Psych 7

• Sound waves


  Undulating displacement of molecules caused by changing pressure

  
• Sound waves


  • Compression and rarefaction of molecules in a fluid

  
• Summary of wave qualities

  • Amplitude (loudness)
  • Frequency (pitch)
  • Purity (timbre)

  
• Pure tones


  Sounds with a single frequency
• Complex tones


  Sounds with a mixture of frequencies
• Fundamental frequency


  Rate at which the complex waveform pattern repeats

  
• Overtones


  Set of higher-frequency sound waves that vibrate at whole-number (integer) multiples of the fundamental frequency

  
• The auditory system collects sound waves from the surrounding air, converts (transduces) mechanical energy to electrochemical neural energy, and includes information about frequency, amplitude, and complexity

  
• Three major parts of the ear

  • External ear (pinna, ear canal)
  • Middle ear (the ossicles)
  • Inner ear (the cochlea)

  
• External/outer ear


  • Pinna funnels sound waves into the ear canal, which amplifies and directs them to the eardrum

  
• Middle ear


  • Ossicles (hammer, anvil, stirrup) connect the eardrum to the oval window of the cochlea

  
• Inner ear


  • Cochlea contains the auditory receptor cells, basilar membrane, and hair cells

  
• Place theory


  Pitch perception corresponds to the vibration of different portions, or places, along the basilar membrane

  
• Frequency theory


  Pitch perception corresponds to the rate, or frequency, at which the entire basilar membrane vibrates

  
• Pitch perception depends on both place and frequency coding of vibrations

  
• Transduction


  Sound waves are transduced to neural activity in the hair cells

  
• Hair cells


  • Inner hair cells (auditory receptors)
  • Outer hair cells (alter stiffness of tectorial membrane)

  
• Transduction


  • Movement of cilia on hair cells changes membrane potential and alters neurotransmitter release

  
• Pathways to the auditory cortex

  1. Inner hair cells synapse on bipolar cells whose axons form the auditory/cochlear nerve

  2. Enters the brainstem, synapses in the cochlear nucleus

  3. Goes to both hemispheres to integrate processing

  4. Cochlear nucleus projects to superior olive and trapezoid body

  5. From the hindbrain, information projects into the inferior colliculus

  6. Two distinct pathways from inferior colliculus: ventral medial geniculate nucleus to primary auditory cortex, dorsal medial geniculate nucleus to other auditory regions

  
• Primary auditory cortex


  • Lies within Heschl's gyrus in left hemisphere, has specialized response to music in right hemisphere

  
• Lateralization


  Process whereby functions become localized primarily on one side of the brain
• About 70% of left-handed people have language in the left hemisphere, while the remaining 30% have speech represented either in the right hemisphere or bilaterally
• Insular cortex


  Multifunctional cortical tissue containing regions related to language, perception of taste, and social cognition
• Tonotopic representation of the basilar membrane is reproduced in the cochlear nucleus and maintained throughout the auditory pathways and into the primary auditory cortex

  
• Detecting location


  • Neurons in brainstem compute difference in sound wave's arrival time at each ear (interaural time difference), and relative loudness on the left and right (interaural intensity difference)

  
• Ventral pathway


  Decodes spectrally complex sounds (auditory object recognition), including meaning of speech sounds

  
• Dorsal pathway


  Integrates auditory and somatosensory information to control speech production (audition for action)

  
• Innate and learned language

  Genetic constraints responsible for common structural characteristics across languages, experience required for language learning
• Localizing language in the brain

  • Broca's area (anterior speech area) functions with motor cortex to produce speech movements, Wernicke's area (posterior speech area) regulates language comprehension

  
• Broca's aphasia

  Inability to speak fluently despite normal comprehension and intact vocal mechanisms
• Wernicke's aphasia


  Inability to understand or produce meaningful language even though the production of words is still intact
• Somatosensory system


  Responsible for perception of bodily sensations such as touch, temperature, pain, position in space, and movement of the joints
• Somatosensory system


  • Distributed system, essential in guiding motor movements, closely integrated with the motor system
• Glabrous skin


  Covers areas used to interact with the environment, does not have hair follicles, higher density of sensory receptors, more sensitive
• Hairy skin


  Covers the rest of the body, has hair follicles, lower density of sensory receptors, less sensitive
• Rapidly adapting receptor


  Body sensory receptor that responds briefly to the beginning and end of a stimulus on the body
• Slowly adapting receptor


  Body sensory receptor that responds as long as a sensory stimulus is on the body
• Rapidly adapting receptors


  • Meissner corpuscle (respond to rapid vibrations on glabrous skin)
  • Pacinian corpuscle (respond to rapid vibrations and deep pressure)
• Slowly adapting receptors


  • Merkel discs (respond to light touch on hairy skin)
  • Ruffini corpuscle (respond to slow stretching of the skin)
• Classifying Somatosensory Receptors


  • Rapidly Adapting Receptors
  • Slowly Adapting Receptors