Neurons to make decision

Optical Imaging of Neuronal Populations During Decision-Making (from Kristan's lab)

Understanding how a neuronal network makes a behavioral decision is one of a major goal in neuroscience. In this paper, Briggman et al. imaged the activity of a population of leech neurons using voltage-sensitive dye when the leech makes decision of swimming vs. crawling. They excited the (reduced) animal repeatedly with identical stimuli that stochastically produce crawling and swimming with roughly equal probabilities. Principal component (PC) analysis showed that the activity patterns of the cell population diverge toward two different region in the PC space earlier than the actual response. They identified neurons contributing highly to the discriminant in a linear-discriminant analysis. Interestingly, modulating voltage of one of the identified cells (cell 208) by an electrode biased the decision-making.

Calcium imaging to analyze circuit

Functional imaging with cellular resolution reveals precise micro-architecture in visual cortex (2005), Ohki K. et al.Nature 433, 597 - 603 (Reid lab.)

Congratulations, Ohki-san!!!!! The column structure in the cortex has fascinated many brain researchers: why are cells that response to similar stimulations clustered to form a column ? Using a combination of bulk loading of AM-calcium sensor and a two-photon microscope, Ohki et al. meausred the orientation selectivity of the visual cortex at a single-cell resolution. The sharpness of the boundary between two orientation columns is almost shocking. Supposedly the input orientation map is much broader as dendritic arbor spreads over hundreds of microns. It would be interesting how a single cell process inputs to "choose" one (or sometimes two) selectivity. Another interesting aspect of the orientation selectivity is that mice have poorly organized structure in contrast to cats. To perform complicated information processing, it may be required for animals to have higher organization of a column.