Neurobiology Questions Final

Which ion is the membrane more permeable to, K+ or Na+?

The membrane is more permeable to K+ (potassium) ions.

What does the K+ permeability mean for neuronal function?

It is crucial for maintaining the resting membrane potential of neurons.

What would the resting potential be without proteins passing ions across the membrane?

The resting potential would be zero.

Why is the resting membrane potential negative in a concentrated K+ environment?

K+ ions move out of the cell, leaving behind negatively charged proteins.

Why is myelination important for muscle responses?

It increases the speed of action potential conduction along the axon.

What are the phases of an action potential?

Depolarization, repolarization, and hyperpolarization.

What happens during depolarization of an action potential?

Na+ channels open, allowing Na+ to enter the cell.

What happens during repolarization of an action potential?

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

What occurs during hyperpolarization of an action potential?

K+ channels remain open longer, making the membrane potential more negative.

Name one application of the whole-cell patch clamp technique.

Measures electrical activity of the entire cell.

What is the focus of the inside-out patch clamp technique?

Measures activity of ion channels from the inside of the membrane.

What does the outside-out patch clamp technique measure?

Measures activity of ion channels from the outside of the membrane.

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

Na+ channels open quickly and close quickly, while K+ channels open slowly and stay open longer.

What is the function of a voltage sensor?

Detects changes in membrane potential and triggers opening or closing of ion channels.

How does an ion selectivity filter function?

Allows specific ions to pass through while blocking others, based on size and charge.

Differentiate between symport and antiport.

Symport transports ions in the same direction, while antiport transports ions in opposite directions.

Describe the Na/K ATPase cycle.

Pumps 3 Na+ ions out and 2 K+ ions in, using ATP to maintain gradients.

What does an agonist do?

Activates the receptor to produce a biological response.

What is the role of an antagonist?

Blocks the receptor and prevents a biological response.

What does an inverse agonist do?

Induces the opposite effect of an agonist by binding to the receptor.

Define a biased agonist.

Activates specific signaling pathways preferentially over others.

Describe dopamine biosynthesis.

Synthesized from the amino acid tyrosine through L-DOPA.

How do dopamine receptors function?

They are G-protein coupled receptors mediating various physiological effects.

Why do neurotransmitters have multiple receptors?

Allow diverse effects in different tissues under various conditions.

What is homology in biology?

Similarity between characteristics in different species due to shared ancestry.

How can homology identify new genes/proteins?

By comparing sequences among organisms to find conserved regions indicating similar functions.

Name neurotransmitters present in invertebrates but not mammals.

Octopamine and tyramine.

What are functional differences between mammalian and invertebrate nervous systems?

Mammalian systems have more neurons and complex synaptic connections than invertebrates.

Can differences in nervous systems benefit health or financial interests?

Yes, insights from invertebrate systems can help develop neurological disorder treatments.

What are key principles of signaling pathways?

Specificity, amplification, integration, feedback regulation.

Why are signaling principles useful in transduction?

They ensure accurate signal transmission, amplification, integration, and regulation.

Give an example of signaling pathway cross-talk.

MAPK and PI3K/Akt pathways interacting during cell growth and survival.

How can a protein be transported to a specific subcellular compartment?

Using signal peptides or targeting sequences.

How can a protein be directed to everything except one specific compartment?

Using exclusion signals or mutated targeting sequences.

What are the main classes of learning studied?

Associative learning and non-associative learning.

Differentiate between short-term and long-term memory.

Short-term memory is temporary storage; long-term is more permanent with structural changes.

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

Ethical concerns, complexity of behavior, difficulty controlling variables.

Why consider validity in behavioral tests?

To ensure the test accurately measures the intended construct and generalizes to other contexts.

Different forms of validity and their representations include:

Construct, internal, and external validity.

Give an example of genetically encoded biosensor technique.

Calcium imaging with GCaMP.

What is a technique to detect specific neurotransmitter release?

Microdialysis.

How can activity in a single neuron be monitored?

Using patch clamp recording.

What is a good question for in vivo microdialysis study?

How does dopamine release in the striatum change with behavioral stimuli?

What is the function of a hair cell?

Converts mechanical vibrations into electrical signals.

How does the receptor potential form in hair cells?

Deflection of stereocilia opens ion channels, depolarizing the cell.

What divisions make up the vestibular apparatus?

Semicircular canals and otolith organs.

What stimuli do otolith organs detect?

Otoliths register linear accelerations and head position.

How do the utricle and saccule differ?

Utricle detects horizontal movements, saccule detects vertical movements.

What provides three-dimensional information from otolith organs?

Combined input from both utricle and saccule.

How do semicircular canals work?

Detect rotational movements through endolymph fluid movement.

Why are semicircular canals insensitive to gravity?

They detect angular acceleration rather than static gravitational effects.

What is the difference between the three semicircular canals?

They provide information about rotation in three planes.

What similarities exist between semicircular canals in left versus right ears?

They are mirror images allowing for full directional detection.

When does the vestibular apparatus aid in balance?

During movement and head position changes.

Function of the vestibulospinal tract in balance?

Maintains posture and balance by sending signals to the spinal cord.

What is the vestibuloocular reflex?

It stabilizes gaze during head movements by coordinating eye movements.

Where is the reflex pathway for vestibuloocular reflex located?

In the brainstem.

Describe the organ of Corti.

Contains hair cells in the cochlea that convert sound vibrations into signals.

How does sound stimulate hair cells in the organ of Corti?

Sound waves vibrate the basilar membrane, stimulating hair cells based on sound frequency.

How are different sound frequencies identified in the cochlea?

By the specific locations along the basilar membrane that vibrate in response to frequency.

What is the function of outer hair cells?

Amplify sound vibrations and enhance inner hair cell sensitivity.

What does tonotopic organization in the primary auditory cortex mean?

Different sound frequencies are represented in specific areas.

What strategies does the auditory system use for sound direction determination?

Uses interaural time and level differences.

What is the difference between the 'where stream' and 'what stream' in hearing?

'Where stream' processes sound location; 'what stream' processes sound identity.

What are the mechanisms for photoreceptor receptor potential generation?

Absorption of light changes ion channel activity.

How does light activate retinal ganglion cells despite photoreceptor hyperpolarization?

Hyperpolarization reduces neurotransmitter release, activating bipolar cells, then ganglion cells.

What are the functional differences between rods and cones?

Rods enable night vision; cones enable color vision in bright light.

What visual field is projected to the left visual cortex?

The right visual field.

What happens at the optic chiasm?

Fibers from the nasal retina cross to the opposite side.

What is the function of simple cell receptive fields?

Constructed by converging inputs from multiple retinal ganglion cells.

What is the primary visual cortex’s organization?

Includes hypercolumns, orientation columns, and ocular dominance columns.

What is the difference between motion-sensitive cells in V5 and the primary visual cortex?

V5 cells are specialized for motion detection, while V1 cells process initial motion information.

How are color-sensitive cells in area V4 different from those in the primary visual cortex?

Area V4 integrates color with form and texture, while V1 detects initial color.

Examples of hierarchical processing in the visual system include:

Information processed from V1 to V2 to V4.

What does 'where stream' and 'what stream' refer to in vision?

'Where stream' processes spatial info; 'what stream' filters object identity.

What criteria define a reflex?

Involuntary, rapid, and predictable response to a stimulus.

How do reflexes compare to voluntary movements in classical and modern views?

Classical: simple, automatic responses; Modern: reflexes can be modulated by higher brain centers.

What is degree of freedom in movement control?

Number of independent variables defining a movement.

Explain the problem of redundancy in movement control.

Selecting one movement from many patterns to achieve a goal.

Why arm movements are controlled by a motor program?

Evidence shows movements are pre-planned, executed as muscle activation sequences.

What is meant by a motor program in motor control?

A pre-structured set of neural commands defining a movement pattern.

Explain the salted peanut problem.

Challenge of controlling repetitive, coordinated movements.

Describe Libet's experiment and its conclusion.

Timing of conscious intention to act and brain activity shows that brain activity precedes intention.

What is muscle synergy? Give examples.

Coordinated activation of muscle groups; examples include walking or reaching.

What is reciprocal innervation?

Activation of one muscle while its antagonist is inhibited.

Where is the neural network for locomotion located? What is its name?

Located in the spinal cord and called the central pattern generator.

Why are there multiple descending tracts in the brain?

To control various types of movements and provide redundancy.

How does the brain manage posture and balance?

Integrates sensory information and sends motor commands to muscles.

What are functions of the rubrospinal and tectospinal tracts?

Rubrospinal controls limb movements; tectospinal controls head/eye movements to visual stimuli.

Does the primary motor cortex map muscles or movements?

Maps movements rather than muscles, with regions associated with coordinated movements.

What is the function of the corticospinal tract?

Controls voluntary movements, particularly fine motor skills.

How do basal ganglia and cerebellum assist in motor control?

Modulate movement patterns for smooth execution but don't connect directly with spinal cord.

What are 'action zones' in the monkey motor cortex?

Regions associated with specific types of movements.

What does it mean that the brain has models of familiar objects?

Stores representations allowing for recognition and interaction based on past experiences.

Does the brain need to plan movements?

Yes, planning is essential for coordination, accuracy, and efficiency.

Impact of glycosylation on neuronal proteins?

Affects stability, localization, and activity, influencing signaling and synaptic function.

Roles of sialic acid in the brain include?

Cell communication, synaptic plasticity, and neuroprotection.

Difference between split-brain surgery and callosotomy?

Split-brain severing corpus callosum for epilepsy; callosotomy is a targeted split type.

How can tachistoscopes study split-brain subjects?

Present stimuli to one hemisphere at a time for independent functioning study.

Is lateralization of brain function unique to humans? Examples?

No, seen in birds and primates too.