Neurodevelopment Flashcards
(26 cards)
What is neurogenesis?
Neurogenesis is the process by which new neurons are generated from neural stem cells. This process primarily occurs during embryonic development but continues in certain regions of the adult brain, such as the hippocampus.
What are the main stages of neurogenesis?
- Proliferation – Neural stem cells divide to produce progenitor cells.
- Differentiation – Progenitor cells become specialized into neurons or glia.
- Migration – Newly formed neurons move to their destined locations in the brain.
- Integration – Neurons establish connections with existing neural circuits.
What role do neural stem cells play in neurogenesis?
Neural stem cells are undifferentiated cells capable of self-renewal and can differentiate into various neural cell types (neurons, astrocytes, and oligodendrocytes). They are crucial for generating the diverse cell types needed for brain development and repair.
What happens during the differentiation of neural progenitor cells?
During differentiation, progenitor cells receive signals (chemical cues) that trigger changes in gene expression, leading them to become specific types of neurons or glial cells. This process involves the activation of transcription factors that dictate cell fate.
What factors influence the differentiation of neural progenitor cells?
Factors include:
- Extrinsic signals – Growth factors and cytokines (e.g., BDNF, FGF).
- Intrinsic factors – Transcription factors that regulate gene expression.
- Environmental cues – The local microenvironment, including extracellular matrix components.
What is the migration process of newly formed neurons?
After differentiation, neurons migrate from their birthplace to their final destination in the brain. This migration can be radial (moving along radial glial fibers) or tangential (moving parallel to the brain surface) and is crucial for the proper organization of neural circuits.
What mechanisms facilitate neuronal migration?
Radial migration - involves neurons using radial glial cells as guides.
Tangential migration - may involve movement through the existing neural tissue.
Chemotaxis – Neurons respond to chemical gradients that guide their movement.
How do new neurons integrate into existing circuits?
Newly migrated neurons extend their axons and dendrites to form synaptic connections with other neurons. This process is influenced by experience and activity in the neural network, crucial for the functional integration of new neurons.
What is target innervation?
Target innervation is the process where developing neurons extend their axons to specific target tissues, forming the necessary connections for functional neural circuits. This process is crucial for proper brain function and connectivity.
What initiates axon growth during target innervation?
Axon growth is initiated by guidance cues in the environment, which include various chemotropic factors that attract or repel growing axons, guiding them towards their specific targets.
What are the roles of guidance cues in target innervation
Guidance cues, such as attractants and repellents, direct axons to their appropriate targets. They ensure correct navigation through the extracellular environment, facilitating accurate wiring of neural circuits.
How do axons recognize their target cells?
Axons recognize their target cells through molecular interactions between surface proteins on the axon and receptors on the target cells, which is crucial for establishing synaptic specificity.
What occurs during synapse formation in target innervation?
Synapse formation involves the clustering of synaptic proteins and the establishment of pre- and postsynaptic specializations, creating functional connections between neurons for effective communication.
What is the role of activity-dependent refinement in synapse development?
Activity-dependent refinement adjusts the strength of synaptic connections based on neuronal activity, leading to the pruning of excess synapses and the stabilization of those that are functional.
What happens during the maturation of synapses?
During synapse maturation, newly formed synapses stabilize, enhancing neurotransmission and ensuring the effective functioning of neural circuits, which is essential for proper brain activity.
What is the role of neurotrophic factors in target innervation?
Neurotrophic factors, such as Nerve Growth Factor (NGF), are crucial for the survival and growth of neurons, supporting synapse formation and maintenance during the process of target innervation.
What are the key principles of synapse formation?
Synapse formation involves several key principles: axon growth towards target cells, recognition of target cells through molecular interactions, clustering of synaptic proteins, and establishment of pre- and postsynaptic structures. This process ensures functional connections that are essential for neural communication.
What factors influence synapse formation?
Factors influencing synapse formation include neurotrophic factors (e.g., NGF, BDNF), guidance cues (e.g., ephrin, netrin), and synaptic activity. These factors promote axon guidance, cell recognition, and synaptic assembly, shaping the development of neural circuits.
What is synaptic plasticity and its role in synapse formation?
Synaptic plasticity refers to the ability of synapses to strengthen or weaken over time, based on activity levels. This plasticity is crucial for learning and memory and influences synapse formation by adjusting synaptic strength in response to neuronal activity.
What are the mechanisms of synapse elimination?
Synapse elimination involves mechanisms such as synaptic pruning, where excess synapses are removed during development. This process is mediated by activity-dependent signaling, the influence of glial cells, and the removal of weaker synaptic connections to enhance overall circuit efficiency.
How does activity-dependent signaling contribute to synapse elimination?
Activity-dependent signaling contributes to synapse elimination by promoting the removal of less active synapses while strengthening those that are frequently used. This selective elimination is vital for refining neural circuits and optimizing synaptic connections.
What role do glial cells play in synapse formation and elimination?
Glial cells, particularly astrocytes and microglia, play a significant role in synapse formation and elimination by providing support, releasing signaling molecules, and clearing out excess synaptic connections. They help maintain the balance of synaptic formation and removal.
What is the impact of neurotrophic factors on synapse elimination?
Neurotrophic factors influence synapse elimination by promoting the survival of specific synapses while signaling the degradation of others. They help fine-tune neural circuits during development and in response to experience.
