Chapter 4: Audition and Somatosensation

Question 1

acoustic energy

Answer 1

The movement of molecules f the gases that make up the air that’s all around us; or, when underwater, collisions between and movement of molecules of water.

Question 2

basilar membrane

Answer 2

The membrane within the cochlea whose vibrations effect the spectral transformation of sound, which is subsequently encoded in the cochlear nucleus’s place code. The base of the basilar membrane is the portion nearest the oval window, and is maximally displaced by high frequencies. The apex is the “far end” of the basilar membrane, and is maximally displaced by low frequencies.

Question 3

inner hair cells

Answer 3

Cells that are attached to the basilar membrane, the vibration of which causes them to release neurotransmitter onto a neuron of the cochlear nucleus, thereby effecting the transduction of acoustic energy into a neural signal.

Question 4

ganglion (pl. -glia)

Answer 4

Ganglion is a synonym for nucleus. The basal ganglia are a group of nuclei located near the base of the cerebrum, and anterior and lateral to the thalamus (see Figure 2.4). Their function is considered first in Chapter 7.

Question 5

barrel cortex

Answer 5

The region of rodent somatosensory cortex containing groupings of neurons in layer IV–“barrels”–that, together, represent somatosensory signals coming from a single whisker.

Question 6

outer hair cells

Answer 6

Cells anchored at one end to the basilar membrane, and at the other to the cochlea; their coordinated activity can dampen the vibrations of the basilar membrane in precise areas.

Question 7

rate code

Answer 7

A neural code whereby information about a change in some metric property is conveyed by a change in the rate at which a neuron fires.

Question 8

place code

Answer 8

The scheme whereby the representation of frequency (pitch) in the cochlear nucleus is laid out in a linear fashion, from high to low.

Question 9

traveling wave

Answer 9

A wave that propagates energy through a medium In the case of the cochlea, it characterizes the propagation of vibrational energy from the oval window along the length of the basilar membrane

Question 10

mechanoreceoptors

Answer 10

Receptors in the skin that respond to mechanical forces: pressure, texture, flutter, vibration, and stretch.

Question 11

power spectrum

Answer 11

A representation of the magnitude of each frequency resulting from a Fourier (or spectral) transform.

Question 12

power

Answer 12

The magnitude of an oscillatory component in a signal.

Question 13

spectrogram

Answer 13

A representation of how a power spectrum evolves over time.

Question 14

epilepsy

Answer 14

A chronic condition of repeating seizures.

Question 15

homunculus

Answer 15

A “little human” in the brain. In the context of somatosensory and motor neuroscience, the homunculus refers to the somatotopic representation of the post- and precentral gyri, respectively; in the context of psychology, the homunculus refers to a hypothetical little person inside the brain who is responsible for one’s cognitive functions.

Question 16

gating

Answer 16

The process of allowing certain signals to pass through a circuit, and preventing others.

Question 17

tonotopy

Answer 17

The organization of primary auditor cortex by frequency, which derives from the place code originating in the cochlear nucleus.

Question 18

thermoreceptors

Answer 18

Receptors in the skin that are tuned to detect heat or cold.

Question 19

resonant frequency

Answer 19

The frequency at which oscillations are most readily induced in a system, and at which it can oscillate at the greatest amplitude.

Question 20

plasticity

Answer 20

The property of nervous tissue that its structure and function can modify in response to a change in environmental inputs (or, indeed, to systematic changes of mental activity).

Question 21

proprioception

Answer 21

The sense of where different parts of the body are relative to one another.