Module 2: Cognitive Neuroscience Flashcards
Which of the following are necessary for synapse formation? (choose all that apply)
a. formation of the axonal growth cone
b. an appropriate concentration of extracellular sodium
c. the presence of signaling molecules in the extracellular matrix
d. the release of growth factors
A,b and d
Which of neural processing schemes is most vulnerable to damage?
serial
The end result of disinhibition on a neural circuit is:
Excitation
describe the phenomenon of convergence within neural circuits
A single neuron can receive synaptic contacts from multiple neurons.
What is the main goal of neuroscientists studying the human connectome?
Their goal is to map all neural circuits present in the central nervous system.
Migrating neurons follow ____ molecules and ____ molecules
Signal transduction
Cell adhesion
Signaling molecules allow the ______ to identify the correct pathways
Axonal growth pathways
_______ assist with growth of the axon, formation of the synapse and modulating the number of synaptic connections
Growth factors
LTP requires ______ presynaptic and postsynaptic neuronal firing (glutamate and its NMDA receptor)
Simultaneous/synchronous
What is unique about the NMDA receptors?
They are dually gated (ligand and voltage gated)
LTD requires ______ presynaptic and postsynaptic neuronal firing (glutamate and its NMDA receptor)
Asynchronous
Single transduction pathways associated with LTP result in _____ influx of calcium ions and activation of protein ______
Large
Kinases
Single transduction pathways associated with LTD result in a _____ influx of calcium ions and activation of protein ______
Small
Phosphatases
arrangement of neurons within an assembly that is linear
Serial processing scheme
More susceptible to damage
Arrangement of neurons within an assembly that contains multiple interconnections
Distributed processing scheme
Less susceptible to damage
In what kind of excitatory connection does a neuron at lower level of processing excite a neuron at higher level of processing
Feedforward excitatory connection
In what kind of excitatory connection does a neuron at higher level of processing excite a neuron at lower level of processing
Feedback excitatory connection
In what kind of excitatory connection do neurons at the same level of processing excite each other
Lateral excitation connection
The inhibition of inhibition (disinhibition) results in _____.
Excitation
One neuron sends projection to many neurons
Divergence
Several neurons send projections to a single neuron
Convergence
What is an examples of convergence?
Rods to bipolar cells in the retina
The type of processing that occurs within hierarchical neural circuits where info flows from one area to another in sequence
Serial processing
The type of processing that occurs within hierarchichal neural circuits where info flows in a side by side manner
Parallel processing
The type of processing that occurs within hierarchical neural circuits where info flows back and forth
Reciprocal processing
Circuits found within all three of the hierarchical circuits are called?
Local circuits
What percentage of brain volume is devoted to neurons and glial cells?
80%
What percentage of our brain volume is devoted to extracellular space?
15%
What percentage of brain volume is devoted to vascular space?
5%
Glial cells outnumber neurons by a factor of ____ and account for grater than ____ of the brains volume
10, half
What is the function of neuroglia?
Provide structural support
Carry out many numerous and diverse functions
What are the main classes of neuroglia in the CNS?
Oligodendrocytes
Astrocytes
Microglia
What are the main neuroglia cell types in the PNS
Schwann cells
Satellite cells
What is the function of Oligodendrocytes
Form myelin sheaths around CNS axons
A single oligodendrocyte can send multiple processes to contact and _____ multiple axons
Myelinate
What is the largest and most numerous glial cell type?
Astrocytes
What is the function of astrocytes during development?
- Produce extracellular matrix proteins, adhesion molecules and chemotactic signals to guide axons to their correct targets
- secrete growth factors for neuronal differentiation, proliferation and survival
What are the function of astrocytes after fetal development?
- aid in formation fo the blood brain barrier by using “end feet” to form tight junctions with vascular epithelial cells
- aid in NT removal from nearby synaptic clefts via uptake
- sequester harmful material to protect the CNS
- Intracellular signaling and potentially even intercellular signaling
through the generation of intracellular Ca2+ waves which can travel to
adjacent cells - Mediate astrogliosis (an increase in the # of astrocytes) and
recruitment in response to neural injury or disease
What are the smallest glial cells of the CNS?
Microglia
What is the function of microglia during development?
-secrete growth factors during development which aid in formation of fiber tracts, gliogenesis, angiogenesis
WHat is the the function of microglia cells after development?
- mediate immune responses within the CNS
- Become “reactive” and phagocytic during pathological circumstances in the adult CNS
What are the phases of microglia immune response?
- Resting phase: microglia are sampling ECF
- reactive phase: microglia activate in response to pathology to change shape, increase in number and engulf harmful debris or compromised cells
What is the function of Schwann cells?
- Myelinate peripheral axons in PNS
- mediate regeneration of axons following injury by secreting growth factors, removing debris and providing scaffolding for the growth cone
A Schwann cells myelinates _______ of an axon
A single segment
I.e. multiple Schwann cells required to fully myelinate one axon
Myelination in the CNS vs the PNS
CNS: oligodendrocytes do the myelination and a single cell can myelinate multiple axons. In axonal injury, cells secrete inhibitory factors. Myelin in CNS is also 30% thinner.
PNS: Schwann cells do the myelination and several cells are required to myelinate single axon. In axonal injury, cells secrete growth factors, remove debris and provide axonal guidance
What does the tripartite synapse consist of?
- pre synaptic neuron
- post synaptic neuron
- astrocytes
What are the three glialtransmitters?
- ATP
- glutamate
- D-serine
What are the functions of glial cells?
- regulate glucose and O2 availability
- release growth factor
- mediate immune response
- promote regeneration
- CNS detoxification
- make saltatory conduction possible via myelination
- aid in synaptic transmission
- participate in gliotransmission
How can neural activity be measured directly in the brain?
EEG (electroencephalography) and MEG (magnetoencephalography)
How can neural activity be measure indirectly in the brain?
PET (positron emission tomography), fMRI (functional magnetic resonance imaging) or photo acoustic imaging
These methods quantify substrates of metabolic activity as indicators of neural activity
Electroencephalography (EEG) measures _______ produced by large populations of neurons through electrodes placed on the scalp
Electrical potentials
EEG pattern associated with different behavioral states (sleep, wake, etc.) are _______
Predictable
Clinical applications of EEG:
- can be used to measure responses to cognitive tasks
An EEG has _____ temporal resolutions and ______ spatial resolution.
Good: less precise
Active neurons produce ____ in addition to electrical activity
Magnetic fields
MEG records _____ signals produced by synaptic activity
Magnetic
How does the temporal and spatial resolution of the MEG compare to the EEG?
Similar temporal resolution but the MEG has better spatial resolution
Clinical application of MEG:
Useful in neurosurgery (establishes boarders of tumor) due to reliable spatial resolutions
PET scans are measuring _____ which correlated with neural activity
Metabolic changes
Why is the PET scan more invasive than MEG or EEG?
A radioactive tracer must be injected
Clinical application of PET:
Can be utilized while patient is performing a cognitive task and compared to scan of subject at rest
The change ins regional cerebral blood flow between the two scans indicated brains regions activated during the task
The PET detects changes in ________ while a subject is engaged in a cognitive task
cerebral blood flow
Regional cerebral blood flow (rCBF)
_______ hemoglobin is more paramagnetic than _______ hemoglobin
Deoxygenated: oxygenated
fMRI measures _____ in metabolically active brain regions?
Oxygen levels
Increased neural activity = increased cerebral blood flow = ratio of oxygenated to deoxygenated hemoglobin will ______
increase
Which has better spatial resolution, PET or fMRI?
FMRI
Which is more invasive, PET or fMRI
PET
Which has a limited number of scans that can be done per year?
PET due to use of radioactive isotope injections
Which has better temporal resolution, PET or fMRI
FMRI
specialized structures at the tip of an extending axon that respond to various signaling molecules in order to identify the correct pathways
Axonal growth cones
axonal growth, synapse formation, and the number of connections between axons and their targets are influenced by _______
secreted growth factors
Once growth cones are converted to specialized presynaptic structures called ________, the formation of neural circuits and networks occurs.
terminal buttons
specialized cells for rapid communication through the conduction of nerve
impulses and exchanging information with other neurons.
Neurons
Why are microglial cells unique?
They retain the ability to divide
Important cellular elements are integrated to comprise neurotypically functioning brain tissue. These integral functional and structural components of the CNS are termed _____
Neural triad
The neural triad is composed of:
- neurons
- neuroglial cells
- cerebral vasculature
How do neurons contribute to the neurotypically functioning brain?
They provide complex cell to cell interactions among individuals neurons as well as groups of neurons
How do neuroglial cells contribute to the neurotypically functioning brain?
They provide structural and functional support
How does cerebral vasculature contribute to the neurotypically functioning brain?
supports brain development and function by:
- Contributes to neurogenesis
- Transports O2 and nutrients to and removes waste from the brain
- help form the blood-brain barrier
Ca2+ Signaling of Astrocytes Involves:
release of calcium from intracellular stores in response to metabotropic
receptor activation on the astrocyte that initiates a signal transduction pathway (STP) that prompts the release of stored calcium within the astrocyte
Slight changes in the concentration of intracellular Ca2+ following activation go metabotropic receptors on the astrocyte can lead to:
Ca2+-dependent
release of neurotransmitter (NT) molecules
- these are considered to be “gliotransmitters”
Does Ca2+ signaling within astrocytes display all-or-none features?
No
an increase in intracellular calcium may occur in only a portion of an astrocyte’s process and may or may not spread to other parts of the astrocyte and can transfer to adjacent astrocytes
Astrocytes are believed to influence synapse function by:
regulating homeostasis of the interstitial fluid within a synapse via aquaporins and a variety of ion transporters which allow them to regulate pH, as well as maintain appropriate levels of ions and neurotransmitters
What is the target of the gliotransmitter ATP?
Glia to glia
What is the receptor for the gliotransmitter, ATP?
Metabotropic receptors
What is the function/action of the gliotransmitter, ATP/
Decreases glial cell calcium levels
What is the target of the gliotransmitter, glutamate?
Neurons and glia
What is the receptor of the gliotransmitter, glutamate on neurons?
Ionotropic (AMPAR’s and NMDAR’s)
What is the receptor of the gliotransmitter, glutamate on astrocytes/glia?
Metabotropic
What is the function/action of the gliotransmitter, glutamate?
- enhances NT release
- enhances EPSPs
- modulates glial calcium levels (increase or decrease)
What is the target of the gliotransmitter, D-serine?
Postsynaptic neuron
What is the receptor of the gliotransmitter, D-serine?
Ionotropic (NMDAR’s)
What is the function/action of the gliotransmitter, D-serine?
Enhances EPSP’s
The radioactive tracer injected for a PET scan will emit ______
Gamma rays/photons
The ratio of oxygenated to deoxygenated hemoglobin is referred to as the _______ effect
blood oxygenation level-dependent (BOLD)
Photoacoustic imaging relies on ______ to produce an image.
light and ultrasound waves
Photoacoustic imaging (photoacoustic tomography) can be used for what type of imaging?
Static and functional
Photoacoustic imaging (photoacoustic tomography) can be used to measure:
- blood oxygenation saturation
- blood flow
- temperature
In Photoacoustic Imaging (photoacoustic tomography), a pulsed laser directs photons into the tissue, which heats the tissues
and creates _______ which are received by a transducer outside the tissue and analyzed by computers
pressure waves (ultrasonic waves)
Photoacoustic Imaging (photoacoustic tomography) can be used in conjunction with ____ or _____.
Tracer or probe
What is the main benefit of Photoacoustic imaging over fMRI and PET?
safe and non-invasive and can provide real-
time high-contrast images
- safer than PET as it utilizes nonionizing laser illumination
- Image production is faster than MRI and associated costs are
less
Photoacoustic imaging produces _____ (high/low) spatial resolution images with greater tissue penetration ability and specificity
high
functional neural pathways comprised of neurons within specific nuclei that release one type of signaling molecule that influence numerous other target brain areas.
Single-source divergent networks (SSDNs)
This is the structure of a cognitive network
Describe the axons of neurons within single-source divergent networks (SSDNs)
long axons which diverge and send projections to multiple brain regions
What are the characteristics of cognitive networks?
- Appear early during embryonic development
- Support all cognitive functions of the brain
- Constantly modulate neural activity and are referred to as “brain state modulatory controls”
- Regulate widespread information flow throughout the brain
- Organized in a hierarchy (local division of labor within the network)
- Exhibit functional stability in the face of local network damage
- Are created and altered by synaptic plasticity processes
- Consist of many long-reaching axonal branches
- Categorized by the neurotransmitter utilized
Defects in the networks that utilize biogenic amine neurotransmitters often result in _______.
certain psychiatric disorders
- these circuits are often the targets of pharmacological interventions for psychiatric disorders
biogenic amine neurotransmitters include:
- Dopamine
- Norepinephrine/ Epinephrine
- Histamine
- Serotonin
What are the 5 Single-source Divergent Networks?
- Dopamine (DA)
- Norepinephrine (noradrenaline/adrenaline)(NE/NA)/Epinephrine (Epi)
- Histamine (His)
- Serotonin (5-HT)
- Acetylcholine (ACh)
- All 5 networks are interconnected and work cooperatively together to control overall brain state (consciousness, attention, etc.)
Network neurons have ______ axons that are highly _______ which synapse on many target cells in various brain regions
unmyelinated, arborized
Describe how neural networks work together
within the neural networks are local circuits which contain excitatory and inhibitory synapses, and various processing connections such as: serial, parallel and reciprocal. These connection types are also found between each network, making them highly interconnected.