overproduction of neurons in brain development

Therefore, the neurons in the visual cortex prune the synapses with neurons in the spinal cord, and the motor cortex severs connections with the superior colliculus. The neurons in each cortex are selectively pruned, leaving connections that are made with the functionally appropriate processing centers. Variations Regulatory pruning Īt birth, the neurons in the visual and motor cortices have connections to the superior colliculus, spinal cord, and pons. Pruning is influenced by environmental factors and is widely thought to represent learning. After adolescence, the volume of the synaptic connections decreases again due to synaptic pruning. Two factors contribute to this growth: the growth of synaptic connections between neurons and the myelination of nerve fibers the total number of neurons, however, remains the same. The infant brain will increase in size by a factor of up to 5 by adulthood, reaching a final size of approximately 86 (± 8) billion neurons. It was traditionally considered to be complete by the time of sexual maturation, but this was discounted by MRI studies. During pruning, both the axon and dendrite decay and die off. Pruning starts near the time of birth and continues into the late-20s. QBI researchers are exploring how the brain changes during these critical periods of growth.Synaptic pruning, a phase in the development of the nervous system, is the process of synapse elimination that occurs between early childhood and the onset of puberty in many mammals, including humans. Yet lacking impulse and emotional control makes teens vulnerable to stress and mental health problems.Įpidemiological studies have shown that about half of all lifetime mental disorders start by the mid-teens and three-quarters by the mid-twenties. This delay in maturation may help explain typical risky, short-sighted teenage behaviour and the often-apparent lack of control over impulses and emotions.ĭuring this period, the adolescent brain remains highly malleable and still acts like a sponge for learning. This area is involved in planning, judgement and decision making, and it also processes emotional information sent from the amygdala - the fight or flight centre of the brain. The last to mature is the dorsolateral prefrontal cortex at the very front of the frontal lobe. The sensory and motor areas mature first, followed by regions involved in language and spatial orientation, and then those involved in higher-order cognitive processes and executive functions, such as flexible thinking, reasoning, and self-control. Meanwhile, the amount of white matter increases.īut these changes do not affect all brain areas simultaneously. Teenagers lose about 1% of their grey matter every year until their early twenties.

Frequently used connections, say those used when playing a musical instrument, are reinforced and become hardwired.

Overproduction of neurons in brain development