Changes in absolute theta power in bipolar patients during a saccadic attention task.

The present study analyzed absolute theta power (ATP) in brain areas involved with attention in the three phase of BD while the patients performing a saccadic attention task. We hypothesized that patients in depression and mania states show a higher ATP compared to euthymic patients, since a higher ATP is indicative of attention deficit. We analyzed the frontal (F7, F3, Fz, F4 and F8) and central (C3, Cz and C4) areas. Thirty bipolar patients were enrolled in this study. The subjects performed a saccadic attention task while their brain activity pattern was recorded using quantitative electroencephalography (20 channels). Our results showed a main effect for group over C3, C4, Cz, F7, F4, F8 electrodes, and a main effect for moment over Cz, F7, F8 electrodes. These results indicate that both task and groups produce changes in theta activity in distinct cortical areas that participate in the organization of attention. Our results therefore demonstrate that, although it is well established in the literature that theta has a relevant role in the attention process, it is necessary to deepen the investigations to better understand the specifics of theta during visual processing tasks that have a demand for attention.

Changes in saccadic eye movement (SEM) and quantitative EEG parameter in bipolar patients.

BACKGROUND: There is increasing evidence that neurocognitive dysfunction is associated with the different states in Bipolar Disorder. Gamma coherence is strongly related to cognitive processes and cortico-cortical communication. This paper aims at shedding light on the relationship between cortical gamma coherence within bipolar patients and a control group during a prosaccadic attention task. We hypothesized that gamma coherence oscillations act as a main neural mechanism underlying information processing which changes in bipolar patients. METHOD: Thirty-two (12 healthy controls and 20 bipolar patients) subjects were enrolled in this study. The subjects performed a prosaccadic attention task while their brain activity pattern was recorded using quantitative electroencephalography (20 channels). RESULTS: We observed that the maniac group presented lower saccade latency when compared to depression and control groups. The main finding was a greater gamma coherence for control group in the right hemisphere of both frontal and motor cortices caused by the execution of a prosaccadic attention task. LIMITATIONS: The findings need to be confirmed in larger samples and in bipolar patients before start the pharmacological treatment. CONCLUSIONS: Our findings suggest a disrupted connection of the brain's entire functioning of maniac patients and represent a deregulation in cortical inhibitory mechanism. Thus, our results reinforce our hypothesis that greater gamma coherence in the right and left frontal cortices for the maniac group produces a "noise" during information processing and highlights that gamma coherence might be a biomarker for cognitive dysfunction during the manic state.