As scientists across fields continue to innovate functional, structural, and molecular imaging tools, the potential for using advanced strategies to analyze large physiological and anatomical datasets is rising dramatically. These technologies have the capacity to facilitate high-impact discoveries in basic and applied neuroscience, especially when combined in optimal ways. This short course from Neuroscience 2018 will offer practical considerations for combining imaging tools that will help you select those that will most assist you in investigating a specific scientific question in your basic or translational research. You’ll come away with an understanding of: • Optimization of optogenetics for interrogating neural circuits. • Miniature microscopes, voltage imaging techniques, and other techniques to examine neural ensemble activity. • Adaptive optics for in vivo imaging. • Technologies to extract single-neuron activity from large datasets. • Statistical modeling of connectomes. • Expansion microscopy, optogenetic control, and fluorescent imaging of neural dynamics.

Recording the spiking activity from subcellular compartments of neurons such as axons and dendrites during mouse behavior with 2-photon calcium imaging is increasingly common yet remains challenging due to low signal-to-noise, inaccurate region-of-interest (ROI) identification, movement artifacts, and difficulty in grouping ROIs from the same neuron. To address these issues, we present a computationally efficient preprocessing pipeline for subcellular signal detection, movement artifact identification, and ROI grouping. For subcellular signal detection, we capture the frequency profile of calcium transient dynamics by applying fast Fourier transform (FFT) on smoothed time-series calcium traces collected from axon ROIs. We then apply bandpass filtering methods (e.g., 0.05–0.12 Hz) to select ROIs that contain frequencies that match the power band of transients. To remove motion artifacts from z -plane movement, we apply principal component analysis on all calcium traces and use a bottom-up segmentation chang...

In the Syngap+/− model of SYNGAP1-related intellectual disability (SRID), excessive neuronal protein synthesis is linked to deficits in synaptic plasticity. Here, we use Translating Ribosome Affinity Purification and RNA-seq (TRAP-seq) to identify mistranslating mRNAs in Syngap+/− CA1 pyramidal neurons that exhibit occluded long-term potentiation (LTP). We find the translation environment is significantly altered in a manner that is distinct from the Fmr1−/y model of fragile X syndrome (FXS), another monogenic model of autism and intellectual disability. The Syngap+/− translatome is enriched for regulators of DNA repair and mimics changes induced with chemical LTP (cLTP) in WT. This includes a striking upregulation in the translation of mRNAs with a longer-length (>2 kb) coding sequence (CDS). In contrast, long CDS transcripts are downregulated with induction of Gp1 metabotropic glutamate receptor-induced long-term depression (mGluR-LTD) in WT, and in the Fmr1−/y model that exhibits occluded mGluR-LTD. Tog...

Sleep consists of two alternating states—rapid eye movement (REM) and non-REM (NREM) sleep. Neurons adjust their firing activity based on brain state, however, the extent to which this modulation varies across neurons and brain regions remains poorly understood. This study analyzed previously acquired 17-h continuous recordings of single-unit activity and local field potentials in the ventral hippocampal CA1 region, prelimbic cortex layer 5, and basolateral nucleus of the amygdala of fear-conditioned rats. The findings indicate that more than half of the neurons fired faster during REM sleep than during NREM sleep, although a notable subset of neurons exhibited the opposite preference, firing preferentially during NREM sleep. During sleep, the overall firing activity of both REM- and NREM-preferring neurons decreased. However, fast network oscillations, including hippocampal sharp-wave ripples (SWRs), amygdalar high-frequency oscillations, cortical ripples, and cortical spindles, differentially modulated R...

Principal neurons (PNs) of the lateral superior olive (LSO) are a critical component of brain circuits that compare information between the two ears to extract sound source-location-related cues. LSO PNs are not a homogenous group but differ in their transmitter type, intrinsic membrane properties, and projection pattern to higher processing centers in the inferior colliculus. Glycinergic inhibitory LSO PNs have higher input resistance than glutamatergic excitatory LSO PNs (∼double). This suggests that the inhibitory cell type has a lower minimum input or signal intensity required to produce an output (activation threshold) which may impact how they integrate binaural inputs. However, cell-type-specific differences in the strength of synaptic drive could offset or accentuate such differences in intrinsic excitability and have not been assessed. To evaluate this possibility, we used a knock-in mouse model to examine spontaneous and electrically stimulated (evoked) synaptic events in LSO PN types using volta...

From lamprey to monkeys, the organization of the descending control of locomotion is conserved across vertebrates. Reticulospinal neurons (RSNs) form a bottleneck for descending commands, receiving innervation from diencephalic and mesencephalic locomotor centers and providing locomotor drive to spinal motor circuits. Given their optical accessibility in early development, larval zebrafish offer a unique opportunity to study reticulospinal circuitry. In fish, RSNs are few, highly stereotyped, uniquely identifiable, large neurons spanning from the midbrain to the medulla. Classically labeled by tracer dye injections into the spinal cord, recent advances in genetic tools have facilitated the targeted expression of transgenes in diverse brainstem neurons of larval zebrafish. Here, we provide a comparative characterization of four existing and three newly established transgenic lines in larval zebrafish. We determine which identified neurons are consistently labeled and offer projection-specific genetic access...

The medial prefrontal cortex (mPFC) is thought to play a central role in human social perception, cognition, and behavior. In adults, the mPFC is involved in representing and interpreting the mental states in self and others. Developmental research using neuroimaging techniques like functional near-infrared spectroscopy and functional magnetic resonance imaging has begun to extend these findings into infancy. Novel evidence reviewed in this opinion demonstrates that infant mPFC (1) plays a specialized, proactive, and evaluative role in social perception, (2) is involved in connecting with other minds while interacting and when watching other minds interact, and (3) predicts overt social behavior beyond infancy. These findings suggest that, from early in human ontogeny, the mPFC plays a multifaceted role in social perception, cognition, and behavior.

Activation of hypothalamic paraventricular oxytocin (OXTPVN) neurons by social or stress stimuli triggers OXT release to promote social investigation and buffer adverse effects of stress, respectively. Astrocytes, a type of glial cells, can bidirectionally interact with hypothalamic neurons to participate in local activity regulation within the paraventricular nucleus (PVN). It remains unknown whether contextual factors related to stimuli, as well as biological factors such as sex, influence OXTPVN neuronal or astrocyte activity and/or their interactions. To address this question, we performed dual-color fiber photometry in freely behaving male and female mice to simultaneously record Ca2+ dynamics in OXTPVN neurons and astrocytes during acute social (i.e., interactions with familiar vs. unfamiliar conspecifics) and stress (i.e., looming shadow) stimuli. During social stimuli, we observed the most pronounced Ca2+ changes in OXTPVN neurons in females, revealing sex and familiarity context specificity. No as...

Temporal lobe epilepsy (TLE) is a devastating disease, often pharmacoresistant and with a high prevalence of 1% worldwide. There are a few disease-modifying therapies; thus, prevention has become a health priority. The overarching goal of this research project is to highlight the system's dynamics at different stages before TLE onset to identify an early shift in network dynamics trajectory toward disease onset. Researchers often investigate collective brain activity by tracking dynamical interactions of the signal recorded at multiple sites. However, these interactions are usually only computed between pairs of brain regions, at the risk of missing simultaneous interactions of three or more areas, an aspect that is crucial in a networked disease such as TLE. We thus propose to track, on a rich dataset of electrophysiological brain signals recorded within the temporal lobe (TL) of adult male Wistar Han rats, the formation and dissolution of high-order informational multiplets in time during distinct natura...

Pain sensation often involves mechanical modalities. Mechanically activated (MA) ion channels on sensory neurons underly responsiveness to mechanical stimuli. MA current properties have mainly been derived from rodent sensory neurons. This study aimed to address gaps in knowledge regarding MA current properties in trigeminal (TG) neurons of a higher-order species, common marmoset nonhuman primates (NHP). MA currents triggered by a piezoactuator were recorded in patch-clamp configuration. MA responses were associated with action potential (AP) properties, such as width, dV/dt on the falling phase, and presence/absence of AP firing in NHP TG neurons. According to responsiveness to mechanical stimuli and AP properties, marmoset TG neurons were clustered into four S-type and five M-type groups. S-type TG neurons had broader AP with two dV/dt peaks on the AP falling phase. Only one S-type group of NHP TG neurons produced small MA currents. M-type TG neurons had narrow AP without two dV/dt peaks on the AP fallin...