The latest visualization tool created by scientists at HHMI’s Janelia Research Campus aids researchers in identifying activity trends within extensive neural recordings. This marks a significant step towards forming new insights into how individual neurons and their circuits contribute to behavior.
Neuroscientists have gained considerable knowledge—such as identifying which neurons and circuits correspond to specific behaviors—by tracking the activity of small groups of neurons.
But what occurs when you monitor thousands of neurons simultaneously? Or when you’re trying to understand the function of neurons without a clear external stimulus or you aren’t sure what to investigate?
This is where Rastermap becomes invaluable.
The newly developed visualization tool by the Stringer and Pachitariu labs at HHMI’s Janelia Research Campus aids researchers in identifying activity patterns in extensive neural recordings—an essential initial step in shaping new theories about how neurons and circuits drive behavior.
“To delve into your data, visualizing it is crucial,” explains Janelia Group Leader Carsen Stringer. “There may be unexpected insights within that data, so you want to visualize it in a manner that sparks new hypotheses you may not have considered before.”
Rastermap is an algorithm designed to classify the activity of thousands of neurons into groups based on the similarities in their activity, even if their firing times differ or their actions don’t align with observable behaviors. These groups are then displayed on a raster plot, a type of graph showing spikes over time, enabling researchers to visualize and detect patterns within the data for further examination in the laboratory.
In contrast to earlier visualization methods that averaged neuronal activity across multiple experimental trials to seek patterns, Rastermap allows researchers to observe neuronal activity from a single trial. This capability reveals patterns in the data that prior techniques found challenging to identify. Furthermore, Rastermap also enables researchers to investigate neuronal activity patterns in the absence of external stimuli.
Thus far, Rastermap, featuring a user-friendly graphical interface, has assisted scientists in visualizing neuronal activity across a variety of species, including flies, zebrafish, mice, rats, and primates.
“While you can’t directly communicate with animals about their thoughts, this unsupervised method allows you to uncover potentially new insights related to the cognitive processes occurring within them,” says Stringer. Moreover, if neuronal activity is influenced by an external factor, “Rastermap clarifies that visualization process.”
