The anterior thalamic nucleus (ATN) is thought to play an important role in a brain network involving the hippocampus and neocortex, which enables human memories to be formed. However, its small size and location deep within the brain have impeded direct investigation in humans with non-invasive techniques. Here we provide direct evidence for a functional role for the ATN in memory formation from rare simultaneous human intrathalamic and scalp electroencephalogram (EEG) recordings from eight volunteering patients receiving intrathalamic electrodes implanted for the treatment of epilepsy, demonstrating real-time communication between neocortex and ATN during successful memory encoding. Neocortical-ATN theta oscillatory phase synchrony of local field potentials and neocortical-theta-to-ATN-gamma cross-frequency coupling during presentation of complex photographic scenes predicted later memory for the scenes, demonstrating a key role for the ATN in human memory encoding.DOI:http://dx.doi.org/10.7554/eLife.05352.001

Background: The thalamic anteroventral nucleus (AV) is a promising target structure for deep brain stimulation (DBS) in patients suffering from refractory epilepsy. Direct visualization of the AV would improve spatial accuracy in functional stereotactic neurosurgery for treatment of this disease. Methods: On 3-tesla magnetic resonance imaging (MRI), acquisition parameters were adjusted for optimal demarcation of the AV in 1 healthy subject. Reliability of AV visualization was then evaluated in 5 healthy individuals and 3 patients with refractory epilepsy. Results: In all individuals, an adjusted T₁-weighted sequence allowed for demarcation of the AV. It was clearly distinguishable from hyperintense myelin-rich lamellae surrounding it ventrally and laterally and appeared hypo-intense compared to the adjacent thalamic nuclei. Image resolution and contrast facilitated direct stereotactic targeting of the AV prior to DBS surgery in all 3 patients. Conclusions: Direct targeting of the AV can be achieved, which has immediate implications for the accuracy of MRI-guided DBS in patients with refractory epilepsy.

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SUMMARYPeriventricular nodular heterotopias (PNHs) are frequently associated with pharmacoresistant epilepsy. They are considered part of a dysfunctional network, connected to the overlying cortex. Therefore, removal of the PNHs and additional cortectomy or lobectomy seem to be essential for significant and long-lasting seizure reduction. These procedures, however, can have considerable limitations, especially in patients with functional eloquent cortex adjacent to the PNH. Alternatively, stereotactic neurosurgery can reduce the surgical trauma. Presented is a 56-year-old man who became seizure-free after stereotactically guided radiofrequency lesioning of a solitary PNH. KEY WORDS: Epileptogenity, Epilepsy surgery, Network, Stereotaxy, Thermoablation, Thermocoagulation.Pharmacologic treatment of patients with periventricular nodular heterotopias (PNHs) is oftentimes unsatisfactory (Raymond et al., 1994), even if the extent of PNH is limited to one brain region and neurologic examination is normal (D'orsi et al., 2004). Standard resective neurosurgery also does not necessarily result in cessation of seizures (Li et al., 1997). In case of adjacent eloquent cortex, this approach must be abandoned or is further complicated by the need for invasive electroencephalography (EEG) monitoring, such as implementation of grid electrodes. As far back as 60 years ago, stereotactically guided radiofrequency lesioning (RFL) using depth electrode recordings in the rhinencephalon was thought to circumvent this problem (Marossero et al., 1980). Generally accepted indications and target zones for this procedure, however, have been missing since (Ojemann & Ward, 1975).The presented case illustrates that RFL can be used to deactivate effectively an epileptogenic zone associated with PNH if it is performed in combination with high-resolution magnetic resonance imaging (MRI) and electrophysiologic selected target detection. Patient and MethodOn admission, this 56-year-old, right-handed male patient presented with poorly controlled epilepsy manifested as frequent unspecific auras, daily clonic, aphasic seizures and one bilateral tonic-clonic seizure per week. In addition, he complained about memory and concentration difficulties. Current treatment was lamotrigine 850 mg/day and carbamazepine 800 mg/day.Since onset of epilepsy at the age of 3, several antiepileptic drugs have been used. From childhood to adolescence, the patient took phenobarbital, phenytoin, and valproic acid. Later oxcarbazepine and topiramate treatment was discontinued because of poor seizure control and intolerable sideeffects. Birth and child development was unremarkable other than for measles encephalitis in early childhood. A third-degree relative of the patient allegedly had epilepsy. He had no other affliction apart from medically controlled hyperlipidemia.The main findings on cranial MRI (Fig. 1A) were a solitary PNH dorsal to the left caput caudatum at the level of the ventricular wall and atrophy of the left-sided superior insular cortex and the cerebellum. ...