity. The thalamus is a structure located in the diencephalon, the central region of the brain that receives, processes and distributes information captured by the main human senses such as sight, hearing. Touch – for different brain areas.
“Plasticity has been the focus of our group’s research for many years, and in this case of cross-modal plasticity in congenitally blind people, where distant regions of the brain present this communication, we see the origin of the phenomenon Because the thalamus, a brain structure responsible for connecting several cortical regions, may be an area with little change in axonal circuitry. [part of the neuron responsible for conducting electrical impulses] It will be able to connect cortices that are far away from each other,” commented the neuroscientist.
The study also observed that in blind individuals, the area of the thalamus dedicated to connections with the occipital cortex (visual) is smaller and weaker, giving space to connections with the temporal cortex (auditory). . It can be seen by people who are not visually impaired. This means that in addition to the visual cortex being activated, it is also invaded by connections that refine other senses such as hearing and touch.
This is the first study in humans to describe an alternative mapping in the connections between the thalamus and the occipital and temporal cortices, and these plastic reorganizations explain how non-visual stimuli reach and activate the visual cortex. It could be an explanation mechanism. congenitally blind.
“Neuroimaging studies allow us to navigate brain structures and better understand the diversity of brain plasticity, which could also pave the way for discoveries such as new visual rehabilitation initiatives.” and Tovar-Moll, PhD, are still involved in other studies in congenitally blind people in which her research group explores structural as well as functional adaptations of brain plasticity in this population. .
About this visual neuroscience research news
author: Leandro Tavares
sauce: IDOR
contact: Leandro Tavares – IDOR
image: image is public domain
Original research: open access.
“Reorganization of thalamocortical connections in congenitally blind humansby Fernanda Tovar-Moll et al. mapping the human brain
See also
overview
Reorganization of thalamocortical connections in congenitally blind humans
Over the past decades, crossmodal plasticity in visually impaired individuals has been reported, showing that non-visual information is transmitted and processed by ‘visual’ brain structures. However, despite multiple efforts, the structural basis of crossmodal plasticity in congenitally blind individuals remains unclear.
We mapped thalamocortical connectivity and assessed white matter integrity in 10 congenitally blind individuals and 10 sighted controls.
We hypothesized that abnormal thalamocortical connectivity patterns occur in the absence of visual stimuli from birth as a potential mechanism of crossmodal plasticity. In addition to microstructural disturbances in the visual white matter fascicles, changes in structural connectivity between the thalamus and occipital and temporal cortices were observed.
Specifically, the thalamic regions dedicated to connections with the occipital cortex were small and showed weak connectivity in congenitally blind individuals, whereas those that connected with the temporal cortex were larger in volume and showed weaker connectivity. showed increased connectivity. The abnormal pattern of thalamocortical connections involved the lateral and medial geniculate and thalamic nuclei.
For the first time in humans, remapping of structural thalamocortical connections involving both unimodal and multimodal thalamic nuclei has been demonstrated, shedding light on possible mechanisms of crossmodal plasticity in humans.
The current findings may help us understand the functional adaptations commonly found in congenitally blind people.
