But how do we get in there to investigate?
Detecting brain activity from the outside (MRI, EEG, ...).
Brain anomalies: problems in area X lead to difficulties with task Y. The anomalies could be congenital, result of brain damage, or even temporary as in Transcranial magnetic stimulation.
Using the opportunity of brain surgery to selectively activate parts.
Animals.
Modelling?
These are usually based on individual cases with particular conditions:
Pauline “is considered to be deficient intellectually (her IQ is 70) and was diagnosed as autistic at the age of 2. Language was delayed, with the first words articulated at 30 months and the first two word sentences at 48 months. In contrast, Pauline has always shown a keen interest for music and has displayed remarkable musical skills.”
“Pauline has an exceptional memory for music; she is able to reproduce a conventional piece of music composed for experimental purposes after hearing it only once. Her reproduction is informative because she does not reproduce the piece as a recording machine; rather, she harmonizes and improvises in a skilful manner. She also possesses absolute pitch,” (Peretz 2002)
Brain damage (following a stroke for instance) can result in particular inabilities:
“Following bilateral lesions of the auditory cortex, patients can show highly specific disorders of music perception and recognition (e.g., Peretz 1996; Peretz and others 1997). This music-specific impairment is readily discernable in experiments testing memory recognition. In the music memory test, subjects are presented with 20 tunes (taken from familiar songs) to memorize. The melodies are then represented among 20 unstudied (but equally familiar) melodies that are randomly mixed. The subject is requested to indicate which melodies were heard in the study phase. For comparison purposes, in the lyrics and the environmental sound tests, subjects are given similar opportunities to learn and recognize 20 spoken lyrics (taken from the same familiar songs) and 20 environmental sounds (e.g., a barking dog), respectively. The three tests are performed in different sessions.” (Peretz 2002)
Peretz also describes cases of epileptic seizures triggered exclusively by music and that stimulating parts of the auditory cortex can result in musical hallucinations.
EEG can measure brain activity following a timed event. The article describes a study comparing congruent and incongruent event for melody and lyrics.
She is arguing that there is music-specific circuitry in the brain. Others prefer the view that music shares mechanisms with other functions such as speech processing.