Relapse is a major challenge to the treatment of substance use disorders. A progressive increase in cue-induced drug craving, termed incubation of craving, is observed after withdrawal from multiple drugs of abuse in humans and rodents. Incubation of cocaine craving involves strengthening of excitatory synapses onto nucleus accumbens (NAc) medium spiny neurons via postsynaptic accumulation of high-conductance Ca2+-permeable AMPA receptors. This enhances reactivity to drug-associated cues and is required for the expression of incubation. Additionally, incubation of cocaine craving is associated with loss of the synaptic depression normally triggered by stimulation of metabotropic glutamate receptor 5 (mGlu5), leading to endocannabinoid production, and expressed presynaptically via cannabinoid receptor 1 activation. Previous studies have found alterations in mGlu5 and Homer proteins associated with the loss of this synaptic depression. Here we conducted co-immunoprecipitation studies to investigate associati...

Knee joint trauma can cause an osteochondral defect (OD), a risk factor for osteoarthritis and cause of debilitating pain in patients. Rodent OD models are less translatable due to their smaller joint size and open growth plate. This study proposes sheep as a translationally relevant model to understand the neuronal basis of OD pain. Unilateral 6 mm deep OD was induced in adult female sheep. 2-6 weeks post-operation, lumbar dorsal root ganglia (DRG) neurons were collected from the contralateral and OD side of operated sheep. Functional assessment of neuronal excitability and activity of the pain-related ion channels TRPV1 and P2X3 was carried out using electrophysiology and Ca2+-imaging. Immunohistochemistry was utilized to verify expression of pain-related proteins. We observed that an increased proportion of OD DRG neurons (sheep, N = 3; Ctrl neurons, n =15, OD neurons, n = 16) showed spontaneous electrical excitability (Ctrl: 20.33 ± 4.5%; OD: 50 ± 10%; p = 0.009, unpaired t-test) and an increased propo...

Autism spectrum disorders (ASDs) are characterized by abnormal behavioral traits arising from neural circuit dysfunction. While a number of genes have been implicated in ASDs, in most cases, a clear understanding of how mutations in these genes lead to circuit dysfunction and behavioral abnormality is absent. The autism susceptibility candidate 2 ( AUTS2 ) gene is one such gene, associated with ASDs, intellectual disability and a range of other neurodevelopmental conditions. Yet, the role of AUTS2 in neural development and circuit function is not at all known. Here, we undertook functional analysis of Auts2a, the main homolog of AUTS2 in zebrafish, in the context of the escape behavior. Escape behavior in wild type zebrafish is critical for survival and is therefore, reliable, rapid, and has well-defined kinematic properties. Auts2a mutant zebrafish are viable, have normal gross morphology and can generate escape behavior with normal kinematics. However, the behavior is unreliable and delayed, with high tr...

Human infants who suffer from intrauterine growth restriction (IUGR), which is a failure to attain their genetically pre-determined weight, are at increased risk for postnatal learning and memory deficits. Hippocampal dentate gyrus (DG) granule neurons play an important role in memory formation, however it is unknown whether IUGR affects embryonic DG neurogenesis, which could provide a potential mechanism underlying abnormal postnatal learning and memory function. Using a mouse model of the most common cause of IUGR, induced by hypertensive disease of pregnancy, we first assessed adult learning and memory function. We quantified the percentages of embryonic hippocampal DG neural stem and progenitor cells and developing glutamatergic granule neurons, as well as hippocampal volumes and neuron cell count and morphology 18 and 40 days after delivery. We characterized the differential embryonic hippocampal transcriptomic pathways between appropriately-grown and IUGR mouse offspring. We found that IUGR offspring...

Epilepsy affects 3.4 million people in the United States, and despite availability of numerous antiepileptic drugs, 36% of patients have uncontrollable seizures, which severely impacts quality of life. High frequency oscillations (HFOs) are a potential biomarker of epileptogenic tissue that could be useful in surgical planning. As a result, research into the efficacy of HFOs as a clinical tool has increased over the last two decades. However, detection and identification of these transient rhythms in intracranial electroencephalographic recordings remain time-consuming and challenging. Although automated detection algorithms have been developed, their results are widely inconsistent, reducing reliability. Thus, manual marking of HFOs remains the gold standard, and manual review of automated results is required. However, manual marking and review are time-consuming and can still produce variable results due to their subjective nature and the limitations in functionality of existing open-source software. Our...

Recent evidence suggests that alteration of axon initial segment (AIS) geometry (i.e., length or location along the axon) contributes to CNS dysfunction in neurological diseases. For example, AIS length is shorter in the prefrontal cortex of type 2 diabetic mice with cognitive impairment. To determine the key type 2 diabetes-related factor that produces AIS shortening we modified levels of insulin, glucose, or the reactive glucose metabolite methylglyoxal in cultures of dissociated cortices from male and female mice and quantified AIS geometry using immunofluorescent imaging of the AIS proteins AnkyrinG and βIV spectrin. Neither insulin nor glucose modification altered AIS length. Exposure to 100 but not 1 or 10 µM methylglyoxal for 24 h resulted in accumulation of the methylglyoxal-derived advanced glycation end-product hydroimidazolone and produced reversible AIS shortening without cell death. Methylglyoxal-evoked AIS shortening occurred in both excitatory and putative inhibitory neuron populations and ...

The hedgehog signaling pathway is best known for its role in developmental patterning of the neural tube and limb bud. More recently, hedgehog signaling has been recognized for its roles in growth of adult tissues and maintenance of progenitor cell niches. However, the role of hedgehog signaling in fully differentiated cells like neurons in the adult brain is less clear. In mammals, coordination of hedgehog pathway activity relies on primary cilia and patients with ciliopathies such as Bardet-Biedl and Alström syndrome exhibit clinical features clearly attributable to errant hedgehog such as polydactyly. However, these ciliopathies also present with features not clearly associated with hedgehog signaling such as hyperphagia-associated obesity. How hedgehog signaling may contribute to feeding behavior is complex and unclear, but cilia are critical for proper energy homeostasis. Here, we provide a detailed analysis of the expression of core components of the hedgehog signaling pathway in the adult mouse hypo...

The ability to measure changes in neuronal activity in a quantifiable and precise manner is of fundamental importance to understand neuron development and function. Repeated monitoring of neuronal activity of the same population of neurons over several days is challenging and, typically, low-throughput. Here, we describe a new biochemical reporter assay that allows for repeated measurements of neuronal activity in a cell type-specific manner. We coupled activity-dependent elements from the Arc/Arg3.1 gene with a secreted reporter, Gaussia luciferase, to quantify neuronal activity without sacrificing the neurons. The reporter predominantly senses calcium and NMDA receptor-dependent activity. By repeatedly measuring the accumulation of the reporter in cell media, we can profile the developmental dynamics of neuronal activity in cultured neurons from male and female mice. The assay also allows for longitudinal analysis of pharmacological treatments, thus distinguishing acute from delayed responses. Moreover, ...

Narrative comprehension involves a constant interplay of the accumulation of incoming events and their integration into a coherent structure. This study characterizes cognitive states during narrative comprehension and the network-level reconfiguration occurring dynamically in the functional brain. We presented movie clips of temporally scrambled sequences to human participants (male and female), eliciting fluctuations in the subjective feeling of comprehension. Comprehension occurred when processing events that were highly causally related to the previous events, suggesting that comprehension entails the integration of narratives into a causally coherent structure. The functional neuroimaging results demonstrated that the integrated and efficient brain state emerged during the moments of narrative integration with the increased level of activation and across-modular connections in the default mode network. Underlying brain states were synchronized across individuals when comprehending novel narratives, wi...

The mechanisms underlying accumulation of Alzheimer’s disease (AD)-related tau pathology outside of the medial temporal lobe (MTL) in older adults are unknown but crucial to understanding cognitive decline. A growing body of evidence from human and animal studies strongly implicates neural connectivity in the propagation of tau in humans, but the pathways of neocortical tau spread and its consequences for cognitive function are not well understood. Using resting state fMRI and tau PET imaging from a sample of 97 male and female cognitively normal older adults, we examined MTL structures involved in medial parietal tau accumulation and associations with memory function. Functional connectivity between hippocampus and retrosplenial cortex, a key region of the medial parietal lobe, was associated with tau in medial parietal lobe. By contrast, connectivity between entorhinal and retrosplenial cortices did not correlate with medial parietal lobe tau. Further, greater hippocampal-retrosplenial connectivity was a...