Pitch

Question 1

Heffner and Whitfield

Answer 1

1976, trained cats to distinguish auditory cues. Cats still behaved appropriately when spectral energy from fundamental frequency removed.

Question 2

Cynx and Shapiro

Answer 2

1986, trained European Starlings to respond to tones. Responded equally well to pure tones and complex tones with missing fundamental.

Question 3

Moore

Answer 3

1973, showed pitch distinguishing degrades above 4kHz

Question 4

Shackleton and Carylon

Answer 4

1994, showed resolved harmonics dominate the pitch percept

Question 5

Cariani and Delgutte

Answer 5

1996, showed that F0 could be extracted from the autocorrelation of ANFs spiking patterns

Question 6

Winter

Answer 6

2001, recording onset chopper neurons AVCN of guinea pig. Autocorrelation of the spiking patterns showed an overrepresentation of the pitch period (strongly representing F0).
1st order interval most enhanced, facilitating pitch extraction.
Each neuron enhanced periodicity representations at its prefered interval (which shortens as sound level increases). So, each cell responds best to certain periodicities at certain sound levels.

Question 7

Schreiner and Lange

Answer 7

1988, postulated that periodicity tuned neurons could be arranged systematically to create a periodicity map in IC. Found evidence for a periodicity map in cat IC, which ran primarily caudal -> rostral for high -> low

Question 8

Baumann

Answer 8

2011, fMRI imaging in monkeys provided evidence for periodicity map in IC, but it ran primarily medio-dorsal -> latero-ventral (so different orientation)

Question 9

Krishna and Semple

Answer 9

2000, evidence against a periodotopic map. recording from gerbil IC whilst presenting amplitude-modulated best frequency tones with varying sound levels.
Found that the relationship between periodicity and firing rate was not clear in all these neurons.
Plus, periodcity selectivity was often affected by irrelevant variables (eg sound level)

Question 10

Whitfield

Answer 10

1979, provided evidence that auditory cortex is critical for pitch perception. Normally, cats use periodicity to determine pitch. But, after bilateral lesion of the cortex, the animal perceived pitch as each of the individual frequency components of the complex sound

Question 11

Schulze

Answer 11

2002, looking in gerbil A1. Found periodotopic map that overlies frequency map (with different orientation)
BUT - used stimuli that don’t evoke pitch in humans, and only one type of stimulus so we can’t know if this generalises…

Question 12

Nelken

Answer 12

2008, repeated experiment in ferrets. Found that the periodicity sensitive maps for SAM tones did not generalise to other stimuli.
Concluded there is no periodotopic representation

Question 13

Krumbholtz

Answer 13

2003, magnetic field recordings in humans presented stimuli that morphed from pitchless to pitch-evoking.
MEG showed a transient increase in activity just passed the point of change, and termed this the POR.
MEG recordings showed some localisation fot he POR to the auditory cortex. Indicates that A1 detects when periodicity dis/appears from soundscape

Question 14

Bendor and Wang

Answer 14

2005, recording in non-primary marmoset auditory cortex.
Single-unit extracellular recordings in areas adjacent to/distinct from A1.
Foudn that 40% of neurons here responded equally well to pure tones of a particular frequency and complex sounds missing the fundamental, indicating they were interested in periodicity
BUT - we know that spectral cues also inform pitch perception, and there was no evidence of these neurons being sensitive to spectral cues.
Perhaps they were periodicity tuned, but not directly involved in pitch perception

Question 15

Patterson

Answer 15

2002, fMRI of humans listen to stimuli that morphed from pitchless to single-pitch evoking or pitch-melodies (IRNs).
Found evidence for hierarchical processing: the lateral HG activated to both pitch types, whereas areas beyond (superior temporal gyrus, planum polare) were only activated by pitch-melodies.
Seems HG is involved in short-term pitch processing, and areas beyond in evaluating pitch changes.
BUT - only fMRI…

Question 16

Plack

Answer 16

2009, fMRI in humans listening to a range of different pitch-evoking stimuli.
Found that IRNs generated preferential responses in lateral HG, but other stimuli preferentially activated other areas (inc planum temporale).
Thus, multiple distinct sites are invovled, cannot assign status to one region

Question 17

Bizley

Answer 17

2009, electrophysiological mapping studies in ferrets using stimuli that varied in pitch, timbre, sound direction.
Found that no neuron was sensitivie to pitch alone.
Led to idea of MOSAIC model: no obvious pitch area, rather pitch pertion is distributed throughout the cortex

Question 18

Griffith

Answer 18

2010, study looking at the perceptual quality of pitch.
Electrode recordings of local field potentials in human auditory cortex whilst subjects listened to stimuli that morphed from pitchless to pitch-evoking.
Results indicated that neural acitivty related to both stimulus periodicity (stimulus property) and to perceived pitch (perception).
Thus, perception also important determinant of neural acitivity.