Studies of auditory evoked magnetic and electric responses: Modality specificity and modelling

SummaryThe sources of auditory evoked electric and magnetic responses were modelled with multiple current dipoles. The activity at the auditory cortices, 2.6 cm beneath the skull, explains the observed % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrVeFv0de9GqpGe9Ff% ea0dXdd91qFHe9FjuP0-is0dXdbba9pGe9xq-Jbba9suk9fr-xfr-x% frpeWZqaaeaabiGaciaacaqabeaadaqaaqaaaOqaamaanaaabaGaam% OtaiaaigdacaaIWaGaaGimamXvP5wqonvsaeHbfv3ySLgzaGqbciab% -1gaTbaaaaa!4065! $$\overline {N100m}$$ field distribution. An additional current source near the vertex is needed to explain the corresponding potential distributions. The locations of the current sources of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrVeFv0de9GqpGe9Ff% ea0dXdd91qFHe9FjuP0-is0dXdbba9pGe9xq-Jbba9suk9fr-xfr-x% frpeWZqaaeaabiGaciaacaqabeaadaqaaqaaaOqaamaanaaabaGaam% OtaiaaigdacaaIWaGaaGimamXvP5wqonvsaeHbfv3ySLgzaGqbciab% -1gaTbaaaaa!4065! $$\overline {N100m}$$ did not show any systematic dependence on the tonal frequency.RiassuntoLe sorgenti di risposte uditive magnetiche ed electtriche stimolate sono state formate con dipoli a corrente multipli. L’attività a livello delle cortecce uditive, 2.6 cm al di sotto della calotta cranica, spiega la distribuzione di campo osservata % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrVeFv0de9GqpGe9Ff% ea0dXdd91qFHe9FjuP0-is0dXdbba9pGe9xq-Jbba9suk9fr-xfr-x% frpeWZqaaeaabiGaciaacaqabeaadaqaaqaaaOqaamaanaaabaGaam% OtaiaaigdacaaIWaGaaGimamXvP5wqonvsaeHbfv3ySLgzaGqbciab% -1gaTbaaaaa!4065! $$\overline {N100m}$$ . Un’ulteriore sorgente di corrente vicino al vertice è necessaria per spiegare le corrispondenti distribuzioni di potenziale. La posizione delle sorgenti di corrente di % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrVeFv0de9GqpGe9Ff% ea0dXdd91qFHe9FjuP0-is0dXdbba9pGe9xq-Jbba9suk9fr-xfr-x% frpeWZqaaeaabiGaciaacaqabeaadaqaaqaaaOqaamaanaaabaGaam% OtaiaaigdacaaIWaGaaGimamXvP5wqonvsaeHbfv3ySLgzaGqbciab% -1gaTbaaaaa!4065! $$\overline {N100m}$$ non ha mostrato alcuna dipendenza sistematica dalla frequenza tonale.