Integrated approach for studying adaptation mechanisms in the human somatosensory cortical network.

Magnetoencephalography and independent component analysis (ICA) was utilized to study and characterize neural adaptation in the somatosensory cortical network. Repetitive punctate tactile stimuli were applied unilaterally to the dominant hand and face using a custom-built pneumatic stimulator called the TAC-Cell. ICA-based source estimation from the evoked neuromagnetic responses indicated cortical activity in the contralateral primary somatosensory cortex (SI) for face stimulation, while hand stimulation resulted in robust contralateral SI and posterior parietal cortex (PPC) activation. Activity was also observed in the secondary somatosensory cortical area (SII) with reduced amplitude and higher variability across subjects. There was a significant difference in adaptation rate between SI and higher-order somatosensory cortices for hand stimulation. Adaptation was significantly dependent on stimulus frequency and pulse index within the stimulus train for both hand and face stimulation. The peak latency of the activity was significantly dependent on stimulation site (hand vs. face) and cortical area (SI vs. PPC). The difference in the peak latency of activity in SI and PPC is presumed to reflect a hierarchical serial-processing mechanism in the somatosensory cortex.

Neurochemical analysis of primary motor cortex in chronic low back pain.

The involvement of the primary motor cortex (M1) in chronic low back pain (LBP) is a relatively new concept. Decreased M1 excitability and an analgesic effect after M1 stimulation have been recently reported. However, the neurochemical changes underlying these functional M1 changes are unknown. The current study investigated whether neurochemicals specific to neurons and glial cells in both right and left M1 are altered. N-Acetylaspartate (NAA) and myo-inositol (mI) were measured with proton magnetic resonance spectroscopy in 19 subjects with chronic LBP and 14 healthy controls. We also examined correlations among neurochemicals within and between M1 and relationships between neurochemical concentrations and clinical features of pain. Right M1 NAA was lower in subjects with LBP compared to controls (p = 0.008). Left M1 NAA and mI were not significantly different between LBP and control groups. Correlations between neurochemical concentrations across M1s were different between groups (p = 0.008). There were no significant correlations between M1 neurochemicals and pain characteristics. These findings provide preliminary evidence of neuronal depression and altered neuronalglial interactions across M1 in chronic LBP.

TAC-Cell inputs to human hand and lip induce short-term adaptation of the primary somatosensory cortex.

A new pneumatic tactile stimulator, called the TAC-Cell, was developed in our laboratory to non-invasively deliver patterned cutaneous stimulation to the face and hand in order to study the neuromagnetic response adaptation patterns within the primary somatosensory cortex (S1) in young adult humans. Individual TAC-Cells were positioned on the glabrous surface of the right hand, and midline of the upper and lower lip vermilion. A 151-channel magnetoencephalography (MEG) scanner was used to record the cortical response to a novel tactile stimulus which consisted of a repeating 6-pulse train delivered at three different frequencies through the active membrane surface of the TAC-Cell. The evoked activity in S1 (contralateral for hand stimulation, and bilateral for lip stimulation) was characterized from the best-fit dipoles of the earliest prominent response component. The S1 responses manifested significant modulation and adaptation as a function of the frequency of the punctate pneumatic stimulus trains and stimulus site (glabrous lip versus glabrous hand).

[Anemia in COPD]. / Anemia în BPOC.

COPD, a "trendy" disease, didn't yet reveal all its secrets. A frequently subject discussed lately in the specialty literature is about its association to anemia. This is taking in consideration that in all pneumology books COPD is considered a disease associated to the polyglobulia. The authors demonstrate in this review the impact of anemia on the disease as well as the analogies between this obstructive disease and other chronic diseases. In order to do so, the details of pathogenetic impact of disease, the clinical features and possible corrections of this association are reviewed.

[Obesity--hypoventilation syndrome: sometimes a difficult diagnosis]. / Sindromul obezitate-hipoventilatie--un diagnostic adesea dificil.

Described in the specialty literature for over one century under the name of Pickwick syndrome, the obesity--hypoventilation syndrome (OHS) includes the triad: obesity--hypoventilation--hypersomnia. In Romania, this entity is rarely recognized and, despite the developments in specific investigations, the disease is frequently difficult to differentiate from other respiratory disorders during sleep. The authors try to clarify some issues related to pathophysiologic mechanism and contribution of mechanical factors or of respiratory nervous center etc. References are made about the leptin involvement. Clinical appearance and therapy modalities are added to the description of the disease.