Direct electrical stimulation of the human cortex can produce subjective visual sensations,yet these sensations are unstable.The underlying mechanisms may stem from differences in electrophysiological activity within ...Direct electrical stimulation of the human cortex can produce subjective visual sensations,yet these sensations are unstable.The underlying mechanisms may stem from differences in electrophysiological activity within the distributed network outside the stimulated site.To address this problem,we recruited 69 patients who experienced visual sensations during invasive electrical stimulation while intracranial electroencephalography(iEEG)data were recorded.We found significantly flattened power spectral slopes in distributed regions involving different brain networks and decreased integrated information during elicited visual sensations compared with the non-sensation condition.Further analysis based on minimum information partitions revealed that the reconfigured network interactions primarily involved the inferior frontal cortex,posterior superior temporal sulcus,and temporoparietal junction.The flattened power spectral slope in the inferior frontal gyrus was also correlated with integrated information.Taken together,this study indicates that the altered electrophysiological signatures provide insights into the neural mechanisms underlying subjective visual sensations.展开更多
Electrically pumped high power terahertz （THz） emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12...Electrically pumped high power terahertz （THz） emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz （20 meV and 50 meV） that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively deep binding energies of the nitrogen donors, above 100 meV, and the high thermal conductivity of the SiC substrates, the THz output power and operating temperature were significantly higher than previous dopant based emitters. With peak applied currents of a few amperes, and a top surface area of 1 mm2, the device emitted up to 0.5 mW at liquid nitrogen temperature （77 K）, and tens of microwatts up to 333 K. This result is the highest temperature of THz emission reported from impurity-based emitters.展开更多
基金supported by STI2030-Major Projects(2021ZD0204300 and 2022ZD0205000)the National Natural Science Foundation of China(32020103009)+2 种基金a Ministry Key Project(GW089000)the Scientific Foundation of the Institute of Psychology,Chinese Academy of Sciences(E2CX4215CX)the CAAE Epilepsy Research Fund-UCB Fund(CU-2023-052).
文摘Direct electrical stimulation of the human cortex can produce subjective visual sensations,yet these sensations are unstable.The underlying mechanisms may stem from differences in electrophysiological activity within the distributed network outside the stimulated site.To address this problem,we recruited 69 patients who experienced visual sensations during invasive electrical stimulation while intracranial electroencephalography(iEEG)data were recorded.We found significantly flattened power spectral slopes in distributed regions involving different brain networks and decreased integrated information during elicited visual sensations compared with the non-sensation condition.Further analysis based on minimum information partitions revealed that the reconfigured network interactions primarily involved the inferior frontal cortex,posterior superior temporal sulcus,and temporoparietal junction.The flattened power spectral slope in the inferior frontal gyrus was also correlated with integrated information.Taken together,this study indicates that the altered electrophysiological signatures provide insights into the neural mechanisms underlying subjective visual sensations.
基金supported by the NSF Award No.DMR-0601920ONR Contract No.N0001-4-00-1-0834
文摘Electrically pumped high power terahertz （THz） emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz （20 meV and 50 meV） that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively deep binding energies of the nitrogen donors, above 100 meV, and the high thermal conductivity of the SiC substrates, the THz output power and operating temperature were significantly higher than previous dopant based emitters. With peak applied currents of a few amperes, and a top surface area of 1 mm2, the device emitted up to 0.5 mW at liquid nitrogen temperature （77 K）, and tens of microwatts up to 333 K. This result is the highest temperature of THz emission reported from impurity-based emitters.
