Flexible Polymer Electrodes for Stable Prosthetic Visual Perception in Mice.

Brain interfaces that can stimulate neurons, cause minimal damage, and work for a long time will be central for future neuroprosthetics. Here, the long-term performance of highly flexible, thin polyimide shanks with several small (<15 µm) electrodes during electrical microstimulation of the visual cortex, is reported. The electrodes exhibit a remarkable stability when several billions of electrical pulses are applied in vitro. When the devices are implanted in the primary visual cortex (area V1) of mice and the animals are trained to detect electrical microstimulation, it is found that the perceptual thresholds are 2-20 microamperes (µA), which is far below the maximal currents that the electrodes can withstand. The long-term functionality of the devices in vivo is excellent, with stable performance for up to more than a year and little damage to the brain tissue. These results demonstrate the potential of thin floating electrodes for the long-term restoration of lost sensory functions.

The Impact of Eye Closure on Anticipatory α Activity in a Tactile Discrimination Task.

One of the very first observations made regarding α oscillations (8-14 Hz), is that they increase in power over posterior areas when awake participants close their eyes. Recent work, especially in the context of (spatial) attention, suggests that α activity reflects a mechanism of functional inhibition. However, it remains unclear how eye closure impacts anticipatory α modulation observed in attention paradigms, and how this affects subsequent behavioral performance. Here, we recorded magnetoencephalography (MEG) in 33 human participants performing a tactile discrimination task with their eyes open versus closed. We replicated the hallmarks of previous somatosensory spatial attention studies: α lateralization across the somatosensory cortices as well as α increase over posterior (visual) regions. Furthermore, we found that eye closure leads to (1) reduced task performance; (2) widespread increase in α power; and (3) reduced anticipatory visual α modulation (4) with no effect on somatosensory α lateralization. Regardless of whether participants had their eyes open or closed, increased visual α power and somatosensory α lateralization improved their performance. Thus, we provide evidence that eye closure does not alter the impact of anticipatory α modulations on behavioral performance. We propose there is an optimal visual α level for somatosensory task performance, which can be achieved through a combination of eye closure and top-down anticipatory attention.

Depression, trauma and mentalizing: No influence of depressive symptoms on spontaneous theory of mind in a subclinical sample.

BACKGROUND: Depressive symptoms are associated with impaired social functioning, arguably because of reduced mentalizing abilities. However, findings in persons with depressive symptoms and/or major depressive disorder (MDD) are presently mixed, finding evidence both for and against the hypothesis of reduced mentalizing abilities. AIMS: This study investigated spontaneous cognitive mentalizing in 36 age-, sex- and education-matched students with depressive symptoms and 45 comparisons with minimal depressive symptoms. METHOD: To assess spontaneous mentalizing, we used the implicit theory of mind (ToM) task, which looks specifically at spontaneous computation of false belief. RESULTS: Bayesian analysis did not support the hypothesis of impaired mentalizing; in fact, it suggested that the results were 3.90 times more likely to have occurred under the null hypothesis. Results remained stable when comparing depressed and non-depressed individuals without maltreatment exposure but were inconclusive in the maltreatment-exposed groups. CONCLUSION: The findings suggest no effect of spontaneous mentalizing in a high-functioning depressed sample. Moreover, the findings also emphasize the need to control for childhood maltreatment experiences in future ToM and social functioning research, as these may constitute subgroups within depressed samples. Tailored therapy for maltreated depression individuals may be beneficial.