The Structure of the Nervous System

Vocabulary practice flashcards covering structural neuroanatomy, embryonic brain vesicles, neuroimaging techniques, and modern connectomics from Chapter 7: The Structure of the Nervous System.

Computed Tomography (CT) Scan

A living brain imaging method developed by Allan M. Cormack and Godfrey N. Hounsfield (awarded the $1979$ Nobel Prize) that uses X-rays to generate cross-sectional views rapidly with no magnetic field hazard, but provides lower resolution than MRI and exposes patients to radiation.

Magnetic Resonance Imaging (MRI)

A living brain structural imaging technique recognized with a Nobel Prize in $2003$ that provides superior spatial resolution and avoids ionizing radiation, but requires longer acquisition times and poses safety risks near ferromagnetic materials.

Positron Emission Tomography (PET) Scan

A functional imaging technique that detects unstable radioactive isotopes attached to tracer molecules to visualize cellular metabolism (such as using $2$-deoxyglucose) or locate specific pathology (such as detecting $\beta$-amyloid with florbetapir).

Functional Magnetic Resonance Imaging (fMRI)

A functional imaging technique that measures hemodynamic changes in blood oxygen levels as a proxy measure for localized neuronal activity in the brain.

Neurulation

The embryonic developmental process occurring approximately $21\text{--}23$ days after conception in which the neural plate folds along the neural groove to form the neural tube and neural crest.

Neural Crest

A temporary population of ectodermal cells pinched off from the margins of the folding neural plate that gives rise to the peripheral nervous system (PNS).

Neural Tube

The primitive hollow cylinder formed by the fusion of the neural folds during embryogenesis that develops into the entire central nervous system (CNS), including the brain and spinal cord.

Three Primary Vesicles

The initial three rostral swellings of the neural tube during early embryonic differentiation: the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain).

Prosencephalon

The embryonic forebrain vesicle that subsequently differentiates into the telencephalon, diencephalon, and optic cups.

Mesencephalon

The embryonic midbrain vesicle that differentiates into the tectum on its dorsal side, the cerebral aqueduct, and the tegmentum on its ventral floor.

Rhombencephalon

The embryonic hindbrain vesicle that differentiates rostrally into the cerebellum and pons, and caudally into the medulla oblongata.

Telencephalon

The secondary forebrain division that expands bilaterally into two cerebral hemispheres, encompassing the cerebral cortex, basal telencephalon, and olfactory bulbs, while encasing the lateral ventricles.

Diencephalon

The central secondary forebrain structure located beneath and between the cerebral hemispheres that gives rise to the thalamus and hypothalamus while enclosing the third ventricle.

Optic Cups

Paired lateral outpocketings emerging from the embryonic diencephalon that differentiate into the retinas of the eyes.

Internal Capsule

A major subcortical forebrain white matter tract through which axons carry information between the cerebral cortex and lower brainstem or spinal cord.

Corpus Callosum

The massive cerebral commissural white matter bridge connecting cortical neurons between the left and right cerebral hemispheres.

Tectum

The dorsal roof region of the midbrain composed primarily of the superior colliculi and inferior colliculi.

Tegmentum

The ventral floor division of the midbrain containing nuclei involved in movement control, including the substantia nigra and red nucleus.

Cerebral Aqueduct

The narrow ventricular conduit running through the core of the midbrain connecting the third ventricle to the fourth ventricle.

Medullary Pyramids

Prominent paired triangular white matter ridges on the ventral surface of the medulla oblongata carrying descending corticospinal motor axons.

Precentral Gyrus

The frontal lobe convolution positioned immediately anterior to the central sulcus that executes voluntary movement control.

Postcentral Gyrus

The parietal lobe convolution located directly posterior to the central sulcus that serves as the primary cortical area for the sense of touch.

Subthalamic Nucleus

A basal ganglia-associated nucleus targeted by deep brain stimulation (DBS) implants to alleviate motor symptoms in Parkinson's disease by bypassing damaged substantia nigra circuits.

Superior Colliculus

A paired midbrain tectal nucleus that receives direct optic input and directs orientation reflexes and eye movements.

Inferior Colliculus

A paired midbrain tectal structure serving as an obligatory auditory relay nucleus that routes ascending sound information to the medial geniculate nucleus.

Superior Olive

A brainstem auditory processing nucleus situated in the rostral medulla/pons that receives binaural signals from cochlear nuclei to compute auditory localization.

Medial Geniculate Nucleus (MGN)

The specific thalamic relay nucleus dedicated to the auditory pathway that conveys sound signals via acoustic radiation to the primary auditory cortex.

Tupaia glis

The scientific name for the tree shrew, an animal model utilized by Carey, Bear, and Diamond ($1980$) to investigate the laminar organization of reciprocal projections between the claustrum and striate cortex.

Phonemic Paraphasia

A specific phonological naming error elicited in Patient AG during intraoperative awake brain mapping using direct electrical cortical stimulation during picture-naming trials.

Caenorhabditis elegans Connectome

The first completely mapped wiring diagram of an animal nervous system, consisting of exactly $302$ neurons and their synaptic connections described by Cook et al. ($2019$).

NEURD

An automated proofreading and quantitative morphological feature-extraction framework designed for dense electron microscopy connectomics datasets.