7.3

• A band of areas of secondary auditory cortex surrounding the core region.

  Belt
• Areas of secondary auditory cortex outside the belt.

  Parabelt areas
• There seem to be about 13 separate areas of auditory cortex in primates.
• Three important principles of organization of primary auditory cortex:

  1. The primary auditory cortex is organized in functional columns.
  2. Auditory cortex has a tonotopic organization.
  3. Periodotopy
• Auditory cortex is also organized according to the temporal components of sound; that is, variations in the amplitude of particular sound frequencies over time.

  Periodotopy
• What analyses does the auditory cortex perform?

  It is also known to integrate information about the current perceptions and behaviors of an animal in order to produce auditory signals that are relevant to the animal’s current situation.
• Two streams of auditory cortex:

  1. prefrontal cortex
  2. posterior parietal cortex
• This pathway is more involved in identifying sounds (what).

  anterior auditory pathway
• This pathway is more involved in locating sounds (where).

  posterior auditory pathway
• True or False, sensory system interaction is not merely tagged on after unimodal (involving one system) analyses are complete; sensory system interactions seem to be an early and integral part of sensory processing.

  True
• Where does the perception of pitch occur?

  One small area just anterior to primary auditory cortex that contained many neurons that responded to pitch rather than frequency.
• Importance of studying the damage of the auditory system:

  1. It provides information about how the auditory system works.
  2. Serve as a source of information about the causes and treatment of clinical deafness.
• When there are bilateral lesions in the primary auditory cortex, it usually causes complete loss of hearing which presumably results from the shock of the lesion because hearing recovers in the ensuing weeks.
• The major permanent effects of bilateral lesions in the primary auditory cortex are loss of the ability to process the structural aspects of sounds— an ability that is necessary for the processing of speech sounds
• Patients with bilateral auditory cortex lesions are often said to be “word deaf”
• Hearing impairment affects more than one’s ability to detect sounds: it can lead to

  (1) feelings of social isolation and has been

  (2) associated with an increased risk for dementia.
• Total deafness is rare, occurring in only 1 percent of hearing-impaired individuals.
• Two common classes of hearing impairments:

  1. Conductive Deafness
  2. Nerve Deafness
• Associated with damage to the ossicles.

  Conductive Deafness
• Associated with damage to the cochlea or auditory nerve. One of its major cause of nerve deafness is a loss of hair cell receptors.

  Nerve Deafness