Psychedelic medicine (New Rochelle, N.Y.)
June 1, 2024
Abshir S Adam, Kayleigh S LaMalfa, Yasaman Razavi et al.
6 citations
MDMA produces dose-dependent increases in reward responsivity, a measure of anhedonia, in rats, along with dose-dependent deficits in attention and short-term memory, and increases in prosocial interaction in male but not female rats. The desirable prohedonic effects and undesirable cognitive disruptions do not persist beyond 24 hours. These results characterize MDMA as a promising prohedonic treatment despite short-lived cognitive impairment following acute administration.
British journal of pharmacology
November 1, 2025
Yasaman Razavi, Stephen J Kohut, Jack Bergman et al.
1 citation
Adolescent monkeys exposed daily to the cannabis compound Δ9-THC for six months, then tested about a year later as adults on a touchscreen attention task, required higher acute doses of Δ9-THC to impair their performance compared with animals that had not been exposed during adolescence. The impairment itself was dose-related and occurred whether the drug was given by injection or orally, though potency and timing differed. These results suggest that heavy cannabis use during adolescence can produce a lasting tolerance that persists into adulthood, even after a long period of abstinence.
bioRxiv : the preprint server for biology
January 24, 2026
Kwang-Hyun Hur, Lisa D Nickerson, Jack Bergman et al.
THC, the psychoactive compound in cannabis, selectively amplifies behavioral and brain responses to cues that predict rewards, without affecting responses to neutral cues or baseline reward consumption. In squirrel monkeys, a low dose of THC (3 μg/kg) increased conditioned approach behavior toward a visual stimulus associated with food delivery. Functional MRI showed that THC enhanced activity in reward-related brain regions—anterior cingulate cortex, striatum, hippocampus, and substantia nigra-ventral tegmental area (SN-VTA)—while leaving visual and motor cortices unaffected. Resting-state connectivity analyses revealed that THC strengthened communication within mesocorticolimbic networks, with the SN-VTA acting as a central hub. These findings indicate that THC boosts incentive salience and motivational drive toward reward-associated stimuli through selective modulation of this circuitry.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
October 1, 2025
Andrew Jin Soo Byun, Harshawardhan U Deshpande, Jessi Stover et al.
Chronic delta-9-tetrahydrocannabinol (THC) exposure during adolescence alters functional connectivity between the default mode and central executive networks in the adult brain in a dose-dependent manner. In squirrel monkeys given daily low (0.32 mg/kg) or high (3.2 mg/kg) THC injections for six months during adolescence, only the low dose increased connectivity between these networks during the exposure period, an effect that reversed after discontinuation. The high dose and vehicle controls showed no such change. The central executive network appeared to drive this effect. The findings suggest that adolescent THC exposure can produce non-linear, dose-dependent disruptions in large-scale brain networks.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
February 1, 2025
Brian D Kangas, Harshawardhan U Deshpande, Sarah L Withey et al.
Chronic exposure to THC during adolescence in squirrel monkeys produces long-lasting changes in brain functional connectivity and motivation that persist into adulthood. Daily treatment with either a low (0.32 mg/kg) or high dose (3.2 mg/kg) of THC for six months during adolescence led to persistent alterations in connectivity of the medial orbitofrontal cortex, caudate, and ventral striatum. In economic demand tests, THC-treated subjects showed dosage-dependent disruption in reward sensitivity and motivation, unlike vehicle-treated subjects who displayed the expected inverse relationship between reward magnitude and effort. The findings indicate that adolescent THC exposure causes enduring neurocognitive abnormalities in reward processing.