All Questions: 91-120

Correct answer: B

A cerebral shunt is the most common treatment for hydrocephalus. A shunt system consists of a plastic tube connected to a valve and a catheter. One end of the catheter is placed in a ventricle where CSF is accumulating, and the other is typically placed in the abdominal cavity. The shunt diverts CSF to the abdominal cavity, where it can safely drain and be absorbed into the bloodstream.

Correct answer: B

The primary motor cortex is found in the precentral gyrus. It is an important area in the brain for voluntary movement.

Correct answer: C

Oxytocin is involved with increasing uterine contractions during labor and with the milk let-down reflex, which causes milk to be released during breastfeeding. Some research suggests it is involved with positive social interactions and feelings of trust, empathy, and social bonding. In truth, however, the research in this area is very unclear, and there is no consensus on oxytocin's effects on behavior.

Correct answer: B

The soma (aka cell body) contains the nucleus of the cell.

Correct answer: C

Neurotransmitter reuptake is a method neurons use to remove excess neurotransmitters from the synaptic cleft. The inhibition of reuptake leads to higher levels of neurotransmitters in the synaptic cleft. Thus, SSRIs increase serotonin levels in the synaptic cleft, an effect which is either directly or indirectly related to an improvement in the symptoms of depression.

Correct answer: B

The primary visual cortex, also known as V1, is a brain region that is critically important for the processing of visual information. It is found in the occipital lobe, surrounding and extending into a sulcus called the calcarine sulcus.

Correct answer: D

Ependymal cells are a type of glial cell found in the central nervous system (CNS). They line the ventricles of the brain and the central canal of the spinal cord. Their primary function is to produce cerebrospinal fluid (CSF) and to help circulate it.

Correct answer: D

The rupture of a brain aneurysm typically causes bleeding into the area surrounding the brain---a condition known as subarachnoid hemorrhage. Subarachnoid hemorrhage is an extremely dangerous situation with high rates of fatality.

Correct answer: B

The central sulcus is a fissure that runs down the side of the brain and separates the frontal and parietal lobes.

Correct answer: A

Serotonin was first discovered in blood serum in the late 1940s and found to cause blood vessels to constrict. It was named serotonin, with sero- referring to serum and -tonin referring to tone (as in vascular tone). It was initially thought that serotonin's only role was in regulation of the circulatory system, but it was later discovered to play a key role in the nervous system as a neurotransmitter.

Correct answer: D

Wernicke-Korsakoff syndrome typically involves a severely impaired ability to form new memories, disrupted recall of previously-formed memories, and a variety of other symptoms. It is caused by a thiamine deficiency, and is often (although not always) linked to alcoholism.

Correct answer: B

In a famous experiment in 1921, Otto Loewi demonstrated that chemical signaling played a key role in neural communication by showing a chemical he called Vagusstoff could affect the activity of the vagus nerve. Prior to that experiment, many neuroscientists believed neural communication was only electrical. In 1936, Henry Dale isolated Loewi's Vagusstoff and named it acetylcholine.

Correct answer: B

The spinal cord is divided into segments, each of which gives rise to a pair of spinal nerves. There are 31 segments, named for their location: there are 8 cervical segments, 12 thoracic segments, 5 lumbar segments, 5 sacral segments, and 1 coccygeal segment.

Correct answer: C

While the internal carotid arteries carry about 70-80% of the blood to the brain, the vertebral arteries carry the remaining 20-30%. The carotid system provides the majority of blood flow to the cerebral hemispheres, while the vertebral system primarily supplies the brainstem, cerebellum, and posterior parts of the cerebral hemispheres.

Correct answer: D

The ventral tegmental area (VTA) and substantia nigra are the two largest areas of dopamine neuron concentration (and production) in the brain. There are several major dopamine pathways that carry dopamine from these areas of concentration to other parts of the brain.

Correct answer: A

Curare acts as an antagonist at acetylcholine receptors. Specifically, it blocks nicotinic acetylcholine receptors, which are typically activated to cause muscle contraction. By blocking these receptors, curare causes paralysis. Studying curare helped scientists to understand the function of acetylcholine at the neuromuscular junction---where neurons synapse on muscles to cause them to contract.

Correct answer: D

At the optic chiasm, about 60% of the axons from the optic nerve cross over to the other side of the brain, while the rest stay on the side they originated on. The result of this is that all of the information from the right visual field ends up traveling to the left side of the brain, and vice versa. After the optic chiasm, the visual fibers are no longer called the optic nerve; they’re now called the optic tract.

Correct answer: B

Olfaction, or smell, is unique in that olfactory information does not get sent to the thalamus before being sent to the cortex. Instead, it is sent to the olfactory cortex, where the initial processing of olfactory information occurs. It's unknown why exactly this unique pathway exists; some have hypothesized it is an evolutionary adaptation to enable faster processing of olfactory information.

Correct answer: A

Alcohol is thought to act as a positive allosteric modulator at GABA receptors, in the process increasing the effects of GABA. This increased GABA signaling may help to explain alcohol's sedative and anxiolytic effects. Alcohol also inhibits activity at glutamate receptors.

Correct answer: B

The cochlea is a coiled structure that resembles a snail shell (cochlea comes from the Greek kochlos, which means "snail"); it is found within the inner ear. It contains the organ of Corti, which is the main receptor organ for hearing.

Correct answer: C

When Leborgne came under Broca's care, one of the only sounds he was able to make--unless antagonized, which could prompt him to curse--was an utterance that resembled the word "tan." Examining Leborgne's brain (after he died) helped Broca to identify the region that would eventually become known as Broca's area. Leborgne's verbal deficit would become known as Broca's aphasia.

Correct answer: D

Santiago Ramon y Cajal helped to demonstrate that neurons are individual cells, and his work helped to disprove reticular theory, the idea that the nervous system is made up of one continuous network of nerve fibers. Ramon y Cajal was also well known for his beautiful drawings of neurons and nervous system structures.

Correct answer: B

Huntington's disease can be traced back to a mutation in the huntingtin (HTT) gene. The mutation causes a high degree of trinucleotide repetition in the gene. The mutation is an autosomal dominant mutation, meaning that if it's inherited it will be expressed, and offspring have a 50% chance of inheriting the mutated gene if one parent has it.

Correct answer: C

The trigeminal nerve is responsible for carrying touch and pain sensations from the face and head, and it has three main branches. The branch that handles sensations from the forehead is the ophthalmic branch of the trigeminal nerve.

Correct answer: A

Although mechanisms can vary slightly for different types of seizures, in general seizures are caused by excessive and synchronized electrical activity in the brain. In a typical seizure, large groups of neurons fire at the same time, leading to spikes in neural activity. During a seizure, this abnormal neural activity can spread due to the failure of inhibitory mechanisms, leading to widespread abnormalities in brain function.

Correct answer: C

The agent in prion diseases (also called transmissible spongiform encephalopathies) is thought to be a misfolded form of a protein called prion protein, or PrP. This misfolded form of the protein seems to be able to induce other proteins to become abnormally folded, and it has been shown to be able to transmit disease in certain situations.

Correct answer: B

When a neuron is at rest, there is a higher concentration of sodium ions outside the cell. When the neuron becomes depolarized (e.g., due to neurotransmitter binding and resulting influx of positively-charged ions), sodium channels open and allow sodium to rush into the cell, generating an action potential.

Correct answer: D

Hemispatial neglect (aka contralateral neglect) typically emerges after a stroke that affects the right cerebral hemisphere, especially when the stroke impacts the parietal lobe. Patients with hemispatial neglect experience a deficit in attention to one side of the visual field (typically the side opposite the stroke damage).

Correct answer: A

While the right cerebral hemisphere primarily controls voluntary movement in the left side of the body, the right cerebellar hemisphere is primarily responsible for the right side of the body. Jean might experience symptoms such as impaired coordination, unrefined movements, tremors, etc., and they would likely be more prominent on the right side of the body.

Correct answer: A

Postganglionic neurons of the parasympathetic nervous system primarily release acetylcholine, while the postganglionic neurons of the sympathetic nervous system primarily release norepinephrine. The preganglionic neurons of both the parasympathetic and sympathetic nervous systems primarily release acetylcholine.