Neuro I Exam II

The substantia nigra and PAG (periaqueductal gray) are both structures located in the midbrain. The substantia nigra is involved in the production of dopamine and plays a crucial role in movement control. It is primarily associated with Parkinson's disease, as the loss of dopamine-producing cells in this region leads to motor symptoms. The PAG is involved in pain modulation and is responsible for the body's response to pain. It also plays a role in the regulation of emotions and behaviors. Both the substantia nigra and PAG are important components of the midbrain.

Serotonin, also known as 5-HT, is synthesized in the raphe nuclei of the midbrain, pons, and medulla. These regions of the brain are responsible for producing and releasing serotonin, which plays a crucial role in regulating mood, appetite, sleep, and other important physiological functions. The raphe nuclei are a group of nuclei located along the midline of the brainstem, and they are the primary source of serotonin in the central nervous system.

Krabbe's Disease is the correct answer because it is a demyelinating leukodystrophy that is characterized by the presence of macrophages filled with cerbroside, forming multinucleated cells around blood vessels, also known as "globoid" cells. This accumulation of cerbroside leads to the destruction of the myelin sheath in the nervous system, resulting in neurological symptoms. Metachromatic leukodystrophy is also a demyelinating leukodystrophy, but it is characterized by the accumulation of sulfatides, not cerbroside. Progressive multifocal leukodystrophy and Pick's disease are unrelated conditions and do not involve the presence of macrophages filled with cerbroside.

Neurofibrillary tangles are histological findings that contain an abnormally hyperphosphorylated form of the tau protein. In this case, the 70-year-old woman with dementia and clinical symptoms consistent with Alzheimer's disease had cortical atrophy affecting the frontal, parietal, and temporal lobes, which is characteristic of Alzheimer's disease. The microscopic examination of the brain sections confirmed the clinical diagnosis, and the presence of neurofibrillary tangles is consistent with Alzheimer's disease.

The correct answer is the corticospinal pathway which decussates in the medulla. This pathway carries neural signals for voluntary movement and the decussation (crossing over) of the pathway occurs in the medulla. This means that the signals originating from one side of the brain will control movement on the opposite side of the body. The midbrain, dorsal column-medial lemniscus pathway, pyramidal tract, and spinothalamic tract are not involved in the decussation of voluntary movement signals.

Norepinephrine is synthesized in the nucleus coeruleus. This region of the brainstem is responsible for producing and releasing norepinephrine, which is a neurotransmitter involved in various functions such as regulating mood, attention, and arousal. The nucleus coeruleus is located in the pons, near the fourth ventricle, and sends projections to different areas of the brain, including the cortex, hippocampus, and spinal cord.

Dopamine is the correct answer because it is distributed in the midbrain, ventral tegmental area, and hypothalamus. It plays a role in pleasure, reward, movement, attention, and memory. Drugs like cocaine, amphetamine, and methamphetamine increase the levels of dopamine in the brain's reward pathway.

Progressive multifocal leukoencephalopathy is a viral encephalitis that specifically infects oligodendrocytes. Oligodendrocytes are responsible for producing the myelin sheath, which insulates and protects nerve fibers in the central nervous system. By preferentially infecting oligodendrocytes, the virus disrupts the production and maintenance of myelin, leading to demyelination. This results in impaired nerve function and the symptoms associated with progressive multifocal leukoencephalopathy.

The correct answer is "Macrophages with lipids (myelin breakdown products), and perivascular mononuclear inflammatory cells." This answer is supported by the description of active plaques of multiple sclerosis showing the presence of macrophages containing lipids, which are breakdown products of myelin. Additionally, the presence of perivascular mononuclear inflammatory cells suggests an inflammatory response in these plaques. This explanation is consistent with the known pathology of multiple sclerosis, which involves the destruction of myelin in the central nervous system.

The correct answer is "thick and hyalinized." In a 75-year-old man with long standing diabetes, the non-healing ulcer on his lower extremity suggests the presence of peripheral vascular disease. Thickening and hyalinization of the endoneurial arterioles is a characteristic finding in this condition. This thickening and hyalinization can lead to reduced blood flow to the affected area, impairing wound healing and causing the ulcer to persist.

Neurofibrillary tangles are intracellular aggregates of hyperphosphorylated tau protein that are commonly seen in Alzheimer's disease. The degree of neurofibrillary tangles correlates with the severity of dementia in Alzheimer's disease. Although neurofibrillary tangles are not specific to Alzheimer's disease, they are a key pathological feature and play a significant role in the development and progression of the disease.

The correct answer is the Spinothalamic tract which is laterally located throughout the length of the brainstem. This pathway is responsible for transmitting pain and temperature information from the body to the brain. Unlike the other pathways mentioned, the Spinothalamic tract does not decussate (cross over) in the medulla or midbrain. Instead, it remains on the same side of the body throughout the brainstem. This allows for the accurate relay of pain and temperature signals to the appropriate regions of the brain for processing and perception.

Farber's disease is a rare genetic disorder characterized by the accumulation of ceramide in various tissues. Ceramidase is the enzyme responsible for breaking down ceramide. A decrease in ceramidase activity would result in an increased accumulation of ceramide, which is consistent with the molecular finding associated with Farber's disease.

The correct answer is VII. The lamina of Rexed are subdivisions of the spinal grey matter that relate to the location of the spinal nuclei. The intermedial lateral column, which contains preganglionic sympathetic fibers, is found in lamina VII.

A tumor in the brainstem at the level of the pons near the 4th ventricle is likely to affect facial expression. The facial nerve, which controls the muscles of facial expression, passes through the pons. Therefore, a tumor in this area can compress or damage the facial nerve, leading to weakness or paralysis of the facial muscles and affecting facial expression.

The spinotectal tract is responsible for orienting the eyes and head towards a stimulus. This tract carries sensory information from the spinal cord to the superior colliculus in the midbrain, which then coordinates the movement of the eyes and head in response to the stimulus. The cuneocerebellar tract carries proprioceptive information from the upper limbs to the cerebellum, the spinoreticular tract carries pain and temperature information to the reticular formation in the brainstem, and the spinocerebellar tract carries proprioceptive information from the lower limbs to the cerebellum.

The correct answer is the dorsal column medial meniscus pathway. This tract is responsible for touch perception, proprioception, and vibration. It carries sensory information from the body to the brain, specifically to the somatosensory cortex. The dorsal column medial meniscus pathway consists of two tracts: the fasciculus gracilis, which carries information from the lower body, and the fasciculus cuneatus, which carries information from the upper body. Together, they transmit sensory signals related to touch, position sense, and vibration to the brain for interpretation and perception.

Phospholipase A2 is the correct answer because it is the enzyme responsible for releasing arachidonic acid from cell membrane phospholipids, which is the precursor for prostaglandin synthesis. Inhibiting phospholipase A2 would therefore decrease prostaglandin synthesis.

The ventral tegmental area (VTA) has been implicated in addiction. It is a region in the midbrain that plays a crucial role in the brain's reward system. The VTA contains dopamine neurons that project to various areas of the brain, including the nucleus accumbens, prefrontal cortex, and amygdala, which are all involved in the experience of reward and reinforcement. Activation of the VTA and the release of dopamine in these target regions are associated with the pleasurable effects of drugs and other addictive substances, leading to the development of addiction.

The superior cerebellar peduncles send descending projections to the spinal cord via the red nuclei and the rubrospinal tract. These projections are involved in motor control and coordination. The red nuclei are involved in the control of voluntary movements, while the rubrospinal tract is responsible for the transmission of motor signals from the red nuclei to the spinal cord. Therefore, the correct answer is that the superior cerebellar peduncles send descending projections to the spinal cord via the red nuclei and the rubrospinal tract.

Restless leg syndrome is commonly seen in pregnancy, hemodialysis or peritoneal dialysis for renal failure, and iron-deficiency anemia. Studies have shown that this sleep disorder is associated with abnormal iron metabolism within the central nervous system.

A patient with medial medullary syndrome is likely to present with impaired motor control of limbs and impaired control of the tongue. This is because medial medullary syndrome is caused by damage to the medial part of the medulla oblongata, which is responsible for controlling motor function and coordination. The limbs may be weak or paralyzed, and the tongue may be affected, leading to difficulty in speaking and swallowing. Impaired ocular control and loss of pain sensation are not typically associated with medial medullary syndrome. Loss of pain sensation ipsilateral to the lesion and impaired motor function and loss of temperature sensation are more commonly seen in other conditions such as Brown-Séquard syndrome.

Acetylcholine is synthesized in the nucleus of Mynert.

Niemann Pick disease is a rare genetic disorder characterized by the accumulation of sphingomyelin in the cells. Sphingomyelinase is the enzyme responsible for breaking down sphingomyelin. In this disease, there is a decrease in the activity of sphingomyelinase, leading to the accumulation of sphingomyelin. Therefore, the correct answer is a decrease in sphingomyelinase activity and increased accumulation of sphingomyelin.

Neurons in Brodmann's area 42 will increase their activity during auditory stimulation. This is because Brodmann's area 42, also known as the primary auditory cortex, is responsible for processing auditory information. When there is auditory stimulation, such as hearing a sound or a voice, the neurons in this area become more active in order to process and interpret the auditory signals.

The key event in long-term potentiation (LTP) that specifically facilitates the postsynaptic influx of calcium ions (Ca2+) through an otherwise blocked ion channel is postsynaptic depolarization. When the postsynaptic membrane depolarizes, it removes the block on the NMDA receptors, allowing calcium ions to enter the postsynaptic neuron. This influx of calcium ions is crucial for the signaling pathways that lead to the strengthening of the synaptic connection and the formation of long-term memories.

The glutamatergic theory proposes that prolonged postsynaptic ion influx can lead to excitotoxicity, which is the excessive stimulation of neurons by the neurotransmitter glutamate. This excessive stimulation can cause an influx of calcium ions into the neurons, leading to cell damage and ultimately neuronal death. In the context of Alzheimer's disease, this pathway suggests that excessive glutamate activity and excitotoxicity contribute to the death of neurons, leading to the onset of the disease.

The perforant pathway is a neural pathway that carries information from the entorhinal cortex to the hippocampus. It is an afferent pathway, meaning it is directed towards the hippocampus. The other options provided in the question are not accurate descriptions of the perforant pathway.

Decarboxylation of serine produces phosphatidylethanolamine. Serine is an amino acid that can undergo decarboxylation, which involves the removal of a carboxyl group (-COOH). This process results in the formation of phosphatidylethanolamine, which is a type of phospholipid found in cell membranes. Phosphatidylethanolamine plays a crucial role in maintaining the integrity and fluidity of cell membranes, as well as participating in various cellular processes such as signaling and protein trafficking.

An ether linkage between a fatty acid and glycerol is typical of plasmalogen. Plasmalogens are a type of phospholipid that contain a vinyl ether bond at the sn-1 position of the glycerol backbone. This unique structure gives plasmalogens important biological functions, such as being involved in cell membrane structure and function, as well as serving as a precursor for the synthesis of other important molecules like platelet-activating factor.

When sour taste is detected, taste buds on the lateral edges of the tongue are predominantly activated. The sour taste is mainly due to the presence of hydrogen ions (H+ ions) in the food. These H+ ions bind to specific receptors on the taste buds, which then send signals to the brain, resulting in the perception of sour taste.

First-order neurons in the olfactory pathway synapse to second-order neurons in the glomeruli of the olfactory bulb. The olfactory bulb is a structure located in the brain that receives input from the olfactory epithelium, which is responsible for detecting odors in the nasal cavity. The glomeruli in the olfactory bulb are specialized structures where the synapses between the first-order and second-order neurons occur. This synapse allows for the transmission of olfactory information from the periphery to higher brain regions involved in processing smell.

Dorsal column medial lemniscus afferents project to the Ventral posterolateral nucleus (VPL) of the thalamus. This nucleus is responsible for relaying sensory information related to touch, proprioception, and vibration from the body to the primary somatosensory cortex. The other thalamic nuclei mentioned in the options have different functions and receive inputs from different sensory pathways. Therefore, the correct answer is the Ventral posterolateral nucleus.

The habenula is a small structure located in the epithalamus, which is a region of the brain. It is responsible for regulating various functions such as sleep-wake cycles, reward processing, and stress responses. The other options listed are not part of the epithalamus. The superior colliculus is part of the midbrain, the hypothalamus is a separate region responsible for regulating bodily functions, the ventral tegmental area is part of the mesencephalon, the periaqueductal gray is part of the midbrain, and the habenula itself is part of the epithalamus.

The correct answer is the nucleus of Mynert. Dopamine is synthesized in various regions of the brain, including the ventral tegmental area, substantia nigra, and tubero-infundibular system. However, it is not synthesized in the nucleus of Mynert.

Poor development of peroxisomes due to genetic causes, such as in Zellweger syndrome, is associated with decreased synthesis of plasmalogen.

The thalamus is a brain area that is crucial for conscious awareness. Damage or disruption to the neural links to the thalamus can lead to a loss of conscious awareness. This suggests that the thalamus plays a key role in the emergence of awareness.

The lentiform nucleus is a structure located in the brain that is part of the basal ganglia. It is composed of the putamen and the globus pallidus. These two structures work together to regulate movement and motor control. The putamen receives input from the cortex and relays it to the globus pallidus, which then sends signals to other areas of the brain to coordinate movement. Therefore, the correct answer is "The putamen and globus pallidus."

The spinoreticular tract is responsible for the perception of visceral pain, postural control, and orientation. It carries sensory information from the spinal cord to the reticular formation in the brainstem. The reticular formation plays a crucial role in regulating arousal, attention, and consciousness. Therefore, the spinoreticular tract is involved in transmitting pain signals from internal organs, maintaining balance and posture, and helping us orient ourselves in space.

The presence of Lewy bodies in the brain is a characteristic finding in Parkinson's disease. Lewy bodies are abnormal protein aggregates that are primarily composed of alpha synuclein. Therefore, the protein that would most likely be found within the Lewy bodies in this case is alpha synuclein.

Microglial nodules would best characterize AIDS-dementia complex. In this condition, HIV infection leads to inflammation in the brain, causing the activation of microglial cells, which are the resident immune cells in the central nervous system. These activated microglial cells form nodules, which are clusters of cells that can be seen under microscopic examination. This finding is characteristic of AIDS-dementia complex and helps differentiate it from other neurodegenerative diseases.

The dominant component of the amyloid core in the brain of a patient with dementia is the abeta peptide. This is indicated by the presence of focal spherical collections of dilated, tortuous, silver staining processes around the central amyloid core, surrounded by a clear halo.

Neurons in the pars reticulata division of the substantia nigra project to the thalamus. The substantia nigra is a midbrain structure involved in the regulation of movement. The pars reticulata division of the substantia nigra is responsible for inhibiting the activity of the thalamus. This inhibition helps to regulate motor output and prevent unwanted movements. Therefore, the correct answer is thalamus.

The head of the caudate is the correct answer because it is located in the medial aspect of the internal capsule. The internal capsule is a white matter structure in the brain that separates the caudate nucleus and the thalamus from the putamen. The head of the caudate is positioned closer to the midline of the brain, making it medial to the internal capsule.

The cortical neurons that project to the thalamus are located in lamina V.

Phosphatidyl ethanolamine is the best choice of lipid for building a model bilayer membrane with the lowest possible net charge at neutral pH and very low ionic strength. This is because phosphatidyl ethanolamine is a zwitterionic lipid, meaning it has both a positively charged amino group and a negatively charged phosphate group. These charges cancel each other out, resulting in a neutral net charge. Additionally, phosphatidyl ethanolamine is commonly found in biological membranes, making it a suitable choice for modeling a natural membrane environment.

A decreased availability of choline could contribute to a limitation of the liver's ability to export lipids. Choline is an essential nutrient that is required for the synthesis of phosphatidylcholine, a major component of lipoproteins that transport lipids out of the liver. If there is a decreased availability of choline, it could lead to a decrease in the synthesis of phosphatidylcholine, thereby impairing the liver's ability to export lipids.

Farber's disease is a rare genetic disorder characterized by the accumulation of fatty substances called ceramides in various tissues and organs of the body. The impaired motor ability and difficulty with swallowing seen in the newborn patient suggest a neurological involvement, which is consistent with Farber's disease. Defects in the Ceramidase gene, which encodes an enzyme involved in the breakdown of ceramides, would lead to a decreased ability to break down ceramides, resulting in their accumulation and the symptoms observed in the patient. Therefore, the correct answer is defects in the Ceramidase gene.

Left-side hemiparesis and paralysis of eye muscles suggest a lesion in the right side of the brainstem. The brainstem is responsible for controlling various functions, including motor control and eye movements. The ventral side of the brainstem is involved in motor function, while the dorsal side is involved in sensory function. Since the symptoms mentioned in the question are related to motor function, the lesion is most likely in the right ventral midbrain.

Modafinil (Provigil) is a medication used to treat excessive daytime sleepiness in patients with sleep-wake disorders. The main mechanism of action of modafinil is by inhibiting the re-uptake of norepinephrine. By preventing the re-uptake of norepinephrine, modafinil increases the levels of this neurotransmitter in the brain, leading to increased wakefulness and alertness. This helps the patient stay awake during the day and reduces excessive sleepiness.