Kardamakis Andreas A, Pérez-Fernández Juan, Grillner Sten
Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
Elife. 2016 Sep 16;5:e16472. doi: 10.7554/eLife.16472.
Animals integrate the different senses to facilitate event-detection for navigation in their environment. In vertebrates, the optic tectum (superior colliculus) commands gaze shifts by synaptic integration of different sensory modalities. Recent works suggest that tectum can elaborate gaze reorientation commands on its own, rather than merely acting as a relay from upstream/forebrain circuits to downstream premotor centers. We show that tectal circuits can perform multisensory computations independently and, hence, configure final motor commands. Single tectal neurons receive converging visual and electrosensory inputs, as investigated in the lamprey - a phylogenetically conserved vertebrate. When these two sensory inputs overlap in space and time, response enhancement of output neurons occurs locally in the tectum, whereas surrounding areas and temporally misaligned inputs are inhibited. Retinal and electrosensory afferents elicit local monosynaptic excitation, quickly followed by inhibition via recruitment of GABAergic interneurons. Multisensory inputs can thus regulate event-detection within tectum through local inhibition without forebrain control.
动物整合不同的感官以促进在其环境中导航时的事件检测。在脊椎动物中，视顶盖（上丘）通过不同感觉模态的突触整合来指挥眼动转移。最近的研究表明，视顶盖可以自行制定眼动重新定向指令，而不仅仅是充当从上游/前脑回路到下游运动前中枢的中继站。我们发现，视顶盖回路能够独立进行多感官计算，从而配置最终的运动指令。如在七鳃鳗（一种系统发育上保守的脊椎动物）中所研究的那样，单个视顶盖神经元接收汇聚的视觉和电感觉输入。当这两种感觉输入在空间和时间上重叠时，输出神经元的反应增强会在视顶盖局部发生，而周围区域以及时间上未对齐的输入则受到抑制。视网膜和电感觉传入神经引发局部单突触兴奋，随后很快通过招募GABA能中间神经元而受到抑制。因此，多感官输入可以通过局部抑制在没有前脑控制的情况下调节视顶盖内的事件检测。
