Biology subjects

Simons, R.

Publications and source records attributed to Simons, R..

3 recordsLinked to original sources

bioRxiv2025

Behavioral Decoding Reveals Cortical Endocannabinoid Potentiation during Δ9-THC Impairment

How {Delta}9-tetrahydrocannabinol (THC) impairs natural behaviors in mice remains unknown. We developed a video-monitored behavioral platform with machine learning classifiers to unravel discrete changes in natural mouse behaviors. THC infusion into the medial prefrontal cortex (mPFC) disrupted walking kinematic features characteristic of impairment responses. THC predominantly increased mPFC GABAergic activity preceding walk initiation shifting the mPFC excitatory/inhibitory (E/I) balance. Pose-defined closed loop photo-stimulation of mPFC GABAergic neurons demonstrated that THC exacerbates selected parameters of motor impairment. Surprisingly, THC also induced a time locked, movement-induced, transient potentiation of mPFC endocannabinoid (eCB) release and ensuing CB1R-mediated synaptic inhibition. Here we establish that THC-modifies mPFC E/I balance to excitation via dynamic changes in eCB release which acts to induce behavioral impairment.

neuroscience↗

bioRxiv2025

Impacts of changing ocean circulation, temperature, and food supply on larval recruitment of purple sea urchins in Southern California: A biophysical modeling study

Changes in ocean conditions among years and across decades can alter populations in marine ecosystems. This study evaluates the impact of changing ocean conditions on larval recruitment of purple sea urchins in the Southern California Bight using 3D biophysical modeling, surface chlorophyll, and recruitment data. The influence of circulation, temperature, and food supply on larval recruitment is quantified using five modeled variables, larval dispersal distance, larval source location, larval food supply, and temperature exposure for larvae and adults, which are derived for 18 years and five larval recruitment sites. Sensitivity testing of the variables to different plankton larval durations (PLDs), larval behaviors, and nearshore retention is performed. All variables are found to be relatively insensitive to changes in PLD greater than 26 days. Larval dispersal distance and source location, representing changes in circulation, are found to be more sensitive to larval behavior and nearshore retention than larval food supply and temperature exposure for larvae and adults. All variables are statistically compared to recruitment field data. Temperature exposure for adults during the fall reproductive season is found to be a strong driver of larval recruitment while temperature exposure for larvae during the spring recruitment season is not. Food supply is not found to be a driver of larval recruitment. Circulation is found to be a driver of larval recruitment if larvae have behavior that reduces their dispersal distance, allowing them to come from source sites near to the recruitment sites. Overall, we hypothesize that larval behavior which reduces dispersal improves recruitment and that the timing of recruitment and reproduction can predict the impact of temperature on recruitment.

ecology↗

bioRxiv2022

Reward contingency gates selective cholinergic suppression of amygdala neurons

Basal forebrain cholinergic neurons modulate how organisms process and respond to environmental stimuli through impacts on arousal, attention, and memory. It is unknown, however, whether basal forebrain cholinergic neurons are directly involved in conditioned behavior, independent of secondary roles in the processing of external stimuli. Using fluorescent imaging, we found that cholinergic neurons are active during behavioral responding for a reward - even in prior to reward delivery and in the absence of discrete stimuli. Photostimulation of basal forebrain cholinergic neurons, or their terminals in the basolateral amygdala (BLA), selectively promoted conditioned responding (licking), but not unconditioned behavior nor innate motor outputs. In vivo electrophysiological recordings during cholinergic photostimulation revealed reward-contingency-dependent suppression of BLA neural activity, but not prefrontal cortex (PFC). Finally, ex vivo experiments demonstrated that photostimulation of cholinergic terminals suppressed BLA projection neuron activity via monosynaptic muscarinic-receptor-signaling, while also facilitating firing in GABAergic interneurons. Taken together, we show that the neural and behavioral effects of basal forebrain cholinergic activation are modulated by reward contingency in a target-specific manner.

neuroscience↗