Background: Pathophysiological models of bipolar disorder postulate that mood dysregulation arises from fronto-limbic dysfunction, marked by reduced prefrontal cortex (PFC) inhibitory control. This might occur due to both disruptions within PFC networks and abnormal inhibition over subcortical structures involved in emotional processing. However, no study has examined global PFC dysconnectivity in bipolar disorder and tested whether regions with within-PFC dysconnectivity also exhibit fronto-limbic connectivity deficits. Furthermore, no study has investigated whether such connectivity disruptions differ for bipolar patients with psychosis history, who might exhibit a more severe clinical course. Methods: We collected resting-state functional magnetic resonance imaging at 3T in 68 remitted bipolar I patients (34 with psychosis history) and 51 demographically matched healthy participants. We employed a recently developed global brain connectivity method, restricted to PFC (rGBC). We also independently tested connectivity between anatomically defined amygdala and PFC. Results: Bipolar patients exhibited reduced medial prefrontal cortex (mPFC) rGBC, increased amygdala-mPFC connectivity, and reduced connectivity between amygdala and dorsolateral PFC. All effects were driven by psychosis history. Moreover, the magnitude of observed effects was significantly associated with lifetime psychotic symptom severity. Conclusions: This convergence between rGBC, seed-based amygdala findings, and symptom severity analyses highlights that mPFC, a core emotion regulation region, exhibits both within-PFC dysconnectivity and connectivity abnormalities with limbic structures in bipolar illness. Furthermore, lateral PFC dysconnectivity in patients with psychosis history converges with published work in schizophrenia, indicating possible shared risk factors. Observed dysconnectivity in remitted patients suggests a bipolar trait characteristic and might constitute a risk factor for phasic features of the disorder.
COBISS.SI-ID: 50776418
Control of thought and behavior is fundamental to human intelligence. Evidence suggests a frontoparietal brain network implements such cognitive control across diverse contexts. We identify a mechanism 'global connectivity' by which components of this network might coordinate control of other networks. A lateral prefrontal cortex (LPFC) regionʼs activity was found to predict performance in a high control demand workingmemorytask and also to exhibit high global connectivity. Critically, global connectivity in this LPFC region, involving connections both within and outside the frontoparietal network, showed a highly selective relationship with individual differences influid intelligence. These findings suggest LPFC is a global hub with a brainwide influence that facilitates the ability to implement control processes central to human intelligence.
COBISS.SI-ID: 49395554
Electrodiagnostic methods are well established in the evaluation of the sacral nervous system, which has a critical role in the control of bladder, bowel, and sexual functions. They have been proposed for both research and diagnostic applications in patients with suspected neurogenic sacral dysfunction. The chapter describes mainly established tests that are of diagnostic value in the assessment of individual patients (electromyography, bulbocavernosus reflex studies, and pudendal somatosensory evoked potentials). Other tests that are not of clinical diagnostic value are also briefly presented.
COBISS.SI-ID: 669868
We noted clinically that the penilo-cavernosus reflex is much more difficult to elicit in circumcised men. Therefore we prospectively examined groups of consecutively referred men with varying foreskin status, without sacral neuropathic lesions. The reflex was clinically non-elicitable in 73%, 64% and 8% of 30 circumcised men, 15 men with foreskin retraction, and 29 control men, respectively. The scored reflex elicitability was significantly (P ( 0.001) higher in control men than in the other two groups clinically, but not neurophysiologically. The study thus confirmed the lower clinical and similar neurophysiological elicitability of the penilo-cavernosus reflex in circumcised men and in men with foreskin retraction. Probable reason for this finding is crucial role of the foreskin innervation for elicitation of the reflex.
COBISS.SI-ID: 29503449
Objective Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by degeneration of the upper and lower motor neurons. Each voluntary movement, including inspiration, is preceded by movement-related cortical potential (MRCP) that can be recorded from the scalp. MRCPs of ALS patients with severe upper motor neuron involvement are smaller. Our aim was to explore whether the inspiratory-(sniffing)-related cortical potentials (SRCPs) and index-finger-flexion MRCPs (FFRCPs) can be used as markers of cortical involvement in ALS. Methods Thirteen ALS patients and 15 healthy volunteers were assessed for their hand dexterity and strength, respiratory function, speech capacity, spasticity, electromyographic parameters and functional rating scales. EEG was recorded during self-paced sniffing and the right index finger flexion. The MRCP amplitudes were assessed at the relevant electrode positions. Results No statistically significant difference was found between the MRCP amplitudes of the ALS patients and the control subjects. However, patients with more severely affected upper limb functions generated smaller FFRCPs and those with more affected respiratory functions generated smaller SRCPs. Excessively high FFRCPs were associated with better while excessively low FFRCPs with worse scores on some of the clinical measures of the upper limb function. Conclusion Our preliminary results demonstrate that it is feasible to record SRCP in ALS patients, which combinedwith FFRCP, may be useful to determine the spectrum of motor control changes in this population.
COBISS.SI-ID: 176812