Neuroscience Chapter: Growth and Development of Neurons

Questions and Answers

What is primarily believed to occur during the process that seems wasteful for retaining memories prior to 4 years of age?

Refinement of nervous system connectivity (correct)

Strengthening synaptic connections

Permanent loss of early memories

Rapid production of new neurons

What characteristic of the brain allows it to modify its structure and function in response to injury?

Neuronal stability

Neurosynthetic healing

Synaptic stagnation

Neural plasticity (correct)

At what age does the critical period for visual pathways reach its peak?

Between 1 and 2 years (correct)

During adolescence

Between 3 and 4 years

At birth

Which factor is not involved in stimulating neural plasticity throughout life?

Hormonal changes Signup and view all the answers

What is significant about the production of new neurons in the adult brain?

It can be increased through exercise and cognitive stimulation Signup and view all the answers

What happens to an axon segment after it is severed but the neuron’s cell body remains intact?

It degenerates and grows a growth cone Signup and view all the answers

What slows the return of function following a peripheral nerve injury?

Rate of axon regrowth Signup and view all the answers

What is a key reason that learning a language becomes more difficult after adolescence?

Slower and more subtle changes in plasticity Signup and view all the answers

What initiates the development of the nervous system in the embryo?

Divisions of undifferentiated precursor cells Signup and view all the answers

What is the role of the growth cone during neuronal development?

To find the correct route and target for extending axons Signup and view all the answers

What influences the route that an axon follows during its growth?

Attracting, supporting, and inhibiting molecules from surrounding cells Signup and view all the answers

What happens to newly formed neurons and synapses during development?

Many undergo programmed self-destruction called apoptosis Signup and view all the answers

What is a potential consequence of maternal infections during pregnancy, such as Zika virus?

Permanent damage to the developing fetal nervous system Signup and view all the answers

Which type of molecules play a significant role in axonal guidance?

Cell adhesion molecules and neurotrophic factors Signup and view all the answers

What is the typical fate of 50% to 70% of neurons in the developing central nervous system?

They undergo apoptosis Signup and view all the answers

During which stage do factors like malnutrition and drugs exert effects on the developing fetal nervous system?

Before birth and during infancy Signup and view all the answers

Study Notes

Growth and Development of Neurons

Nervous system development starts with divisions of undifferentiated precursor cells (stem cells).
Each daughter cell from division differentiates, migrates, and develops axons and dendrites.
Growth cones at the tip of extending axons facilitate correct routing towards specific targets.
Axon growth is influenced by various molecules, including cell adhesion molecules on glia and soluble neurotrophic factors in the surrounding fluid.
Neurodevelopment is vulnerable to external factors like alcohol, drugs, and viruses, with potential long-term effects on fetal nervous system, such as microcephaly from Zika virus.

Neuron and Synapse Degeneration

Post-axon development, a significant proportion of neurons (50%-70%) undergo apoptosis, a programmed cell death process.
Apoptosis may play a role in refining neural connectivity, contributing to patterns of memory retention, particularly in early childhood.

Neural Plasticity

The brain exhibits plasticity, allowing structural and functional modifications in response to stimulation or injury.
Neural plasticity processes include both the generation of new neurons and the remodeling of synaptic connections.
Exercise and cognitively challenging activities enhance plasticity, which varies with age.
Visual pathways need stimulation during critical developmental phases (peaks around ages 1-2) for proper processing capability.
Language acquisition is easier up to adolescence but becomes progressively more difficult thereafter.

Neuronal Circuit Stability and Lifelong Changes

Major neuronal circuit shapes remain stable after formation, but synaptic connections can be created or removed throughout life.
New neuron production was previously thought to stop at birth, but evidence shows certain brain regions can regenerate neurons in adulthood.
Cognitive stimulation and exercise can increase neuron count in learning-associated regions.
Some antidepressants' effectiveness hinges on the generation of new neurons in emotion-regulating regions.

Axon Regeneration

Axons can self-repair post-injury if damage occurs outside the CNS and does not impact the cell body.
Degeneration occurs in the axon segment disconnected from the cell body, while the remaining part generates a growth cone for regrowth towards the effector organ.
Axon regrowth is slow, averaging about 1 mm per day, leading to delayed functional restoration after peripheral nerve injuries.
Recovery times can be lengthy; for instance, restoring sensation in a thumb after shoulder injury may take up to 2 years.

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Description

Explore the fascinating journey of neuronal growth and differentiation through this quiz. Delve into the processes that lead undifferentiated precursor cells to become specialized neurons. Understand how specific axon growth directs the formation of intricate neuronal networks within the developing nervous system.