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Chronic large-scale recording with Neuropixels 2.0 probes
Abstract BodyHow dynamic activity in neural circuits gives rise to behaviour is a central area of interest in neuroscience. A key experimental approach for addressing this question involves measuring extracellular activity of neurons in rodent animal models performing behavioural tasks. Recently developed Neuropixel probes have become a key enabling technology for measuring neural activity in large tissue volumes with high spatiotemporal resolution. Here, we report extracellular recordings obtained with the next-generation Neuropixel 2.0 probes. These probes have a smaller base PCB which facilitates their chronic use in mice. Moreover, in addition to the 1-shank design, a 4-shank probe has been fabricated. As in the previous version, 384 channels can be recorded simultaneously. To allow for performing repeated measurements of neural activity day after day, we have developed a fixture for chronic probe implantation. The fixture is composed of a probe mount to which the probe is permanently attached and which is reversibly mounted on a probe base, which is implanted on the animal. At the end of an experiment, probes can be safely recovered for re-implantation in another experimental animal by removing the probe mount from the probe base, which remains on the animals’ skull. We implanted up to two 4-shank probes in the olfactory cortex of mice and recorded singe-unit responses to odorant stimulation over weeks. Taken together, we believe Neuropixel 2.0 probes provide a key tool for enabling routine chronic recordings, overall increasing the resolution and reliability of in vivo electrophysiology experiment.
Measuring distributed correlates of visually-guided behavior across the mouse brain
Vision, choice, action and behavioural engagement arise from neuronal activity that may be distributed across brain regions. To delineate the spatial distribution of neurons underlying these processes, we used Neuropixels probes to record from approximately 30,000 neurons in 42 brain regions of mice performing a visual discrimination task. Neurons in nearly all regions responded non-specifically when the mouse initiated an action. By contrast, neurons encoding visual stimuli and upcoming choices occupied restricted regions in the neocortex, basal ganglia and midbrain. Choice signals were rare and emerged with indistinguishable timing across regions. Midbrain neurons were activated before contralateral choices and were suppressed before ipsilateral choices, whereas forebrain neurons could prefer either side. Brain-wide pre-stimulus activity predicted engagement in individual trials and in the overall task, with enhanced subcortical but suppressed neocortical activity during engagement. These results reveal organizing principles for the distribution of neurons encoding behaviourally relevant variables across the mouse brain.
Real-time readout from large neuronal populations using template-matching based spike sorting
Decision making across the larval zebrafish brain
Widefield imaging of brain-wide calcium activity in behaving animals
Distal brain areas must coordinate their activity in order to execute everyday behaviors, but many neural recording methods are limited to recording from either a small number of local neurons, or proxies of brain activity in global networks. By using widefield imaging to record from large swaths of dorsal cortex in headfixed, behaving animals, researchers can survey cortical areas involved in a variety of cognitive tasks in an unbiased manner. We'll go over the benefits and drawbacks of widefield imaging, discuss practicalities, how to design experiments that make best use of this method, and how to handle resulting datasets.