Although there has been a decrease in the prevalence of tobacco smoking in many developed countries, exposure to nicotine/tobacco during pregnancy remains a substantial problem worldwide. Further, given the recent escalation in e-cigarette use among var...

An increasing number of de novo SCN8A mutations have been identified in patients with catastrophic, treatment-resistant childhood epilepsy. De novo SCN8A mutations have also been found in patients with autism, intellectual disability and developmental d...

Working memory is an executive function that orchestrates the use of limited amounts of information, referred to as working memory capacity, in cognitive functions. Cannabis exposure impairs working memory in humans; however, it is unclear whether Cannabis facilitates or impairs rodent working memory and working memory capacity. The conflicting literature in rodent models may be at least partly because of the use of drug exposure paradigms that do not closely mirror patterns of human Cannabis use. Here, we used an incidental memory capacity paradigm where a novelty preference is assessed after a short delay in spontaneous recognition-based tests. Either object or odor-based stimuli were used in test variations with sets of identical [identical stimuli test (IST)] and different [different stimuli test (DST)] stimuli (three or six) for low-memory and high-memory loads, respectively. Additionally, we developed a human-machine hybrid behavioral quantification approach which supplements stopwatch-based scoring ...

Chronic marijuana use has been associated with the inability to develop successful decision-making strategies during performance of the Iowa Gambling Task (IGT) (Whitlow et al., 2004). Because the IGT is a highly complex task that includes motivational ...

The psychoactive constituent in marijuana Δ9-tetrahydrocannabinol (THC) pharmacologically activates the mesolimbic reward pathways (Gardner, 2005). Similarly highly palatable foods also activate the reward circuitry of the brain (Volkow and Wise, 2005)....

Cannabinoids, including cannabidiol (CBD), a non-psychoactive component of cannabis sativa, have been shown to exhibit anticonvulsant properties in animal models of epilepsy (Wallace et al. 2001; 2003). To investigate cannabinoid-mediated seizure control, CBD was compared to the synthetic CB1 receptor agonist HU-210 in a rat model of kainate-induced temporal lobe seizures (TLS) in vivo. Multiple single-unit and local field potentials (LFPs) were recorded from the hippocampus of male Sprague Dawley rats (200-300g) anaesthetised with urethane (1.3g kg-1 i.p.) or isoflurane/N2O/O2 using 16-channel micro-wire electrodes (NB Labs) and a Plexon Map system. Kainate (KA: 10mg kg-1), cannabidiol (10 or 40mg kg-1) or HU-210 (100μg kg-1) were administered i.p. Data was analysed with Neuroexplorer, including firing frequency, burst analysis, T50 for KA-induced effects, and LFP power spectral density (PSD). While CBD reduced basal firing in ∼20% of cells, CBD did not alter KA-induced firing administered before (n=63 ce...

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Most studies of human drug abuse highlight dependence on one primary agent without explicitly considering use of other psychoactive agents such as marijuana (MJ). We previously showed regional cerebral dysfunction in methamphetamine (MA) abusers, particularly in limbic/paralimbic areas, and now assess the combined effects of MJ and MA on cerebral function. We studied 14 MA abusers who reported MA as their drug of choice, had on average used MA for >8 years, and used it on most of the 30 days prior to entering the study. We separated this sample into one group of subjects who reported no substantial drug use other than MA abuse (-MJ, n=7), and another group of subjects who either used MJ frequently (>1 joint/wk) or met DSM-IV criteria for THC dependence (+MJ,n=7). Both groups abstained from all illicit drug use for 5–11 days before assay of global and regional cerebral glucose metabolism (CMRglc, rCMRglc) with PET during performance of an attentional task. The +MJ group had 6% lower CMRglc than the -MJ grou...

Rats previously exposed to amphetamine (AMPH) show enhanced locomotor and nucleus accumbens (NAcc) dopamine (DA) responding to the drug as well as enhanced self-administration of AMPH and cocaine. The present experiments assessed the effects of pre-exposing rats to Δ9-THC. Rats in different groups were given five pre-exposure injections of saline or one of five doses of Δ9-THC (0.4, 0.75, 1.5, 3.0, 6.0 mg/kg, IP), one injection every third day, and tested two to three weeks later. Previous exposure to all but the lowest dose of Δ9-THC enhanced the locomotor response to AMPH (0.75 mg/kg, IP) but all failed to enhance NAcc DA overflow in response to AMPH. Previous exposure to 3.0 mg/kg (IP, the most effective Δ9-THC dose above) also enhanced forskolin-evoked adenylyl cyclase activity in the NAcc and rats’ locomotor response to the direct DA receptor agonist apomorphine (1.0 mg/kg, SC), suggesting that previous exposure to Δ9-THC enhances locomotor responding to AMPH by up-regulating postsynaptic DA receptor ...

Cannabis sativa L. derivatives are emerging as therapeutics for some forms of epilepsy, with one formulation being FDA approved (Devinsky et al., 2017, 2018). Cannabidiol (CBD) administration to patients with certain treatment-resistant epilepsies signi...