Exam 1 Flashcards
an experiment in which a specific component is added to a system; it is often used to test whether the added component is sufficient for the system to function in a specific context.
Gain-of-function experiment
an experiment in which a specific component is disrupted, often used to determine if the missing component is necessary for the system to function.
loss-of-function experiments
an experiment in which key parameters in a biological system are altered, usually under the experimenter’s control, in order to study the consequences.
perturbation experiments
signaling that uses continuous values to represent information.
Digital signaling: signaling that uses discrete values (0s and 1s) to represent information.
analog signaling
an information processing method; utilizing a large number of units to perform a set of coordinated computations in parallel. It is a key feature of the nervous system.
Massively parallel processing
an information processing method in which processing units are arranged in sequential steps.
Serial processing
(part of the temporal cortex overlying the hippocampus), where maps represent spatial information of the outside world.
Entorhinal cortex
corresponding to movement of specific body parts: nearby neurons in the motor homunculus control the movement of nearby body parts.
Topographic map
a map in the primary somatosensory cortex; it corresponds to sensation of specific body parts. Nearby somatosensory cortical areas represent sensation from nearby surfaces.
Sensory homunculus
a map in the primary motor cortex that corresponds to movement of specific body parts. Nearby areas in the motor cortical areas represent movement control of nearby body parts.
Motor homunculus
which monitors signals originating from changes in blood flow that results from local neuronal activity.
Functional magnetic resonance imaging (fMRI)
is a medical condition characterized by recurrent seizures-strong urges of abnormal electrical activity that affect part or all of the brain.
Epilepsy
the part of the cortex that analyzes auditory signals.
Auditory cortex
-were associated with defects in language.
-Discovered by Carl Wernicke
-Patients have great difficulty understanding language, but they can speak fluently, although often unintelligently and incoherently.
Wernicke’s Area
-is the area in the human left frontal lobe in patients who could not speak.
-Discovered by Paul Broca
-Patients had great difficulty producing language, whether in speech or writing, but their understanding of language is largely intact.
Broca’s Area
majors folds separating the lobes.
Fissures
Each hemisphere of the of the cerebral cortex is divided into four lobes:
- Frontal lobe
- Parietal lobe
- Temporal lobe
- Occipital lobe
-a discipline in the 1800s with the goal of mapping the functions of brain areas by studying the shape and size of bumps and ridges on the skull, which were thought to be correlated with an individual’s talents and character traits.
-Developed by Franz Joseph Gall
Phrenology
sends descending output directly and indirectly to spinal cord motor neurons to control muscle contractions, in case we want to move our leg voluntarily (in contrast to the knee-jerk reflex, which is involuntary).
Primary motor cortex
the part of the cerebral cortex that first receives somatosensory input from the body.
Primary somatosensory cortex
the postsynaptic excitatory neuron synapses onto an inhibitory neuron, which synapses back onto the postsynaptic excitatory neuron.
Feedback inhibition
an excitatory neuron synapses onto both an excitatory neuron and an inhibitory neuron, and the inhibition neuron further synapses onto the excitatory postsynaptic neuron.
Feedforward inhibition
neurons that transmit parallel streams of information can also excite each other forming this excitation.
Recurrent (lateral) excitation
when a postsynaptic neuron synapses onto its own presynaptic partner.
Feed-back excitation
propagates information across multiple brain regions, as in the relay of somatosensory stimuli to the primary somatosensory cortex
Feed-forward excitation
refers to a motif wherein a single neuron synapses onto multiple postsynaptic targets via branched axons (axonal branches are also called collaterals).
Divergent excitation
refers to a circuit motif wherein several neurons synapse onto the same postsynaptic neuron.
Convergent excitation
common configurations of neural circuits that allow the connection patterns of individual neurons to execute specific functions.
Circuit motifs
whose axons link different regions of the nervous system.
Projection neurons
a second type of postsynaptic neuron targeted by the sensory axons.
Inhibitory interneurons
referring to axons that project from the CNS to peripheral targets.
Efferents
referring to axons projecting from peripheral tissues to the CNS
Afferents
sensory neurons embed their endings in specialized apparatus.
Muscle spindles
the involuntary forward movement of the lower leg due to contraction of the quadriceps femoris muscle (an extensor) and relaxation of the hamstring muscle (a flexor).
Knee jerk reflex
The simplest circuits in vertebrates, those that mediate the spinal reflexes, comprise as few as two interconnected neurons:
- A sensory neuron that receives external stimuli.
- A motor neuron that controls muscle contraction.
ensembles of interconnected neurons that act together to perform specific functions.
Neural circuits
at chemical synapses, they rely on neurotransmitter release and reception.
Interneuronal communication
is achieved by membrane potential changes in the form of graded potentials and action potentials.
Intraneuronal communication
the process of neurotransmitter release from the presynaptic neuron and neurotransmitter reception by the postsynaptic neuron
Synaptic transmission
How is information transmitted between neurons?
-At electrical synapses, membrane potential changes are directly transmitted from one neuron to another by ion flow across gap junctions.
-At chemical synapses, the arrival of action potentials (or graded potentials in non-spiking neurons) at presynaptic terminals triggers neurotransmitter release.
the site of action potential initiation adjacent to the soma.
Axon initial segment (axon hillock)
In most neurons, the purpose of these synaptic potentials determine whether, when, and how frequently the neuron should fire action potentials so that information can propagate along its axon to its own postsynaptic target neurons.
…
There are two kinds of inputs:
- Excitatory inputs: facilitate action potential production in the postsynaptic neuron.
- Inhibitory inputs: impede action potential production.
use graded potentials to transmit information, even in their axons.
Non-spiking neurons
Another important form of communication with neurons are graded potentials-membrane potentials that vary continuously in magnitude.
-One type of graded potential: synaptic potentials, is produced at postsynaptic sites in response to neurotransmitter release from presynaptic partners.
-Receptor potentials: are a type of graded potential induced at the peripheral endings of sensory neurons by sensory stimuli.
…
what uses the frequency of action potentials to convey the intensity of signals.
neurons
The presence of an elementary unit of nerve impulses that axons use to convey information across long distances; we now call this elementary unit an action potential.
…
-the electrical potential difference across the neuronal membrane.
-When neurons are excited, their membrane potential changes transiently, creating nerve impulses that propagate along their axons.
membrane potential
most often are unipolar, extending a single process giving rise to both dendritic and axonal branches.
invertebrate neurons
-was composed by Ramon y Cajal. The transmission of neuronal signals proceeds from dendrites and cell bodies to axons.
-Every neuron has (1) a receptive component, the cell body and dendrites; (2) a transmission component, the axon; and (3) an effector component, the axon terminals.
-Cajal took advantage of the fact that, in sensory systems, information must generally flow from sensory organs to the brain.
Theory of dynamic polarization
most vertebrate neurons have both dendrites and an axon leaving the cell body
Multipolar
-processes bodily sensations.
-Are pseudounipolar because it gives rise to both peripheral and central branches.
Somatosensory system
wrap their axon terminals around the cell bodies of pyramidal cells in the cerebral cortex or Purkinje cells in the cerebellum.
Bracket cells
the most frequently encountered type of neuron in the mammalian cerebral cortex and hippocampus, has a pyramid-shaped cell body with an apical dendrite and several basal dendrites that branch extensively.
Pyramidal neuron
Neurons have 2 kinds of processes:
- Dendrites
- Axons
In vertebrate neurons, information generally flows from dendrites to cell bodies to axon
…
Neurons communicate with each other by electrical synapses mediated by gap junctions which have gap junction channels that directly link the cytoplasms of two adjacent neurons, allowing ions and small molecules to travel between them.
…
Synaptic partners are not symmetric: presynaptic terminals of neurons contain small synaptic vesicles filled with neurotransmitters, which, upon stimulation, fuse with the plasma membrane and release neurotransmitters into the synaptic cleft.
-Postsynaptic target cells have:
-Postsynaptic specializations (also called postsynaptic densities) enriched in neurotransmitter receptors on their plasma membrane surfaces.
…
a technique allowing visualization of structures at nanometer (nm) resolution.
Electron microscopy
changes its shape dynamically as axons extend.
Growth cone
a site at which information is transferred from one neuron to another neuron or a muscle cell; it consists of a presynaptic terminal and a postsynaptic specialization separated by a synaptic cleft.
Synapse
-postulated that neuronal processes do not fuse to form a continuous reticulum. Instead, neurons intimately contact each other, with communication between distinct neurons occurring at these sites.
-Ramon y Cajal supported the neuron doctrine.
Neuron doctrine
-the reticulum as a whole, rather than its individual cells, constituted the unit of the nervous system.
-Camillo Golgi supported the reticular theory of the nervous system.
-Discovered the golgi apparatus
-Invented the Golgi stain.
reticular theory
all living organisms are composed of cells as their basic units.
cell theory
specialized structures that participate in the transfer of information between neurons.
Presynaptic terminals
The nervous system is made up two major categories of cells:
Neurons (nerve cells): has two kinds of neuronal processes (cytoplasmic extensions)
1. Axon: a long, thin process which often extends far beyond the cell body (soma).
2. Dendrites: thick, busy processes which are usually close to the soma.
-Are decorated with small protrusions called dendritic spines which likewise function in intercellular information transfer.
Glia: nonneuronal cells. There are 4 major types of glia in the vertebrate nervous system:
1. Oligodendrocytes: play analogous functions in the CNS.
They wrap axons with their cytoplasmic extensions, called myelin sheath, which increases the speed at which information propagates along axons.
Oligodendrocytes and myelinated axon constitute white matter in the CNS because myelin is rich in lipids and thus appears white.
2. Schwann cells: play analogous functions in the PNS.
They wrap axons with their cytoplasmic extensions, called myelin sheath, which increases the speed at which information propagates along axons.
3. Astrocytes: plays many roles in neural development and regulation of neuronal communication; they are presented in the gray matter of the CNS, which is enriched in neuronal cell bodies, dendrites, axon terminals, and connections between neurons
4. Microglia
The brain can be divided into:
Forebrain
Midbrain
Hindbrain
refers to the two sides of the brain.
Hemispheres
The nervous system is divided into:
-The central nervous system (CNS): consists of the brain and spinal cord
-Peripheral nervous system (PNS): made up of nerves (dictates bundles of axons) connecting the brainstem and spinal cord with the body and internal organs as well as isolated ganglia (clusters of cell bodies and nerve cells) outside the brain and spinal cord.
refers to changes in the nervous system in response to experience and learning.
Neural plasticity
a field of study that emphasizes observing animal behavior in natural environments, refers to such instinctive behaviors as following fixed action patterns.
Neuroethology
a trait or behavior that is genetically programmed and is thus with an organism from birth rather than acquired by experience.
Innate
refer to changes made to DNA and chromatin that do not modify DNA sequences but can alter gene expression– these include DNA methylation and various modifications of histones, the proteins component of chromatin.
Epigenetic modifications
the difference between correlations of monozygotic and dizygotic twins multiplied by 2 (because the genetic difference is 50% between monozygotic and dizygotic twins).
Heritability
-originate from two independent eggs fertilized by two independent sperm.
-They are 50% identical in their genes according to Mendel’s law of inheritance
Fraternal twins or Dizygotic twins
share 100% of their genes in almost all cells, as they are products of the same fertilized egg, or zygote.
Identical twins or Monozygotic twins
what are the part of the neuron?
- dendrites
-axon - cell body (soma)
what are the parts of the synapse?
- the presynaptic membrane
- post synaptic membrane
- synaptic cleft
what does Ohm’s law mean?
An equation that relates current (I) to voltage (V) and resistance (R)
- what are the types of refractory periods?
- What’s happening in each one?
- What causes each one?
- What can’t happen in each one?
- Relative and Absolute
2.
What is the resting membrane potential?
- the membrane potential of a neuron at rest (i.e., in the absence of action potentials or synaptic input), which is typically between -50 and -80 millivolts relative to extracellular fluid.
What is the action potential?
An elementary unit of nerve impulses that axons used to convey information across long distances. It is all-or-nothing, regenerative, and propagates unidirectionally in an axon. It is also called a spike.
What does hyperpolarized mean?
A change in the electrical potential inside a cell toward a more negative value.
What does depolarized mean?
A change in the electrical potential inside a cell towards a less negative value.
What are graded potentials?
membrane potentials that can change in continuous values, as opposed to the all-or-none property of action potentials.
What does resistance mean?
the degree to which an object or substance oppose passage of electrical current; it is the inverse of conductance
What does conductance mean?
the degree to which an object or substance passes electricity; it is the inverse of resistance
What does capacitance mean?
the ability of a capacitor to store charge.
- What’s the role of myelin in the nervous system?
- Who lays down myelin?
- What is myelin good for?
myelin is a cytoplasmic extensions of oligodendrocytes and Schwann cells that wrap around axons with multilayered glial plasma membranes to increase resistance and decrease capacitance for action potential propagation.
- What are the general distributions of the ions (where’s Ca, Na, Cl, and K)?
- Which one(s) are the membrane permeable to?
- Which one is most permeable?
- What would happen if we started messing around with the ions?
- What would happen to resting membrane if we started changing concentrations?
- What are the receptor types?
- whats the culongeric receptor?
- What are the other receptors in terms of structure?
- Are some receptors faster or slower?
- metabotropic receptor: A NT receptor that regulated ion channel conductance indirectly through intracellular signaling cascades, modulating membrane potentials over a times scale.
Ionotropic receptor: A neurotransmitter that functions as a neurotransmitter-gated ion channel to allow membrane potential changes in response to neurotransmitter binding. - GABA and Glycine receptors: typically open Cl channels which hyperpolarize and mediate inhibition and can prevent APs
- ionotropic is faster than metabotropic.
What might happen if we mutated a channel or receptor?
- What are the types of gradients?
- What maintains those gradients in terms of Na+/K+ pumps
- Electrical and Chemical
How are toxins used to study neurons? (there are 2 we talked about in class)
- these toxins specifically block Na or K channels.
the 2 toxins are: tetrodotoxin which blocks Na channels and tetraethylammonium (TEA): which blocks voltage gated K channels
What are the steps in NT release?
- action potential reaches terminal
- voltage gated Ca2+ channels open/Ca2+ rushes in
- Ca2+ binding proteins/motor proteins
- vesicles docked to presynaptic membrane
- SNARE proteins merge vesicle to membrane
- NT are released
What’s needed to make sure a vesicle of NT can actually be released?
How do we study NT release and function experimentally?
How is the synapse organized and what are important things to keep it organized?
- What happens in the NT cycle?
- Name the 7 Neurotransmitters and tell about them?
- enzymatic destrcution (ex. Ach)
- reuptake
diffuse away
- glial cells
- enzymatic destrcution (ex. Ach)
- Acetylcholine: Motor neurons that excite muslce; ANS neurons; CNS excitatory and modulatory neurons
Glutamate: Most CNS excitatory neurons; most sensory neurons.
GABA: most CNS inhibitory neurons.
Glycine: Some CNS inhibitory neurons (mostly in the brainstem and spinal cord).
Serotonin (5-HT): CNS modulatory neurons; neurons in the GI tract
Dopamine: CNS modulatory neurons
Norepinephrine: CNS modulatory neurons; ANS neurons
- How are NMDA and AMPA receptors important?
- What influences them?
- What do they influence?
NMDA receptors: a glutamate-gated ion channel that conducts Na, K, and Ca and can be activated by the drug NMDA. It’s opening requires both binding of glutamate and postsynaptic depolarization. harder to get to work
AMPA receptors: a glutamate-gated ion channel that conducts mostly Na and K and can be selectively activated by the drug AMPA
How can presynaptic inputs enhance or degrade what’s happening in the synapse?
In terms of the cell integrating inputs, what are the types?
Spatial integration: the summation of postsynaptic potential produced by synchronous activation of synapses located at different spatial locations on the postsynaptic neuron.
Temporal summation: the summation of postsynaptic potentials produced by activation of synapses within a finite time window
Metabotropic in detail
- ligand binding
- G protein coupling and nucleotide exchange
- activated G protein subunits regulating effector proteins
- GTP hydrolysis and inactivation of G protein
- reassembly of heterotrimeric G protein
