Acute, but not repeated, cocaine exposure alters allopregnanolone levels in the midbrain of male and female rats.

Rationale: Multiple psychiatric disorders are associated with altered brain and serum levels of neuroactive steroids, including the endogenous GABAergic steroid, allopregnanolone. Clinically, chronic cocaine use was correlated with decreased levels of pregnenolone. Preclinically, the effect of acute cocaine on allopregnanolone levels in rodents has had mixed results, showing an increase or no change in allopregnanolone levels in some brain regions.

Intracortical Microelectrode Array Unit Yield under Chronic Conditions: A Comparative Evaluation.

While microelectrode arrays (MEAs) offer the promise of elucidating functional neural circuitry and serve as the basis for a cortical neuroprosthesis, the challenge of designing and demonstrating chronically reliable technology remains. Numerous studies report "chronic" data but the actual time spans and performance measures corresponding to the experimental work vary. In this study, we reviewed the experimental durations that constitute chronic studies across a range of MEA types and animal species to gain an understanding of the widespread variability in reported study duration.

Chronic Intracortical Recording and Electrochemical Stability of Thiol-ene/Acrylate Shape Memory Polymer Electrode Arrays.

Current intracortical probe technology is limited in clinical implementation due to the short functional lifetime of implanted devices. Devices often fail several months to years post-implantation, likely due to the chronic immune response characterized by glial scarring and neuronal dieback. It has been demonstrated that this neuroinflammatory response is influenced by the mechanical mismatch between stiff devices and the soft brain tissue, spurring interest in the use of softer polymer materials for probe encapsulation.