Re: Some limitations of the pitch-based grouping

[chen-gia tsai <tsai.cc@xxxxxxxxx>]

Dear all,

It is interesting to consider the visual analogue of pitch in terms of brain lateralization. Some brain imaging studies using musical intervals showed neural activation in the right frontal lobe, which is also related to spatial information processing. See, for example

Janata, P. et al. (2002) The cortical topography of tonal structures underlying Western music, Science 298, 2167-2170.

Zatorre, R.J. et al. (1998) Functional anatomy of musical processing in listeners with absolute pitch and relative pitch. Proceedings of the National Academy of Sciences (U.S.A.), 95, 3172-3177.

The study of Zatorre et al. (1998) is of special interest because it distinguished the activated regions in the frontal lobe of AP (absolute pitch) and RP (relative pitch) possessors. Activity within the RIGHT inferior frontal cortex was observed in RP possessors but not in AP possessors during the interval-judgment task. On the contrary, the AP group demonstrated activation of the LEFT posterior dorsolateral frontal cortex.

Accepted the lateralization of the frontal cortices that "right = spatial or non-verbal / left = verbal", RP possessors process musical intervals with a spatial-like ability, whereas AP possessors tend to rely on verbal-tonal associations in musical interval cognition.

It is not a new idea that the notions of musical interval and pitch are analogous to the spatial notions of distance, direction and height. But the approach of brain lateralization may shed light on this issue.

Zatorre et al. (2002) proposed a theory of lateralization in the auditory cortices: temporal resolution is better in left auditory cortical areas and spectral resolution is better in right auditory cortical areas.

Zatorre, R.J., Belin, P. & Penhune, V.B. (2002) Structure and function of auditory cortex: music and speech. Trends in Cognitive Sciences, 6, 37-46.

Because the cognition of musical intervals requires precise detection of frequency relations, it is processed in right auditory cortical areas. It is interesting to note that a similar cortical asymmetry exists in the prefrontal cortices (PFC).

[quoted from J.N. Wood & J. Grafman. Human prefrontal cortex: processing and representational perspectives. Nature Neuroscience Vol. 4, Feb. 2003.]

Left PFC: sequential dependences between single adjacent events, fast activation of events, strong inhibition of neighboring events
Right PFC: cross-temporal integration of meaning across multiple events, slow activation of events, weak facilitation of neighboring events

[end of quote]

It seems that temporal resolution is better in the left hemisphere, while spectral resolution is better in the right hemisphere.

The cognition of musical pitches and intervals may be related to spatial ability because it requires cross-temporal integration of meaning across multiple events and a low temporal resolution.

This analogue is supported by the hotly debated "Mozart effect", which asserts improvements in spatial ability can be achieved after listening to music.

Activity in the visual cortical area "mind's eye" has been observed in auditory imagery. Activity in the right occipital cortex was observed in tonal perception (Zatorre et al. 1998). It is very interesting to note that the AP and RP groups showed a difference in occipital cortex activation.

Although evidence from brain imaging studies suggests that the right hemisphere subserves both tonal and spatial perception, the binding problems in audition and vision are very different. The notions of pitch, chord can be related to the notions of height and position relation, but I think the pitch-based grouping has no counterpart in visual sensation.


--------- Original Message ---------

DATE: Tue, 20 Jan 2004 01:53:39
From: Peter Cariani <peter@EPL.MEEI.HARVARD.EDU>
To: AUDITORY@LISTS.MCGILL.CA
Cc:

>One might argue for spatial frequency, since there is there is a
>missing fundamental phenomenon in vision

I wonder if spatial frequency is a visual analogue of pitch. Indeed, some objects show repetitive patterns. The question is: are such objects more easily recognized?
Image a snake whose body shows a one-dimensional luminance-contrast grating. Are the different parts of its body more easily "grouped" because one can notice a constant spatial frequency? Or, the snake has developed such a pattern in appearance to hide from preys?

Repetitive spatial patterns are widely used in decorations (e.g. wallpaper). But I think they just evoke the sensation of symmetry (translation-invariance). A constant spatial frequency cannot help solve the binding problem.

While laws of nonlinear mechanics assert that a specific type of oscillators produce sounds composed of harmonically-related components, I cannot find similar mechanical laws that govern the visual world.

______________________________________
Chen-Gia Tsai
Ph.D Musicology, Humboldt University Berlin
tsai.cc@lycos.com



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