[P200 parameters in patients with diabetes mellitus type 2 (DM2)]. / Parámetros de la P200 en pacientes con diabetes mellitus tipo 2 (DM2).

INTRODUCTION: A complication underserved in diabetic patients is the cognitive deficits that can reach dementia. Studying the association between electrophysiological, neuropsychological, and biochemical measures could provide a breakthrough in the understanding of this phenomenon. OBJECTIVES: To compare P200 parameters between subjects with and without diabetes mellitus type 2 and to determine their relationship with biochemical and neuropsychological indicators. METHODS: This is an observational, prospective, transversal and analytical study. Seventy-four participants were divided into two groups: 37 with diabetes mellitus type 2, and 37 subjects as controls. P200 latency, amplitude, and rate of rise to somatosensory stimuli were measured and related to the Mini Mental State Examination (MMSE) test and blood glucose and glycosylated hemoglobin. RESULTS: Diabetics showed longer latency (p < 0.042, 1-tail) and lower MMSE score (p < 0.0001) than controls. Negative associations of amplitude and rising rate with glycosylated hemoglobin were observed in patients (p < 0.025); also, between amplitude and blood glucose (p < 0.038, 1-tail) and between MMSE score and time with diabetes mellitus type 2 (p < 0.007). CONCLUSIONS: The P200 parameters of the somatosensory system are sensitive to metabolic deterioration of diabetic patients, so its use in monitoring the cognitive state of patients is recommended.

The Relationship between Parameters of Long-Latency Evoked Potentials in a Multisensory Design.

In previous papers, we have shown that parameters of the omitted stimulus potential (OSP), which occurs at the end of a train of sensory stimuli, strongly depend on the modality. A train of stimuli also produces long-latency evoked potentials (LLEP) at the beginning of the train. This study is an extension of the OSP research, and it tested the relationship between parameters (ie, rate of rise, amplitude, and peak latency) of the P2 waves when trains of auditory, visual, or somatosensory stimuli were applied. The dynamics of the first 3 potentials in the train, related to habituation, were also studied. Twenty healthy young college volunteers participated in the study. As in the OSP, the P2 was faster and higher for auditory than for visual or somatosensory stimuli. The first P2 was swifter and higher than the second and the third potentials. The strength of habituation depends on the sensory modality and the parameter used. All these findings support the view that many long-latency brain potentials could share neural mechanisms related to wave generation.

Alcohol effects on the P2 component of auditory evoked potentials.

This is a second part of a research aimed to study the effects of alcohol on the electrophysiological processes in student volunteers. The first part showed that alcohol slowed the Omitted Stimulus Potential (OSP). This work studied the ethanol effects on the parameters (i.e. rate of rise, amplitude and peak latency) of the P2 component of the evoked potentials (EPs) yielded by trains of auditory stimuli. It is hypothesized here that if P2 and OSP waves share some common neural processes then alcohol should also affect these specific parameters. A dose of 0.8 g/kg of alcohol or a placebo (0 g/kg) was administered to two groups of 15 young men who were tested before and again after treatment. The pre-post treatment change in each of the measurements was used to assess the treatment effects. The results showed that compared to placebo, alcohol slowed the P2 rise rate and reduced its amplitude, with no effects on peak latency. The rise rate is more sensitive to alcohol but more resistant to the adaptation process. Alcohol resembles the response inhibition model acting against the adaptation. The rise rate of the P2 and the OSP waves are affected by alcohol in a similar fashion, suggesting similar neural generative mechanisms.

[Optical coherence tomography and visual evoked potentials in patients with type 2 diabetes with and without retinopathy: preliminary report]. / Tomografía de coherencia óptica y potenciales evocados visuales en pacientes con diabetes mellitus tipo 2 con y sin retinopatía: informe preliminary.

INTRODUCTION: Diabetic retinopathy remains the leading visual complication of diabetes mellitus type 2 (DM2) in productive patients. It evolves from a non-proliferative stage, occasionally asymptomatic, until a proliferative phase with neovascularization, retinal detachment and blindness. There are many reports that compare visual, biochemical or electrophysiological parameters among diabetic patients and healthy controls. However, much less information has been published comparing parameters between diabetics with and without non-proliferative retinopathy. Thus, it is essential to know what changes take place in the retina and the visual post retinal pathway as the disease progresses, but before the establishment of a proliferative process involving blindness. Therefore, the purpose of this study was to compare and correlate electrophysiological and visual parameters of diabetics with and without non-proliferative retinopathy, using modern, non invasive techniques. These data will allow us to a better understanding of the process and to determine the use of these parameters in the monitoring of diabetes and its complications. MATERIAL AND METHODS: This is an observational, prospective, transversal and analytical study. Twenty-two patients with DM2 were divided into two groups (50% on each group): group with non-proliferative retinopathy and group without retinopathy. We measured the central fovea thickness (CFT) by optical coherence tomography, the P100 wave of the Visual Evoked Potentials (VEP) and other visual and biochemical parameters. RESULTS: Retinopathy patients had lower visual acuity (p < 0.047), lower P100 amplitude (p < 0.043) and lower rate of rise (p < 0.026, 1-tailed). They also showed a more biochemical disturbance with higher glycemia (p < 0.015) and HbA1c (p < 0.033), and longer disease duration (p < 0.011), compared with those without retinopathy. Visual acuity showed a negative correlation with disease duration (r = -0.65; p < 0.017) and severity of ocular damage (r = -0.76; p < 0.007) in patients with retinopathy. CONCLUSIONS: Patients with retinopathy have lower visual acuity, decreased central visual fibers and a tendency to increase the ECF. Although the data favor the use of these non-invasive techniques to monitor the disease and prevent progression of visual complications, additional studies are needed with larger sample size to confirm the results obtained here.

Multiunit recording of the cerebellar cortex, inferior olive, and fastigial nucleus during copulation in naive and sexually experienced male rats.

The sexual behavior of male rats constitutes a natural model to study learning of motor skills at the level of the central nervous system. We previously showed that sexual behavior increases Fos expression in granule cells at lobules 6 to 9 of the vermis cerebellum. Herein, we obtained multiunit recordings of lobules 6a and 7 during the training period of naive subjects, and during consecutive ejaculations of expert males. Recordings from both lobules and the inferior olive showed that the maximum amplitude of mount, intromission, and ejaculation signals were similar, but sexual behavior during training tests produced a decrease in the amplitude for mount and intromission signals. The fastigial nucleus showed an inverse mirror-like response. Thus, the cerebellum is involved in the neural basis of sexual behavior and the learning of appropriate behavioral displays during copulation, with a wiring that involves the cerebellar cortex, inferior olive, and fastigial nucleus.