NE203 Lecture 1: Studying the Nervous System Flashcards

Comprehensive vocabulary flashcards covering key definitions, cellular components, genetics, optogenetics, and neuroimaging modalities from Lecture 1: Studying the Nervous System.

Synapse

The specialized point of functional communication between two neurons where signal transmission occurs.

Myelin

An insulating lipid-rich sheath wrapped around neuronal axons that is formed by oligodendrocytes in the central nervous system (CNS) or Schwann cells in the peripheral nervous system (PNS).

Soma

The neuronal cell body where the majority of protein synthesis occurs before proteins and organelles are trafficked across long distances to the axon terminal.

Divergence

A neural circuit organization in which a small number of presynaptic neurons form synaptic connections with a larger number of postsynaptic target cells.

Convergence

A neural circuit organization in which input from many presynaptic neurons converges onto a smaller number of postsynaptic cells.

Astrocytes

Star-shaped central nervous system glial cells that help form the blood-brain barrier, buffer ion concentrations and neurotransmitters, and secrete chemical signals necessary for synaptogenesis.

Oligodendrocytes

Central nervous system glial cells responsible for wrapping and synthesizing myelin sheaths around central axons.

Microglia

Central nervous system glial cells derived from immune precursors that exhibit macrophage phagocytic activity and secrete signaling cytokines.

Schwann cells

Peripheral nervous system glial cells that myelinate axons + participate in functional recovery following peripheral nerve injury.

Cresyl violet

A histological stain that targets RNA to delineate neuronal soma structure in both the central and peripheral nervous systems.

Nissl stain

A histological staining technique that labels cellular nucleic acids, including RNA, DNA, and ribosomes, within nerve cells.

Golgi stain

A silver-impregnation technique that completely stains a small fraction of individual neurons, revealing their detailed cell bodies, dendrites, and axonal arborizations.

Neuropil

A dense, complex feltwork of neuronal dendrites, axon terminals, and glial processes lying between neuronal cell bodies in neural circuits.

Afferent neurons

Neurons or axons that transmit sensory information towards the central nervous system (CNS).

Efferent neurons

Neurons or axons that convey motor or regulatory commands away from the central nervous system (CNS) to target organs or muscles.

Interneurons

Neurons with relatively short axons that process information locally within a specific neural circuit.

Myotatic reflex

The simple reflex loop (knee-jerk reflex) wherein tapping a tendon stretches leg extensor muscle sensory receptors, directly exciting extensor motor neurons while concurrently exciting interneurons that inhibit flexor motor neurons. (input-output geometry)

Optogenetics

A neurotechnological method where genes for light-sensitive proteins (opsins) are introduced into specific neurons to control their electrical activity and signaling via light stimuli.

Channelrhodopsin

A light-sensitive non-selective cation channel used in optogenetics that conducts cations like $\text{Na}^+$, $\text{Ca}^{2+}$, $\text{H}^+$, and $\text{K}^+$ across the plasma membrane to depolarize and excite neurons upon illumination.

Halorhodopsin

A light-activated chloride pump used in optogenetics that transports $\text{Cl}^-$ into the cell during green light illumination, hyperpolarizing and inhibiting neuronal firing.

GAL4/UAS system

A bipartite genetic tool in Drosophila melanogaster where cell-specific GAL4 transcription factors bind to the Upstream Activation Sequence (UAS) to selectively express a target transgene like CsChrimson in targeted cell populations.

All-trans retinal

An essential light-absorbing co-factor required to form functional light-activated channelrhodopsin opsins in optogenetic assays.

GMR42E06

A DNA enhancer sequence derived from near the gene 'jim lovell' in Drosophila melanogaster used to regulate GAL4 expression in specific brain and ventral nerve cord cells.

Topographic map

An organizational feature of neural systems in which spatial relationships between sensory receptors or muscle groups are systematically reflected across neural structures.

Computational map

A neural representation that organizes sensory or motor information based on integration of temporal sequence or complex sensory parameters rather than physical spatial dimensions.

Receptive field

The specific area in sensory space or on the body surface where a given stimulus alters the electrical firing response of a sensory neuron.

Central nervous system (CNS)

The primary structural division of the nervous system consisting of the brain and spinal cord, responsible for analyzing and integrating sensory and motor information. Motor (Visceral + somatic) commands sent to PNS (efferent)

Peripheral nervous system (PNS)

The division of the nervous system external to the brain and spinal cord, including cranial nerves, spinal nerves, sensory ganglia, and peripheral autonomic plexuses. Sensory info sent to CNS (afferent)

Autonomic ganglia

Where visceral motor neurons synapse onto peripheral motor neurons that innervate smooth muscles, cardiac muscles, and glands.

Sympathetic division

A division of the visceral motor system originating from the thoracic and lumbar spinal cord levels via the sympathetic trunk.

Parasympathetic division

A division of the visceral motor system originating from the brainstem (cranial nerves) and sacral spinal cord segments. Rest n digest!

Enteric division

GI tract

Nucleus (neuroanatomy)

a collection of neurons with about the same structure + function

Gray matter

cell bodies

White matter

myelin-covered axon tracts; brain = commissures; SC = columns

Commissures

Myelinated white matter axon tracts in the brain that cross the midline to connect corresponding structures between the right and left hemispheres.

Columns (spinal cord)

Large longitudinal bundles of myelinated white matter axon pathways located in the spinal cord.

Human nervous system gene expression

Approximately $84\%$ of human genes are expressed in the nervous system, with approximately $30\%$ expressed exclusively in the brain.

ASPM gene

Abnormal Spindle-like Microcephaly-associated gene; a gene critical for brain development whose mutation leads to severe microcephaly.

Splice variant

Different mature mRNA molecules produced from the same gene by alternative splicing, enabling a single gene to encode multiple distinct protein isoforms.

Genome-wide association studies (GWAS)

used to expand single-gene analysis in inheritance in a single family to analysis of large cohorts

Transgenic animals

Organisms produced by introducing a novel cloned gene construct into early embryonic stem cells or a fertilized zygote.

Homologous recombination

A genetic engineering process that uses matching DNA sequences to precisely target and substitute or insert exogenous DNA into a specific genomic locus.

Conditional mutations

Genetic manipulations that selectively knock out or suppress target gene expression in a specific cell type, tissue, or developmental stage.

Electroencephalogram (EEG)

A non-invasive technique that records macroscopic surface electrical potentials generated by cortical neuronal activity using scalp electrodes, evaluated via event-related potentials (ERPs).

Transcranial magnetic stimulation (TMS)

used to correlate broad areas of the brain with ongoing behavior; used for neurologic + psychiatric conditions

Computerized tomography (CT)

A radiological technique using a rotating narrow tube of X-rays to provide detailed anatomical structure

Positron emission tomography (PET)

A functional imaging technique where a patient is injected with a radio-labeled compound (e.g., dopamine) to visualize localized uptake and metabolic activity in structures like the basal ganglia.

Magnetic resonance imaging (MRI)

A non-invasive imaging modality that aligns tissue hydrogen protons ($\text{H}^+$) using strong magnetic fields and measures energy signals emitted following radiofrequency pulse excitation to generate structural images. BEST for anatomical structures

Diffusion-tensor imaging (DTI)

detects white matter tracts bc water molecules can diffuse in limited directions along the length of the axon; useful for diagnoses

Functional magnetic resonance imaging (fMRI)

A functional neuroimaging technique that detects localized metabolic changes/activity in regional cerebral blood flow and oxygen content during cognitive or motor tasks.

Blood oxygen level-dependent (BOLD) signal

The physiological contrast mechanism measured during fMRI, reflecting local changes in the ratio of oxyhemoglobin to deoxyhemoglobin in active brain tissue.

Magnetoencephalography (MEG)

A high-temporal-resolution functional imaging technique that records magnetic fields produced by electrical currents within active cortical neurons.

Magnetic source imaging (MSI)

Combines structural MRI with MEG

Neuron Doctrine

Fundamental concept that the brain + PNS are composed of discrete cells that interact through specialized, non-continuous junctions

Highly Polarized Shape

long axon with distant terminal from which synaptic vesicles release ntms

How to visualize neurons in CNS & PNS?

1. Golgi Stain

2. Fluorescent Dye

3. Nissl Stain

4. Cresyl Violet

Ways to visualize + analyze neural circuits

1. Genetically engineered virus to visualize pre + post synaptic targets

2. Ca2+ imaging using Ca2+ dye labels

3. Optogenetics

Neural System

Organization of individual neural circuits according to the type of info they carry into broader networks + larger volumes so that more complex behaviors can be generated → unity of function!

Structural analysis of neural systems

1. Lesion studies reveal direction of info flow

2. Ways to label: Transgenic reporters (genes), antibody labeling (proteins), in situ hybridization (mRNA)

Functional analysis of neural systems

Determine what neurons do from moment to moment in an NS!

Use receptive field + single-unit recording to find relationship between peripheral stimuli + neuronal responses

Genomics

Analysis of the complete DNA sequence of a species or an individual; genome controls brain organization + function

Genetic analysis of neural systems

1. Genotype determines phenotype

2. Homozygosity mapping

3. GWAS

What is imaging the brain used for?

1. Discerning various anatomical structures

2. Diagnoses of medical problems, like tumor or stroke

3. Characterize activity of the brain as it performs complex tasks

Cognitive neuroscience

focuses on the underlying structural + functional representations manifesting as behaviors