Brain And Behavior Exam 3

In the development of the visual cortex, axons from each eye compete for synaptic targets. Hebbian synapses refer to a concept in neuroscience where synapses that are frequently and simultaneously activated become stronger, while those that are rarely activated become weaker. Therefore, in this context, Hebbian synapses explain how the axons from each eye grow stronger or weaker depending on their ability to affect a postsynaptic cell during the competition for synaptic targets.

Mutants are individuals with altered genes, which can result in differences in their behavioral phenotype. This means that their genetic makeup has changed, leading to changes in their physical or behavioral characteristics compared to the typical or wild-type individuals of the same species. These alterations in genes can be caused by mutations, which are changes in the DNA sequence. Mutations can occur naturally or be induced by various factors, such as exposure to radiation or chemicals. Therefore, mutants can exhibit unique traits or behaviors that distinguish them from others in their species.

Binocular deprivation refers to the condition where there is a lack of visual input to both eyes. This deprivation of visual stimuli leads to changes in the neurons in the visual cortex. These changes can result in a condition called amblyopia, also known as "lazy eye," which is characterized by reduced vision in one or both eyes. Therefore, binocular deprivation can cause alterations in the visual cortex and ultimately lead to amblyopia.

Synapse rearrangement, or synaptic remodeling, refers to the process of refining synaptic connections. One factor that influences the survival of synapses is neural activity. Neural activity, which is the electrical activity generated by neurons, plays a crucial role in determining which synapses are strengthened or weakened. Therefore, it is true that neural activity can contribute to synaptic survival.

A mutation is a change in genetic structure. Mutations can occur spontaneously or be induced by external factors such as radiation or chemicals. They can result in changes to an organism's DNA sequence, which can lead to new traits or characteristics. Mutations can be harmful, beneficial, or have no effect on an organism's survival and reproduction. They are an important driving force for evolution, as they provide the genetic variation necessary for natural selection to act upon.

Induction refers to the influence of one set of cells on the fate of nearby cells. It is a process where certain cells release signaling molecules that affect the development and differentiation of neighboring cells. This communication between cells plays a crucial role in embryonic development, tissue formation, and organogenesis. Through induction, cells can instruct nearby cells to adopt specific fates and differentiate into specialized cell types, ultimately contributing to the overall organization and function of tissues and organs.

The correct answer is "Identifiable neurons." Mauthner cells are a specific type of identifiable neurons found in some fishes. These neurons are unique because they are easily distinguishable and have a characteristic shape and location within the fish's brain. Mauthner cells are involved in the fish's escape response and play a crucial role in coordinating rapid swimming movements.

Monocular deprivation refers to the condition where one eye is deprived of visual stimulation during a critical period of development. This deprivation causes the deprived eye to not respond in adulthood. During the sensitive period, which is a specific time frame in early childhood, the brain is highly plastic and can be shaped by sensory experiences. If one eye is deprived of visual input during this period, the brain does not develop the necessary connections for that eye, leading to a lack of response in adulthood.

The correct answer is "neural environment." This is because the term "cell-autonomous" refers to a cell's ability to function independently and not be influenced by other cells. On the other hand, the phrase "neural environment" suggests that cells are affected by the surrounding neural tissue and the interactions with neighboring cells. Therefore, the influence of other cells on a particular cell's behavior is more accurately described by the concept of the neural environment.

Lamellipodia are sheetlike extensions that are responsible for cell movement. They are thin, flat protrusions from the leading edge of a migrating cell and play a crucial role in cell migration and tissue formation. Lamellipodia are composed of a network of actin filaments that push against the cell membrane, causing the extension of the cell's leading edge. Filopodia, on the other hand, are thin, finger-like extensions that are involved in cell adhesion and sensing the environment. Therefore, the correct answer is lamellipodia.

Chemorepellents are substances that repel growth cones. Growth cones are specialized structures found at the tips of growing axons or dendrites in developing neurons. They navigate through the surrounding environment to establish connections with their target cells. Chemorepellents act as guidance cues, guiding growth cones away from certain areas or repelling them from specific molecules. This helps to ensure proper wiring and connectivity in the developing nervous system. In contrast, chemoattractants attract growth cones towards certain molecules or areas, promoting axonal or dendritic growth in specific directions.

Myelination refers to the process of adding a protective covering called myelin around axons, which are the long, slender projections of nerve cells. This process is carried out by glial cells. The correct answer suggests that the addition of myelin by glial cells increases the rate at which axons send messages. Multiple sclerosis is a neurological disorder that affects the central nervous system, causing damage to the myelin sheath. The chemoaffinity hypothesis, on the other hand, is a theory that explains how neurons establish specific connections during development.

A transgenic organism refers to an organism that has been genetically modified by introducing a new or altered gene from another species. This process involves the insertion of the desired gene into the organism's DNA, resulting in the expression of the new gene and the production of a specific protein or trait. Therefore, a transgenic organism fits the description of having a new or altered gene.

Clones are genetically identical animals. This means that they have the same DNA and are essentially exact copies of each other. Cloning can occur naturally, such as in the case of identical twins, or it can be artificially induced through various scientific techniques. In either case, the result is a group of organisms that are genetically identical to each other, making them clones. Identifiable neurons, on the other hand, refers to specific neurons that can be distinguished or recognized based on certain characteristics or markers.

Filopodia and lamellipodia are structures found in the growth cone of developing neurons. They are responsible for exploring the environment and guiding the growth of the neuron. These structures adhere to the surrounding environment and exert pulling forces, which help direct the growth cone in a specific direction. Therefore, the statement that filopodia and lamellipodia adhere to the environment and pull the growth cone in a particular direction is true.

Brain-derived neurotrophic factor (BDNF) is the correct answer because the question is asking for "other factors" that are similar to nerve growth factor (NGF) and members of the neurotrophin family. BDNF is a member of the neurotrophin family, just like NGF. Therefore, BDNF can be considered as one of the "other factors" that are similar to NGF and members of the neurotrophin family.

Cell migration refers to the process in which cells move from one location to another within an organism. In the given context, it is explained that cells move to establish distinct populations. This means that during development, cells migrate to specific regions or areas in the body where they will form distinct groups or populations. These distinct populations can then differentiate into specific cell types, such as neurons or glial cells, depending on the signals and cues they receive in their new location. Therefore, cell migration plays a crucial role in the establishment of different cell populations and the formation of diverse cell types in the body.

Multiple sclerosis is a neurological disorder in which the immune system mistakenly attacks the protective covering of nerve fibers, known as myelin. This destruction of myelin disrupts the normal functioning of the nerves, leading to sensory and motor impairments. The symptoms vary depending on the location and extent of the damage, but commonly include muscle weakness, coordination difficulties, and sensory disturbances. Therefore, multiple sclerosis is the correct answer as it accurately describes the condition in which myelin is destroyed, leading to sensory and motor dysfunction.

A fertilized egg is called a zygote. After fertilization, when the sperm and egg combine, they form a single cell called a zygote. This zygote contains all the genetic material necessary for the development of a new organism. The zygote undergoes cell division and differentiation to form an embryo, which eventually develops into a fully formed organism. The term "ectoderm" refers to one of the germ layers in the developing embryo, and "neural groove" is a structure that forms during the early stages of neural tube development.

Differentiation refers to the process by which cells become specialized and acquire distinct characteristics. In this context, the correct answer suggests that during differentiation, cells undergo a transformation and develop into either neurons or glial cells, which are two different types of cells in the nervous system. This process is essential for the proper functioning of the nervous system as it allows for the specialization and organization of cells into specific roles and functions.

Cell differentiation is the process by which a cell becomes specialized to perform a specific function. During differentiation, cells undergo changes in gene expression and morphology that allow them to acquire specific features and functions. This process is crucial for the development and maintenance of multicellular organisms, as it ensures that different cells can perform their specific roles in the body. Therefore, the statement that cell differentiation allows a cell to acquire its specific appearance and function is true.

The notochord is a structure found in the early development of vertebrate embryos. It releases a protein that plays a crucial role in directing certain cells in the spinal cord to differentiate into motoneurons. Motoneurons are specialized cells responsible for transmitting signals from the central nervous system to muscles, enabling movement. Therefore, the correct answer is notochord.

Synaptogenesis is the correct answer because it refers to the formation of synapses, which are the connections between brain cells. During early life, brain cells undergo significant changes, including the formation of new synapses. This process is crucial for the development and organization of the brain's neural circuitry, allowing for the transmission of information between neurons. Process outgrowth, on the other hand, is a more general term that does not specifically refer to the formation of synapses.

Phenylketonuria (PKU) is a disorder of protein metabolism caused by the absence of an enzyme that is responsible for metabolizing phenylalanine in foods. This means that individuals with PKU are unable to properly break down phenylalanine, leading to its accumulation in the body. This can cause a variety of symptoms and complications if left untreated. The other options provided in the question, such as a transient lack of oxygen or inheriting extra trinucleotide repeats, are not accurate explanations for PKU.

Neurogenesis refers to the production of new nerve cells. It is a process that occurs in the brain, specifically in the ventricular zone, where neural stem cells divide and differentiate into neurons. Mitosis, on the other hand, is a general cell division process that occurs in various tissues, including nerve cells, but it does not specifically refer to the production of nerve cells. Therefore, neurogenesis is the correct answer as it accurately describes the production of nerve cells.

Radial glial cells are a type of cell found in the developing central nervous system. They serve as a scaffold for migrating cells, providing a physical pathway for them to move along. These glial cells have long processes that extend from the inner to the outer surface of the brain, and migrating cells use these processes as guides to reach their final destinations. Therefore, it is true that radial glial cells act as guides for cells to migrate along.

During cell migration, cells do move away from the ventricular layer. Cell migration is a process in which cells move from one location to another within an organism. In the context of the question, the ventricular layer refers to a layer of cells lining the ventricles of the brain. During brain development, cells in the ventricular layer undergo migration to different regions of the brain, contributing to the formation of various brain structures. Therefore, the statement that cells do not move away from the ventricular layer during cell migration is false.

The term "phenotype" refers to all of the physical characteristics of an organism. It encompasses the observable traits, behaviors, and physical features that are determined by both genetic and environmental factors. The phenotype is the result of the interaction between an organism's genotype (its genetic makeup) and the environment in which it develops. The genotype refers to the specific genetic information carried by an organism, while the genome refers to the complete set of genetic material present in an organism. However, neither the genotype nor the genome alone fully encompasses all of the physical characteristics of an organism, making "phenotype" the correct answer.

Fragile X syndrome is a genetic disorder that is caused by inheriting extra trinucleotide repeats, which are repetitions of nucleotides, in the same gene. This leads to the gene not functioning properly and results in the characteristic symptoms of Fragile X syndrome.

During the first 10 weeks of development, a developing human is called an embryo. After this period, it is referred to as a fetus.

Neuronal cell death refers to the process of selective death of some nerve cells. This means that certain neurons undergo programmed cell death, leading to their elimination from the neural network. This process is a normal part of development and also occurs in response to injury or disease. It is important for maintaining the proper functioning and balance of the nervous system. The other options, establishment of synaptic connections and loss or development of synapses, fine-tuning, are not accurate definitions of neuronal cell death.

Caspases are a family of proteases that play a crucial role in apoptosis, which is a programmed cell death process. They are responsible for cutting up proteins and DNA, leading to the dismantling and removal of cellular components. Caspases are activated in response to various signals, such as DNA damage or cellular stress, and their activation triggers a cascade of events that ultimately result in cell death. Therefore, caspases are the correct answer as they are directly involved in the process of cutting up proteins and DNA during apoptosis.

The term "sensitive period" refers to a specific time frame during development when experience or treatment can have a lasting impact on an individual. This means that during this period, the brain is more receptive to certain stimuli and is more likely to undergo permanent alterations based on the experiences it encounters. In the context of the given question, the sensitive period is the correct answer because it accurately describes the period in which experience or treatment can make permanent alterations in development.

Bcl-2 proteins are known to block apoptosis, a process of programmed cell death. They do so by preventing the release of Diablo, a protein that promotes apoptosis. Therefore, the statement that Bcl-2 proteins block apoptosis by preventing the release of Diablo is true.

Cell adhesion molecules (CAMs) are proteins that play a crucial role in promoting the adhesion of different cells in the nervous system. They help in the formation of connections between neurons, as well as in the guidance of axons during development. CAMs are involved in various processes such as cell migration, synapse formation, and neural circuit formation. Therefore, it is true that CAMs promote adhesion of parts of the nervous system to guide cells.

Anterograde degeneration refers to the degeneration of the distal portion of an axon after an injury to the axon. This means that the part of the axon that is further away from the cell body will degenerate. In contrast, retrograde degeneration refers to the degeneration of the proximal portion of the axon, closer to the cell body. In the given explanation, it is mentioned that Wallerian degeneration is the loss of the distal portion of an axon after an injury, which aligns with the concept of anterograde degeneration. Therefore, the correct answer is anterograde degeneration.

Chemorepellents are chemical signals that repel or discourage the growth cones of axons, while chemoattractants are chemical signals that attract or encourage the growth cones of axons. Since the question states that axons are guided by chemicals released by the target cells, it implies that the target cells release chemical signals that attract the growth cones of axons. Therefore, the correct answer is chemoattractants.

The neural tube forms from the neural ridges.

Synapse rearrangement refers to the process of both losing and developing synapses, which allows for the fine-tuning of synaptic connections. This means that some synapses may be lost while new ones are formed, resulting in the refinement and optimization of neural circuits. This process is crucial for the establishment of proper synaptic connections and the efficient functioning of the nervous system.

Filopodia are the fine outgrowths of growth cones. Filopodia are thin, finger-like extensions that protrude from the tips of growth cones. They are responsible for exploring the environment and guiding the growth of axons during neural development. Filopodia contain actin filaments, which provide structural support and enable them to extend and retract. They play a crucial role in axon guidance and establishing connections between neurons.

An ocular dominance histogram is a graphical representation of the response of brain neurons to stimuli presented to either eye. It shows the distribution of cortical neurons' preference for one eye over the other. In a normal situation, most cortical neurons respond equally to stimuli from both eyes. The ocular dominance histogram helps to understand the balance of input and processing between the two eyes in the visual system.

The correct answer is Ectoderm. During embryonic development, the outer layer of cells, known as the ectoderm, gives rise to various structures including the nervous system. The ectoderm undergoes further differentiation and forms the neural tube, which eventually develops into the brain and spinal cord. Therefore, the ectoderm is responsible for the formation of the nervous system in a human embryo.

Stem cells are undifferentiated cells that have the ability to differentiate into different cell types based on their location and the signals they receive from their environment. They can undergo self-renewal and give rise to specialized cells in order to regenerate and repair tissues in the body. This process of differentiation allows stem cells to assume a new cell fate and become the appropriate cell type for their specific location.

The neural groove forms between the ridges of the ectoderm during early embryonic development. This groove eventually closes and forms the neural tube, which gives rise to the central nervous system. The zygote refers to the fertilized egg, while the neural groove is the initial structure that precedes the formation of the neural tube. Therefore, the correct answer is neural groove.

The anterior part of the neural tube is divided into three subdivisions: the forebrain, midbrain, and hindbrain. The forebrain is responsible for higher cognitive functions, such as thinking and problem-solving. The midbrain is involved in sensory processing and motor control. The hindbrain controls basic functions like breathing and heart rate. Therefore, the correct answer is forebrain, midbrain, and hindbrain.

Nonneural cells divide through mitosis, which is the process of cell division that results in the formation of two identical daughter cells. The ventricular zone refers to a region in the developing brain where neurogenesis, the process of generating new neurons, takes place. Therefore, the correct answer is mitosis, ventricular zone, as it accurately describes the division of nonneural cells and the formation of new neurons in the ventricular zone through mitosis.

The chemoaffinity hypothesis suggests that each cell has a chemical identity that guides development at a synapse. This means that specific chemicals or molecules are responsible for guiding the formation of connections between neurons in the brain. After injury, the brain will try to reestablish the original connection using this chemical identity. Myelination and multiple sclerosis are not directly related to the concept of chemical identity guiding development at a synapse.

A knockout organism refers to an organism in which a specific gene has been disabled or "knocked out" through genetic manipulation. This can be achieved by introducing mutations or deleting the gene entirely. The disabled gene prevents the production of the corresponding protein, allowing researchers to study the effects of its absence on the organism's phenotype. Therefore, the statement "Knockout organism has a gene disabled" accurately describes the concept of a knockout organism.

Synaptogenesis refers to the process of the establishment of synaptic connections between neurons. During synaptogenesis, new synapses are formed between neurons, allowing for communication and transmission of signals in the nervous system. This process is crucial for the development and functioning of the brain, as it enables the formation of neural networks and the fine-tuning of connections. Mitosis, on the other hand, is the process of cell division that produces new cells, including neurons, but it is not specifically related to synaptogenesis. The other options, loss or development of synapses and selective death of some nerve cells, are not accurate definitions of synaptogenesis.

Diablo is a protein that binds to inhibitors of apoptosis proteins (IAPs) and prevents them from inhibiting caspases. This allows caspases to function normally and initiate apoptosis, the process of programmed cell death. Therefore, the statement "True" accurately describes the interaction between Diablo and IAPs in inhibiting caspases.