8.1 + 8.2 Flashcards
What is the relationship between brain and behavioral development?
Brain and behavior develop apace, indicating they are closely linked.
What are the three perspectives from which neuroscientists study the relationship between brain and behavioral development?
- Structural development correlated with emerging behaviors
- Behavioral development predicted by underlying circuitry
- Influence of factors like hormones, injury, or socioeconomic status
Which brain structures develop quickly and exhibit their functions sooner?
The visual system.
What is one of the last cognitive behaviors to develop in humans?
The ability to plan efficiently.
What task is used to measure planning skills in the laboratory?
The Tower of Hanoi test.
At what age can most solve simple configurations in the Tower of Hanoi test?
Around age 10.
What do mature adults with acquired frontal lobe injuries fail to perform well on?
The Tower of Hanoi test.
What can we infer about neural maturation from the emergence of new abilities?
Corresponding changes in the underlying neural structures.
At birth, what ability do children lack due to underdeveloped brain structures?
The ability to speak.
What structures undergo maturation to support the emergence of spoken language?
Speech-related structures in the brain.
What influences both brain function and behavior?
- Sensory experience
- Injuries
- Hormones
- Genes
- Socioeconomic status
What must be studied to understand how brain structures function and produce behaviors?
The events that shape those structures.
True or False: The mere emergence of a fully developed brain structure is enough to explain ensuing behaviors.
False.
What hormone is mentioned as influencing the organization and function of specific hypothalamic nuclei?
Testosterone.
What can happen if testosterone secretion is atypical during development?
Changes in hypothalamic structure, sexual preference, and possibly gender identity.
What concept did Seneca the Younger propose about the human embryo?
That a human embryo is an adult in miniature
This idea is known as preformation.
What led to the decline of the preformation theory in the mid-1800s?
Realization that embryos look nothing like the adults they become
Embryos of different species resemble one another more than their respective parents.
Which vertebrate structures are similar in early embryonic stages?
Primitive head, region with bumps or folds, and a tail
This similarity supports the idea of a common ancestor for vertebrates.
At what stage of development does the human brain begin to resemble a person?
By 7 weeks (49 days) after conception
The brain looks distinctly human by about 100 days after conception.
What is the role of the neural tube during development?
It serves as the nursery for the rest of the central nervous system
The open region in the tube matures into the brain’s ventricles and the spinal canal.
What are the prenatal stages of human development?
Zygote: Fertilization to 2 weeks, Embryo: 2 to 8 weeks, Fetus: 9 weeks to birth
These stages outline the progression from conception to birth.
What is the significance of neural stem cells in the human brain?
They have an extensive capacity for self-renewal and can give rise to progenitor cells
They are multipotent and contribute to the formation of neurons and glia.
How do neural stem cells contribute to the central nervous system?
They give rise to progenitor cells, which produce neuroblasts and glioblasts
These then mature into specialized neurons and glial cells.
What discovery did Sam Weiss and his colleagues make about stem cells?
Stem cells remain capable of producing neurons and glia into early adulthood
This implies that neurons that die in an adult brain should be replaceable.
What is gene expression?
The process whereby information from a gene is used in the synthesis of a gene product
This process determines what type of cell a stem cell becomes.
What is DNA methylation?
An epigenetic mechanism that suppresses gene expression during development
It involves the attachment of a methyl group to the nucleotide base cytosine.
What role do neurotrophic factors play in brain development?
They signal cells to develop in particular ways
They stimulate the production of progenitor cells and influence the differentiation of neuroblasts.
What is the process of neurogenesis?
The formation of neurons during brain development
It occurs rapidly, with approximately 250,000 neurons produced per minute at peak development.
What are the stages of brain development?
Cell birth, neural migration, cell differentiation, neural maturation, synaptogenesis, cell death, and myelogenesis
These stages outline the progression of brain development from conception to adulthood.
How does prenatal stress affect gene expression?
It can reduce gene methylation by 10%
Stressed infants may express 2000 more genes than unstressed infants.
What is the significance of the hippocampus in brain development?
New neurons continue to develop throughout life in the hippocampus
It is critical to memory and is vulnerable to stress.
What is the role of radial glial cells in neuronal migration?
They form a path that migrating cells follow to reach different parts of the cortex
This process aids in the organization of the cerebral cortex.
What is the cortical map?
A representation that predisposes cells formed in a certain ventricular region to migrate to a specific cortical location.
How do migrating cells know where to find different parts of the cortex?
They follow a path formed by radial glial cells.
What is the role of radial glial fibers?
They extend from the subventricular zone to the cortical surface, guiding neuronal migration.
Describe the process of cortical layer development.
Cortical layers develop from the inside out, with neurons of innermost layer (VI) migrating first, followed by those destined for layer V, and so on.
What influences the thickness of cortical layers?
Local environmental signals, specifically chemicals produced by other cells.
What are the two main events in dendrite development?
- Dendritic arborization (branching)
- Growth of dendritic spines
How does dendritic growth compare to axonal growth?
Dendrites grow at a slow rate of microns per day, while axons grow at about a millimeter per day.
What is the significance of the differing growth rates of axons and dendrites?
The faster-growing axon can reach its target cell before the dendrites are fully formed, influencing dendritic differentiation.
What is Autism Spectrum Disorder (ASD)?
A range of behavioral conditions including impaired social interaction, communication difficulties, and restricted interests.
What was noted about the prevalence of ASD over the past four decades?
The rate of ASD has increased from fewer than 1 in 2000 in 1980 to an estimated 1 in 54 children in 2020.
What are some characteristics of children with ASD?
- Failure to interact socially
- Repetitive movements
- Impairments in language development
- Resistance to changes in routine
What is the role of growth cones in axon development?
They extend and send out filopodia to find appropriate target cells.
What are cell adhesion molecules (CAMs)?
Molecules that provide a surface for growth cones to adhere to or signal them to move toward or away.
What are tropic molecules?
Molecules produced by target cells that attract or repel growth cones.
What is synaptic development?
The process where synapses are formed, guided by local environmental cues and signals.
What is synaptic pruning?
The process of eliminating excess synapses to refine neural connections.
What is neural Darwinism in the context of the brain?
The concept that competition among neurons leads to the survival of the fittest connections.
What happens during synaptic pruning?
Neurons compete, leading to the elimination of less fit synaptic connections.
What leads to the emergence of distinct cell types in the brain?
The interaction of genetic instructions, timing, and signals from the local environment.
What is the process by which the brain eliminates excess neurons?
Neural Darwinism
This concept describes the competition among neurons for survival based on environmental pressures.
What happens to neurons that are deprived of synaptic targets?
They eventually die due to lack of neurotrophic factors
Neurotrophic factors are produced by target cells and are crucial for neuronal survival.
What is apoptosis?
A programmed process leading to cell death
This process accounts for the death of overabundant neurons.
Who proposed a theory for synapse loss that includes competition?
Jean-Pierre Changeux
His theory suggests synapses persist only if they are part of functional neural networks.
What declines in infants’ ability as they grow older regarding speech sounds?
The ability to discriminate speech sounds from different languages
This decline is linked to synapses related to less frequently encountered sounds being eliminated.
What role does synaptic pruning play in brain development?
It allows the brain to adapt flexibly to environmental demands
This flexibility is essential for successful development in diverse cultural environments.
What unique characteristic do all humans share?
Language
Language plays a critical role in cognition and has a long learning time.
What happens to cortical thickness from ages 2–5 to age 20?
The cortex generally thins, except major language regions show an increase in gray matter
This indicates a different developmental pattern for language processing areas.
What are astrocytes and oligodendrocytes responsible for?
Astrocytes nourish neurons; oligodendrocytes myelinate axons
Myelination increases the efficiency of axonal function.
What did Paul Flechsig observe about cortical myelination?
Cortical myelination begins just after birth and continues until at least 18 years of age
He noted that different cortical regions myelinate at varying rates.
What is the significance of neurogenesis in the adult brain?
It retains the capacity to generate new neurons
Adult neurogenesis primarily occurs in the hippocampus and other specific brain regions.
What discrepancy exists in the research on adult neurogenesis in humans?
Different studies reach contrasting conclusions about its significance in the hippocampus
This is due to variations in methods used to preserve postmortem brain tissue.
What is the last brain region to mature?
The frontal lobe
Its maturation extends beyond age 20, particularly in the dorsolateral prefrontal cortex.
What correlation does frontal lobe development have with adult intelligence?
Changes in cortical thickness and connectivity in the default network
These changes are associated with higher scores on intelligence tests.
Fill in the blank: The central nervous system begins as a sheet of cells, which folds inward to form the _______.
[neural tube]
Fill in the blank: The growth of neurons is referred to as ______, whereas formation of glial cells is known as ______.
[neurogenesis], [gliogenesis]
Fill in the blank: Growth cones are responsive to two types of cues: ______ and ______.
[attractive cues], [repulsive cues]
Fill in the blank: Erickson and colleagues’ studies suggested that neurogenesis continues in the ______ in adulthood.
[hippocampus]
What is one functional significance of prolonged frontal lobe development?
It is sensitive to epigenetic influences and correlates with adult intelligence
Aversive childhood experiences can negatively impact frontal lobe development.
