Biomedical subjects

Marty Woldorff

Publications and source records attributed to Marty Woldorff.

3 recordsLinked to original sources

PubMed2005

Effects of attention on the neural processing of harmonic syntax in Western music.

The effects of selective attention on the neural response to the violation of musical syntax were investigated in the present study. Musical chord progressions were played to nonmusicians while Event-Related Potentials (ERPs) were recorded. The five-chord progressions included 61% harmonically expected cadences (I-I(6)-IV-V-I), 26% harmonically unexpected cadences (I-I(6)-IV-V-N(6)), and 13% with one of the five chords having an intensity fadeout across its duration. During the attended condition, subjects responded by pressing a button upon detecting a fadeout in volume; during the unattended condition, subjects were given reading comprehension materials and instructed to ignore all auditory stimuli. In response to the harmonic deviant, an Early Anterior Negativity (EAN) was observed at 150-300 ms in both attention conditions, but it was much larger in amplitude in the attended condition. A second scalp-negative deflection was also identified at 380-600 ms following the harmonic deviants; this Late Negativity onset earlier during the attended condition. These results suggest strong effects of attention on the neural processing of harmonic syntax.

Acoustic Stimulation↗

PubMed2004

Timing in the baby brain.

Ten-month-old infants and adults were tested in an auditory oddball paradigm in which 50-ms tones were separated by 1500 ms (standard interval) and occasionally 500 ms (deviant interval). Both infants and adults showed marked brain responses to the tone that followed a deviant inter-stimulus interval (ISI). Specifically, the timing-deviance event-related-potential (ERP) difference waves (deviant-ISI ERP minus standard-ISI ERP) yielded a significant, fronto-centrally distributed, mismatch negativity (MMN) in the latency range of 120-240 ms post-stimulus for infants and 110-210 ms for adults. A robust, longer latency, deviance-related positivity was also obtained for infants (330-520 ms), with a much smaller and later deviance-related positivity observed for adults (585-705 ms). These results suggest that the 10-month-old infant brain has already developed some of the same mechanisms as adults for detecting deviations in the timing of stimulus events.

Acoustic Stimulation↗

PubMed2002

BOLD signal compartmentalization based on the apparent diffusion coefficient.

Functional MRI (fMRI) can detect blood oxygenation level dependent (BOLD) hemodynamic responses secondary to neuronal activity. The most commonly used method for detecting fMRI signals is the gradient-echo echo-planar imaging (EPI) technique because of its sensitivity and speed. However, it is generally believed that a significant portion of these signals arises from large veins, with additional contribution from the capillaries and parenchyma. Early experiments using diffusion-weighted gradient-echo EPI have suggested that intra-voxel incoherent motion (IVIM) weighting inherent in the sequence can selectively attenuate contributions from different vessels based on the differences in the mobility of the blood within them. In the present study, we used similar approach to characterize the apparent diffusion coefficient (ADC) distribution within the activated areas of BOLD contrast. It is shown that the voxel values of the ADCs obtained from this technique can infer various vascular contributions to the BOLD signal.

Algorithms↗