Background Subthalamic deep brain stimulation is superior to medical therapy for the motor symptoms of advanced Parkinson’s disease, and additional evidence suggests that it improves refractory symptoms of essential tremor, primary generalized dystonia, and obsessive-compulsive disorder. Despite this, its therapeutic mechanism is unknown. We hypothesized that subthalamic stimulation activates cerebral cortex at short latencies after stimulus onset during clinically effective stimulation for Parkinson disease. Methods In 5 subjects (6 hemispheres) electroencephalography measured the response of cortex to subthalamic stimulation across a range of stimulation voltages and frequencies. Novel analytical techniques reversed the anode and cathode electrode contacts and summed the resulting pair of event related potentials to suppress the stimulation artifact. Results Subthalamic brain stimulation at 20 Hertz activates somatosensory cortex at discrete latencies (mean latencies 1.0 ± 0.4, 5.7 ± 1.1, and 22.2 ± 1.8 milliseconds, denoted R1, R2, and R3, respectively). The amplitude of the short latency peak (R1) during clinically effective high frequency stimulation is nonlinearly dependent on stimulation voltage (p < 0.001, repeated measures analysis of variance), and its latency is less variable than that of R3 (1.02 versus 19.46 milliseconds, p < 0.001, Levene’s test). Conclusions Clinically effective subthalamic brain stimulation in humans with Parkinson disease activates cerebral cortex at one millisecond after stimulus onset, most likely by antidromic activation. Our findings suggest that alteration of the precise timing of action potentials in cortical neurons with axonal projections to the subthalamic region is an important component of the therapeutic mechanism of subthalamic brain stimulation.

Nine patients had composite lymphoma in which Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) involved the same anatomic site. Two of these patients had relapses of their tumors. In one, the initial biopsy specimen contained follicular and diffuse large cell NHL with unclassifiable HD, but the relapse showed diffuse large cell NHL with nodular sclerosis HD. In the other patient, both biopsy specimens showed follicular mixed NHL; the HD component in the initial biopsy specimen was nodular sclerosis, whereas, at relapse, it had the appearance of interfollicular HD. In the remaining seven patients, the HD component was subclassified as nodular sclerosis (three specimens) or mixed cellularity (three specimens), or it was unclassifiable (one specimen). The NHL component was categorized as diffuse large cell (two specimens), diffuse large cell immunoblastic (two specimens), follicular and diffuse large cell (one specimen), diffuse mixed small and large cell (one specimen), and lymphocytic lymphoma of intermediate differentiation (modified Rappaport classification) (one specimen). Paraffin section immunoperoxidase studies were done on the NHL component in eight patients (nine specimens) and on the HD component in six patients (seven specimens). In each of these, the NHL component was leukocyte common antigen (LCA) positive and Leu-M1 negative. In addition, the neoplastic cells were L26 positive and UCHL-1 negative, indicating a B-cell phenotype. In five of seven immunophenotyped cases, Reed-Sternberg (RS) and Hodgkin's (H) cells from the HD areas were Leu-M1 positive and LCA negative, reflecting an immunophenotype that is typical of non-lymphocyte-predominant HD. In two specimens, the malignant cells were negative for Leu-M1 and LCA (with positive internal controls). Composite lymphomas composed of HD and NHL are unusual, and cases of coexistent HD of the non-lymphocyte-predominant subtype and NHL are even less common. The results of the current study and a review of the literature indicate that this phenomenon usually involves a B-cell NHL that coexists with HD, perhaps further suggesting a close relationship between the malignant cells of HD (RS and H cells) and B lymphocytes.

Deep brain stimulation relieves disabling symptoms of neurologic and psychiatric diseases when medical treatments fail, yet its therapeutic mechanism is unknown. We hypothesized that ventral intermediate nucleus stimulation for essential tremor activates cortex at short latencies and that this potential is related to suppression of tremor in the contralateral arm. We measured cortical activity with electroencephalography in 5 subjects (7 brain hemispheres) across a range of stimulator settings, and reversal of the anode and cathode electrode contacts minimized the stimulus artifact, allowing visualization of brain activity. Regression quantified the relationship between stimulation parameters and both the peak of the short latency potential and tremor suppression. Stimulation generated a polyphasic event related potential in ipsilateral sensorimotor cortex with peaks at discrete latencies beginning less than one millisecond after stimulus onset (mean latencies 0.9±0.2, 5.6±0.7, and 13.9±1.4 milliseconds, denoted R1, R2, and R3, respectively). R1 showed more fixed timing than the subsequent peaks in the response (p<0.0001, Levene’s test), and R1 amplitude and frequency were both closely associated with tremor suppression (p<0.0001, respectively). These findings demonstrate that effective ventral intermediate nucleus thalamic stimulation for essential tremor activates cerebral cortex at approximately one millisecond after the stimulus pulse. The association between this short latency potential and tremor suppression suggests that deep brain stimulation may improve tremor by synchronizing the precise timing of discharges in nearby axons, and by extension the distributed motor network, to the stimulation frequency or one of its subharmonics.

The use of optogenetics in metabolic engineering for light-controlled microbial chemical production raises the prospect of utilizing control and optimization techniques routinely deployed in traditional chemical manufacturing. However, such mechanisms require well-characterized, customizable tools that respond fast enough to be used as real-time inputs during fermentations. Here, we present OptoINVRT7, a new rapid optogenetic inverter circuit to control gene expression in Saccharomyces cerevisiae. The circuit induces gene expression in only 0.6 h after switching cells from light to darkness, which is at least 6 times faster than previous OptoINVRT optogenetic circuits used for chemical production. In addition, we introduce an engineered inducible GAL1 promoter (P GAL1-S ), which is stronger than any constitutive or inducible promoter commonly used in yeast. Combining OptoINVRT7 with P GAL1-S achieves strong and lighttunable levels of gene expression with as much as 132.9 ± 22.6-fold induction in darkness. The high performance of this new optogenetic circuit in controlling metabolic enzymes boosts production of lactic acid and isobutanol by more than 50% and 15%, respectively. The strength and controllability of OptoINVRT7 and P GAL1-S open the door to applying process control tools to engineered metabolisms to improve robustness and yields in microbial fermentations for chemical production.