Neurobiology Questions Final

Which ion (K+ or Na+) is the membrane more permeable to? And what does this mean for neuronal function?

• The membrane is more permeable to K+ (potassium) ions. This permeability is crucial for maintaining the resting membrane potential of neurons, which is typically negative due to the higher concentration of K+ inside the cell compared to Na+ outside.

What would the resting potential be if there were no proteins in the membrane that can pass ions across the membrane?

• Without proteins to pass ions, the resting potential would be zero because there would be no ion movement to create a charge difference across the membrane.

Why is the resting membrane potential negative when the inside of the cell/membrane is a highly concentrated K+ environment?

• The resting membrane potential is negative because K+ ions tend to move out of the cell through leak channels, leaving behind negatively charged proteins and other molecules, thus creating a negative charge inside the cell.

Why is myelination of neurons so important for muscle responses?

• Myelination increases the speed of action potential conduction along the axon, enabling rapid and efficient communication between neurons and muscles, which is essential for quick muscle responses.

Name the different phases of an action potential and describe the molecular functions behind these phases.

• Depolarization: Na+ channels open, allowing Na+ to enter the cell.

• Repolarization: Na+ channels close, and K+ channels open, allowing K+ to exit the cell.

• Hyperpolarization: K+ channels remain open longer than needed, causing the membrane potential to become more negative than the resting potential.

Name 3 different ways that you can use the patch clamp technique and describe the functional difference for each one of these as well as what sort of data collection you can do for each one of them.

• Whole-cell patch clamp: Measures the electrical activity of the entire cell. Useful for studying overall ion channel activity and membrane potential changes.

• Inside-out patch clamp: Measures the activity of ion channels from the inside of the membrane. Useful for studying intracellular factors affecting ion channels.

• Outside-out patch clamp: Measures the activity of ion channels from the outside of the membrane. Useful for studying extracellular factors affecting ion channels.

What are the big functional differences between Na+ and K+ voltage-gated channels?

• Na+ channels: Open rapidly in response to depolarization and close quickly, initiating the action potential.

• K+ channels: Open more slowly and stay open longer, helping to repolarize the membrane and restore the resting potential.

How does a voltage sensor work?

• A voltage sensor detects changes in membrane potential and triggers the opening or closing of ion channels. It typically involves movement of charged residues within the channel protein in response to voltage changes.

How does an ion selectivity filter work in ligand-gated ion channels?

• The ion selectivity filter allows specific ions to pass through the channel while blocking others. It is based on the size, charge, and hydration shell of the ions.

What is the difference between a symport and an antiport?

• Symport: Transports two or more ions or molecules in the same direction across the membrane.

• Antiport: Transports ions or molecules in opposite directions across the membrane.

Describe the cycle of Na/K ATPase.

• The Na/K ATPase pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell using ATP. This cycle maintains the electrochemical gradients essential for cell function.

Explain the difference between antagonist, agonist, inverse agonist, and biased agonist.

• Agonist: Activates the receptor to produce a biological response.

• Antagonist: Blocks the receptor and prevents a biological response.

• Inverse agonist: Binds to the receptor and induces the opposite effect of an agonist.

• Biased agonist: Activates specific signaling pathways preferentially over others.

For a neurotransmitter of your choice, briefly explain its (i) biosynthesis and (ii) sensing by receptors.

• Dopamine:

  • Biosynthesis: Synthesized from the amino acid tyrosine through the intermediate L-DOPA.

  • Sensing by receptors: Dopamine receptors (D1-D5) are G-protein coupled receptors that mediate various physiological effects.

Why do neurotransmitters have multiple receptors?

• Multiple receptors allow neurotransmitters to exert diverse effects in different tissues and under different conditions, providing fine-tuned regulation of physiological processes.

What is homology?

• Homology refers to the similarity between characteristics in different species due to shared ancestry.

How can we use homology for trying to identify new genes/proteins?

• Homology can be used to identify new genes/proteins by comparing sequences from different organisms to find conserved regions that indicate similar functions.

Name some neurotransmitters that exist in invertebrates but not in mammals.

• Examples include octopamine and tyramine.

Name a few functional differences between mammalian and invertebrate nervous systems.

• Mammalian nervous systems are more complex, with a larger number of neurons and more intricate synaptic connections. Invertebrates often have simpler nervous systems with fewer neurons and less complex synaptic arrangements.

Are there aspects of the difference between invertebrate and mammalian nervous systems that can be used for health benefits/financial interest?

• Yes, studying simpler invertebrate systems can provide insights into basic neural functions and potential drug targets, which can be beneficial for developing treatments for neurological disorders.

What are key principles of signaling pathways?

• Key principles include specificity, amplification, integration, and feedback regulation.

Why are these key principles useful in signal transduction?

• These principles ensure that signals are accurately transmitted, appropriately amplified, integrated with other signals, and regulated to maintain cellular homeostasis.

Provide an example of how cross-talk between signaling pathways could occur.

• Cross-talk can occur when a signaling molecule from one pathway activates or inhibits components of another pathway, such as MAPK and PI3K/Akt pathways interacting in cell growth and survival.

How could you transport a protein specifically to one subcellular compartment?

• Use signal peptides or targeting sequences that direct the protein to the desired compartment.

How could you transport a protein specifically to everything except one subcellular compartment (i.e., excluding it)?

• Use exclusion signals or mutate targeting sequences to prevent the protein from entering the undesired compartment.

What are the two main classes of learning that we often study?

• Associative learning (e.g., classical conditioning) and non-associative learning (e.g., habituation).

Is there a difference between short-term and long-term memory? If yes, what?

• Yes, short-term memory involves temporary storage of information, while long-term memory involves more permanent storage and structural changes in the brain.

What are the limitations to studying memory formation in higher order animals like rodents?

• Limitations include ethical concerns, complexity of behavior, and difficulty in controlling environmental variables.

Why do we need to think about different forms of validity when using/designing a behavioral test?

• Different forms of validity ensure that the test accurately measures what it is intended to measure and can be generalized to other contexts.

Name some forms of validity and what they represent.

• Construct validity: Measures the concept it is intended to measure.

• Internal validity: Ensures that the results are due to the manipulation of the independent variable.

• External validity: Ensures that the results can be generalized to other settings.

Give an example of a technique that uses a genetically encoded biosensor.

• Calcium imaging using genetically encoded calcium indicators like GCaMP.

Name a technique that can detect the release of a specific neurotransmitter.

• Microdialysis can be used to detect neurotransmitter release.

It can be very valuable to follow the activity in a single neuron over time. Can you describe one method in which you can do this and how this method works?

• Patch clamp recording allows for the measurement of ion channel activity in single neurons over time.

Can you think of a question that would be well suited to address using in vivo microdialysis?

• How does the release of dopamine in the striatum change in response to different behavioral stimuli?

Describe the function of a hair cell and how a receptor potential is generated in that kind of receptor cells.

• Hair cells in the inner ear convert mechanical vibrations into electrical signals. The receptor potential is generated when the hair cell's stereocilia are deflected, causing ion channels to open and depolarize the cell.

What are the divisions of the vestibular apparatus? What types of stimuli do they register?

• The vestibular apparatus includes the semicircular canals (register rotational movements) and the otolith organs (register linear accelerations and head position).

How do the otolith organs work? What is the difference between the utricle and the saccule? What mechanisms contribute to three-dimensional information from the otolith organs?

• The otolith organs contain hair cells embedded in a gelatinous layer with calcium carbonate crystals (otoliths). The utricle detects horizontal movements, while the saccule detects vertical movements. The combined input from both organs provides three-dimensional information.

How do the semicircular canals work? Why are those sense organs insensitive to gravity (in contrast to the otolith organs)? What is the difference between the three semicircular canals? What is the difference between the semicircular canals in the left versus the right inner ear?

• The semicircular canals detect rotational movements through the movement of endolymph fluid. They are insensitive to gravity because they detect angular acceleration. The three canals are oriented at right angles to each other, providing information about rotation in three planes. The canals in the left and right ears are mirror images, allowing for detection of head rotation in all directions.

In what situations can the vestibular apparatus contribute to the control of balance? What is the function of the vestibulospinal tract in that respect?

• The vestibular apparatus contributes to balance during movement and changes in head position. The vestibulospinal tract helps maintain posture and balance by sending signals from the vestibular nuclei to the spinal cord.

What is the function of the vestibuloocular reflex? At which level of the CNS is the reflex pathway located?

• The vestibuloocular reflex stabilizes gaze during head movements by coordinating eye movements with head movements. The reflex pathway is located in the brainstem.

Describe the organ of Corti.

• The organ of Corti is located in the cochlea and contains hair cells that convert sound vibrations into electrical signals.

How can sound stimulate hair cells in the organ of Corti? What is a traveling wave?

• Sound waves cause the basilar membrane to vibrate, creating a traveling wave that stimulates hair cells at specific locations based on the frequency of the sound.

How are different frequencies of sound identified in the basilar membrane and coded in the cochlear nerve?

• Different frequencies cause vibrations at specific locations along the basilar membrane, with high frequencies near the base and low frequencies near the apex. These vibrations are coded by the cochlear nerve as electrical signals.

What is the function of outer hair cells and how do they work?

• Outer hair cells amplify sound vibrations and enhance the sensitivity of inner hair cells by changing their length in response to sound.

The primary auditory cortex is organized tonotopically. What do we mean by that?

• Tonotopic organization means that different frequencies of sound are represented in specific areas of the auditory cortex.

What strategies does the auditory system use to determine the direction of sound?

• The auditory system uses interaural time differences and interaural level differences to determine the direction of sound.

What do we mean by the terms "where stream" ("spatial stream") and "what stream" ("object stream") with respect to the auditory system?

• The "where stream" processes spatial information about sound location, while the "what stream" processes information about sound identity.

What are the mechanisms underlying the receptor potential in photoreceptors?

• Photoreceptors generate receptor potentials through the absorption of light by photopigments, leading to changes in ion channel activity.

Photoreceptors hyperpolarize in light. How then can light activate the retinal ganglion cells?

• Light causes photoreceptors to hyperpolarize, reducing their release of neurotransmitters. This reduction in neurotransmitter release activates bipolar cells, which in turn activate retinal ganglion cells.

What are the functional differences between rods and cones?

• Rods are sensitive to low light levels and are responsible for night vision, while cones are sensitive to bright light and are responsible for color vision.

What part of the visual field is projected to the visual cortex in the left hemisphere?

• The right visual field is projected to the visual cortex in the left hemisphere.

What is the difference in the visual information forwarded by the optic nerves versus the optic tracts? In other words, what happens in the optic chiasm?

• The optic nerves carry information from each eye to the optic chiasm, where fibers from the nasal half of each retina cross to the opposite side. The optic tracts carry information from both eyes to the visual cortex.

What is the explanation for how the receptive field of simple cells is constructed?

• The receptive field of simple cells is constructed by the convergence of inputs from multiple retinal ganglion cells, creating

What is the explanation for how the receptive field of simple cells is constructed?

• The receptive field of simple cells is constructed by the convergence of inputs from multiple retinal ganglion cells, creating elongated regions that respond to specific orientations of light.

Describe the functional architecture of the primary visual cortex in terms of hypercolumns, orientation columns, and ocular dominance columns.

• Hypercolumns: Functional units that contain all the necessary information to process visual stimuli from a specific region of the visual field.

• Orientation columns: Groups of neurons that respond to specific orientations of visual stimuli.

• Ocular dominance columns: Groups of neurons that respond preferentially to input from one eye.

How do motion-sensitive cells in area V5 differ from motion-sensitive cells in the primary visual cortex?

• Motion-sensitive cells in area V5 (MT) are specialized for detecting motion and direction, while motion-sensitive cells in the primary visual cortex (V1) are involved in initial processing of motion information.

How do cells in area V4, sensitive to color, differ from color-sensitive cells in the primary visual cortex?

• Cells in area V4 are involved in higher-order processing of color information, integrating color with form and texture, while color-sensitive cells in the primary visual cortex (V1) are involved in initial color detection.

Provide some examples of hierarchical and parallel processing in the visual system.

• Hierarchical processing: Information is processed in a stepwise manner from lower to higher levels (e.g., from V1 to V2 to V4).

• Parallel processing: Different types of information (e.g., color, motion, form) are processed simultaneously in separate pathways.

What do we mean with the terms "where stream" and "what stream" in relation to the visual system? In what regions of the brain are those processing streams located?

• The "where stream" (dorsal pathway) processes spatial information and is located in the parietal lobe. The "what stream" (ventral pathway) processes object identification and is located in the temporal lobe.

What are the criteria for a reflex? How does a reflex differ from a voluntary movement? Give a classical and a modern view of these differences.

• Criteria for a reflex: Involuntary, rapid, and predictable response to a stimulus.

• Classical view: Reflexes are simple, automatic responses.

• Modern view: Reflexes can be modulated by higher brain centers and are integrated with voluntary movements.

Explain degree of freedom and the problem of redundancy in movement control.

• Degree of freedom: The number of independent variables that define the movement.

• Problem of redundancy: The challenge of selecting one movement pattern from many possible patterns to achieve a goal.

Why was it concluded that the movement of the arm towards the target is controlled by a motor program?

• It was concluded based on evidence that movements are pre-planned and executed as a sequence of muscle activations, rather than being continuously adjusted.

What is meant by motor program in motor control?

• A motor program is a pre-structured set of neural commands that define a movement pattern.

Explain the salted peanut problem.

• The salted peanut problem refers to the challenge of controlling repetitive movements, such as eating peanuts, where each movement must be precisely coordinated.

Describe Libet's experiment. What is the main conclusion of this study?

• Libet's experiment involved measuring the timing of conscious intention to act and the corresponding brain activity. The main conclusion was that brain activity precedes conscious intention, suggesting that unconscious processes initiate voluntary actions.

Define muscle synergy, give examples.

• Muscle synergy refers to the coordinated activation of groups of muscles to produce a movement. Examples include the muscles involved in walking or reaching.

Define reciprocal innervation.

• Reciprocal innervation is the process by which the activation of one muscle is accompanied by the inhibition of its antagonist muscle.

Where is the neural network for locomotion located? What is it called?

• The neural network for locomotion is located in the spinal cord and is called the central pattern generator.

Why are there several descending tracts in the brain?

• There are several descending tracts to allow for the control of different types of movements and to provide redundancy in case of injury.

How does the brain control posture and balance?

• The brain controls posture and balance through the integration of sensory information from the vestibular system, proprioceptors, and visual inputs, and by sending motor commands to the muscles.

What are the functions of rubrospinal and tectospinal tracts?

• Rubrospinal tract: Involved in the control of limb movements.

• Tectospinal tract: Involved in the control of head and eye movements in response to visual stimuli.

Does the primary motor cortex contain a map of the muscles or a map of movements? Give the arguments supporting your position.

• The primary motor cortex contains a map of movements rather than muscles. This is supported by evidence that specific regions of the motor cortex are associated with coordinated movements rather than individual muscle activations.

What is the function of the corticospinal tract?

• The corticospinal tract is involved in the control of voluntary movements, particularly fine motor skills.

How do the basal ganglia and cerebellum contribute to motor control? Do they have connections with the spinal cord?

• The basal ganglia and cerebellum contribute to motor control by modulating movement patterns and ensuring smooth execution. They do not have direct connections with the spinal cord but influence motor output through connections with the motor cortex.

What means "action zones" in the motor cortex of the monkey?

• "Action zones" refer to regions of the motor cortex that are associated with specific types of movements or actions.

What means the statement that "the brain has models of familiar objects"?

• The statement means that the brain stores representations of familiar objects, allowing for recognition and interaction with those objects based on past experiences.

Does the brain need to plan movements?

• Yes, the brain needs to plan movements to ensure coordination, accuracy, and efficiency.

Explain the impact of glycosylation on the functioning of neuronal proteins.

• Glycosylation affects the stability, localization, and activity of neuronal proteins, influencing processes such as cell signaling and synaptic function.

What are some of the roles of sialic acid in the brain?

• Sialic acid plays roles in cell-cell communication, synaptic plasticity, and neuroprotection.

What are the differences between split-brain surgery and callosotomy?

• Split-brain surgery involves severing the corpus callosum to treat epilepsy, while callosotomy is a specific type of split-brain surgery that targets the corpus callosum.

Explain how a tachistoscope can be used to study split-brain subjects.

• A tachistoscope presents visual stimuli to one hemisphere at a time, allowing researchers to study the independent functioning of each hemisphere in split-brain subjects.

Is lateralization of brain function unique to humans? Give examples.

• No, lateralization is not unique to humans. Examples include lateralized functions in birds and primates.

What is the advantage of lateralization?

• Lateralization allows for specialization of functions in each hemisphere, increasing efficiency and cognitive capacity.

Describe the specialization of the left and right hemispheres.

• The left hemisphere is typically specialized for language and analytical tasks, while the right hemisphere is specialized for spatial and creative tasks.

Explain the statement that functional asymmetry is to a large extent the result of structural asymmetry.

• Functional asymmetry arises from differences in the structure of the two hemispheres, such as variations in cortical thickness and connectivity.

Describe macro and microanatomical right-left differences between the two hemispheres.

• Macroanatomical differences include variations in the size and shape of brain regions, while microanatomical differences include variations in cell types and connectivity.

Why does the corpus callosum offer a good model for understanding communications between different cortical areas of the brain?

• The corpus callosum connects the two hemispheres, facilitating communication and integration of information between cortical areas.

Explain homotopic and heterotopic callosal connections.

• Homotopic connections link corresponding areas in the two hemispheres, while heterotopic connections link different areas.

What are genetic and epigenetic mechanisms of structural and functional asymmetry?

• Genetic mechanisms involve inherited differences in brain structure, while epigenetic mechanisms involve changes in gene expression influenced by environmental factors.

Give examples of interhemispheric transfer of neural plasticity.

• Examples include the transfer of learning and memory between hemispheres and the recovery of function after brain injury.

What is the function of the corpus callosum? Does the corpus callosum play an inhibitory or an excitatory function?

• The corpus callosum facilitates communication between the hemispheres and can play both inhibitory and excitatory roles depending on the context,

Explain the hard problem of consciousness.

• The hard problem of consciousness refers to the challenge of explaining how subjective experiences (qualia) arise from physical processes in the brain.

What are neural correlates of consciousness?

• Neural correlates of consciousness are the specific brain processes and structures that correlate with conscious experiences.

Explain the problem of mental causation.

• The problem of mental causation involves understanding how mental states (thoughts, beliefs) can cause physical actions in the body.

How does modern neuroscience answer the question "DOES CONSCIOUSNESS CAUSE BEHAVIOR?"

• Modern neuroscience suggests that consciousness is a result of complex neural processes and that behavior can be influenced by both conscious and unconscious processes.

How do different theories explain the function of consciousness?

• Global Workspace Theory: Consciousness arises from the integration of information across different brain regions.

• Integrated Information Theory: Consciousness is a measure of the brain's ability to integrate information.

• Higher-Order Thought Theory: Consciousness involves higher-order thoughts about one's own mental states.

Explain the mismatch negativity and the error-related negativity.

• Mismatch negativity (MMN): An ERP component elicited by unexpected changes in a sequence of auditory stimuli, reflecting automatic detection of deviations.

• Error-related negativity (ERN): An ERP component associated with the detection of errors in performance, reflecting the brain's monitoring of actions.

What is The Brain's Default Mode Network?

• The Default Mode Network (DMN) is a network of brain regions that are active during rest and involved in self-referential and introspective activities.

Explain the stream of consciousness.

• The stream of consciousness refers to the continuous flow of thoughts, feelings, and perceptions in the mind.

Explain the statement that the brain is a dynamic self-organizing and creative system.

• This statement highlights the brain's ability to adapt, reorganize, and generate new patterns of activity in response to experiences and environmental changes.

Explain the quote "I AM WHO I AM BECAUSE MY BRAIN IS WHAT IT IS".

• This quote emphasizes the idea that an individual's identity, thoughts, and behaviors are shaped by the unique structure and function of their brain.

How could you transport a protein specifically to one subcellular compartment? - Use signal peptides or targeting sequences that direct the protein to the desired compartment.

How could you transport a protein specifically to everything except one subcellular compartment (i.e., excluding it)? - Use exclusion signals or mutate targeting sequences to prevent the protein from entering the undesired compartment.

What are the differences between split-brain surgery and callosotomy? - Split-brain surgery involves severing the corpus callosum to treat epilepsy, while callosotomy is a specific type of split-brain surgery that targets the corpus callosum.

Explain how a tachistoscope can be used to study split-brain subjects. - A tachistoscope presents visual stimuli to one hemisphere at a time, allowing researchers to study the independent functioning of each hemisphere in split-brain subjects.

Is lateralization of brain function unique to humans? Give examples. - No, lateralization is not unique to humans. Examples include lateralized functions in birds and primates.

What is the advantage of lateralization? - Lateralization allows for specialization of functions in each hemisphere, increasing efficiency and cognitive capacity.

Describe the specialization of the left and right hemispheres. - The left hemisphere is typically specialized for language and analytical tasks, while the right hemisphere is specialized for spatial and creative tasks.

Explain the statement that functional asymmetry is to a large extent the result of structural asymmetry. - Functional asymmetry arises from differences in the structure of the two hemispheres, such as variations in cortical thickness and connectivity.

Describe macro and microanatomical right-left differences between the two hemispheres. - Macroanatomical differences include variations in the size and shape of brain regions, while microanatomical differences include variations in cell types and connectivity.

Why does the corpus callosum offer a good model for understanding communications between different cortical areas of the brain? - The corpus callosum connects the two hemispheres, facilitating communication and integration of information between cortical areas.

Explain homotopic and heterotopic callosal connections. - Homotopic connections link corresponding areas in the two hemispheres, while heterotopic connections link different areas.

What are genetic and epigenetic mechanisms of structural and functional asymmetry? - Genetic mechanisms involve inherited differences in brain structure, while epigenetic mechanisms involve changes in gene expression influenced by environmental factors.

Give examples of interhemispheric transfer of neural plasticity. - Examples include the transfer of learning and memory between hemispheres and the recovery of function after brain injury.

What is the function of the corpus callosum? Does the corpus callosum play an inhibitory or an excitatory function? - The corpus callosum facilitates communication between the hemispheres and can play both inhibitory and excitatory roles depending on the context.

Explain the hard problem of consciousness. - The hard problem of consciousness refers to the challenge of explaining how subjective experiences (qualia) arise from physical processes in the brain.

What are neural correlates of consciousness? - Neural correlates of consciousness are the specific brain processes and structures that correlate with conscious experiences.

Explain the problem of mental causation. - The problem of mental causation involves understanding how mental states (thoughts, beliefs) can cause physical actions in the body.

How does modern neuroscience answer the question "DOES CONSCIOUSNESS CAUSE BEHAVIOR?" - Modern neuroscience suggests that consciousness is a result of complex neural processes and that behavior can be influenced by both conscious and unconscious processes.

How do different theories explain the function of consciousness? - Global Workspace Theory: Consciousness arises from the integration of information across different brain regions. - Integrated Information Theory: Consciousness is a measure of the brain's ability to integrate information. - Higher-Order Thought Theory: Consciousness involves higher-order thoughts about one's own mental states.

Explain the mismatch negativity and the error-related negativity. - Mismatch negativity (MMN): An ERP component elicited by unexpected changes in a sequence of auditory stimuli, reflecting automatic detection of deviations. - Error-related negativity (ERN): An ERP component associated with the detection of errors in performance, reflecting the brain's monitoring of actions.

What is The Brain's Default Mode Network? - The Default Mode Network (DMN) is a network of brain regions that are active during rest and involved in self-referential and introspective activities.

Explain the stream of consciousness. - The stream of consciousness refers to the continuous flow of thoughts, feelings, and perceptions in the mind.

Explain the statement that the brain is a dynamic self-organizing and creative system. - This statement highlights the brain's ability to adapt, reorganize, and generate new patterns of activity in response to experiences and environmental changes.

Explain the quote "I AM WHO I AM BECAUSE MY BRAIN IS WHAT IT IS". - This quote emphasizes the idea that an individual's identity, thoughts, and behaviors are shaped by the unique structure and function of their brain.

How could you transport a protein specifically to one subcellular compartment? - Use signal peptides or targeting sequences that direct the protein to the desired compartment.

How could you transport a protein specifically to everything except one subcellular compartment (i.e., excluding it)? - Use exclusion signals or mutate targeting sequences to prevent the protein from entering the undesired compartment.