Exam 3: Development, Degeneration and Recovery of the Nervous System

A) enhance the activity of growth cones
B) induce neuronal proliferation in the ventricular zone
C) inhibit the glial processes that suppress regeneration
D) remove all microglia

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The potential for synaptic change is a crucial aspect of brain function, as it allows for the brain to adapt and learn throughout development and into adulthood. Synaptic change refers to the ability of the connections between neurons, known as synapses, to strengthen or weaken in response to experience and activity. This process, known as synaptic plasticity, is essential for learning and memory, as it allows for the formation of new connections and the strengthening of existing ones in response to new information and experiences. During development, synaptic change is particularly important as the brain is rapidly growing and forming new connections. This period of heightened plasticity allows for the brain to be shaped by experiences and environmental stimuli, laying the foundation for future cognitive and emotional functioning. However, this also means that the developing brain is vulnerable to disruptions in synaptic change, such as exposure to toxins or trauma, which can lead to long-term dysfunction. In adulthood, synaptic change continues to play a critical role in brain function, as it underlies the brain's ability to adapt to new challenges and experiences. This ongoing plasticity allows for continued learning and adaptation, as well as the potential for recovery from injury or disease. However, it also means that the adult brain remains susceptible to dysfunction, as disruptions in synaptic plasticity can contribute to cognitive decline, mental illness, and neurodegenerative diseases. Overall, the potential for synaptic change is essential for brain function at all stages of life, allowing for learning, adaptation, and recovery. However, it also means that the brain is vulnerable to dysfunction, particularly during development and in aging, highlighting the importance of understanding and supporting synaptic plasticity for overall brain health.

A) cause the parent neuron to die, thus saving resources
B) enable fully formed circuits to be present in the brain at birth
C) ensure that the brain is not too big for the head to pass through the birth canal
D) remove dysfunctional synapses

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A) Cells which will go on to produce those that form the foetal brain are not identifiable until week 3 after fertilisation of the egg.
B) Differential gene expression is only observed once cells begin to undergo differentiation into mature neurons.
C) Glial cells are not produced until mature neurons have been produced.
D) The cellular and molecular processes that underpin early human brain development are unique to humans.

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The processes of neuronal proliferation ...

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A) expression of a subset of the cell's genes as appropriate to the cell's function
B) initiating action potential firing
C) massive expansion in cell numbers
D) the movement of cells to the anterior end of the embryo

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A) is extensive, but the neurons produced are unable to form functional connections
B) is related to the age of the individual
C) is responsible for producing brain tumours
D) is sufficient to account for the relatively low incidence of human neurodegenerative disease

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A) impossible in the central nervous system because the cell bodies die
B) inhibited in the peripheral nervous system due to the actions of the glia
C) limited in the central nervous system because the glia suppress axon regrowth
D) only possible in the peripheral nervous system because no new neurons can be born in the postnatal brain

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C

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Early embryonic brain development is a c...

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A) It is caused by a genetic mutation.
B) It only involves retraction of synapses.
C) It always results in loss of discrete neuron populations.
D) The deficits produced will be determined by the location of the degeneration.

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A) a substance released by a presynaptic cell when it reaches its target neurons to induce synapse formation
B) a substance that interrupts proliferation or migration of cells during brain development
C) the name for a form of glial cell that acts as scaffolding during development
D) the general name for a gene involved in development which is mutated

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A) It is an evolutionarily recent process.
B) It occurs whilst the immature neurons are migrating to their final destination.
C) It relies on glia to produce a physical track for the axons to follow.
D) The growth cone expresses receptors that allow it to interact with specific substances in the environment.

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A) they are able to inhibit glial activity in the brain
B) they are found in regions of the brain that are often damaged
C) they can act to guide the migrating immature neurons
D) they have the potential to divide to form new stem cells and immature neurons

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A) all synaptic formation ceases at this age
B) at this age the brain has its maximum number of neurons, synapses and myelinated axons
C) neurons are only produced to replace ones that have died
D) the skull cannot expand to house a bigger brain

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A) as soon as neurons are born during the proliferation phase
B) for some considerable period of time postnatally
C) once all synapse formation has ceased
D) while axons are extending towards their targets

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A) looking for evidence of incorporation of a marker into DNA
B) measuring brain size
C) observing any signs of functional recovery following neurodegeneration
D) recording electrical activity form individual neurons

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A) It will not solve the problem of neuronal loss because the new neurons also need to be functional.
B) It will only be important for situations where neurons die due to apoptosis.
C) It will only produce functional recovery in the brains of young children.
D) We will also need to find ways to increase the capacity of the brain to produce glia.

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Experimental evidence has indeed shown that neuronal repair and replacement leading to functional recovery is possible in the peripheral nervous system. However, the extent to which the same is true for the central nervous system is more limited. One reason for this difference is the environment in which the neurons exist. The peripheral nervous system has a more permissive environment for regeneration, with Schwann cells providing a supportive environment for axon growth. In contrast, the central nervous system has a less permissive environment, with inhibitory factors such as myelin-associated inhibitors and glial scar formation hindering regeneration. Additionally, the central nervous system has a more complex and delicate structure, with a higher density of neurons and more intricate neural connections. This makes it more challenging for new neurons to integrate into the existing neural circuitry and regain full functionality. Furthermore, the central nervous system has a limited capacity for neurogenesis, or the generation of new neurons, especially in the adult brain. While some neurogenesis does occur in certain regions such as the hippocampus, it is not as robust as in the peripheral nervous system. Despite these challenges, there is ongoing research and experimentation aimed at promoting neuronal repair and replacement in the central nervous system. Strategies such as stem cell therapy, gene therapy, and the modulation of inhibitory factors are being explored to enhance regeneration and functional recovery in the central nervous system. In conclusion, while experimental evidence suggests that neuronal repair and replacement leading to functional recovery is possible in the peripheral nervous system, the same is more limited in the central nervous system due to its less permissive environment, complex structure, and limited capacity for neurogenesis. However, ongoing research offers hope for potential advancements in promoting regeneration and functional recovery in the central nervous system.