The BCI competition IV stands in the tradition of prior BCI competitions that aim to provide high quality neuroscientific data for open access to the scientific community. As experienced already in prior competitions not only scientists from the narrow field of BCI compete, but scholars with a broad variety of backgrounds and nationalities. They include high specialists as well as students. The goals of all BCI competitions have always been to challenge with respect to novel paradigms and complex data. We report on the following challenges: (1) asynchronous data, (2) synthetic, (3) multi-class continuous data, (4) session-to-session transfer, (5) directionally modulated MEG, (6) finger movements recorded by ECoG. As after past competitions, our hope is that winning entries may enhance the analysis methods of future BCIs.

Maps of the body surface in somatosensory cortex have been shown to be highly plastic, altering their configuration in response to changes in use of body parts. The current study investigated alterations in the functional organization of the human somatosensory cortex resulting from massed practice. Over a period of 4 weeks, subjects were given synchronous tactile stimulation of thumb (D1) and little finger (D5) for 1 hr/d. They had to identify the orientation of the stimuli. Neuroelectric source localization based on high-resolution EEG revealed that, when subjects received passive tactile stimulation of D1 or D5, the representations of the fingers in primary somatosensory cortex were closer together after training than before. There was also an apparently correlative tendency to anomalously mislocalize near-threshold tactile stimuli equally to the distant finger costimulated during training rather than preferentially to the finger nearest to the finger stimulated in a post-training test. However, when the stimulus discrimination had to be made, neuroelectric source imaging revealed that the digital representations of D1 and D5 were further apart after training than before. Thus, the same series of prolonged repetitive stimulations produced two different opposite effects on the spatial relationship of the cortical representations of the digits, suggesting that differential activation in the same region of somatosensory cortex is specific to different tasks.

We used magnetic source imaging in human subjects to reveal within-subject variations of the homuncular hand representation within the primary somatosensory cortex modulated by attention. In one condition subjects were trained to detect sequential leftward or rightward stimulus motion across the fingers of the left hand (“hand” condition) and in a different condition to detect stimulus motion at a specific finger on this hand (“finger” condition). Afferent input was controlled by applying exactly the same stimulus pattern to the digits in the two tasks. Segregation of the somatotopic hand representation (an increase in the distance between the representations of digits 2 and 5) was observed, commencing with the onset of practice, in the finger relative to the hand condition. Subsequent training in the hand and finger conditions with feedback for correctness did not modify segregation, indicating that segregation was a task effect and not a training effect. These findings indicate that the hand representation within the primary somatosensory cortex is not statically fixed but is dynamically modulated by top-down mechanisms to support task requirements. A greater capacity for modulation of the functional cortical organization was positively correlated with superior learning and task performance.

Intensive and long-lasting experience of altered sensory input induces permanent changes in the functional organization of the somatosensory cortex. In addition, an increasing body of evidence suggests the existence of dynamic, short-term and task-dependent adaptation of representational maps within somatosensory cortex. It is hypothesized that somatosensory maps can, not only, be acquired within a short period of time, but might also be set up during periods of training related to specific tasks and subsequently activated dynamically upon performance of that particular task. In order to test this hypothesis we studied the functional organization of somatosensory cortex for a heavily overlearned and frequently performed task for which no new acquisition of a sensory map had to be assumed. To this end, the functional organization of somatosensory cortex for handwriting was compared with the organization during rest in healthy humans. Functional organization of the somatosensory cortex was assessed using non-invasive, neuromagnetic source imaging based on tactile stimulation of the thumb (D1) and little finger (D5) during writing and rest. In different blocks, subjects wrote with their right, dominant and their left hand, respectively. During writing, D1 and D5 of the writing hand were stimulated. To test the reliability of our results all measurements were repeated after 1 week. It was found that amplitudes of somatosensory evoked magnetic fields with latencies of 45 ms were reduced during writing compared with rest. This finding is in accordance with the sensorimotor gating effect. Using source localization we could show that cortical representations of D1 and D5 are more distant during writing with either hand compared with rest. Our data suggest that somatosensory cortical maps undergo rapid modulation depending on task-specific involvement of sensory processing in daily-life overlearned movements. As it is unlikely that a new sensory map is always acquired when a frequently used task such as writing is performed, we suggest that somatosensory cortex switches between different, concurrently pre-existing maps depending on actual requirements. Task-dependent activation of pre-existing maps might be a powerful mechanism to optimize stimulus processing.