Because of the legalization of Cannabis in many jurisdictions and the trend of increasing Δ9-tetrahydrocannabinol (THC) content in Cannabis products, an urgent need exists to understand the impact of Cannabis use during pregnancy on fetal neurodevelopment and behavior. To this end, we exposed female Sprague Dawley rats to Cannabis smoke daily from gestational day 6 to 20 or room air. Maternal reproductive parameters, offspring behavior, and gene expression in the offspring amygdala were assessed. Body temperature was decreased in dams following smoke exposure and more fecal boli were observed in the chambers before and after smoke exposure in dams exposed to smoke. Maternal weight gain, food intake, gestational length, litter number, and litter weight were not altered by exposure to Cannabis smoke. A significant increase in the male-to-female ratio was noted in the Cannabis -exposed litters. In adulthood, male and female Cannabis smoke-exposed offspring explored the inner zone of an open field significantl...

Stress has been identified as a major contributor to human disease and is postulated to play a substantial role in epileptogenesis. In a significant proportion of individuals with epilepsy, sensitivity to stressful events contributes to dynamic symptomatic burden, notably seizure occurrence and frequency, and presence and severity of psychiatric comorbidities [anxiety, depression, posttraumatic stress disorder (PTSD)]. Here, we review this complex relationship between stress and epilepsy using clinical data and highlight key neurobiological mechanisms including the hypothalamic-pituitary-adrenal (HPA) axis dysfunction, altered neuroplasticity within limbic system structures, and alterations in neurochemical pathways such as brain-derived neurotrophic factor (BNDF) linking epilepsy and stress. We discuss current clinical management approaches of stress that help optimize seizure control and prevention, as well as psychiatric comorbidities associated with epilepsy. We propose that various shared mechanisms o...

Most human navigation studies in MRI rely on virtual navigation. However, the necessary supine position in MRI makes it fundamentally different from daily ecological navigation. Nonetheless, until now, no study has assessed whether differences in physical body orientation (BO) affect participants’ experienced BO during virtual navigation. Here, combining an immersive virtual reality navigation task with subjective BO measures and implicit behavioral measures, we demonstrate that physical BO (either standing or supine) modulates experienced BO. Also, we show that standing upright BO is preferred during spatial navigation: participants were more likely to experience a standing BO and were better at spatial navigation when standing upright. Importantly, we report that showing a supine virtual agent reduces the conflict between the preferred BO and physical supine BO. Our study provides critical, but missing, information regarding experienced BO during virtual navigation, which should be considered cautiously ...

Every so often, I conclude that life is not possible. It is not uncommon for me to walk out of a seminar about the pathways and dynamics of biochemical signaling or the structure of biological molecules to conclude that the complexities of life processes defy imagination. Our ability to maintain a sense of wonder about the mysteries of biological mechanisms is what drives us as scientists, as otherwise wresting new insights from the recalcitrant world of interacting pathways would be too frustrating. So all successful biologists must, paradoxically, see both the proverbial forest and their trees, and recognize both the elegant simplicity and the confounds characteristic of living organisms. That sense of mystery and wonder is somewhat at odds with our common sense. It is common sense that is now too often lost, as we grapple with new technologies and large datasets in our science. As scientists, today, we must balance our common sense with our growing reliance on big data to extract the new insights about...

The sensory system allows humans to not only explore the world but also to monitor their own bodies for injury and disease through the sensation of pain. After an injury, signals from the injured tissues travel along the nerves, entering the central nervous system through the spinal cord before going into the brain. In the acute stages, pain modulates behavior in ways that promote healing, including limiting mobility. In most cases, pain resolves as the injury heals, but, in some cases, pain persists and becomes chronic. Chronic pain is a massive issue, affecting up to 20% of Americans and leading to reduced quality of life for those affected. The factors leading to chronic pain are complex, and new approaches are needed to improve understanding of chronic pain and find effective treatments. In the current issue of eNeuro , Haroun et al. (2023) use a new approach to transiently silence sensory neurons in uninjured mice as well as mouse models of acute and chronic pain using a technique known as chemogenet...

It is often claimed that tools are embodied by their user, but whether the brain actually repurposes its body-based computations to perform similar tasks with tools is not known. A fundamental computation for localizing touch on the body is trilateration. Here, the location of touch on a limb is computed by integrating estimates of the distance between sensory input and its boundaries (e.g., elbow and wrist of the forearm). As evidence of this computational mechanism, tactile localization on a limb is most precise near its boundaries and lowest in the middle. Here, we show that the brain repurposes trilateration to localize touch on a tool, despite large differences in initial sensory input compared with touch on the body. In a large sample of participants, we found that localizing touch on a tool produced the signature of trilateration, with highest precision close to the base and tip of the tool. A computational model of trilateration provided a good fit to the observed localization behavior. To further ...

During early development, neurons in the brain often form excess synaptic connections. Later, they strengthen some connections while eliminating others to build functional neuronal circuits. In the olfactory bulb, a mitral cell initially extends multiple dendrites to multiple glomeruli but eventually forms a single primary dendrite through the activity-dependent dendrite pruning process. Recent studies have reported that microglia facilitate synapse pruning during the circuit remodeling in some systems. It has remained unclear whether microglia are involved in the activity-dependent dendrite pruning in the developing brains. Here, we examined whether microglia are required for the developmental dendrite pruning of mitral cells in mice. To deplete microglia in the fetal brain, we treated mice with a colony-stimulating factor 1 receptor (CSF1R) inhibitor, PLX5622, from pregnancy. Microglia were reduced by >90% in mice treated with PLX5622. However, dendrite pruning of mitral cells was not significantly affec...

The detection of a single photon by a rod photoreceptor is limited by two sources of physiological noise, called discrete and continuous noise. Discrete noise occurs as intermittent current deflections with a waveform very similar to that of the single-photon response to real light and is thought to be produced by spontaneous activation of rhodopsin. Continuous noise occurs as random and continuous fluctuations in outer-segment current and is usually attributed to some intermediate in the phototransduction cascade. To confirm the origin of these noise sources, we have recorded from retinas of mouse lines with rods having reduced levels of rhodopsin, transducin, or phosphodiesterase. We show that the rate of discrete noise is diminished in proportion to the decrease in rhodopsin concentration, and that continuous noise is independent of transducin concentration but clearly elevated when the level of phosphodiesterase is reduced. Our experiments provide new molecular evidence that discrete noise is indeed pr...

Real science is not only about “the data” but also about theoretical, sociological, economic, and political matters. Reflecting on the struggles of the ongoing adversarial collaboration to test theories of consciousness, here I suggest to “ask not what neuroscience can do for consciousness but what consciousness can do for neuroscience.” “Big fish: Aren’t these waters fascinating and treacherous? Small fish: What waters?” – Anonymous Richard Feynman is notorious for his witty quotes, including that “philosophy of science is about as useful to scientists as ornithology is to birds.” Indeed, some neuroscientists would look perplexed in front of analytic accounts of their own practices, methods, and foundations. Starlings fly by flapping their feathered wings and yet, regardless of their individual skills and collective choreographies, they may be ignorant about how and why they do it. A tweet-long crash course in philosophy of science could suffice to realize that binary thinking (“Is it true or not?”) co...

Neuroscientists endeavor to unravel the mysteries of brain functions and dysfunctions. A common research strategy involves measuring specific parameters across various conditions. These measurements are then typically repeated, averaged, and used to infer general patterns or rules. The act of averaging data is an ancient practice; for instance, early astronomers in Babylonian, Chinese, and Indian cultures implicitly averaged observations of celestial phenomena to predict significant periods, such as those crucial for agriculture. Averaging is a sound approach when the process being studied follows to a mathematical function, represented as y = f(x), where f is a very general function. This is true even if the exact function is not known at the outset of the experiments. Implicit in this method is the assumption that any variations in measurements arise from imperfections in the recording process since a consistent mathematical rule suggests that identical inputs should always yield the same output. In ess...