Neural responses of dorsal visual area V7 and lateral occipital complex (LOC) have been shown to correlate with changes in behavioral metrics of depth sensitivity observed as a function of object context, although it is unclear as to whether the behavioral manifestation results from an alteration of early depth-specific responses in V7 or arises as a result of alterations of object-level representations at LOC that subsequently feed back to affect disparity readouts in dorsal cortex. Here, we used online transcranial magnetic stimulation (TMS) to examine the roles of these two areas in giving rise to context–disparity interactions. Stimuli were disparity-defined geometric objects rendered as random-dot stereograms, presented in geometrically plausible and implausible variations. Observers’ sensitivity to depth (depth discrimination) or object identity (plausibility discrimination) was indexed while receiving repetitive TMS at one of the two sites of interest (V7, LOC) along with a control site (Cz). TMS ov...

In the article “Differential Electrographic Signatures Generated by Mechanistically-Diverse Seizurogenic Compounds in the Larval Zebrafish Brain,” by Joseph Pinion, Callum Walsh, Marc Goodfellow, …

CRISPR/Cas9-mediated knock-in methods enable the labeling of individual endogenous proteins to faithfully determine their spatiotemporal distribution in cells. However, reliable multiplexing of knock-in events in neurons remains challenging because of cross talk between editing events. To overcome this, we developed conditional activation of knock-in expression (CAKE), allowing efficient, flexible, and accurate multiplex genome editing. To diminish cross talk, CAKE is based on sequential, recombinase-driven guide RNA (gRNA) expression to control the timing of genomic integration of each donor sequence. We show that CAKE is broadly applicable in rat neurons to co-label various endogenous proteins, including cytoskeletal proteins, synaptic scaffolds, ion channels and neurotransmitter receptor subunits. To take full advantage of CAKE, we resolved the nanoscale co-distribution of endogenous synaptic proteins using super-resolution microscopy, demonstrating that their co-organization correlates with synapse siz...

A hallmark of human reaching movements is that they are appropriately tuned to the task goal and to the environmental context. This was demonstrated by the way humans flexibly respond to mechanical and visual perturbations that happen during movement. Furthermore, it was previously showed that the properties of goal-directed control can change within a movement, following abrupt changes in the goal structure. Such online adjustment was characterized by a modulation of feedback gains following switches in target shape. However, it remains unknown whether the underlying mechanism merely switches between prespecified policies, or whether it results from continuous and potentially dynamic adjustments. Here, we address this question by investigating participants’ feedback control strategies in presence of various changes in target width during reaching. More specifically, we studied whether the feedback responses to mechanical perturbations were sensitive to the rate of change in target width, which would be in...

In similar states, neural circuits produce similar outputs across individuals despite substantial interindividual variability in neuronal ionic conductances and synapses. Circuit states are largely shaped by neuromodulators that tune ionic conductances. It is therefore possible that, in addition to producing flexible circuit output, neuromodulators also contribute to output similarity despite varying ion channel expression. We studied whether neuromodulation at saturating concentrations can increase the output similarity of a single identified neuron across individual animals. Using the lateral pyloric (LP) neuron of the crab stomatogastric ganglion, we compared the variability of f–I (frequency–current) curves and rebound properties in the presence of neuropeptides. The two neuropeptides we used converge to activate the same target current, which increases neuronal excitability. Output variability was lower in the presence of the neuropeptides, regardless of whether the neuropeptides significantly changed...

Neuroestrogens are synthesized within the brain and regulate social behavior, learning and memory, and cognition. In song sparrows, Melospiza melodia , 17β-estradiol (17β-E2) promotes aggressive behavior, including during the nonbreeding season when circulating steroid levels are low. Estrogens are challenging to measure because they are present at very low levels, and current techniques often lack the sensitivity required. Furthermore, current methods often focus on 17β-E2 and disregard other estrogens. Here, we developed and validated a method to measure four estrogens [estrone (E1), 17β-E2, 17α-estradiol (17α-E2), estriol (E3)] simultaneously in microdissected songbird brain, with high specificity, sensitivity, accuracy, and precision. We used liquid chromatography tandem mass spectrometry (LC-MS/MS), and to improve sensitivity, we derivatized estrogens using 1,2-dimethylimidazole-5-sulfonyl-chloride (DMIS). The straightforward protocol improved sensitivity by 10-fold for some analytes. There is substan...

Typical everyday sounds, such as those of speech or running water, are spectrotemporally complex. The ability to recognize complex sounds (CxSs) and their associated meaning is presumed to rely on their stable neural representations across time. The auditory cortex is critical for the processing of CxSs, yet little is known of the degree of stability of auditory cortical representations of CxSs across days. Previous studies have shown that the auditory cortex represents CxS identity with a substantial degree of invariance to basic sound attributes such as frequency. We therefore hypothesized that auditory cortical representations of CxSs are more stable across days than those of sounds that lack spectrotemporal structure such as pure tones (PTs). To test this hypothesis, we recorded responses of identified layer 2/3 auditory cortical excitatory neurons to both PTs and CxSs across days using two-photon calcium imaging in awake mice. Auditory cortical neurons showed significant daily changes of responses to ...

Opioid misuse among pregnant women is rapidly increasing in the United States. The number of maternal opioid-related diagnoses increased by 131% in the last 10 years, resulting in an increased number of infants exposed to opioids in utero and a subsequent increase in infants developing neonatal abstinence syndrome (NAS). The most prescribed treatment to combat maternal opioid use disorder is buprenorphine, a partial μ-opioid receptor agonist and κ-opioid receptor antagonist. Buprenorphine treatment effectively reduces NAS but has been associated with disrupted cortical development and neurodevelopmental consequences in childhood. Less is known about the long-term neurodevelopmental consequences following buprenorphine exposure in utero . Previous research has shown that gestational buprenorphine exposure can induce anxiety-like and depressive-like phenotypes in adult rats, suggesting that exposure to buprenorphine in utero may render individuals more susceptible to psychiatric illness in adulthood. A commo...

Drinking behavior has been used in fundamental research to study metabolism, motivation, decision-making and different aspects of health problems, such as anhedonia and alcohol use disorders. In the majority of studies, liquid intake is measured by weighing the bottles before and after the experiment. This method does not tell much about the drinking microstructure, e.g., licking bouts and periods of preference for each liquid, which could be valuable to understand drinking behavior. To improve data acquisition of drinking microstructure, companies have developed lickometer devices that acquire timestamps when animals approach or drink from a specific sipper. Nevertheless, commercially available devices have elevated costs. Here, we present a low-cost alternative for a lickometer system that allows wireless data acquisition of licks from eight cages with two sippers each. We ran a three-phase validation protocol to ensure (1) proper choice of the sensor to detect licks; (2) adaptation of the device to a wi...

As readers of eNeuro , we would agree that neurons are important cells—you are using them right now to read and understand this article [unless you are a sentient AI (artificial intelligence)–LaMDA (Language Model for Dialogue Applications); I would love to be friends!]. There are still a lot of unknowns about how neuronal proteins contribute to neuronal function. What exactly are the proteins in your neurons doing as you are reading this? We may not be able to determine that yet, but being able to visualize proteins in living neurons in culture is an important step toward that goal. The benefit of being able to “see” proteins is that you can determine where they go and how they move around in living cells. You can also get an idea of which proteins are interacting with each other. Fluorescent labeling of proteins has proven to be a useful tool for visualizing proteins in living cells. Historically, though, this method has had its drawbacks. In order to add a fluorescent tag to a protein, a gene encoding ...