Attention-dependent modulation of neural activity in primary motor cortex

In this study we investigated the impact of attention on neural activity in human motor areas 4a and 4p by means of fMRI. We first performed a localizer scan during which our 12 right-handed subjects simply tapped with either their right or left index finger. From the activated regions within (anatomically defined) primary motor cortex, we chose the most inferior, posterior and medial region as area 4p, and the next more superior, anterior and lateral region as area 4a. In our main experiment we then looked for attention effects within these predefined areas. Our 12 subjects had to tap with a frequency of 2Hz (i…