Audition- Stimulus EncodingSlide 2TonotopyAudition- Stimulus EncodingSlide 5Slide 6Slide 7Audition- Stimulus EncodingSlide 9Slide 10Audition- Stimulus EncodingSlide 12Slide 13Slide 14Slide 15SummaryAudition- Stimulus Encoding•Where does auditory information go once we’ve detected it?•How are sounds coded for?–Frequency/Pitch–Intensity/Loudness–LocationAuditory pathwaySuperior OliveSpiral GanglionCochleaVentral Cochlear NucleusInferior ColliculusMGN (thalamus) Auditory CortexTonotopyAudition- Stimulus Encoding•Where does auditory information go once we’ve detected it?•How are sounds coded for?–Frequency/Pitch•15-500 Hz•500-5000 Hz•5-200 kHz–Intensity/Loudness–LocationBasilarmembraneAuditoryaxonFrequency (15-500 Hz)AuditoryaxonAuditoryaxonAuditoryaxonFrequency (500-5000 Hz)AuditoryaxonFrequency (5-20 kHz)Audition- Stimulus Encoding•Where does auditory information go once we’ve detected it?•How are sounds coded for?–Frequency/Pitch–Intensity/Loudness–LocationBasilarmembraneIntensity/loudness-depolarization of hair cells/number of auditory nerve cells activated by single hair cellIntensity/loudness-number of auditory nerve cells activated across the tonotopic mapAudition- Stimulus Encoding•Where does auditory information go once we’ve detected it?•How are sounds coded for?–Pitch–Loudness–Location•Horizontal plane–20Hz-2kHz–2kHz-20kHz•Vertical planeLocation- horizontal planefrom leftcochlearnucleus (ear)from rightcochlearnucleus (ear)SuperiorOlive neuronWhich neuron will be maximally activated in response to a sound directly in front of someone?from leftcochlearnucleus (ear)from rightcochlearnucleus (ear)ABCAB CLocation- vertical planeSummary•Auditory information is detected by hair cells that synapse onto spiral ganglion cells. Spiral ganglion cells project to the CNS and synapse on the ipsilateral cochlear nucleus in the medulla. Neurons of the ventral cochlear nuclear project to both superior olives (left and right). Neurons of the superior olives project to the inferior colliculus in the midbrain, which projects to the MGN of the thalamus. MGN neurons project to the auditory cortex in the temporal lobe. Throughout there is a tonotopic map.•The auditory system codes for:–Frequency/Pitch of sound•15-500 Hz- phase locking•500-5000 Hz- labeled line and population coding (phase locking)•5-200 kHz- labeled line–Intensity/Loudness of sound•Number of auditory nerve cells activated by single hair cell•Number of auditory nerve cells activated across the tonotopic map–Location of sound•Horizontal plane•Vertical