Week 1b: Anatomy & Neural Processes

Question 1

Afferent

Answer 1

An axon that conducts action potentials from the periphery toward the central nervous system.

Question 2

Anterior

Answer 2

Towards the front of an animal or structure. Anterior may be used as a synonym for rostral or ventral.

Question 3

Auditory Nerve Bundle

Answer 3

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.

Question 4

Auditory Pathway

Answer 4

Neural structures serving the auditory system from the inner ears to the primary auditory cortex in the temporal lobes.

Question 5

Brainstem

Answer 5

The portion of the central nervous system that lies between the spinal cord and the cerebrum; it comprises the medulla, pons, and midbrain.

Question 6

Central Sulcus

Answer 6

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.

Question 7

Cerebellum

Answer 7

Prominent hindbrain structure that routes much nervous system activity between the cerebrum and spinal cord, especially signals concerned with movement, posture, and balance.

Question 8

Cerebrum

Answer 8

The largest region of the brain in humans and other animals, consisting of two cerebral hemispheres.

Question 9

Cochlea

Answer 9

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.

Question 10

Cochlear Nucleus

Answer 10

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.

Question 11

Contralateral

Answer 11

Relating to or denoting the opposite side of the body from a particular structure or event; cf. ipsilateral.

Question 12

Coronal Plane

Answer 12

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.

Question 13

Corpus Callosum

Answer 13

The large midline fiber bundle connecting the cortices of the two cerebral hemispheres. It is viewed from the sagittal plane.

Question 14

Cortex (pl. Cortices)

Answer 14

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.

Question 15

Efferent

Answer 15

An axon that conducts information away from the central nervous system and towards a muscle or organ.

Question 16

Frontal Lobe

Answer 16

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.

Question 17

Gray Matter

Answer 17

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.

Question 18

Gyrus (pl. Gyri)

Answer 18

The ridges of the folded cortical layer of the brain.

Question 19

Hair Cells

Answer 19

The sensory cells of the inner ear that transduce mechanical activity into electrochemical nerve spikes to produce the sensation of sound.

Question 20

Heschl’s Gyrus

Answer 20

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.

Question 21

Hippocampus

Answer 21

A cortical structure in the medial portion of the temporal lobe; in humans it is essential for memory formation, among many other functions.

Question 22

Inferior Colliculus

Answer 22

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.

Question 23

Inner Ear

Answer 23

The bony labyrinth of the cochlea and semicircular canals that serve hearing and balance; it innervates cranial nerve VIII—the vestibulocochlear nerve.

Question 24

Inner Hair Cells

Answer 24

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.

Question 25

Ipsilateral

Answer 25

Relating to or denoting the same side of the body from a particular structure or event; cf. contralateral.

Question 26

Lateral (Sylvian) Fissure

Answer 26

The anterior to posterior sulcus on each side of the brain that separates the frontal and temporal lobes.

Question 27

Limbic System

Answer 27

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.

Question 28

Lobes

Answer 28

The four major divisions of the cerebral cortex: frontal, occipital, parietal, and temporal.

Question 29

Midbrain

Answer 29

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.

Question 30

Middle Ear

Answer 30

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.

Question 31

Nucleus (pl. nuclei)

Answer 31

Collections of nerve cells in the brain that are anatomically discrete and that typically serve a particular function.

Question 32

Nucleus of the Lateral Lemniscus

Answer 32

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.

Question 33

Occipital Lobe

Answer 33

The posterior lobe of the cerebral hemisphere, it is primarily dedicated to vision processing.

Question 34

Outer Ear

Answer 34

Referring to the auditory pathway from the external meatus (pinnae) and ear canal to the tympanic membrane (eardrum).

Question 35

Outer Hair Cells

Answer 35

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.

Question 36

Parietal Lobe

Answer 36

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.

Question 37

Posterior

Answer 37

Towards the back of an animal or structure. Posterior may be used as a synonym for caudal or dorsal.

Question 38

Primary Auditory Cortex

Answer 38

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.

Question 39

Sagittal

Answer 39

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.

Question 40

Sulcus (pl. Sulci)

Answer 40

The folds or valleys of the folded cortical layer of the brain.

Question 41

Superior Colliculus

Answer 41

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.

Question 42

Superior Olivary Complex (SO)

Answer 42

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.

Question 43

Temporal Lobe

Answer 43

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.

Question 44

White Matter

Answer 44

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.

Question 45

Medial Geniculate Nucleus

Answer 45

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.