Neuroscience Exam 1 Study Guide

What did the monkey experiments of Duke neuroscientist, Miguel Nicolelis teach us generally about nervous system function?

The study showed that it was possible to record impulses from the brain and relate them/translate them to move a robotics arm (without moving one’s actual body)

Describe the “behavioral despair test”. What is it supposed to assess?

This test consists of a rat being placed in a beaker of water. The rat tries to swim and climb out of the beaker. The rat eventually stops swimming. The the test is supposed to assess “depression-like” behavior in animals.

Why is the name of the “behavioral despair test problematic”?

It is problematic because we cannot know if the rat is actually feeling despair. That is an assumption. Rather the test could be called “forced swim test”.

What does a injection of fluoxetine do behaviorally in the forced swim test?

Fluoxetine increases the amount of swimming counts and decreases the number of immobile total counts

What constitutes the central nervous system?

The CNS consists of the brain and the spinal cord

What constitutes the peripheral nervous system?

All the nervous tissue outside of the CNS: cranial nerves, spinal nerves, etc.

What are the four lobes of the human brain and why is it important to know these sections?

Frontal, Parietal, Temporal, and Occipital lobes. These are important because each lobe is generally responsible for different functions.

General role of the thalamus?

Sends information to cerebral cortex - acts as a relay center between higher and lower areas

General role of the mammillary bodies?

Memory formation

General role of ventricles?

They are holes which produce and circulate the cerebral spinal fluid.

What is the Choroid Plexus?

This lines the ventricles and is the location of neurogenesis

General role of CSF?

Protects the central nervous system by acting as an absorbent cushion

Why does a brown bat have a larger inferior colliculi to brain ratio than a human?

The larger inferior colliculi is generally used for auditory sensation. Bats rely on echolocation for food and navigation, so this brain region is highly important for their survival.

Define function. What is the difference between immediate and ultimate function?

Function is ‘what something is for’. Immediate function is what is being done in the moment, whereas ultimate function is more why something functions (associated to evolutionary function).

How is function different from mechanism?

Mechanism is “what something does”. Function is “what something is for”.

What is neuron doctrine? Who won the Nobel Prize for this?

The neuron doctrine is “the neuron is the functional unit of the brain”. Camillo Golgi and Santiago Cajal won the Nobel Prize for this in 1906.

What is localization of function? Why is the brain like a clock?

Localization of function is the general concept of different parts of the brain having different functions. The brain is like a clock because just like a clock, all parts are required for a clock to fully function.

Define ganglion

A collection of neurons in the PNS

Define nucleus

Membrane bound organelle that contains a cell’s DNA

Define nerve

A bundle of axons in the PNS

Define tract

A bundle of axons in the CNS

Define efferent

Motor output coming from CNS

Define afferent

Sensory input coming to CNS

Define grey matter

Made up of dendrites and cell bodies

Define white matter

Myelinated axons

Where is the dorsal root ganglion?

The dorsal root ganglion is near the spinal cord, and brings sensory input to the CNS.

What neuronal somas would you find in the dorsal root ganglion

Pseudounipolar or unipolar afferent sensory neurons are bringing sensory info into the CNS.

Do you think neurons in the mammillary bodies connect with neurons in the hippocampus?

Yes because there is a structure of nerves called the fornix that connects them.

Name and describe the 3 types of cerebral cortex

Sensory (receiving/processing input), motor (output/control), and association cortices (integration).

Name the planes of function

Coronal/frontal, Sagittal, Transverse/horizontal

Sagittal plane

Right and Left

Coronal plane

Saint halo

Horizontal plane

Top and bottom

Dorsal

Towards back or top of brain

Ventral

Towards belly or bottom of brain

Cerebral Hemisphere

One of either right or left forebrain

Distal

Towards the end of a limb

Proximal

Near the trunk or center of an organism

Posterior

Toward tail end

Anterior

Toward the head end

Basal

Toward the bottom of a structure

Inferior

Below

Superior

Above

Contralateral

Pertaining to a location on opposite side of the body

Ipsilateral

Pertaining to location on same side of the body

Lateral

Towards a side

Medial

Toward the middle

What is the most basic function of a neuron?

Communicate using electrochemical or chemical signals

What is the most basic function of a oligodendrocyte?

To produce myelin in the CNS

What is the most basic function of a Schwann cell?

To form myelin in the PNS (and secrete neurotrophic factors)

Name 5 ways one could categorize a neuron?

1. Anatomical (unipolar, multipolar, bipolar, pseudounipolar, anaxonic)

2. Function (output, input, interneuron)

3. Neurotransmitter produced (GABA, Dopamine)

4. Receptor

5. Type of output (Excitatory, Inhibitory, and Modulatory)

What was the signaling molecule in the Firefly Activity? How was it different in form and mechanism from other neurotransmitters?

Nitric Oxide; Small (form) and diffusible through a cell membrane to act on the mitochondria (mechanism)

What is selective permeability and how does it relate to neurotransmission?

Selective permeability is the ability of a membrane to let some molecules in while keeping others out. This control is based on molecule size and charge, and is how the cell maintains a consistent internal environment.

What is concentration gradient?

Differing concentrations of a molecule between separate areas

Does the presence of one molecule alter the movement of another molecule down its concentration gradient?

No, NON-charged molecules diffuse down their gradients independently.

Definite neuroplasticity

Neuroplasticity is the way neurons change

What are the 4 Rs of Neuroplasticity

1. Reweighting (strengthening/weakening of a synapse connection)

2. Reconnecting (new/breaking/reconnecting of previous synapses)

3. Rewiring (Retraction/elongation of synapse)

4. Regeneration (Birth or death of neuron)

Apoptosis

Programmed cell death

Define quantify. Why would we use quantitative vs qualitative measures to describe behavior?

Quantify means measuring something so it has a standardized numerical value. Quantitative measures make it easier to determine cause-and-effect relationships. We also tend to assume aspects of qualitative measures

What is dualism and how is it accepted in neurobiology?

Dualism is the idea that consciousness isn’t just physical, and doesn’t simply come from the brain. It is no longer well accepted in the field.

Apply our input - integration - output - feedback model to a nervous system diagram.

Baby stretches cervix; stretch receptors are stimulated; hypothalamus stimulates the posterior pituitary to release oxytocin; uterus muscles contract; cervix is stretched even more (continues until birth)

Apply a feedback loop to the advancements in prosthetic arms?

If we’re able to implant electrodes into the nerves in arms than the brain can still send signals into the arm.

Define Neural network

Connected nuclei which coordinate function towards a common goal

Gyri

Bumps

Sulci

Grooves

What is the function of the motor basal nuclei neural network?

Motor learning and coordination of voluntary muscle movement

Apply the feedback loop to the motor basal nuclei neural network

Thalamus (Input) - Cortex (integration) - motor muscles (output)

How does alcohol induce Korsakoff’s syndrome?

Alcohol prevents the body from effectively absorbing enough thiamine, and it causes the body to lose more thiamine in urine.

What changes would one see in a CT scan of someone with Korsakoff’s syndrome?

Larger ventricles with smaller mamillary bodies

Where does integration/control happen on a neuron?

The dendrites and soma (ligand-gated channels)

Where does input happen on a neuron?

Dendrites

Where does output happen on a neruon?

Axon terminals

Where are the majority of voltage gated channels on a neuron?

On the axon hillock and the unmyelinated nodes of Ranvier

How do chemical and electrical synapses differ?

A chemical synapse uses chemicals (neurotransmitters) to bind to receptors, whereas electrical synapses send electric signals through special gap junction channels. Electrical synapses are generally faster.

What does potential mean in neuroscience? What are its units?

Potential means the difference in voltage between the inside and outside of a cell. Changes in the membrane potential can cause action potential impulses.

How are ionotropic and metabotropic receptors different?

Ionotropic receptors are linked to channels which open/close. Metabotropic receptors initiate intracellular signaling cascades (slower).

Give an example of a Metabotropic receptor

Dopamine (1a Receptor-induced Adenylyl Cyclase Cascade) can bind a G-protein coupled receptor. This leads to an effector protein sending a second messenger (cAMP), which binds to kinase and leads to active catalytic subunits that act on CREB (in transcription)

Give an example of an ionotropic receptor?

GABA A receptor - inhibits neuron by allowing Cl- to flow in hyperpolarizing

What is membrane potential?

Membrane potential is the separation of charge across a cell membrane and is established by selective permeability and active transport

What is equilibrium potential?

Equilibrium potential is when both sides of the membrane and electrically balanced and there is no net movement of ions

How is membrane potential measured?

By using a microelectrode (mV)

What is resting potential?

Resting potential is the specific potential of a cell when it is not activated or excited

What is electrochemical driving force?

ECDF is comprised of a chemical driving force and an electrical driving force. The net ECDF depends on the magnitude and direction of these forces.

How does one determine the electrochemical driving force?

1. Determine the equilibrium potential (E_x = (RT/zF) ln(X_e/X_i)

2. If the V_m doesn’t equal the E_x then a ECDF will exist that is equal to the magnitude different between V_m - E_x

What variables change in the Nernst equation? Assume a constant temperature

z changes based on the ion, and X_e and X_i change

How do conductivity and permeability relate?

Conductivity is how well something can conduct energy or move through the material, and permeability is how the membrane allows fluids to move through it. Conductivity depends on the fluid and permeability relates to the membrane

What major assumption does the Nernst equation make?

100% permeability

What does the Nernst equation tell us?

The Nernst equation tells us the membrane potential that exactly balances the CDF, thus establishing electrochemical equilibrium

What is represented in the GHK equation which is not represented in the Nernst equation?

Permeability of ions

What determines whether a recieving cell is excited or inhibited?

Both the type of neurotransmitter and the type of receptor. Certain ionotropic receptors can allow Cl- and other negative ions into the membrane and hyperpolarize the cell (less likely to fire action potentials)

EPSPs are

Depolarizing

IPSPs are

repolarizing

Ionotropic ligand gated receptors are responsible for

graded potentials

Voltage gated channels are responsible for

Action potentials (all or nothing)

Where and how are inputs summed?

Summation occurs at the axon hillock, and occurs both in space and time

Difference between conductivity and electrochemical driving force?

Conductivity is part of the material itself, whereas the driving force is a measure of the potential for movement based on conditions. Think of “door being stuck at an open area” as the driving force and the “air” moving through as the conductance?

What are the four necessary components of a ligand-gated ionotropic receptor?

?

How do intercellular signals induce intracellular change?

An intercellular signal will travel and bind to a cell’s membrane receptors. The receptor’s intracellular domain will change. For example: A G-protein coupled receptor changes shape and activates a G protein. The G protein splits into pieces and beta subunit binds an effector protein creating 2nd messengers and causing amplification to bring about a cellular response

Define equilibrium potential

Equilibrium potential is the difference across a cell membrane at which the concentration forces are balanced by electrical forces resulting in no net movement of an ion (dynamic equilibrium)

What equation describes an equilibrium potential?

Nernst equation