NE203 Chapter 1 Flashcards

Neuron doctrine

Nerve cells are discrete entities that are polarized to transmit information, and they communicate through contact, not through continuous channels.

Synapse

The junction between neurons where information is passed from one another.

Neurons

Cells specialized for the generation, conduction, and transmission of electrical signals.

Glial cells

Another class of cells in the nervous system that support neurons.

Gap junctions

Specialized intercellular contacts formed by channels that directly connect the cytoplasm of two cells.

• In neurons, these gap junctions only allow the sharing of cellular proteins instead of the cytoplasm.

Dendrites

Spines that protrude from the nucleus of a neuron.

Glial cells

Other brain cells that interact with the pre and postsynaptic domains of neurons to define synaptic contacts. They are also highly responsive to brain injury.

Astrocytes

Star-shaped glial cells; they aid in the formation of the blood-brain barrier to prevent pathogens from entering the brain and impede neural processes. They also secrete substances that influence the formation of new synaptic connections. They retain the ability to generate neurons in developing and mature brains.

Oligodendrocytes

Form myelin around some axons; they retain the ability to generate new cells in case of injury or disease.

Schwann cells

Myelinate axons in the peripheral nervous system.

Neural circuits

Collections of interconnected neurons mediating a specific function.

Neuropil

Tangle of dendrites, axon terminals, and glial cell processes that is between cell bodies in the gray matter of the brain and spinal cord.

Afferent neurons

Nerve cells that carry information from the PNS towards the CNS.

Efferent neurons

Neurons that carry information away from the CNS to the PNS.

Interneurons

Participate in only the local parts of the circuit function.

Excitatory

Increases the probability of firing a post-synaptic action potential (EPSPs).

Inhibitory

Decreases the probability of firing a post-synaptic action potential (IPSPs).

Modulatory

Doesn’t cause changes in the excitability of a target cell that leads to an action potential, but it makes smaller changes that can bring the target cell closer or farther away from reaching an action potential by modifying the threshold,

Step 1 of knee-jerk arc

Hammer tap stretches the tendon which signals the sensory receptors in the tendon.

Step 2 of the knee-jerk arc

Sensory neurons (that respond to the sensory receptors in the tendon) branch to the spinal cord, where they diverge and synapse on 1) a motor neuron and 2) an interneuron.

Step 3 of the knee-jerk arc

The motor neuron that was synapsed excites the extensor muscle (the quadriceps). The interneuron inhibits the motor neuron that affects the flexor muscle, inhibiting it. This leads to the reaction where the leg extends out in the end.

Electrophysiological recording

measures the electrical activity of a neuron.

Extracellular recording

An electrode is placed near the neuron of interest to measure its activity. This detects temporal patterns of AP activity and relating those to stimulation or in response to behavioral events.

Intracellular recording

An electrode is placed inside the neuron to measure its activity. This detects the smaller graded changes in electrical potential that trigger action potentials.

Calcium imaging

Records changes in the internal concentration of Ca in neurons that are associated with AP firing. This can be used for a wide array of neurons at once.

Optogenetics

The use of genetic tools to make neurons become sensitive to light so that they can be excited or inhibited by being exposed to light. This is the most effective way to manipulate and study neuronal connections.

Bacteriorhodopsin

Has a hyper-polarizing effect on neurons because it conducts H+ out of the cell.

Halorhodopsin

Has a hyper-polarizing effect on neurons because it conducts Cl- into the cell.

channelrhodopsin

Conducts cations and anions, so it can depolarize or hyperpolarize the cell based on the strain and the wavelengths of light used.

Neural systems

Large networks made up of neural circuits that process similar types of information and are therefore integrated to analyze larger volumes of the same general type of information and generate more complex behaviors.

Sensory systems

Acquire and process information from the internal and external environments.

Motor systems

Responds to sensory information by generating movements.

Associational systems

Neural circuits that don’t lie in either of the defined systems; they mediate the most complex and least well-defined brain functions.

Computational maps

Assembly of neural circuits in a specific brain region that represent inputs that don’t have a direct correspondence to a topographic map.

Lesion studies

The method of observing and documenting change in function following damage to a distinct brain region, nerve, or tract. This helped to ID neural systems and link brain regions to specific functions through the resulting impairment.

Anterograde

Signals or impulses that travel forward to trace connections from their source to termination.

Retrograde

Tracing connections backwards from their terminus to the source.

Receptive field

A region of receptive surface within which a specific stimulus elicits the greatest AP response from a sensory cell.

Somatic motor division

The motor axons that connect the nervous system to skeletal muscles.

Autonomic motor division

cells and axons that innervate smooth and cardiac muscls, and glands.

Ganglia

Local accumulations of nerve cell bodies and supporting cells.

Nerves

Bundles of peripheral axons, enveloped by Schwann cells for axon myelination or to provide a single glial covering for protection.

Difference in CNS and PNS development

• CNS = from stem cells of the neural tube

• PNS = stem cells located in the neural crest

Gray matter

Accumulation of cell bodies and neuropil in the brain and spinal cord.

White matter

Axon tracts and commissures.

Nucleus

Local collection of neurons that have similar connections.

Cortex

Sheet-like arrays of nerve cells that cover the cerebral hemispheres and the cerebellum.

Commissures

Tracts that cross the midline of the brain (ex., corpus callosum); they interconnect the cerebral hemispheres.

Autonomic ganglia

Collections of autonomic motor neurons that innervate visceral smooth muscles, cardiac muscles, and glands.

Sympathetic

A division of the ANS that contains its ganglion in the vertebral column and send their axons to a variety of peripheral targets.

Parasympathetic

The division of the ANS that has its ganglion in or near the organs they innervate.

Enteric system

Made up of small groups and individual neurons scattered throughout the wall of the gut.

Genetic analysis

The ________ of the relationship between single genes and phenotypes to which each gene contributes.

Gene

comprised of coding DNA sequences that lead to proteins, and regulatory DNA sequences that control whether and in what quantities a ______ is expressed in a given cell type.

Genomics

Analysis of complete DNA sequences for a species or an individual.

Splice variants

Variable mRNAs transcribed by the same gene.

Mendelian analysis

The assessment of the inheritance of traits and the presumed single genes that control this trait.

Homozygosity mapping

Has been used to identify genes associated with rare brain disorders (though passed through recessive alleles).

Genome-wide association studies

A statistical correlation of likely associated genes drawn from analyses of large cohorts of individuals with the same phenotype or clinical diagnoses.

Orthologous genes

Identical/similar genes in animals based on sequence and chromosomal location.

Genetic engineering

Inducing mutations in genes/editing the structure/function of genes for experimental or therapeutic benefit.

Electroencephalogram

The study of electrical potentials generated in the brain is recorded from electrodes placed on the scalp.

• Used to diagnose epilepsy and assess issues with sleep and wakefulness

• Can be used with fairly small equipment and can be done without supervision

Event-related potential (ERP)

Averaged EEG recordings measure time-locked brain responses to repeated presentations of a stimulation or repeated execution of a motor task.

• Allows for general localization during the performance of different tasks based on positional differences in EEG activity across the brain surface.

Transcranial magnetic stimulation (TMS)

Uses magnetic impulses delivered by a device held at different positions near the scalp; Activity in the underlying cortical tissue is disrupted, leading to a change in behavioral performance.

• Can link broad brain regions to specific ongoing behaviors, and can potentially reset disrupted patterns of activity.

Computerized tomography (CT)

A radiographic procedure in which a three-dimensional image of a body structure is constructed by computer from a series of cross-sectional X-ray images

• Can distinguish gray and white matter, differentiate the ventricles, and show many other brain structures with a spatial resolution of several millimeters

• Can also see lesions if they are within the limits of the CT resolution

Positron emission tomography (PET)

A technique that examines brain function by injection of an unstable, positron-emitting isotope that’s then incorporated into bioactive molecules or metabolites. The emission of the positrons is detected by gamma ray detectors. The images computed indicate the localization and concentration of the isotopes.

• Regions that increase in the uptake and emission of the positron are associated with locally increased function

• People who are in ___ scanners can be tasked with certain behaviors; as the uptake of positron isotopes shifts, the scanner can generally localize what area of the brain is responsible for that function

MRI

A noninvasive technique that uses magnetic energy and radiofrequency pulses to generate images that reveal structural and/or functional information in the living brain.

Diffusion tensor imaging (DTI)

This is a variant of MRI that establishes differences in major axon pathway connectivity, which makes it possible to study individuals with genetic disorders that result in major alterations of axon projections.

Functional magnetic resonance imaging (fMRI)

Imaging that detects changes in blood flow and therefore IDs regions of the brain that are particularly active during a given task

• Considered the safest approach to imaging activity

• Though it takes a while because the signals rely on averaging over time

Blood oxygenation level-dependent (BOLD)

Signals reflecting the oxygenation of hemoglobin in the blood that are modulated by changes in the local level of neural activity.

Magnetoencephalography (MEG)

A passive and noninvasive functional brain-imaging technique that measures the tiny magnetic fields produced by active neurons, to ID regions of the brain that are particularly active during a given task.