Neurogenesis is an endogenous process in which brain precursor cells coordinate their proliferation, differentiation, and migration. It influences brain formation during embryonic development and remains in specific areas of the adult brain known as neurogenic niches. The progressive loss of structure, function, and depletion of neural precursors as a result of age, brain injury, and genetic abnormalities may lead to neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD).
In mice, targeting specific brain cells changed memory retrieval and anxiety-like behaviour. Essentially, scientists increased the electrical activity between cells in the hypothalamus and the hippocampus in order to generate new neurons, a process known as neurogenesis.
One of the sad side effects of aging is the loss of mental acuity, and for people with neurodegenerative diseases like Alzheimer’s or Parkinson’s, cognitive function loss is frequently accompanied by mood problems like anxiety. This can be a frightening experience, but one method to combat cognitive decline and anxiety is to stimulate the formation of new neurons.
We humans lose mental sharpness as we age, which is an undesirable side effect of aging. And for people suffering from neurodegenerative diseases like Alzheimer’s and Parkinson’s, cognitive decline is typically accompanied with mood disorders like anxiety. One strategy for combating cognitive decline and anxiety would be to stimulate the formation of new neurons.
Targeting hypothalamic neurons to boost adult hippocampal neurogenesis would not only help brain functions, but also has the potential to treat cognitive and affective deficiencies associated with many brain illnesses.
Juan Song
For the first time, researchers at the University of North Carolina School of Medicine have targeted a specific type of neuron in mice to promote the generation of neural stem cells and stimulate the formation of new adult neurons in order to impact behavior.
The journal Nature Neuroscience found that targeting these cells changed memory retrieval and anxiety-like behaviour in mice. Essentially, the UNC researchers increased the electrical activity between cells in the hypothalamus and hippocampus in order to generate new neurons, a process known as neurogenesis.
“Targeting hypothalamic neurons to boost adult hippocampal neurogenesis would not only help brain functions, but also has the potential to treat cognitive and affective deficiencies associated with many brain illnesses,” stated senior author Juan Song, PhD, associate professor of pharmacology.
The majority of the neurons we carry with us for the rest of our lives were formed before we were born and arranged during childhood. Neurogenesis, on the other hand, continues into adulthood and throughout life. In fact, the suspension of neurogenesis is one of the causes of cognitive decline and anxiety, as well as disorders like Alzheimer’s.
Song, a member of the UNC Neuroscience Center, has been researching the intricate interplay between brain cells that keeps neurogenesis going. She was aware that adult hippocampus neurogenesis is important in memory and emotion processing, and that neural circuit activity – think ‘electrical activity’ – governs this process in a continually changing manner.
What no one knew was whether this neuronal circuit activity could be adjusted to stimulate neurogenesis to such an extent that the result would be seen as a change in behavior, such as enhanced memory or less worry.
To see the effect of modulating neural activity, the Song lab conducted experiments led by co-first authors Ya-Dong Li, PhD, and Yan-Jia Luo, PhD, both postdoctoral fellows. They used optogenetics — essentially a method using light to trigger neuronal activity — in a small brain structure called supramammillary nucleus (SuM). The SuM is located inside the hypothalamus region of the brain; it helps manage things from cognition to locomotion and sleep/wakefulness.
Song’s team reported a substantial enhancement of neurogenesis at multiple stages after continuously stimulating the SuM neurons. They discovered increased neural stem cell production as well as the formation of new adult-born neurons with improved characteristics. After that, optogenetic activation of these new neurons changed memory and anxiety-like behaviour.
“We also show that the SuM neurons are very responsive when the mice encounter novel stimuli in their environment,” Song added. “In fact, mice require these cells for neurogenesis in a new environment.”
Impaired adult hippocampal neurogenesis correlates with many pathological states, including aging, neurodegenerative diseases, and mental disorders. “As a result,” Song continued, “targeting hypothalamic neurons to enhance adult hippocampal neurogenesis will not only benefit brain functions but also has the potential to treat cognitive and affective deficits associated with various brain disorders.”
