Lecture 24 -Construction_of_Neural_Circuits_Part_1_and_2

Flashcards covering key concepts from Lecture 22 on the construction of neural circuits, focusing on growth cones, neurotrophic factors, and synapse formation.

What is the role of cytoskeleton in growth cone behavior?

The cytoskeleton is important for the structural integrity and motility of growth cones, allowing them to navigate and extend axons during neural development.

What molecular mechanisms enable the extracellular matrix to provide axon guidance?

Extracellular matrix ligands bind to integrin receptors, activating cytoplasmic protein kinases and influencing Ca2+ channel activity.

How do guidance molecules act as chemoattractants or repellents?

Guidance molecules either attract or repel growth cones by interacting with specific receptors that signal the growth direction.

What is the difference between trophic and tropic molecules?

Trophic molecules support neuron survival and growth after contact with targets, while tropic molecules provide guidance to growing axons.

What is the role of NGF in neuronal development?

Nerve Growth Factor (NGF) is crucial for stimulating neurite outgrowth and promoting neuronal survival during development.

How is axonal polarity established?

Axonal polarity is established through the asymmetric distribution of cytoskeletal elements like microtubules and actin, which determine the fate of neurites.

What are growth cones and their function in the developing nervous system?

Growth cones are specialized structures at the tips of growing axons that are sensitive to the extracellular environment and guide axon growth.

How do semaphorins function in neurodevelopment?

Semaphorins act primarily as repulsive signals, causing growth cones to retract and preventing improper axon pathfinding.

What are neurotrophins and their role in neuron survivability?

Neurotrophins are proteins that support neurite growth and neuronal survival, influencing the development of neural circuits.

What is the significance of cadherins and protocadherins in synapse formation?

Cadherins and protocadherins mediate local recognition between pre- and postsynaptic membranes, initiating synaptic differentiation.

What is the role of the cytoskeleton in growth cone behavior?

The cytoskeleton is crucial for growth cone motility, allowing for changes in shape and movement as it navigates towards target cells.

How do microtubules contribute to growth cone behavior?

Microtubules support the structural framework of the growth cone and are involved in directing the cone toward guidance cues.

What role does actin play in growth cone dynamics?

Actin filaments facilitate the extension and retraction of filopodia, which helps the growth cone probe its environment.

How does the extracellular matrix (ECM) assist in axon guidance?

The ECM provides a scaffold and releases guidance cues that facilitate axon pathfinding and target recognition.

What are integrins, and how do they relate to axon guidance?

Integrins are receptors that mediate attachment to the ECM and play a role in signaling pathways involved in axon guidance.

How do guidance molecules influence growth cone direction?

Guidance molecules bind to receptors on growth cones, triggering signaling cascades that direct movement towards or away from the sources of these cues.

What is a chemoattractant?

A chemoattractant is a substance that attracts cells, directing growth cones toward target areas during development.

What is a chemorepellent?

A chemorepellent is a molecule that repels growth cones, steering them away from certain areas to avoid inappropriate connections.

What defines trophic molecules?

Trophic molecules are substances that support the growth, survival, and differentiation of neurons.

What defines tropic molecules?

Tropic molecules are substances that direct the growth of axons towards specific targets.

What role does BDNF play in synaptic plasticity?

Brain-derived neurotrophic factor (BDNF) enhances synaptic transmission and aids in the strengthening of synapses.

How does synaptogenesis occur?

Synaptogenesis involves the formation of synapses between neurons through the interaction of pre- and postsynaptic proteins.

What is the function of synaptic adhesion molecules?

These molecules help stabilize synaptic connections and promote the formation of functional synapses.

What evidence supports activity-dependent competition for synapse elimination?

Studies showing that synapses become weaker and are pruned when not routinely activated suggest a competitive process influenced by neuronal activity.

What is NGF, and what is its role in development?

Nerve growth factor (NGF) is a neurotrophic factor essential for the survival and differentiation of sympathetic and sensory neurons.

How does NGF affect autonomic innervation?

NGF promotes the development of innervation in autonomic pathways by supporting the growth and survival of targeted neurons.

How does neurotrophin signaling promote cell survival?

Neurotrophin signaling activates pathways that prevent apoptosis (programmed cell death) in developing neurons.

What is the impact of neurotrophins on neurite outgrowth?

Neurotrophins stimulate neurite outgrowth by activating signaling pathways that promote cytoskeletal rearrangements.

What is activity-dependent plasticity?

Activity-dependent plasticity refers to the changes that occur in the strength of synapses based on patterns of neuronal activity.

How do different neurotrophins influence neurite outgrowth?

Distinct neurotrophins, like NGF and BDNF, can have varying effects on the growth and branching of neurites depending on their receptor interactions.