Midterm 1 Exam Prep-FINAL PDF

Exam Prep for Midterm 1 The following is provided to help you review L2-L6 in preparation for the midterm exam. It is NOT an exhaustive list of information that we learned this quarter, nor is it a list of everything that will be tested on the midterm exam. If something is not included below it do...

Exam Prep for Midterm 1 The following is provided to help you review L2-L6 in preparation for the midterm exam. It is NOT an exhaustive list of information that we learned this quarter, nor is it a list of everything that will be tested on the midterm exam. If something is not included below it does not mean that it is not important. **[Definitions:]** **Gray matter:** cell bodies of nerve cells **White matter:** bundles of myelinated axons **CNS:** Together, the brain and spinal cord constitute the central nervous system (CNS) The **peripheral nervous system (PNS)** is composed of **nerves** (= bundles of [axons] of nerve cells) and **ganglia** (= clusters of [cell bodies] of nerve cells). **Corpus callosum:** a thick band of axons that provides communication between the right and left cerebral cortices. The right half of the cerebral cortex controls the left side of the body, and vice versa **Split-brain patients:** patients with the corpus callosum severed (e.g., in cases of severe epilepsy) can simultaneously draw two different shapes! **Ventricles:** a series of connected chambers in the brain, filled with cerebrospinal fluid (CSF) **The Cortical Homunculus** (= little man): a topographical representation of the body in the cortex of the brain. Sensory and motor. **fMRI:** functional magnetic resonance imaging. Developed to demonstrate regional, time- varying changes in brain metabolism, which can be induced by brain activity **Cortical mapping**: the effort to correlate brain anatomy with psychological and cognitive function **Multiple Sclerosis:** Immune-mediated disorder in which the body's own immune system (the white blood cells) is directed against the CNS **myelin** (= fatty coating around axons of nerve cells). Myelin is formed by types of glia, oligodendrocytes in the CNS and schwann cells in the PNS. The loss of myelin in brain and spinal cord disrupts the ability of parts of the nervous system to communicate, producing a variety of symptoms **MRI (magnetic resonance imaging):** diagnostic tool that offers the most sensitive non-invasive way of imaging brain structure **Ion:** a charged molecule; can be positively (+) or negatively (-) charged **Permeability:** a measure of how readily a molecule passes through a membrane **Concentration:** how many particles in a given volume **Concentration gradient:** the difference in concentration (amount) between 2 regions **Potential difference (across a membrane):** the difference in the amount of charge across a membrane, also known as **Membrane Potential** **Resting membrane potential:** the value of the membrane potential when the neuron is not active **"Voltage-dependent" channels:** they open when membrane potential reaches a critical value **Channelopathies:** are diseases of ion channels that can underlie many diseases including cystic fibrosis, epilepsy, seizure, tinnitus (ear ringing), movement disorders, and migraine. **Absolute refractory period:** a new spike cannot be triggered, even with a strong stimulus. Happens because Na+ channels are inactivated. **Relative refractory period:** a new spike can be triggered, but with stronger stimulus than originally needed. Happens because membrane potential is more negative than resting membrane potential (further from firing threshold) hence why a stronger stimulus is needed for a new spike. **Action potential:** a rapid change in membrane potential that is used to communicate information **Saltatory conduction:** propagation of action potentials along myelinated axons from one node of Ranvier to the next faster propagation **Nodes of Ranvier:** The myelin sheath is NOT continuous along the axon: there are gaps in the sheath, which are rich in voltage-dependent sodium channels and allow action potentials to regenerate. **The myelin sheath** is created by certain types of glial cells: oligodendrocytes in CNS and Schwann cells in PNS. It forms an electrically insulating layer around axons **Synaptopathy:** pathology of synapses **Excitation:** process that increases the probability that a neuron will be activated **Inhibition:** process that decreases the probability that a neuron will be activated **Synaptic cleft:** the nm-wide space between the pre- and postsynaptic terminals **Neurotransmitters (NTs)** are chemical substances that are released by the presynaptic neuron in the **synaptic cleft** through the fusion of synaptic vesicles with the presynaptic plasma membrane A **membrane receptor** is a membrane protein that receives a chemical signal from outside the cell (e.g., a neurotransmitter; NT). Upon binding of the NT, the NT receptor causes some cellular response, e.g. the opening of a channel **[Key topics/concepts to know:]** Neuronal morphology: Glia cells vs neurons Astrocytes Oligodendrocytes and Schwann cells Central nervous system (CNS) vs Peripheral nervous system (PNS) Somatic vs Autonomic divisions of PNS Nerves vs Neurons 4 lobes of the cerebral hemisphere Cerebellum Brainstem Function of cerebral spinal fluid (CSF) and ventricles Hydrocephalus Brain function and structure How to diagnose multiple sclerosis fMRI vs MRI Demyelination Electrical properties of neurons Membrane potential Action potential Communication between neurons at synapse Balance between excitation and inhibition in the brain Chemical synapse **[Disorders:]** Hydrocephalus: excessive accumulation of cerebrospinal fluid in the brain Brain lesions and aphasias: Phineas Gage: frontal lobe lesion, changed personality Broca's: Generation of speech Wernicke's: Comprehension of language Split-brain patients: patients with the corpus callosum severed (e.g., in cases of severe epilepsy) can simultaneously draw two different shapes! Multiple Sclerosis: Immune-mediated disorder in which the body's own immune system (the white blood cells) is directed against the CNS myelin Channelopathies: are diseases of ion channels that can underlie many diseases including cystic fibrosis, epilepsy, seizure, tinnitus (ear ringing), movement disorders, and migraine. Synaptopathy: pathology of synapses Epilepsy: Imbalance between brain excitation and inhibition Generalized onset seizures: brain wide Focal onset seizures: start in a small part of the brain (epileptic focus) Sudden explained death in epilepsy (SUDEP) **[Key points to remember:]** **Lectures 2-4:** 1. The nervous tissue is made up of neurons and glia 2. Neurons share many biological features with other animal cell types but have striking morphologies and do not replicate 3. Neurons communicate with target cells (other neurons, muscles or glands) through synapses 4. Invasive (e.g., lesions, microstimulation) and non-invasive (e.g., fMRI) approaches are used to study the brain. Each technique has advantages and limitations that must be considered carefully. 5. Even though certain functions reside predominantly in certain brain regions, we now understand that the brain is highly interconnected. 6. All cells have a membrane potential (measured in mV) - The membrane potential is created by differences in the ions and charged proteins inside the cell (cytoplasm) compared to outside (extracellular space) - At rest, the membrane potential is called resting potential - At rest, a healthy neuron is more negative inside (the cytoplasm) than outside (extracellular space) 7. Ions move across cell membranes through ion channels. Some channels are always open (leak channels), others open at a particular membrane potential (voltage-dependent channels) 8. During an action potential, voltage-dependent sodium channels open and let sodium (Na+) in the neuron -\> depolarization 9. As the membrane potential becomes more positive, voltage-dependent potassium channels open and let potassium (K+) out of the neuron. Voltage-dependent sodium channels are inactivated and then closed -\> repolarization 10. At the end of an action potential, the sodium-potassium pump transports Na+ out and K+ in, restoring ionic gradients 11. Action potentials are generated at the specialized region of the axon called axon hillock and propagate down axons to axon terminals 12. Most, but not all, axons are myelinated. In the CNS, myelin is formed by oligodendrocytes; in the PNS by Schwann cells 13. Myelin protects and insulates axons and speeds up action potential propagation 14. In myelinated axons, action potentials "jump" from one node of Ranvier to  another, i.e., they propagate through saltatory conduction 15. Theoretically, we could cure Multiple Sclerosis symptoms if we could stop the process of demyelination; protect/make new oligodendrocytes; and/or grow thicker axons **Lectures 5-6: ** 1. The nervous system is NOT one single continuous network. It is made up of neurons (and glia), which communicate with each other at synapses. Synapses are typically formed between the axonal terminals of a presynaptic neuron and the dendrites of a postsynaptic neuron. Excitatory synapses are typically formed on postsynaptic spines, which are membranous protrusions on dendrites. 2. At chemical synapses, the release of neurotransmitters, such as glutamate and GABA, requires calcium presynaptically.  3. Neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic cell membrane to excite or inhibit postsynaptic neurons  4. Balance between excitation and inhibition is necessary for neurotypical brain  5. The sign of the synapse (excitatory, inhibitory) affects the activity of the downstream neuron. In the CNS, Excitatory synapses are usually glutamatergic and increase activity (more postsynaptic firing) whereas inhibitory synapses are typically GABAergic and decrease activity (less postsynaptic firing).   6. Epilepsy is an imbalance in excitation and inhibition, typically too much excitatory activity which can lead to seizures.  7. There are many different types of seizures, typically defined by their localization and spread within the brain. Also, whether the patient maintains awareness or not. Seizures in different brain regions present different symptoms (e.g. focal onset of a seizure in the motor cortex -\> motor seizures)  8. Electroencephalogram (EEG) measures electrical potentials from the scalp. Can be used to distinguish between several types of seizures. 9. Typical methods to treat epilepsy and seizures are focused on dampening activity in the brain (drugs, neuromodulation), but invasive techniques like deep brain stimulation and surgery can also be employed. Electrocorticogram (EcoG) can be used to record from the surface of the brain and find epileptic foci (=sites). 10. Botox works by cleaving (=cutting) proteins that synaptic vesicles need to fuse with the presynaptic plasma membrane (=cell mebrane), preventing neurotransmitter release at the synapse between the neuron and the muscle and leading to muscle paralysis. **[Test your understanding:]** 1. Which of the following statements is FALSE:\ a. Lesions in the occipital cortex could directly alter one's personality\ b. Hydrocephalus is caused by water accumulation in the ventricles\ c. Lesions in Wernicke's area would impair language production\ d. All of the above 2. During his famous cortical mapping experiments, Penfield stimulated\ various brain regions in awake patients undergoing surgery. Which of the\ following could have happened when he stimulated the left motor cortex?\ a. The patient moved her left hand\ b. The patient moved her right hand\ c. The patient felt tingling in her right hand\ d. The patient felt tingling in her left hand 3. Which of the following is correct: Multiple sclerosis\ a. can be diagnosed with fMRI\ b. results in CSF overproduction and enlarged ventricles\ c. affects both the brain and spinal cord\ d. affects the brain but not the spinal cord 4. If the membrane potential of a neuron is 0 mV:\ a. The inside of the neuron is more negative than the outside\ b. The inside of the neuron is more positive than the outside\ c. There is no potential difference between the inside and outside of the neuron\ d. None of the above 5. How would you build a class of neurons that would be able to propagate action\ potentials down very long axons and in a very rapid manner?\ a) with a very small axon diameter and myelination\ b) with a very large axon diameter but no myelination\ c) with a very large axon diameter and myelin that completely covers the entire\ axon with no gaps\ d) With a very large axon diameter and myelination with regularly spaced gaps 6. In principle, which of the following would restore function in multiple\ sclerosis?\ a. Make more voltage-dependent potassium channels\ b. Make more Schwann cells\ c. Make more CSF\ d. None of the above 7. Which of the following is correct about the membrane potential:\ a. It can change depending on which channels are opened or closed\ b. It repolarizes, then depolarizes during an action potential\ c. It is a unique feature of neurons\ d. It cannot be positive 8. Which of the following is true about chemical synaptic\ transmission?\ a. it requires flow of calcium (Ca+2) out of the postsynaptic terminal\ b. it relies on fusion of synaptic vesicles with the postsynaptic membrane\ c. it happens when the presynaptic terminal is hyperpolarized\ d. it converts the electrical signal of the action potential into a chemical signal 9. The space between a neuron and its postsynaptic target is called\ a. Postsynaptic membrane\ b. Dendritic spine\ c. Axon terminal\ d. Synaptic cleft 10. Choose the best answer: All of the following molecules are necessary for an action potential EXCEPT: a\. Na+ b\. ATP c\. K+ d\. Cl- 11. Drugs that block the glutamate receptors would be expected to:\ a. Reduce inhibition\ b. Reduce excitation\ c. Increase excitation\ d. Prevent synthesis of CSF 12. Which of the following statements is true?\ a. GABA is released from presynaptic vesicles\ b. There is no inhibitory neurotransmission in the brain without calcium\ c. Activation of GABA receptors can hyperpolarize the postsynaptic neuron\ d. All of the above 13. All of the following can be potentially used to treat epilepsy except\ a. Deep brain stimulation\ b. Glutamate receptor activators\ c. Cutting the corpus callosum\ d. Dietary changes 14. Your neighbor just told you that she experienced an epileptic seizure earlier today. What type of seizure did she most likely have?\ a. Absence seizure\ b. Focal onset impaired awareness seizure\ c. Focal onset aware seizure\ d. Status epilepticus seizure 15. What is the primary function of the myelin sheath in the nervous system? a. To transmit electrical signals between neurons b. To provide structural support to neurons c. To protect neurons from external damage d. To insulate and speed up the conduction of nerve impulses 16. Which of the following correctly distinguishes the central nervous system (CNS) from the peripheral nervous system (PNS)? a. The CNS includes the brain and spinal cord, while the PNS includes peripheral nerves b. The CNS consists of sensory neurons, while the PNS consists of motor neurons. c. The CNS controls voluntary actions, while the PNS controls involuntary actions. d. The CNS includes all neurons in the body, while the PNS is limited to the brain. 17. What is neural plasticity? a. The ability of neurons to maintain a constant shape throughout life. b. The process of neurons losing their ability to form connections. c. The concept of brain regions being completely static and unchangeable. d. The brain\'s capacity to reorganize and adapt by forming new neural connections. 18. How do neurons communicate with each other at chemical synapses? a. By direct electrical connections b. By physical touch and pressure c. By exchanging hormones d. By releasing neurotransmitters into the synaptic cleft 19 What is the primary role of the sympathetic division of the autonomic nervous system? b. To slow down the heart rate and respiration c. To conserve energy and promote relaxation d. To prepare the body for fight-or-flight responses **[Test your understanding ANSWERS:]** 1. D 2. B 3. C 4. C 5. D 6. D 7. A 8. D 9. D 10. D***[\ ]*** 11. B 12. D 13. B 14. C 15. D 16. A 17. D 18. D 19. D