10 Upper Pathways

Question 1

What is perfect pitch?

Answer 1

The ability of certain people to recognise a sound without a reference

Question 2

What is a definition for the hearing abnormality, Tinnitus?

Answer 2

Tinnitus is the perception of noise or ringing in the ears when no external sound is present. (hearing a sound with no external source)

It’s assumed that tinnitus comes from something which is not working correctly in the Central Auditory system

Question 3

What is sound?

Answer 3

Sound can be defined as a change in air pressure

Question 4

What is the function of the superior olivary nucleus in the auditory pathway?

Answer 4

The superior olivary nucleus detects if the sound is coming from the left or right ear, acting as a localization of the sound by comparing the amplitude and timing of the sound.

Question 5

What is the main nucleus of the auditory midbrain, and what is its role?

Answer 5

The main nucleus of the auditory midbrain is the inferior colliculus, which is the first station where all sound information from the left and right ear is merged together.

Question 6

Which region of the brain receives inputs from the inferior colliculus?

Answer 6

The thalamus receives inputs from the inferior colliculus.

It is then sent to the auditory cortex

Question 7

What are the divisions of the medial geniculate body of the thalamus?

Answer 7

The divisions of the medial geniculate body of the thalamus are central, external, and dorsal.

Question 8

What are the key functions of the amygdala in relation to the auditory pathway?

Answer 8

The amygdala is responsible for processing emotions, and it receives inputs from the auditory thalamus.

Question 9

Describe the organization of the auditory cortex.

Answer 9

The auditory cortex is organized in a canonical way of intermingled excitatory and inhibitory neurons that can be separated into 6 different layers.

Question 10

Where does the auditory cortex receive information from?

Answer 10

The auditory cortex receives information from the thalamus, specifically in the middle of the cortex at layers 3 and 4.

Question 11

What equipment is used in the Brain and Sound lab to measure neuronal activity in the auditory cortex of a mouse?

Answer 11

An electrophysiological rig is used in the Brain and Sound lab to measure neuronal activity in the auditory cortex.

Question 12

How is the activity of neurons in the auditory cortex measured?

Answer 12

The activity of neurons is measured using electrodes, which can be inserted into the auditory cortex to record changes in voltage and extract information about the spiking activity of neurons.

Question 13

What does each dot of a raster plot correspond to in the context of action potentials?

Answer 13

Every dot corresponds to a recorded action potential.

Question 14

How can a neurons sensitivity to specific frequencies be determined?

Answer 14

1. Look at the raster plot response for a specific frequencies
2. By observing the locations of the most responses, one can determine the most sensitive frequency range for a specific neuron
   (a Peri-Stimulus Time Histogram [PSTH] also shows something similar)

Question 15

What does a tonotopic map show?

Answer 15

A tonotopic map shows how different neurons responded to different frequencies.

Question 16

What is synaptic transmission?

Answer 16

Synaptic transmission is the process by which one neuron communicates with another.

Question 17

How is information passed down a neuron?

Answer 17

Information is passed down the axon of the neuron as an electrical impulse known as an action potential.

Question 18

What happens when the action potential reaches the end of the axon?

Answer 18

It needs to be transferred to another neuron.

Question 19

How does the rest of the brain influence sound perception?

Answer 19

The rest of the brain influences sound perception through connections, such as the motor cortex having a direct connection to the auditory cortex.

Question 20

What was shown in EEG measurements regarding sound response in the brain?

Answer 20

EEG measurements indicated that the response to sound in the brain is influenced by activities, such as when humans walk.

Question 21

What are the components of the hearing system?

Answer 21

The hearing system consists of:
- Auditory sensory organs
- Nervous system auditory pathways
- Brain structures that receive, analyze, and interpret sound information.

Question 22

When does sensory neuron plasticity occur?

Answer 22

Sensory neuron plasticity is fundamental during the late intrauterine (3 months before birth in humans) and at childhood/adolescence, where plasticity is highest.

Question 23

What are the impacts of hearing loss?

Answer 23

Hearing loss decreases the ability to perceive sounds, which causes several limitations in individual development and affects the ability to understand information contained in sound, as well as the way an individual may relate to the environment and culture.

Question 24

What does neuroplasticity mean?

Answer 24

Neuroplasticity refers to the ability of the central nervous system to adapt to different stimuli.

Question 25

What is auditory plasticity?

Answer 25

Auditory plasticity is the ability that the auditory system has to change anatomically or functionally.

Question 26

What does brain plasticity allow?

Answer 26

Brain plasticity is an intrinsic property of the nervous system that allows structures to change in response to experience and changes in the environment.

Question 27

What does the alteration of sensory maps indicate?

Answer 27

The alteration of sensory maps indicates that plasticity or reorganization of the sensory map has taken place.

Question 28

What is the time course of plasticity in the auditory system?

Answer 28

The time course of plasticity ranges from very rapid stimulus-specific adaptation to longer-term changes associated with partial hearing loss or perceptual learning.

Question 29

How does the auditory system respond to variations in auditory input?

Answer 29

The auditory system reorganizes itself after any variation in auditory input, which may result from decreased stimulus input, cochlear injury, new postnatal development, cochlear implants, or hearing aids.

Question 30

What changes might occur with age in the auditory nervous center?

Answer 30

Age-related neural stability may change, and plasticity in the auditory nervous center appears to become slower in mature nervous systems, although it persists throughout life.

Question 31

What are the two types of plasticity in the auditory system?

Answer 31

Changes in the anatomical or physiological properties of the central auditory system may be induced by sensorineural hearing loss (primary plasticity), by reintroducing auditory stimuli (secondary plasticity), or by conditioning.

Question 32

How does neural plasticity due to hearing loss affect the tonotopic map?

Answer 32

Neural plasticity due to hearing loss results in tonotopic map changes.

Question 33

What happens when a tip of an electrode is inserted into a single neuron during electrophysiology?

Answer 33

Inserting the tip into a single cell allows direct observation and recording of intracellular electrical activity, but it may reduce the life of the cell and cause leakage of substances across the cell membrane.

Question 34

What is the significance of calcium imaging in neuroscience?

Answer 34

Calcium imaging is significant because electrical activity in neurons is always accompanied by an influx of Ca²⁺ ions, allowing it to monitor the electrical activity of many neurons.

Question 35

What does voltage-sensitive dye imaging (VSDI) visualize?

Answer 35

VSDI visualizes cortical activity of large neuronal populations with high spatial resolution and high temporal resolution.

Question 36

What is the procedure for applying voltage-sensitive dyes in VSDI?

Answer 36

The procedure involves opening the skull and dura mater, applying dye molecules to the cortex surface, allowing them to bind to cell membranes without disrupting normal function.

Question 37

What is stimulus-specific adaptation (SSA)?

Answer 37

Stimulus-specific adaptation is a reduction in the response of a neuron to a repeated stimulus, which does not generalize or only weakly generalizes to other stimuli.

Question 38

What have studies of injury-induced plasticity in other modalities found after weeks or months?

Answer 38

Studies have found evidence of structural changes associated with cortical reorganization.

Question 39

What immediate changes are seen after cochlear trauma in adult animals?

Answer 39

Changes in frequency response areas are seen immediately following cochlear trauma.

Question 40

What is a contrasting form of plasticity produced by cochlear insults?

Answer 40

Increases in spontaneous firing rates, hyperactivity, and neural synchrony occur in the cochlear nucleus and in all higher centers.

Question 41

What symptoms have changes identified in cochlear nuclei been associated with?

Answer 41

These changes have been identified as possible generators of tinnitus and hyperacusis.

Question 42

Is plasticity driven by partial hearing loss adaptive or maladaptive?

Answer 42

Plasticity driven by partial hearing loss is almost certainly maladaptive; the changes do not compensate for the hearing loss.

Question 43

What role does brain plasticity play in cochlear implants?

Answer 43

The remarkable success of cochlear implants in restoring functional hearing in the profoundly deaf is largely attributable to brain plasticity.

Question 44

What phenomenon occurs when one sensory modality is lost?

Answer 44

Loss of one sensory modality can result in enhanced discriminative abilities in other modalities.

Question 45

What do cortical offset responses improve?

Answer 45

Cortical offset responses are amplified and facilitate the detection of sound termination.

Question 46

What can cochlear implants help researchers understand?

Answer 46

Cochlear implants can be used to understand disease models and maladaptive plasticity of the central auditory system.