AUDITION & BODY SENSES

Question 1

How does sound travel through a medium like air?

Answer 1

• Sound travels as oscillations, e.g. > compressions & rarefactions in density of air molecules > forming waves.

Question 2

What is Fourier analysis, and how is it related to sound?

Answer 2

• Fourier analysis decomposes complex waveforms, like sound, into a set of sine waves with different frequencies, intensities, & phases.

Question 3

what are the characteristics of sound?

Answer 3

• frequency (pitch) > rate which waves vibrate > hertz> corresponds to perception of pitch > low freq= low pitched, high freq= high pitched
• amplitude (loudness) > intensity of sound > decibels > corresponds to perception of loudness > high amp = sound sound, low amp = soft sound
• complexity (timbre) > perceived uniqueness > nature of sound e.g. distinguish sound of trombone from violin playing sound > simple/ complex

Question 4

How are sounds described in terms of frequency and intensity

Answer 4

• Frequency = measured in Hertz (Hz) > number of oscillations per unit of time
• Intensity > height of the sine wave, measured in decibels (dB) > w/ a 20 dB increase representing a tenfold sound pressure increase.

Question 5

What distinguishes different sounds, even when they share the same note?

Answer 5

• Most sounds > inc > those from musical instruments, consist of multiple frequency components > contributing to their distinctive timbre.

Question 6

What are the components of the outer ear, and how do they contribute to sound perception?

Answer 6

• outer ear: inc> the pinna (visible ear) & ear canal
• the pinna = aids sound localisation
• the ear canal’s > has a resonant frequency > naturally amplifies sounds in the 3000 Hz range (3 khz) range > which is biologically important for our ability to understand speech & other meaningful sounds in our environment

Question 7

Explain the components and function of the middle ear.

Answer 7

• middle ear: comprises the tympanic membrane (ear drum), ossicles, & oval & round windows
• Ossicles > amplify pressure waves = aiding transmission from air (eardrum) to fluid (inner ear).
• Two muscles (tensor tympani and stapedius muscles) can dampen this amplification as a defense mechanism = protect inner ear from extreme loud sounds

Question 8

How does the inner ear process sound?

Answer 8

• The inner ear’s cochlea contains organ of Corti, hair cells, & basilar membrane
• Sound waves enter ear canal & cause the tympanic membrane (eardrum) to vibrate> vibrations are transmitted through the ossicles (malleus, incus, and stapes) in the middle ear, amplifying the sound> Hair cells respond to sound vibrations > by bending cilia on hair = changes in cell’s membrane potential & release of neurotransmitters > cochlear nerve sends messages to the brain.

Question 9

How is pitch coded in the auditory system?

Answer 9

• The basilar membrane’s variation along its length > allows for place code model > where diff frequencies activate specific locations
• the temporal code > helps determine the frequency of low-frequency sounds.

Question 10

What is the frequency tuning of auditory nerve fibers?

Answer 10

• Auditory nerve fibers exhibit frequency tuning > where each fiber has a preferred frequency but can respond to a range of frequencies.
• individually ambiguous
• rate reflects frequency & intensity

Question 11

How does the brain determine the location of a sound source?

Answer 11

• Sound localisation > involves cues from differences in arrival times & loudness at each ear > combined in superior olive (receives inputs from both ears & integrates info regarding time delay & loudness differences = helps brain determine location)
• Pinna filtering properties also contribute to localisation

Question 12

Describe the primary auditory cortex and its functions.

Answer 12

• The primary auditory cortex > receiving info from inferior colliculus & medial geniculate nucleus (MGN)> contains a tonotopic map (diff frequencies of sound are represented spatially in an organised manner)> responding to different frequencies.
• responsible for receiving, analysing, & beginning the interpretation of auditory signals > It plays a vital role in our ability to perceive auditory information

Question 13

What is somatosensation, and what are its receptors?

Answer 13

• Somatosensation: responsible for perceiving and interpreting sensations related to the body and its interactions with the environment > inc: sensations from cutaneous receptors in skin & proprioceptors in muscles & joints (contributing to body awareness and coordination)
• Receptors inc > free nerve endings & mechanoreceptors (Detect deep pressure and vibration)
  -info gathered by these receptors is transmitted through the nervous system to the brain = allow for perception & appropriate responses to various sensory stimuli

Question 14

How does somatosensory information travel to the brain?

Answer 14

• Somatosensory info > travels through three main pathways: spinothalamic tract (pain), dorsal column medial lemniscus tract (touch, proprioception), & spinocerebellar tract (proprioception to the cerebellum).

Question 15

What is the significance of sensory homunculi in primary somatosensory cortex?

Answer 15

• Sensory homunculi > representation of the human body> body parts are mapped onto specific areas of cortex based on their sensitivity & amount of cortical space dedicated to processing sensory info (somatotopic map)
• reflecting concentration of receptors across the body & indicating tactile acuity > body parts with greater sensory acuity have larger representations

Question 16

What is the Interval Time Difference (ITD) system?

Answer 16

• mechanism used by brain for sound localisation
• relies on detecting time difference between when a sound reaches one ear compared to other
• This temporal info = helps brain determine direction from which sound originates.

Question 17

What are coincidence detector cells?

Answer 17

• neurons in auditory system that respond when they receive simultaneous inputs from both ears
• play in sound localisation > by detecting the slight time differences (interaural time differences) in arrival of sounds at each ear

Question 18

How do the filtering properties of the pinna contribute to sound localisation?

Answer 18

• the external and visible part of the ear
• sounds are filtered as they enter ear canal = brain determine direction of sound sources > accurate spatial localisation based on spectral composition of the incoming sounds.

Question 19

What is the delay line theory/model in sound localisation?

Answer 19

• proposes brain determines direction of a sound source by detecting the slight time differences between when a sound reaches one ear compared to the other
• This time delay provides info for the brain to localise source of sound in space

Question 20

what does the core auditory cortex contain?

Answer 20

• 3 tonotopic map > where diff areas code for diff frequencies > responds well to pure tone stimuli & is surrounded by the belt and parabelt regions > which respond to more complex auditory stimuli such as conspecific calls, swooshes, and glides.

Question 21

what is kinaesthesis?

Answer 21

• provide info about > muscle stretch from muscle spindles, tendon stretch from Golgi tendon organs
• allows us to perceive position & movement of our own body parts > It involves receptors in muscles, tendons, & joints > providing feedback about body’s motion and orientation

Question 22

What is proprioception and movement?

Answer 22

• Proprioception > sense of relative position of one’s own body parts & sense of movement & effort involved in making movements

Question 23

what does it mean if someone has Proprioception impairment?

Answer 23

• difficulty or a lack of awareness regarding position & movement of their own body parts > affect coordination, spatial orientation, & ability to control movements accurately
• result from disruptions in proprioceptive sensory system.
• patients with large fire sensory neuropathy (e.g. Ian waterman) no longer get feedback w/o vision

Question 24

What are the different types of receptors in touch fibres?

Answer 24

• Merkel’s disks (slow-adapting, small receptive fields)
• Ruffini corpuscles (slow-adapting, large receptive fields)
• Meissner’s corpuscles (fast-adapting, small receptive fields)
• Pacinian corpuscles (fast-adapting, large receptive fields)

Question 25

What are mechanoreceptors?

Answer 25

• sensory receptors that respond to mechanical stimuli > e.g. > pressure, touch, or vibration
• inc: Merkel’s disks, Ruffini corpuscles, Meissner’s corpuscles,

Question 26

what are spinal pathways?

Answer 26

• neural circuits within spinal cord > transmit sensory info from periphery to the brain (ascending pathways) or motor commands from the brain to the muscles (descending pathways)
• essential for communication between diff parts of nervous system + role in sensory perception & motor control.

Question 27

What information do spinal pathways transmit?

Answer 27

• transmit sensory info from periphery to brain> touch, pain, temperature, & proprioception
• transmit motor commands from brain to muscles > facilitating voluntary movements & motor control.