neuroscience

Which of the following accurately describes the cranial nerves?

A) Cranial nerves provide motor output to muscles on and above the neck. B) the vagus nerve is a cranial nerve that is part of the autonomic nervous system. C) The auditory, optic, and olfactory nerves are cranial nerves.

Steps of chemical neurotransmission

1) Action potential arrives at the presynaptic terminal. 2) The Ca+ voltage gated ion channels open and the gradient allows the vesicles to release NT's out. 3) The vesicles containing the NT's head towards the membrane. 4) The NT's travel out to the receptors on the post synaptic terminal. 5) The receptors execute the change in the post synaptic cell. 6) The NT's are cleaned up from the synaptic cleft by either a) reputable or b) degradation.

Dr. Ladle has been asked by the National Science Foundation to help study the neurophysiology of the Texas Violet Varmint, a recently discovered cousin to the Siberian Purple Hamster. She is studying a small circuit of neurons involved in sensory transduction in the varmint. She works out the following base connectivity. 1) Name the neuroanatomical structure where the sensory neuron cell bodes are found. 2) Name the cell type, by basic morphology, of the sensory neurons. 3) Explain any differences you would expect in how the action potential is regenerated in neuron A vs neuron B. 4) The three sensory neurons form excitatory synapses on the spinal cord neuron.Resting membrane potential of the spinal cord neuron is -60 mV, and threshold is -40mV. Each time sensory neuron A fires, it can contribute +7 mV of depolarization at the axon hillock. How could activation of sensory neuron A only trigger an action potential? 5) Same conditions apply as in 16a, only now consider that sensory neurons A can B contribute +7mV of depolarization to the spinal cord neuron and C can contribute +10mV of depolarization. What would happen if all three neurons fired at the same time? What is this phenomenon called? 6) In the previous question, sensory neuron C's synapse onto the spinal cord neuron contributes more depolarization toward firing an action potential than neuron A or B's synapses. Give a possible explanation for this.

1) Name the neuroanatomical structure where the sensory neuron cell bodes are found: Dorsal root ganglion 2) Name the cell type, by basic morphology, of the sensory neurons: Unipolar, because there is a branch out from the soma to the dendrite and the axon. 3) Explain any differences you would expect in how the action potential is regenerated in neuron A vs neuron B" Neuron B does not seem to have insulation by way of myelin sheath. A Myelin sheath is important to acorns, because they are integral to the "propagation" of AP's down the axon. When there is no myelin sheath, like on Neuron B, or there is degradation of Schwann cells or oligodendrocytes, which make up the myelin sheath in the PNS and CNS respectively, there will be problems propagating the AP. Meanwhile, Neuron A's AP will travel along the axon smoothly and quickly, because of the insulation that the myelin sheath provides. 4) The three sensory neurons form excitatory synapses on the spinal cord neuron.Resting membrane potential of the spinal cord neuron is -60 mV, and threshold is -40mV. Each time sensory neuron A fires, it can contribute +7 mV of depolarization at the axon hillock. How could activation of sensory neuron A only trigger an action potential? APSP's or excitatory post synaptic potentials, will trigger an AP as long as the right circumstances are present. In spatial summation, multiple synapses send potentials at the same time, and if the net sum of the EPSP's and IPSP's are enough to trigger the AP at the time, it will do so. However, temporal summation, which seems to the care here, uses multiple potentials fir tin in quick succession rather then simultaneously, to trigger an AP, which will happen if the potentials are excitatory and fast enough one right after another. If sensory neuron A can fire enough potentials in quick succession to reach threshold, then it can trigger an action potential. 5) Same conditions apply as in 16a, only now consider that sensory neurons A can B contribute +7mV of depolarization to the spinal cord neuron and C can contribute +10mV of depolarization. What would happen if all three neurons fired at the same time? What is this phenomenon called? Altogether, the depolarization would amount to +17mV, meaning that an AP would be triggered, and this phenomenon is called spatial summation. If multiple potentials from multiple sources reach the target at the same time, and the strength of the EPSPs in the net sum of the potentials is enough, then an AP can be triggered. 6) In the previous question, sensory neuron C's synapse onto the spinal cord neuron contributes more depolarization toward firing an action potential than neuron A or B's synapses. Give a possible explanation for this.

transverse/cross coronal sagittal

transverse/cross: horizontal coronal: frontal sagittal: left and right

Would you expect astrocytes closely associated with electrical synapses or a chemical synapses? Briefly justify your choice.

I would expect to find astrocytes more closely associated with a chemical synapse. One of the functions of astrocytes in the brain is to help remove neurotransmitter from the synaptic cleft to terminate signaling at a chemical synapse. As electrical synapses don't employ neurotransmitters, astrocyte support for neurotransmitter cleanup would not be required.

In Charcot Marie Tooth disease, Schwann cells specifically degenerate and die. What effect might you expect this to have on motor neurons in the peripheral nervous system? What effect would this have on neurons in the motor cortex?

Schwann cells provide the myelin sheath for neurons in the peripheral nervous system. Thus degeneration of Schwann cells will impair action potential propagation in peripheral nervous system motor neurons. Neurons in the brain, like those in the motor cortex, will not be affected as their myelin is provided by oligodendrocytes, not Schwann cells.

Label with: chemical synapses (C), electrical synapses (E), both (B), or neither (N). a) Vesicular release b) Information is transmitted from pre to post synaptic cell c) Present in the CNS d) G protein coupled receptors e) Signal crosses synaptic cleft f) Reuptake pumps g) Ligand gated ion channels h) Gap junctions

a) "C" Vesicular release b) "B" Information is transmitted from pre to post synaptic cell c) "B" Present in the CNS d) "C" G protein coupled receptors e) "B" Signal crosses synaptic cleft gated ion channels f) "C" Reuptake pumps g) "C" Ligand gated ion channels h) "E" Gap junctions

Which of the following accurately describe neuron function and morphology? Circle all that apply.

a) All neurons have only one primary axon. b) The direction of flow of information between neurons is generally presynaptic to postsynaptic. c) Sensory neurons are often unipolar.

Which of the following would increase the membrane potential of (depolarize) a neuron? Circle all that apply.

a) Increasing intracellular sodium (Na+) b) Increasing extracellular potassium (K+) c) Opening a calcium (Ca2+) channel

Which of the following accurately describe the resting membrane potential?

a) It is set by potassium (K+) leak currents at rest. b) It is negative with respect to the outside of the cell. c) Resting membrane potential relies on differential distribution of ions across the membrane. e. Lack of cellular ATP will eventually result in the membrane potential going to 0 mV.**

Which of the following are tenants of phrenology and are compatible with our current (modern) understanding of the brain?

a) The brain is the organ of the mind. b) The brain is not a homogenous unity, but an aggregate of mental organs with specific functions. c) The cerebral organs are topographically localized. D) Other things being equal, the relative size of any particular mental organ is indicative of the power or strength of that organ.

True/False

a) The typical resting membrane potential for a neuron is about -50 to -80 mV b) The resident immune cells of the central nervous system are called microglia c) The dendrites are considered the "input zone" of neurons. d) At rest, there is a balance of K+ flowing out of the cell to follow its chemical gradient and K+ flowing into the cell due to electrical attraction to the intracellular environment. e) The major source of negative charge inside the cell is proteins and other macromolecules. f) Electricasl synapses are formed by channels called gap junctions, and allow for fast, practically synchronous connectivity between neurons. g) The autonomic nervous system is often describes as having 2 major divisions: The sympathetic and parasympathetic. h) An IPSP could be caused by a neurotransmitter binding a ligand gated chloride channel.

Which of the following could hyperpolarize a neuron?

A) Openong a chloride channel B) Opening a potassium channel C) Activating a metabotropic nerurotransmitter receptor (GPCRs)

Which of the following are required for setting the resting membrane potential?

A) Potassium leak channels B) The sodium potassium pump. C) ATP

Which of the following accurately describes glial cells?

A) They are critical in forming the blood-brain barrier. B) They are important for providing structural support for neurons.

1) Broca's area 2) Corpus callosum 3) Cranial nerves 4) Dorsal root ganglion _F_ Hypothalamus 5 )Occipital lobe 6) Parietal lobe 7) Temporal lobe 8) Ventral root ganglion A. Auditory processing B. Peripheral motor neurons C. Somatosensory processing D. Speech production E. Axons connecting the right and left hemisphere F. Master endocrine regulator G. Visual processing H. Facial muscles I. Peripheral sensory neurons

A. Auditory processing-Temporal lobe B. Peripheral motor neurons-Ventral root ganglion C. Somatosensory processing-Parietal lobe D. Speech production-Broca's area E. Axons connecting the right and left hemisphere-Corpus callosum F. Master endocrine regulator-Hypothalamus G. Visual processing-Occipital lobe H. Facial muscles-Cranial nerves I. Peripheral sensory neurons-Dorsal root ganglion

True or False? a) The soma is the part of the neuron responsible for integrating information. b) To determine the direction of flow of ions, the concentration on either side of the membrane must be considered, as well as the electric gradient. c) The specialized structure on dendrites that houses the postsynaptic density is called a spine. d) A cell with one primary dendrite and one primary axon is called a bipolar cell.

All are true.

For each cell type listed below, name one physiological function.

Astrocyte: metabolic support of neuron. Oligodendrocyte: provides myelin for axons in CNS. Microglia: immune cells of CNS.

Basal Ganglia Broca's Area Corpus Callosum Dorsal Root Ganglion Hypothalamus Lambic system Meninges Parietal Lobe Sylvia's or lateral fissure Temporal Lobe

Basal Ganglia: Motor coordination + Learning Broca's Area: Speech Production Corpus Callosum: Connects the cerebral hemispheres Dorsal Root Ganglion: Peripheral sensory neurons Hypothalamus: Master endocrine regulator Lambic system: Emotional Response Meninges: Protective layers of tissue around the CNS Parietal Lobe: Processes somatosensory information Sylvia's or lateral fissure: Separates frontal and temporal lobes Temporal Lobe: Processes auditory information

Compare and contrast an ionotropic neurotransmitter receptor with a metabotropic neurotransmitter receptor.

Ionotropic receptors are a neurotransmitter receptors that are also ion channels. When a ligand‐gated ion channel binds its neurotransmitter, it can open immediately in response. They also close quickly when the neurotransmitter is no longer around. Ligand gated ion channels are thus a type of neurotransmitter receptor that mediates fast and short lived response in the post synaptic cell. Metabotropic receptors, or G‐protein coupled receptors (GPCRs), are receptors for neurotransmitters, but are not themselves an ion channel. Instead, GPCRs initiate a series of events that may result in the opening of an ion channel, or otherwise create a change in they postsynaptic cell. Because there are a couple of steps between receptor and effector, GPCRs are a type of neurotransmitter receptor that mediates slower, but longer lived responses in the post synaptic cell.

In addition to receiving excitatory inputs form sensory neurons, the spinal cord receives inhibitory inputs from the bran. Furthermore, when sensory neurons are stimulated to fire action potentials, the spinal cord neuron has a fast, short lived pose synaptic potential. In contrast, stimulating the descending acorns from the brain produces a slow, long lived pose synaptic potential. Propose an explanation for why this could be.

Isotropic receptors are ion channels as well, and fo not need to communication with G proteins, and thus when they trigger an event, they are much faster than metabotropic receptors, which must employ G proteins, which then triggers a cascade of signaling, and results in a longer process.

Compare "spatial summation" of postsynaptic potentials versus "temporal summation" of postsynaptic potentials.

Spatial summation: postsynaptic potentials from multiple inputs arriving at the same time are summed: depolarizing and hyperpolarizing (excitatory and inhibitory) inputs have a net effect on the potential at the cell body, and if there are sufficient simultaneous excitatory inputs arriving from different synapses at the same time, an action potential will fire. Temporal summation refers to postsynaptic potentials from the same synapse occurring over a period of time. If one synapse is activated multiple times quickly enough, these postsynaptic potentials can be summed resulting in a greater change in membrane potential than a single activation of the synapse. If this is an excitatory input, a sufficient number of depolarizing postsynaptic potentials arriving from the same synapse in quick enough succession can evoke an action potential.

Sulcus Gyrus Saggy tail Coronal Dorsal Ventral Enteric Medical Lateral White matter

Sulcus: The "valley" in a portion of the brain. Gyrus: The "raised" portions of the brain. Saggital: Going through vertically, dividing the brain into right and left. Coronal: Dividing into ventral and dorsal sections. Dorsal: Towards the front Ventral: Towards the back Enteric: "second brain" the ENS operates outside of the CNS Medial: Through/Towards the middle Lateral: Away from the middle White matter: The "whiter" brain and spinal cord tissue. Made out of nerve fibers with myelin sheaths.

What is the function of the axon hillock?

The action hillock is the segment of the cell body adjacent to the axon where the. If there is sufficient depolarization to a neuron from inputs in the dendrites and cell body, particularly at the axon hillock, an action potential will be triggered.

Compare and contrast the role of the axon terminal (bouton) and a dendritic spine in synaptic transmission.

The axon terminal is also called the presynaptic terminal. This is the part of a neuron that contains vesicles (small membrane bound spheres) that contain neurotransmitter. When the action potential arrives at the end of the axon, the axon terminal, the depolarization triggers vesicles to fuse with plasma membrane releasing neurotransmitter. It is thus the presynaptic terminal that is sending information in synaptic transmission. In contrast, a dendritic spine is the location of the post synaptic density, a collection of neurotransmitter receptors and other associated proteins in the membrane closely apposed to the presynaptic terminal. When neurotransmitter is released from the axon terminal, the receptors in the postsynaptic density in the dendritic spine respond. It is thus the dendritic spine that receives information in synaptic transmission.

Briefly explain the role of potassium (K+) leak channels in setting the resting membrane potential.

The cytosol (intracellular environment) contains high concentrations of K+ and organic anions, such as proteins. Potassium leak channels allow K+ to leave the cell, following their concentration gradient. When this happens, organic anions stay in place; they are too big to leave the cell. Thus a net negative charge is left behind inside the cell. This is reflected in the resting membrane potential, which is approximately ‐60mV with respect to the outside.

Phineas Gage became a famous case study in neuroscience after his frontal lobes were damaged in an accident. What kind of symptom(s) might you expect from someone with frontal lobe damage? In other words, what function(s) would you expect to be disrupted?

The frontal lobes are involved in higher order cognitive functions like planning, judgment, suppressing impulsive behavior. After his accident, Phineas Gage became more impulsive (had less control over his behavior) and had a less even temperament, becoming "rude and aimless" (Behavioral Psychology p. 590). He had reduced ability to make plans, keep his emotions in check, and regulate his behavior in a socially acceptable way.

What kind of symptoms might you expect from a patient with occipital lobe damage? In other words, what function(s) would you expect to be disrupted?

The occipital lobe is the part of the brain the processes and interprets visual information. Thus, damage to the occipital lobes could result in vision loss or blindness even though the eyes themselves may work just fine. (Damage to specific occipital association areas involved in, say facial recognition, can result in agnosia‐ inability to recognize what is being seen. Damage to the fusiform face area results in prosopagnosia, inability to recognize faces. )

What is the mechanism that prevents the action potential from traveling backward towards the soma? In other words, explain how the action potential travels only in one direction.

The reason action potentials only travel one way is due to the mechanism of travel. When an action potential is "traveling" there is depolarization in it's path. When the Avon is propagating the AP along, the depolarization of the depolarizer portion begins quickly, but there's a refractory period, where the only candidates for open Na+ ion channels lie ahead, because the recently depolarizer portion is inactive. Although the refractory period is short, it is enough time that the AP is forced forward.

Explain why action potentials travel down the axon in only one direction.

When a segment of the axon is depolarized during the action potential, it is due to the opening of voltage gated sodium channels. These channels then quickly inactivate, and cannot be opened again for a period of time. Depolarization can spread down the axon in both directions, but in the direction from which the action potential originated, the local voltage gated sodium channels are inactive. In contrast, in the part of the axon distal to the origin of the AP, voltage gated sodium channels are openable. Thus, the action potential travels in the direction of openable voltage gated sodium channels, away from the site of action potential origin only.