Physical fitness is associated with neural activity during working memory performance in major depressive disorder

BACKGROUND

Deficits in cognition like working memory (WM) are highly prevalent symptoms related to major depressive disorder (MDD). Neuroimaging studies have described frontoparietal abnormalities in patients with MDD as a basis for these deficits. Based on research in healthy adults, it is hypothesized that increased physical fitness might be a protective factor for these deficits in MDD. However, the relationship between physical fitness and WM-related neural activity and performance has not been tested in MDD, to date. Understanding these associations could inform the development of physical exercise interventions in MDD.

METHODS

Within a larger project, 111 (53female) MDD outpatients and 56 (34female) healthy controls performed an n-back task (0-, 1-, 2-, 3-back) during functional Magnetic Resonance Imaging. Physical fitness from a graded exercise test on a cycle ergometer was performed by 106 MDD patients.

RESULTS

Patients showed reduced performance particularly at high loads of the n-back WM task and prolonged reaction times at all n-back loads. A whole-brain interaction analysis of group by WM load revealed reduced neural activity in six frontoparietal clusters at medium and high WM loads in MDD patients compared to healthy controls. Analysis of covariance within the MDD sample showed that physical fitness was associated with neural activity in right and left superior parietal lobules. Externally defined Regions of Interest confirmed this analysis.

CONCLUSIONS

Results indicate frontoparietal hypoactivity in MDD at high demands, arguing for decreased WM capacity. We demonstrate a parietal fitness correlate which could be used to guide future research on effects of exercise on cognitive functioning in MDD.

Adaptation of Patterns of Motile Filaments under Dynamic Boundary Conditions

Boundary conditions are important for pattern formation in active matter. However, it is still not well-understood how alterations in the boundary conditions (dynamic boundary conditions) impact pattern formation. To elucidate the effect of dynamic boundary conditions on the pattern formation by active matter, we investigate an in vitro gliding assay of microtubules on a deformable soft substrate. The dynamic boundary conditions were realized by applying mechanical stress through stretching and compression of the substrate during the gliding assay. A single cycle of stretch-and-compression (relaxation) of the substrate induces perpendicular alignment of microtubules relative to the stretch axis, whereas repeated cycles resulted in zigzag patterns of microtubules. Our model shows that the orientation angles of microtubules correspond to the direction to attain smooth movement without buckling, which is further amplified by the collective migration of the microtubules. Our results provide an insight into understanding the rich dynamics in self-organization arising in active matter subjected to time-dependent boundary conditions.

The subforaminal stenosis headache

The clinical picture of the so-called subforaminal stenosis headache (Gutmann) and its surgical treatment (Roesner) have been presented. We have analyzed our findings in 119 patients and 55 operations. The clinical picture is characterized by increasing pain in the upper cervical and occipital region which in later stages may be accompanied also by other symptoms like disturbances of concentration, memory, libido, and potency, as well in some cases by symptoms similar to those of a secondary chronic myelopathy. The syndrome is caused by a subforaminal stenosis of the dural sac which regularly is compressed by the posterior atlas arch in connection with either morphological variations of the base of the skull or by static-functional deviations of the cranio-cervical region. The compression of the dural sac of the cranio-cervical region results in an impairment of its air chamber function, and additionally may disturb the connections between the intracranial and intraspinal venous plexus. By both factors the physiologically important smoothing function of the CSF space of the cranio-cervical region concerning intracranial pressure changes is disturbed. Treatment of choice is a laminectomy of the dorsal arch of the atlas and an osteoclastic dilatation of the foramen magnum but without opening of the dura. The results of this procedure are excellent.

[The biomechanical pathogenesis and differentiated therapy of cervical headache (author's transl)]

Dysfunction in the upper region of the cervical vertebral column is largely to be regarded as the primary disorder from which secondary anatomical substrates, especially degenerative manifestations, develop. We must shift our attention from pathomorphology to function. There are two main types of disordered vertebral function which may lead to headache in many cases: 1. hypomobility (blocking) 2. hypermobility. Suggestions are made for selective methods of examination which help the detection of disturbed function. Cinematography can be used for substantiation. Diagnostic differentiation indicates possibilities for special manipulative, physical, surgical and orthopedic treatment.