self assessment three

Question 1

Draw, from memory, the entire central auditory system—Including all nuclei, lemnisci, crossovers, cortices, etc.—from VIII nerve to higher order auditory cortices

Answer 1

• (auditory/VIII CN/ spiral ganglion) →
• cochlear nucleus
• superior olivary complex
• (lateral lemniscus) (lemniscus= bundle of fibers)
• inferior colliculus
• medial geniculate nucleus/body
• auditory cortex

Question 2

Explain what a “complex sound picture” is, what makes up a complex sound picture, and how this concept is important when we consider the central auditory system

Answer 2

A complex sound picture refers to a soundscape that is made up of multiple sounds that interact with each other in some way. What makes up a complex sound picture depends on the context in which it is being used, but generally it includes a combination of sounds that work together to create a more dynamic and nuanced listening experience. For example, in music production, a complex sound picture might be achieved by layering multiple tracks of instruments, vocals, and effects.

The concept of a complex sound picture is important when we consider the central auditory system because it highlights the intricate and interconnected nature of auditory perception. The central auditory system is responsible for processing and organizing sounds that come into the ear, and it does so by analyzing various acoustic features such as pitch, timbre, and spatial location. When multiple sounds are presented simultaneously, the central auditory system must integrate and segregate them in order to create a coherent representation of the auditory scene. This process is made more challenging when dealing with complex sound pictures, as the sounds may be highly overlapping and/or have similar acoustic properties. However, the brain’s ability to process complex sound pictures is critical for understanding speech, music, and other complex auditory stimuli in the real world.

Question 3

List other systems that are connected to the auditory system / use auditory signals in their own processing

Answer 3

• emotion
• language
• speech
• other sensory systems
• attention
• memory
• executive function
• motor

Question 4

Understand all of the general principles of CANS physiology presented in the slides and tie them to specific concepts presented later in the unit

Question 5

Use my basic understanding of Central Auditory Processing Disorder to comprehend what the central auditory system does overall

Answer 5

• deficits in the neural processing of auditory information in the CANS not due to higher order language or cognition, as demonstrated by poor performance on the following tasks
  
  • auditory discrimination
  • temporal processing
    
    • auditory pattern recognition
    • temporal aspects of audition, including
      
      • temporal resolution (gap detection)
      • temporal ordering
      • temporal masking
  • binaural processing (signal to noise, localization and lateralization)

Question 6

Explain how parts of the CANS are tonotopically organized, how this aids in frequency processing, and how plasticity plays into this type of organization

Answer 6

The auditory system is tonotopically organized, meaning sounds of different frequencies are processed in different parts of the central auditory nervous system (CANS). Tonotopy is preserved along the auditory neural axis and reflects the topographically organized projections from the cochlea. High frequency sounds stimulate neurons located in the rostral regions of the auditory system, whereas low frequency sounds stimulate neurons located in the caudal regions. This tonotopic organization helps the brain process different frequencies of sound more efficiently by grouping together the neurons that respond to similar frequency ranges.

Plasticity, the ability of the brain to change and reorganize, also plays a role in tonotopic organization in the auditory system. During critical periods of development, auditory plasticity allows for changes in the tonotopic map to occur in response to changes in the statistical properties of the auditory environment. This plasticity could also result in a functional reorganization of the tonotopic map. Such changes have been described mainly in higher-order auditory regions and have been explained in terms of cross-modal plasticity.

Question 7

Fully describe how localization cues are processed by the various divisions of the superior olivary complex

Answer 7

The KEY to understanding this whole diagram is knowing that neurons A-F cannot fire unless they’re stimulated by incoming signals from BOTH ears
Walk through sound coming from front vs. sound coming from right
When sound is on left, it will send inputs from the left AVCN to all coincidence detector neurons. However, since the sound will take longer to reach the right ear, the neural signal from the right ear won’t meet up with the left ear neural signal until it’s “further away” from the left ear/”closer” to the right ear (i.e., the right ear has to catch up)
Over time, the brain learns that sounds that come far from the left cause coincidence detection (strong signal) at neuron F
Every point along the azimuth has a coincidence detector (receptive field)

Question 8

Differentiate the various divisions of the auditory cortex and explain their respective functions

Answer 8

We can subdivide auditory cortex into core, belt and parabelt regions

Core consists of tonotopically organized cells in two mirror symmetric organizations

Cells tend to have narrow frequency tuning and one peak frequency of interest  preference for pure tone

Belt region not clearly tonotopically organized.

Cells tend to have broader frequency tuning with multiple peak response frequencies  preference for complex tone

Parabelt cortex surrounds lateral part of belt. Anterior portion projects ventrally to anterior temporal and frontal lobe. Posterior portion projects to parietal and superior frontal. Basis of ventral and dorsal pathtyways

Question 9

Talk intelligently about the auditory “what” vs. “where” pathways and how these concepts contribute to our understanding of how speech and language are processed

Answer 9

Recognition/discrimination – recognizing a sound and telling the difference between sounds (even very similar sounds)
Interpretation – would refer to attaching meaning to the sounds that enter the auditory system
Integration – meaning combining sound signals with other sensory information, like visual information, to help in recognition and the formation of objects. By objects, I mean concepts in the brain that have sounds, visual forms, characteristics attached to them as we experience them in the world.
Memory – clearly memory would be involved in recognition, interpretation, integration – connections between the auditory system and different types of memory help us understand our current environment by recalling past experience.
These all have to do with WHAT a sound is
We are also able to tell WHERE a sound is coming from by localizing it. This helps in tasks like speech understanding in noisy situations—these functions are carried out by the CANS.

Question 10

Explain the basics about “non-traditional” and efferent auditory pathways

Answer 10

• getting startled