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Naturalistic signals were created from vibrations made by locusts walking on a Sansevieria plant. Both naturalistic and Gaussian noise signals were used to mechanically stimulate VS-3 slit-sense mechanoreceptor neurons of the spider, Cupiennius salei, with stimulus amplitudes adjusted to give similar firing rates for either stimulus. Intracellular microelectrodes recorded action potentials, receptor potential and receptor current, using current clamp and voltage clamp. Frequency response analysis showed that naturalistic stimulation contained relatively more power at low frequencies, and caused increased neuronal sensitivity to higher frequencies. In contrast, varying the amplitude of Gaussian stimulation did not change neuronal dynamics. Naturalistic stimulation contained less entropy than Gaussian, but signal entropy was higher than stimulus in the resultant receptor current, indicating addition of uncorrelated noise during transduction. The presence of added noise was supported by measuring linear information capacity in the receptor current. Total entropy and information capacity in action potentials produced by either stimulus were much lower than in earlier stages, and limited to the maximum entropy of binary signals. We conclude that the dynamics of action potential encoding in VS-3 neurons are sensitive to the form of stimulation, but entropy and information capacity of action potentials are limited by firing rate.

Full Document: Wall BW, Ash P, Keram E, et al: AAPL Practice Resource for the Forensic Psychiatric Evaluation of Competence to Stand Trial Update 2018. Journal of the American Academy of Psychiatry and the Law Online Supplement 2018, 46 (3). Available at: http://www.jaapl.org/content/46/3_Supplement., (© 2018 American Academy of Psychiatry and the Law.)

The insanity defense is a legal construct that excuses certain mentally ill defendants from legal responsibility for criminal behavior. This practice guideline has delineated the forensic psychiatric evaluation of defendants raising the insanity defense. The document describes acceptable forensic psychiatric practices. Where possible, standards of practice and ethical guidelines have been specified. And where appropriate, the practice guideline has emphasized the importance of analyzing the individual case, the jurisdictional case law and the state (or federal) statute. This practice guideline is limited by the evolving case law, statutory language and legal literature. The authors have emphasized the statutory language of current legal standards, as well as the state or federal courts' interpretation of those standards because the same statutory language has been interpreted differently in different jurisdictions. Similarly, this practice guideline has reviewed the state and federal trends that determine which diagnoses meet the criteria for mental disease or defect. These trends yield to jurisdictional court interpretations. Finally, the authors hope this practice guideline has begun the dialogue about formulating a forensic psychiatric opinion by surveying the various approaches used to analyze case data. The forensic psychiatrist's opinion in each case requires an understanding of the current jurisdictional legal standard and its application, as well as a thorough analysis of the individual case. The psychiatrist's analysis and opinion should be clearly stated in the forensic psychiatric report. It should be noted that the role of a psychiatric expert witness in the criminal justice system is predicated on the law's interest in individualizing the criteria of mitigation and exculpation. Forensic psychiatric analyses and formulations of opinions are, therefore, subject to change as the legal guidance changes.