从科学学到科学社会学

分析科学学到科学社会学这一研究发展趋向。认为科学学最初的定位具有局限性,很难将系统的观点贯彻到底;科学社会学的研究有助于弥补这种局限性,而且也为科学学的研究开辟了广阔的前景;科学社会学不能取代科学学的研究,两者应该按照互相利用对方研究成果及组织联合研究的方针发展。     

Bold claims for optogenetics

In a recent Letter to Nature, Lee and colleagues combined optogenetic stimulation with functional magnetic resonance imaging (ofMRI) to examine the relationship between pyramidal-cell spiking and the blood oxygenation level dependent (BOLD) signal. To do so, they injected an adeno-associated viral vector into the primary motor cortex (M1) of adult rats to drive the expression of channelrhodopsin (ChR2) in cortical projection neurons, thus making them sensitive to light. The authors then used combined light stimulation and functional magnetic resonance imaging (fMRI) to examine the effects of selective activation of the light-sensitive pyramidal cells on the BOLD signal, as well as to probe the value of this methodology for mapping brain connectivity. They found that excitation of these neurons induced positive BOLD signals both in the injected M1 region and in remote target thalamic nuclei receiving direct projections from that region, and concluded that ofMRI reliably links positive BOLD signals with increased local neuronal excitation. However, their analysis neglects the almost immediate activation of other circuits that could lead to the generation of BOLD signals through local perisynaptic rather than spiking activity. Their experiments therefore do not pin down the identity of the specific neuronal signals that give rise to the BOLD signal.