In collaboration with Raeen Mental Health Clinic

Date: November 22, 2024

Lecturers:

Alireza Faridmoayer MD, Neurosurgeon
Dr. Mohsen Gholami, PhD in Cognitive Neuroscience

Neuroplasticity is formed from two words: “plastic,” meaning flexible, and the prefix “neuro,” which refers to the nervous system. Neural flexibility refers to the brain’s capacity to change and adapt to environmental conditions. This capability is a recent discovery with a history of about fifty years. For a long time, it was believed that the brain had a fixed and unchanging structure before this capability was confirmed. This belief traces back to the claims of Broca and Wernicke. These two 19th-century neuroscientists demonstrated that the language comprehension and production areas have specific locations in the brain that, when damaged, lead to disruptions in linguistic activities. Since then, the belief in the brain’s fixed and unchanging structure led to the theory of localizationism.
This theory was the dominant paradigm for about one hundred and fifty years until signs of its incompleteness began to emerge around the 1960s and 1970s. One of the pioneers in this field was Paul Bach-y-Rita, who published groundbreaking results from his various experiments and the development of numerous tools through a significant paper. Alongside Bach-y-Rita, other scientists also reached similar conclusions: Mariganka Sur, by connecting the optic nerve of a weasel to its auditory cortex, found that the auditory cortex was repurposed for visual analysis over time. Two other scientists, Hubel and Wiesel, observed that by sewing one of a kitten’s eyes shut, the visual cortex corresponding to the sewn eye gradually, during a period they termed the “sensitive period,” began to analyze the input from the open eye. They were awarded a Nobel Prize for this discovery.
However, the most significant work in this area was conducted by Michael Merzenich, who through numerous experiments demonstrated that the neural flexibility, which had previously been dismissed, is an undeniable reality of the nervous system. He showed that when a nerve from a monkey’s finger was disabled, the motor cortex responsible for that finger connected with the motor cortex of the healthy fingers. He also showed that the brain has the ability to change over time and redevelop its nerve connections for the most sensitive and intricate activities. Through this body of work, modern neuroscience has amended the localizationist paradigm and introduced neuroplasticity as a true characteristic of the nervous system. Today, this paradigm is used to treat various psychological and neurological disorders.

Socioeconomic status (SES), encompassing education, income, and occupational status, modulates neuroplasticity by shaping access to cognitive and environmental resources, exposure to diverse stimuli, and levels of chronic stress, which influence neurobiological processes such as synaptic pruning, dendritic branching, myelination, and neurotransmitter regulation, ultimately affecting brain structure, connectivity, and functional adaptability. Lower SES is often associated with heightened activation of the hypothalamic-pituitary-adrenal (HPA) axis due to chronic stress, resulting in elevated cortisol levels that impair hippocampal function and reduce neurogenesis. Conversely, enriched environments associated with higher SES promote robust synaptic connectivity and strengthen prefrontal cortex development, which supports executive function and emotional regulation. These SES-related differences in brain development are particularly pronounced during sensitive periods, underscoring the importance of early-life interventions in mitigating neuroplasticity disparities. Furthermore, the neurobiological changes linked to SES have significant implications for cognitive outcomes, including IQ, as chronic stress and limited enrichment in lower SES settings impair working memory, processing speed, and problem-solving skills. In contrast, higher SES environments foster cognitive development through enhanced executive function, language acquisition, and abstract reasoning, contributing to measurable differences in IQ over time.

 

Those interested may access the summaries of the discussions and presentations delivered at the conference through the following link.

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