Frontal Functional Connectivity of Electrocorticographic Delta and Theta Rhythms during Action Execution Versus Action Observation in Humans.

We have previously shown that in seven drug-resistant epilepsy patients, both reaching-grasping of objects and the mere observation of those actions did desynchronize subdural electrocorticographic (ECoG) alpha (8-13 Hz) and beta (14-30) rhythms as a sign of cortical activation in primary somatosensory-motor, lateral premotor and ventral prefrontal areas (Babiloni et al., 2016a). Furthermore, that desynchronization was greater during action execution than during its observation. In the present exploratory study, we reanalyzed those ECoG data to evaluate the proof-of-concept that lagged linear connectivity (LLC) between primary somatosensory-motor, lateral premotor and ventral prefrontal areas would be enhanced during the action execution compared to the mere observation due to a greater flow of visual and somatomotor information. Results showed that the delta-theta (<8 Hz) LLC between lateral premotor and ventral prefrontal areas was higher during action execution than during action observation. Furthermore, the phase of these delta-theta rhythms entrained the local event-related connectivity of alpha and beta rhythms. It was speculated the existence of a multi-oscillatory functional network between high-order frontal motor areas which should be more involved during the actual reaching-grasping of objects compared to its mere observation. Future studies in a larger population should cross-validate these preliminary results.

Alpha, beta and gamma electrocorticographic rhythms in somatosensory, motor, premotor and prefrontal cortical areas differ in movement execution and observation in humans.

OBJECTIVE: In the present study, we tested the hypothesis that both movement execution and observation induce parallel modulations of alpha, beta, and gamma electrocorticographic (ECoG) rhythms in primary somatosensory (Brodmann area 1-2, BA1-2), primary motor (BA4), ventral premotor (BA6), and prefrontal (BA44 and BA45, part of putative human mirror neuron system underlying the understanding of actions of other people) areas. METHODS: ECoG activity was recorded in drug-resistant epileptic patients during the execution of actions to reach and grasp common objects according to their affordances, as well as during the observation of the same actions performed by an experimenter. RESULTS: Both action execution and observation induced a desynchronization of alpha and beta rhythms in BA1-2, BA4, BA6, BA44 and BA45, which was generally higher in amplitude during the former than the latter condition. Action execution also induced a major synchronization of gamma rhythms in BA4 and BA6, again more during the execution of an action than during its observation. CONCLUSION: Human primary sensorimotor, premotor, and prefrontal areas do generate alpha, beta, and gamma rhythms and differently modulate them during action execution and observation. Gamma rhythms of motor areas are especially involved in action execution. SIGNIFICANCE: Oscillatory activity of neural populations in sensorimotor, premotor and prefrontal (part of human mirror neuron system) areas represents and distinguishes own actions from those of other people. This methodological approach might be used for a neurophysiological diagnostic imaging of social cognition in epileptic patients.

Seizure clusters and adverse events during pre-surgical video-EEG monitoring with a slow anti-epileptic drug (AED) taper.

OBJECTIVE: To evaluate the efficiency and safety of pre-surgical video-EEG monitoring with a slow anti-epileptic drug (AED) taper and a rescue benzodiazepine protocol. METHODS: Fifty-four consecutive patients with refractory focal epilepsy who underwent pre-surgical video-electroencephalography (EEG) monitoring during the year 2010 were included in the study. Time to first seizure, duration of monitoring, incidence of 4-h and 24-h seizure clustering, secondarily generalised tonic-clonic seizures (sGTCS), status epilepticus, falls and cardiac asystole were evaluated. RESULTS: A total of 190 seizures were recorded. Six (11%) patients had 4-h clusters and 21 (39%) patients had 24-h clusters. While 15 sGTCS were recorded in 14 patients (26%), status epilepticus did not occur and no seizure was complicated with cardiac asystole. Epileptic falls with no significant injuries occurred in three patients. The mean time to first seizure was 3.3days and the time to conclude video-EEG monitoring averaged 6days. CONCLUSION: Seizure clustering was common during pre-surgical video-EEG monitoring, although serious adverse events were rare with a slow AED tapering and a rescue benzodiazepine protocol. SIGNIFICANCE: Slow AED taper pre-surgical video-EEG monitoring is fairly safe when performed in a highly specialised and supervised hospital setting.

Activity of hippocampal, amygdala, and neocortex during the Rey auditory verbal learning test: an event-related potential study in epileptic patients.

OBJECTIVE: Previous evidence in epileptic subjects has shown that theta (about 4-7Hz) and gamma rhythms (about 40-45Hz) of hippocampus, amygdala, and neocortex were temporally synchronized during the listening of repeated words successfully remembered (Babiloni et al., 2009). Here we re-analyzed those electroencephalographic (EEG) data to test whether a parallel increase in amplitude of late positive event-related potentials takes place. METHODS: Intracerebral electroencephalographic (EEG) activity had been recorded in five subjects with drug-resistant temporal lobe epilepsy, undergoing pre-surgical evaluation. During the recording of the intracerebral EEG activity, the subjects performed a computerized version of the Rey auditory verbal learning test (RAVLT). They heard the same list of 15 common words for five times. Each time, immediately after the listening of the list, the subjects were required to repeat as many words as they could recall. RESULTS: We found that late positive event-related potentials (ERPs) peaking at about 350ms post-stimulus in amygdala, hippocampus, and occipital-temporal cortex had a higher amplitude during the listening of the repeated words that were subsequently recalled than for those that were not recalled. CONCLUSIONS: Late positive ERPs reflect a functional mechanism implemented in a human brain network spanning amygdala, hippocampus, and occipital-temporal cortex which is at the basis of the memorization processes of verbal materials. SIGNIFICANCE: This ERP component is a promising neuromarker of successful memorization of repeated words in humans.

Hippocampal, amygdala, and neocortical synchronization of theta rhythms is related to an immediate recall during rey auditory verbal learning test.

It is well known that theta rhythms (3-8 Hz) are the fingerprint of hippocampus, and that neural activity accompanying encoding of words differs according to whether the items are later remembered or forgotten ["subsequent memory effect" (SME)]. Here, we tested the hypothesis that temporal synchronization of theta rhythms among hippocampus, amygdala, and neocortex is related to immediate memorization of repeated words. To address this issue, intracerebral electroencephalographic (EEG) activity was recorded in five subjects with drug-resistant temporal lobe epilepsy (TLE), under presurgical monitoring routine. During the recording of the intracerebral EEG activity, the subjects performed a computerized version of Rey auditory verbal learning test (RAVLT), a popular test for the clinical evaluation of the immediate and delayed memory. They heard the same list of 15 common words for five times. Each time, immediately after listening the list, the subjects were required to repeat as many words as they could recall. Spectral coherence of the intracerebral EEG activity was computed in order to assess the temporal synchronization of the theta (about 3-8 Hz) rhythms among hippocampus, amygdala, and temporal-occipital neocortex. We found that theta coherence values between amygdala and hippocampus, and between hippocampus and occipital-temporal cortex, were higher in amplitude during successful than unsuccessful immediate recall. A control analysis showed that this was true also for a gamma band (40-45 Hz). Furthermore, these theta and gamma effects were not observed in an additional (control) subject with drug-resistant TLE and a wide lesion to hippocampus. In conclusion, a successful immediate recall to the RAVLT was associated to the enhancement of temporal synchronization of the theta (gamma) rhythms within a cerebral network including hippocampus, amygdala, and temporal-occipital neocortex.

Partial seizures due to sclerosis of the right amygdala presenting as panic disorder. On the importance of psychopathological assessment in differential diagnosis.

The differential diagnosis between panic disorder and focal epilepsy may sometimes pose a serious challenge. We report the case of a 32-year-old woman who complained of paroxysmal episodes of acute anxiety that evaded diagnosis for 8 years. Standard EEGs and brain CT scan showed no clear pathologic findings. Antidepressants, support psychotherapy and several courses of antiepileptic drugs were not beneficial. She was referred to our centre for a comprehensive diagnostic assessment. Clinical and standardized personality assessment did not reveal the personality organization typically associated with proneness to develop phobic anxiety disorders. Also, agoraphobic avoidance was absent, and the patient's main worries during the episodes involved negative social judgments rather than health. A brain MRI revealed a slightly increased signal at FLAIR images in the right amygdala. Video-EEG monitoring was decisive in establishing the diagnosis of drug-resistant right mesial temporal lobe epilepsy. Anteromesial temporal lobectomy was offered and successfully performed. Pathological examination of removed brain tissue revealed amygdalar sclerosis and mild hippocampal neuronal loss. At a 6-month follow-up visit, the paroxysmal episodes had completely disappeared. Depression, anxiety and quality of life were markedly improved. This case suggests that focal epilepsy should be considered in patients with paroxysmal episodes of anxiety, especially if dissociative symptoms and atypical clinical features for panic disorder are present, and if there is no satisfactory response to adequate trials of medication and psychotherapy within one year. A careful psychopathological analysis rather than a descriptive enumeration of symptoms is needed to bring these features to light. In such cases, even if routine EEGs or MRI are inconclusive and there is no response to antiepileptic drugs, it would be advisable to perform video-EEG monitoring to rule out partial seizures.

Factors associated with generic and disease-specific quality of life in temporal lobe epilepsy.

PURPOSE: We aimed at further elucidating the association between quality of life (QOL) and sociodemographic factors, clinical seizure factors, depression and anxiety in drug-resistant temporal lobe epilepsy (TLE). METHODS: We studied 106 consecutive adult right-handed patients (mean age 35.4 +/- 9.7; 50% males; IQ> or = 70) with drug-resistant unilateral (59% right) TLE (70% hippocampal sclerosis, 30% tumors or other lesions), who underwent a comprehensive non-invasive pre-surgical protocol. They completed the Beck Depression Inventory (BDI) and the State Form of the Spielberger State-Trait Anxiety Inventory (STAI). To measure QOL, we used both a generic instrument, the WHOQOL-100, and a disease-specific instrument, the 31-item quality of life in epilepsy (QOLIE-31). Multiple linear regression analysis was used to examine the relationship between each QOL domain and age, gender, education, side of TLE, duration of epilepsy, seizure frequency, and level of depression and anxiety. RESULTS: Severity of depressive symptoms was significantly associated with lower scores across most QOL domains. Depression was consistently the strongest predictor of lower scores on almost all QOL domains. Also, severity of anxiety symptoms was significantly associated with lower scores across many QOL domains. Independent significant relationships between QOL and sociodemographic or clinical epilepsy variables were limited in number and strength. CONCLUSIONS: Our findings suggest that QOL in TLE might be substantially affected by the presence and severity of depressive symptoms and, to a lesser degree, of anxiety symptoms. While clinical seizure variables had a weaker association with QOL, the absence of seizure-free patients might have obscured a relation between seizure frequency and QOL. Healthcare professionals should be aware of the significance of patients' emotional state and of the role it plays for their QOL. Adopting a biopsychosocial approach might be useful to address patients' needs.