[CS] Bharucha Lecture Notes

[Elton Joe]

Here are my notes from the Bharucha lecture, in case anyone wants
them.  It's paraphrases mixed in with my own questions and comments.

My main question is one of basic neuroscience:  What happens,
biologically, when part of the brain "lights up," and what is going on
(or not going on, in comparison) in the rest of the brain?


elton

MUSIC, BRAIN, AND CULTURE
Jamshed Bharucha

Former editor, journal "Music Perception"

It has often been said that culture and brain biology are two separate domains.

However, we "carry our culture in our brains".

We have only begun to talk about culture through cognitive science,
but it will be the norm in 10 years.

Slide of MRI brain scans with "activity" marked.
"Activity" is "greater than chance".
So what is activity, and what is chance?  What is going on in the
areas of the brain not marked, and why is "less" going on there?

Neuroscientists strive for more accuracy in measurement (voxel-size
and temporally).  What would greater accuracy show?

Auditory cortex is marked by greater activity during the listening of
music.  (Machine noise is filtered out statistically - it does
activate the auditory cortex as well.)

These particular scans show activity localized to the left hemisphere
side of the auditory cortex.  The norm is on both sides.

Study:

Participants listened to a particular melody in all 24 major and minor keys.

The music you normally hear within a culture is highly constrained in
terms of transitions from one key to the next.

Transitions - C maj -> G maj is more frequent than C maj -> F# maj

Found that uneducated listeners were still able to distinguish key transitions.

Which part of the brain is correlated with usual/unusual key change?

Hypothesized that the auditory cortex would be involved, since it
lights up during music listening.

Frontal cortex lit up instead, which indicates that there may be
cultural factors involved.

Idea:  brain internalizes culture automatically by being embedded in it.

Study:

Group of college students with little experience with Indian culture.
Group of college students who grew up in India and had exposure to
Hindi and Indian music.  (bilingual and bicultural musically)

Western and Indian classical music
Western and Indian pop music
English and Hindi speech

Participants listened while in an MRI machine, but were not asked to
attend to a particular task (this would be used in an ideal
experiment).

What about singing during the music?  Wouldn't this activate music and
speech at the same time (assuming the brain processes them
differently)?  Is singing music or speech?

Brain vector - a set of numbers that indicate the level of activity in
each of the areas measured.

Brain vectors were paired up to calculate the similarities between participants.

Multi-dimensional scaling (statistical analysis) was used to place
participants in an abstract mathematical space.

Brains which were similar were close together, and brains which were
dissimilar were far apart.

"Cultural space maps on to brain space"

Classical music (Western/Indian) shows distinct separation between the
two groups

Used vocal music to keep the voice aspect constant, but Western
classical music was in non-English languages (Italian, German, etc.)
and Indian classical music was in non-Hindi languages (such as
Sanskrit).

How was classical music defined?  Similar to the problem of defining
speciation, how does one distinguish between variation within a
particular style vs. variation between styles?

NEURAL NETWORKS
How might the brain predict pitches according to cultural bias? 
(simulation project)

Layers of neurons with connections between layers.  Connections have
particular strengths.

If a particular sine wave is played, particular neurons light up.  In
other words, particular parts of the auditory cortex are tuned to
particular frequencies.  (First layer neurons are innately tuned)

Second layers correspond to some sort of cultural conditioning.  The
neuron in the second layer that lights up the most due to a set of
stimuli from the first layer is the "winner" - it corresponds to this
particular stimulus the most and gets stronger.  (Uh oh, grandfather
cell - what happens when you need to represent different things with
the same neurons?  Can one neuron do more than one thing?  What
"measures" the whole process?)

Hebian learning - essentially the neural network connection strength theory

Strengths of the connections (synapses) can be plotted on
multidimensional graphs.

Theory applied to cultural bias building:
When a new stimulus is presented, the vector that it is closest to is
reinforced or tuned to the cultural environment.

"Self-organizing models" - Bharucha says this is how the brain MUST
and WILL learn cultural bias.

Indian scales - they sound foreign to the Western ear.
There are scales (such as Lydian) that fell out of usage by Western music.
(although they have been picked up by jazz)

FLATTED SECOND
The flatted second is common in Indian scales, but not in Western
scales.  Therefore, the Indian brain would infer that the flatted
second was present if all of the other scale tones were played.  The
Greek modes have some flatted seconds.

The brain fills in musically from fragments in order to make a
complete scale it can recognize.

You can move through your environment more easily if you can make
predictions about what to expect culturally.  This is similar to
prototype theories of aesthetics, and in general the idea of schemata.

MOZART EFFECT
Theory was that Mozart contains certain intervals that make you smart.

However, when only one voice was changed by half a step, there was
absolutely no effect.

ORIGIN OF MUSIC
pre-linguistic auditory communication
music is closely linked to movement (dance, etc.)

TALENT
Is talent due to prior tuning of the neural networks?  How does it happen?