Theta-phase-specific modulation of dentate gyrus memory neurons

The theta rhythm, a quasi-periodic 4-10 Hz oscillation, is observed during memory processing in the hippocampus, with different phases of theta hypothesized to separate independent streams of information related to the encoding and recall of memories. At the cellular level, the discovery of hippocampal memory cells (engram neurons), as well as the modulation of memory recall through optogenetic activation of these cells, has provided evidence that certain memories are stored, in part, in a sparse ensemble of neurons in the hippocampus. In previous research, however, engram reactivation has been carried out using open-loop stimulation at fixed frequencies; the relationship between engram neuron reactivation and ongoing network oscillations has not been taken into consideration. To address this concern, we implemented a closed-loop reactivation of engram neurons that enabled phase-specific stimulation relative to theta oscillations in the local field potential in CA1. Using this real-time approach, we tested the impact of activating dentate gyrus engram neurons during the peak (encoding phase) and trough (recall phase) of theta oscillations. Consistent with previously hypothesized functions of theta oscillations in memory function, we show that stimulating dentate gyrus engram neurons at the trough of theta is more effective in eliciting behavioral recall than either fixed-frequency stimulation or stimulation at the peak of theta. Moreover, phase-specific trough stimulation is accompanied by an increase in the coupling between gamma and theta oscillations in CA1 hippocampus. Our results provide a causal link between phase-specific activation of engram cells and the behavioral expression of memory.

Analyzing the therapeutic effects of short wrist splint in patients with carpal tunnel syndrome (CTS) under ibuprofen treatment from an EMG-NCV perspective

Objective: Carpal tunnel symptoms are typical outside nerve involvement and a significant reason of inability. This syndrome often causes weakness and pain in the affected hand. Therefore, the researchers decided to perform a study that aimed to investigate the therapeutic effects of Wrist Splint (short wrist splint) in patients admitted to the neurology clinic of Vali Asr Hospital of Birjand with carpal tunnel syndrome (CTS) under ibuprofen treatment from an EMG-NCV perspective. Methods: This clinical trial was performed on patients admitted to the neurology clinic of Vali Asr Hospital during the spring and summer of 2013. The participants of the study were classified into two teams. The initial team of cases went under medical treatment with ibuprofen (800 mg BID for 4-6 weeks) and the second group of patients went under medical care with ibuprofen (800 mg BID for 4-6 weeks) with a short wrist splint. Results: 40 cases participated in the research. The mean age of participants was 32/ 75 ± 4/ 33 years (range 20 to 48 years), respectively. Most of the participants were females (n = 30, 75% respectively). The mean score, latency and velocity between the two groups were mainly distinct (respectively p = 0.05, 0.001, and 0.003). There were significant differences between amplitude before the start of the study (p = 0.000) among the participants. Discussion: The results showed that patients treated with ibuprofen and wrist splint along the para-clinics presented a better response to treatment.