AUDITORY CORTEX 4 SEPT 21, 2015 – DAY 12 Brain & Language LING NSCI Fall 2015

Course organization Fun with I am still working on grading. 9/21/15Brain & Language - Harry Howard - Tulane University 2

AUDITORY CORTEX 3 The quiz was the review 9/21/15Brain & Language - Harry Howard - Tulane University 3

Summary LH stops & liquids/glides/fricatives lexical stress CONvert ~ conVERT tone languages phrasal stress noun compounding stress retraction clausal stress contrastive stress RH vowels (?) emotional prosody sentence type declarative, interrogative, imperative 9/21/15Brain & Language - Harry Howard - Tulane University 4

9/21/15Brain & Language - Harry Howard - Tulane University 5 Size of temporal integration windows Primary auditory cortex builds high-fidelity representations of the signal and surrounding non-primary areas differentially ‘elaborate’ this signal by analyzing it on different time scales (Poeppel et al., 2008) LH (non-primary) temporal cortex houses neuronal ensembles with somewhat shorter integration constants (say, ms) and therefore LH cortical fields preferentially reflect [fast] temporal properties of acoustic signals RH (non-primary) temporal cortex houses neuronal ensembles a large proportion of which have longer ( ms) integration windows, and therefore are better suited to analyze [slower] spectral change

AUDITORY CORTEX 4 9/21/15Brain & Language - Harry Howard - Tulane University 6

FREQUENCY IN THE VISUAL DOMAIN Spatial frequency 9/21/15Brain & Language - Harry Howard - Tulane University 7

9/21/15Brain & Language - Harry Howard - Tulane University 8 High- vs. low- frequency spatial information What is this?

9/21/15Brain & Language - Harry Howard - Tulane University 9 Salvador Dali “Gala Contemplating the Mediterranean Sea, which at 30 meters becomes the portrait of Abraham Lincoln (Homage to Rothko)”, 1976

9/21/15 Brain & Language - Harry Howard - Tulane University 10 "Lincoln illusion” Harmon & Jules (1973) Blurring acts as a low-pass filter, reducing the high masking frequencies ml ml

Spatial frequency High spatial frequency (two cycles per degree) Low spatial frequency (one cycle per degree) 9/21/15Brain & Language - Harry Howard - Tulane University 11

9/21/15Brain & Language - Harry Howard - Tulane University 12 Spatial frequency: LHD ~ stimulus ~ RHD

9/21/15Brain & Language - Harry Howard - Tulane University 13 Lateralization of frequency RH allows the low frequencies of a stimulus to pass through, ignoring the higher ones (low-pass filter). LH allows the high frequencies of a stimulus to pass through, ignoring the lower ones (a high- pass filter). Duration becomes a measure of frequency in the temporal domain: a brief signal has a high temporal frequency; a prolonged signal has a low temporal frequency, and at least two other domains are recognized, the spectral and the spatial (but we ignore spatial frequency for now).

FINE VS. COARSE CODING 9/21/15Brain & Language - Harry Howard - Tulane University 14

Categorical vs. graded or coordinate spatial relations Is the black dot above or below the bar? Is the black dot near or far from the bar? 9/21/15Brain & Language - Harry Howard - Tulane University 15 Categorical > LHGraded > RH

Fine vs. coarse coding 9/21/15Brain & Language - Harry Howard - Tulane University 16 Fine coding: small receptive field with no overlap Coarse coding: large receptive field with overlap

A conversion to resolution Left hemisphere, fine coding: 9 neurons index 9 regions of space Right hemisphere, coarse coding: 4 neurons index 12+ regions of space 9/21/15Brain & Language - Harry Howard - Tulane University 17

Summary of lateralization of phonology LH fine grained, small window of temporal integration high temporal frequency: rapid cues, like stops high spectral frequency: formants categorical distinctions: lexical, phrasal, clausal stress; lexical tone in Thai/Chinese RH coarse grained, large window of temporal integration low temporal frequency: slow cues, like vowels low spectral frequency: fundamental graded/coordinate distinctions: emotional intonation, sentence type? 9/21/15Brain & Language - Harry Howard - Tulane University 18

CATEGORICAL PERCEPTION of voice-onset time 9/21/15Brain & Language - Harry Howard - Tulane University 19

'BP' for [bi] vs. [p ʰ i] 9/21/15Brain & Language - Harry Howard - Tulane University 20

Voice-onset time (VOT) 9/21/15Brain & Language - Harry Howard - Tulane University 21

Is VOT perceived as a continuum? 9/21/15Brain & Language - Harry Howard - Tulane University 22 What is this? (ignore the fact that it is crooked)

If VOT is gradually lengthened from 0 9/21/15Brain & Language - Harry Howard - Tulane University 23

Altmanna (2014) Categorical speech perception during active discrimination of consonants and vowels 9/21/15Brain & Language - Harry Howard - Tulane University 24 This bar graph depicts the mean (n=15) response amplitudes from 430 to 500 ms after S2 onset within the left temporal cortex cluster as a region-of-interest.

By the way … 9/21/15Brain & Language - Harry Howard - Tulane University 25 Chinchillas do this too!

Conclusion Categorical perception 9/21/15Brain & Language - Harry Howard - Tulane University 26

NEXT TIME Do we have class on Wednesday? Mid-posterior STS, Wernicke’s area 9/21/15Brain & Language - Harry Howard - Tulane University 27