Week 1b: Anatomy & Neural Processes Flashcards
Afferent
An axon that conducts action potentials from the periphery toward the central nervous system.
Anterior
Towards the front of an animal or structure. Anterior may be used as a synonym for rostral or ventral.
Auditory Nerve Bundle
The auditory (or cochlear) nerve bundle is one half of the vestibulocochlear nerve, labeled cranial nerve VIII. It refers to the nerves that carry sensory information from the cochlea to the primary auditory cortex.
Auditory Pathway
Neural structures serving the auditory system from the inner ears to the primary auditory cortex in the temporal lobes.
Brainstem
The portion of the central nervous system that lies between the spinal cord and the cerebrum; it comprises the medulla, pons, and midbrain.
Central Sulcus
A major sulcus that forms the boundary between the frontal and parietal lobes. The primary motor cortex is anterior to the central sulcus; the somatosensory cortex is posterior to the sulcus.
Cerebellum
Prominent hindbrain structure that routes much nervous system activity between the cerebrum and spinal cord, especially signals concerned with movement, posture, and balance.
Cerebrum
The largest region of the brain in humans and other animals, consisting of two cerebral hemispheres.
Cochlea
The coiled structure within the inner ear where vibrations are transduced into mechanical (on the basilar membrane) and electrochemical (in the hair cell) activity that is interpreted as sound.
Cochlear Nucleus
A structural complex that is the first destination for nerve spikes arriving from the cochlea via the auditory nerve, and is the first auditory information processing stage. Left and right cochlear nuclei are located in the medulla of the brainstem.
Contralateral
Relating to or denoting the opposite side of the body from a particular structure or event; cf. ipsilateral.
Coronal Plane
An imaginary plane dividing the brain into front and back halves. A coronal view shows a cutaway of the brain from either the face side or the back of the head.
Corpus Callosum
The large midline fiber bundle connecting the cortices of the two cerebral hemispheres. It is viewed from the sagittal plane.
Cortex (pl. Cortices)
The surface layer of the brain, approximately 2-4 millimeters thick, composed of gray matter. In humans the cortex has multiple folds to permit greater surface area within the skull.
Efferent
An axon that conducts information away from the central nervous system and towards a muscle or organ.
Frontal Lobe
One of the four lobes of the brain; includes all of the cortex that lies anterior to the central sulcus and superior to the lateral fissure.
Gray Matter
General term that describes regions of the central nervous system rich in neuronal cell bodies; it includes the cortices, cerebellum, and the central portion of the spinal cord.
Gyrus (pl. Gyri)
The ridges of the folded cortical layer of the brain.
Hair Cells
The sensory cells of the inner ear that transduce mechanical activity into electrochemical nerve spikes to produce the sensation of sound.
Heschl’s Gyrus
The primary auditory cortex; also called A1. The location of Brodmann’s areas 41 and 42. Heschl’s gyrus is the destination for auditory nerve fibers innervating the cochlea.
Hippocampus
A cortical structure in the medial portion of the temporal lobe; in humans it is essential for memory formation, among many other functions.
Inferior Colliculus
Nuclei (left, right) located in the midbrain innervating the thalamus and primary auditory cortex. Inferior colliculi receive neural signals directly from cochlear nuclei, superior olivary complexes, and somatosensory nuclei. It is the first higher-order processing stage in hearing.
Inner Ear
The bony labyrinth of the cochlea and semicircular canals that serve hearing and balance; it innervates cranial nerve VIII—the vestibulocochlear nerve.
Inner Hair Cells
In humans, mechanical activity from the basilar membrane causes electrochemical activity in a single row of approximately 3,500 inner hair cells (IHC) of the cochlea. Action potentials produced by IHCs send afferent signals up the auditory nerve bundle to reach the primary auditory cortex.
Ipsilateral
Relating to or denoting the same side of the body from a particular structure or event; cf. contralateral.
Lateral (Sylvian) Fissure
The anterior to posterior sulcus on each side of the brain that separates the frontal and temporal lobes.
Limbic System
A term that refers to the cortical and subcortical structures concerned with the emotions. Prominent structures in the limbic system include: cingulate gyrus, hippocampus, amygdala, fornix, septum, and mammillary bodies.
Lobes
The four major divisions of the cerebral cortex: frontal, occipital, parietal, and temporal.
Midbrain
A structure at the topmost (or rostral) portion of the brainstem. The midbrain houses the superior and inferior colliculi and is important for vision, sound, sleep/wake cycles, and thermoregulation.
Middle Ear
The area between the tympanic membrane and oval window, comprising the ossicles and connecting structures. It functions as an impedance matching device to efficiently transfer airborne acoustic energy to the fluid-filled cochlea.
Nucleus (pl. nuclei)
Collections of nerve cells in the brain that are anatomically discrete and that typically serve a particular function.
Nucleus of the Lateral Lemniscus
An auditory processing stage fed from the superior olivary complex and feeding the inferior colliculus. Its function is not known, however it has good temporal resolution compared to other cells and is sensitive to both timing and amplitude changes in sound. The nucleus of the lateral lemniscus is also involved in the acoustic startle reflex.
Occipital Lobe
The posterior lobe of the cerebral hemisphere, it is primarily dedicated to vision processing.
Outer Ear
Referring to the auditory pathway from the external meatus (pinnae) and ear canal to the tympanic membrane (eardrum).
Outer Hair Cells
In humans, efferent signals from the auditory cortex cause electromechanical activity in a (mostly) triple row of approximately 12,000 outer hair cells (OHC) of the cochlea. OHCs expand and contract in response to action potentials, amplifying and attenuating activity on the basilar membrane and helping the listener to focus or ignore sound sources.
Parietal Lobe
The lobe of the brain that lies between the frontal lobe (anterior) and the occipital lobe (posterior), the parietal lobe is mainly responsible for motor skills and relaying inputs from the senses to muscle commands.
Posterior
Towards the back of an animal or structure. Posterior may be used as a synonym for caudal or dorsal.
Primary Auditory Cortex
The major cortical target of the auditory nerve bundle, the primary auditory cortex or A1 is located in the superior temporal gyrus. Its frequency response properties are organized such that there is a one-to-one frequency map on A1 corresponding to the tonotopic organization of the basilar membrane. Low frequencies are processed anterolaterally; high frequencies are processed more deeply in the lateral fissure, posterior to the low frequency region.
Sagittal
The sagittal anatomical plane divides the body or brain into left and right parts. A sagittal view of the brain is a cutaway of either the left or right hemisphere.
Sulcus (pl. Sulci)
The folds or valleys of the folded cortical layer of the brain.
Superior Colliculus
Laminated structure at the top of the midbrain, just above the inferior colliculus; the superior colliculus plays an important role in orienting movement of the head and eyes.
Superior Olivary Complex (SO)
The auditory brainstem structure after the cochlear nuclei and before the nucleus of the lateral lemniscus. The SO processes intensity and timing differences between the left and right ears, mediating spatial localization.
Temporal Lobe
One of the four lobes of the human brain, below the frontal lobe and the lateral fissure; site of the primary auditory cortex and speech processing regions. The word “temporal” refers to timing.
White Matter
A general term to refer to large axon tracts in the brain and spinal cord; the phrase derives from the fact that axonal tracts have a whitish color.
Medial Geniculate Nucleus
Located in the medial region of the left and right thalamus, this nucleus is a major relay
for auditory information between the brainstem and cortex. It is adjacent to the lateral
geniculate nucleus that performs the same function for visual input.
