Intrinsic regulators of the action potential waveform control dopamine release to shape behavior

Despite the widely known role of dopamine in reinforcement learning, how the patterns of dopamine release that are critical to the acquisition, performance, and extinction of conditioned responses are generated is poorly resolved. Here, we demonstrate that the coordinated actions of two ion channels, Kv4.3 and BKCa1.1, control the pattern of dopamine release on different time scales to regulate separate phases of reinforced behavior in mice. Inactivation of Kv4.3 in VTA dopamine neurons increases pacemaker activity and excitability that is associated with increased ramping prior to lever press in a learned instrumental response paradigm. Loss of Kv4.3 enhanced performance of the learned response and facilitated extinction. In contrast, loss of BKCa1.1 increased burst firing and phasic dopamine release that enhanced learning of an instrumental response. Inactivation of BKCa1.1 increased the reward prediction error that was associated with an enhanced extinction burst in early extinction training. These data demonstrate that temporally distinct patterns of dopamine release are regulated by the intrinsic properties of the cell to shape behavior.

Initial state effect on waveform control of high-order harmonic spectrum and attosecond pulse generation

In this paper, the waveform control of high-order harmonic generation and attosecond pulse generation from a different initial state of He atom has been investigated. The results show that (i) by properly controlling the carrier-envelope phases, the time delays and the laser intensities of a 3-color laser pulse, the best waveforms for the harmonic cut-off extension can be found. Although the harmonic cut-offs from the ground initial state and the superposition initial state are almost the same, the harmonic intensities from the superposition initial state are 4 to 5 orders of magnitudes higher than those from the ground initial state. (ii) With the introduction of the inhomogeneous effect, the harmonic cut-offs can be further extended. However, the harmonic intensities from the superposition initial state are remarkably decreased compared with those from the homogeneous pulses, which is unbeneficial to generate the intense attosecond pulses. (iii) When the ground state is chosen to be the initial and with the assistance of the 4th UV pulse, not only the larger harmonic cut-offs can be obtained, but also the stronger harmonic plateaus can be found, which is favorable for producing the intense attosecond pulses. Thus, at the end of this paper, by superposing the harmonics from the best harmonic spectra, the single attosecond pulses with the duration of 36 as can be obtained.

Chirp waveform control to produce broad harmonic plateau and single attosecond pulse

Waveform control of three kinds of chirped pulses (i.e. βt, βt 2 and βt 3) to produce harmonic spectra and attosecond pulses has been investigated. It is found that by properly choosing the chirps, the chirp delays and the other laser parameters, not only the instantaneous frequency of some specific half profiles can be decreased, but also its intensity can be increased. As a result, the free electron can receive more energy when it accelerates in these regions, thus leading to the extension of the harmonic cutoff and harmonic plateau. Finally, through the Fourier transformation of the harmonic spectra and by superposing some harmonics, three single attosecond pulses with the durations of 30 as, 33 as and 39 as can be obtained.