Gamma band dysfunction in patients with schizophrenia during a Sternberg Task: A wavelet analysis

Background

Increasing body of evidence suggest that patients with schizophrenia (SCZ) present dysfunction of the gamma band oscillations (GBO) during cognitive tasks. The current study aimed to explore the GBO activity in SCZ during a Sternberg task.

Materials and methods

Twenty-eight chronic stabilized SCZ and 18 healthy controls (HC), were recruited. Ongoing EEG was recorded during the execution of the Sternberg task. Continuous EEG data were band-pass filtered (1–100 Hz) and corrected for eye blink and muscle artefacts by ICA. For each subject, the event-related-spectral-perturbation (ERSP) and the inter-trial-coherence (ITC) were computed at the Pz channel only for those stimulus-locked segments containing correct responses. GBO wavelet analysis was performed with two different increasing cycle ranges (3 to 5.8 and 12 to 22.6; frequency range: 30–90 Hz), to obtain the best information about temporal and frequency dynamics. Student's t test (with multiple comparisons FDR correction) was used to compare the groups.

Results

During the manteinance phase (4000 to 4600 ms after the stimulus onset), SCZ presented a significant increase, respect to HC, in low GBO activity (range: 30-50 Hz;). In the other phases of the Sternberg task (encoding, probe presentation and response periods), no significant difference in GBO was observed between SCZ and HC.

Conclusions

These findings are in line with the evidence that GBO dysfunction in SCZ is present during selective phases of the working memory task. Future studies have to clarify the role of GBO dysfunction on the cognitive performance and the clinical utility of selective GBO modulation during cognitive rehabilitation.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Intrafusal effects of botulinum toxin in post-stroke upper limb spasticity

A previous study in subjects with focal dystonia suggested that the greater and longer-lasting effect induced by botulinum toxin type A (BoNT-A) on the tonic vibration reflex (TVR) than on the maximal M-wave (M-max) might be the physiological marker of the toxin's action at the level of intrafusal muscle fibres. With this approach, we investigated the possible effect of BoNT-A on fusimotor synapses in eight patients with post-stroke spasticity (four with no residual motor capacity before treatment and four with partially spared muscle strength and residual motor capacity). TVR and M-max were recorded from the wrist and finger flexor muscles before treatment and at 1, 4 and 7 months afterwards. The TVR reduction was greater than the M-max reduction and remained fairly constant over time only in the subjects with a residual motor capacity before the treatment. This pilot study suggests that some degree of strength and active movement is necessary for the action of BoNT-A on intrafusal fibres.

Rheologic changes in the synovial fluid of patients with gonarthritis induced by intraarticular infiltration of hyaluronic acid

The aim of the present study was to evaluate possible changes in synovial fluid viscosity in gonarthritic patients treated with intraarticular infiltration of hyaluronic acid. Thirty patients with radiologically proven (Stage III Kellgren) serious gonarthrosis, local pain and functional limitation were enrolled. All patients had reported at least 4-5 episodes of hydrarthrosis during the previous 12 months. Therefore, two different phases of their illness could be observed: a relatively silent phase of hydrarthrosis and a symptomatic phase. According to the protocol, one sample of synovial fluid was collected for evaluation of baseline viscosity (pretreatment); immediately afterwards, intraarticular administration of high molecular weight sodium hyaluronate (one 20 mg vial/week for 3 weeks) was initiated. During the entire treatment period and for 3 weeks following the end of treatment, intraarticular synovial fluid samples (one sample per week for 3 treatment weeks followed by a further 3 weeks as control) were collected to perform rheologic assessment and viscosimetric analysis. The results of this preliminary study show that exogenous administration of high molecular weight sodium hyaluronate induced normalization of hyaluronic acid viscosity values in patients with high and low baseline hyaluronic acid viscosity values.

Red cell filterability and erythrocyte membrane microviscosity during ticlopidine treatment

The effects of 10 days' treatment with 500 mg/day ticlopidine on the filterability of red blood cells in suspension and on the microviscosity of the red blood cell membrane was evaluated in 11 patients with vascular atherosclerosis. The results show ticlopidine to be effective in influencing the rheological measures of red cell filterability and membrane microviscosity: filterability was increased and microviscosity was decreased. Ticlopidine also decreased the extent of fluorescence polarization. These results are discussed regarding possible mechanisms of action of ticlopidine.

Vascular atherosclerotic disease: evaluation of the whole-blood filterability and red cell membrane microrheological pattern after intravenous administration of a single dose of pentoxifylline

A study was carried out in 10 patients with vascular atherosclerotic disease to investigate the effects of a single dose of 300 mg pentoxifylline, given by intravenous infusion over 30 minutes, on various macrorheological and microrheological parameters. Measurements were made at baseline, at the end of the intravenous infusion and again 30 minutes later, of whole-blood filterability, erythrocyte membrane fluidity (using pyrene as probe) and transverse fluidity gradient (using fluorescent fatty acids as probes). The results showed that there was a significant variation in whole-blood filterability and the red cell membrane fluidity gradient after pentoxifylline. No difference, however, was noted for the membrane fluidity. These data suggest, therefore, that pentoxifylline plays a role in affecting the red cell membrane microrheological pattern.

Blood rheology changes during bezafibrate treatment

To evaluate the effect of bezafibrate on the haemorheological pattern, 30 atherosclerotic non-diabetic patients were enlisted in a double-blind, comparative, parallel group trial with bezafibrate (600 mg daily) or placebo being randomly assigned. The 45-day treatment period was preceded by a three week pharmacological wash-out. Haemorheological parameters such as whole-blood, plasma and serum viscosity, haematocrit, fibrinogen, fibrinogen/albumin ratio and erythrocyte filterability were evaluated before and at the end of treatment. The results showed no change in haemorheological determinants in the placebo-treated group but a significant reduction in whole-blood viscosity, in haematocrit, in fibrinogen and fibrinogen/albumin ratio was observed in the bezafibrate treated patients. No variation was present in the plasma and serum viscosity and in the erythrocyte filterability.

[Behavior of plasma triglycerides and cholesterol in diabetic patients]

34 diabetic patients (24 females and 10 males) were studied and hypertriglyceridemia was found only in females. Obesity seems to be the most important factor determining hypertriglyceridemia and hypercholesterolemia. No correlation was found between glycosylated haemoglobin and triglycerides or cholesterol levels. Only a little correlation was found between fasting plasma glucose and triglycerides levels.