1. When, in connection with the affirmative defense of lack of criminal responsibility by reason of mental disease or defect, a psychiatrist or licensed psychologist testifies at a trial concerning the defendant's mental condition at the time of the conduct charged to constitute a crime, he must be permitted to make a statement as to the nature of any examination of the defendant, the diagnosis of the mental condition of the defendant and his opinion as to the extent, if any, to which the capacity of the defendant to know or appreciate the nature and consequence of such conduct, or its wrongfulness, was impaired as a result of mental disease or defect at that time.

The psychiatrist or licensed psychologist must be permitted to make any explanation reasonably serving to clarify his diagnosis and opinion, and may be cross-examined as to any matter bearing on his competency or credibility or the validity of his diagnosis or opinion.

2. Any statement made by the defendant to a psychiatrist or licensed psychologist during his examination of the defendant shall be inadmissible in evidence on any issue other than that of the affirmative defense of lack of criminal responsibility, by reason of mental disease or defect. The statement shall, however, be admissible upon the issue of the affirmative defense of lack of criminal responsibility by reason of mental disease or defect, whether or not it would otherwise be deemed a privileged communication. Upon receiving the statement in evidence, the court must instruct the jury that the statement is to be considered only on the issue of such affirmative defense and may not be considered by it in its determination of whether the defendant committed the act constituting the crime charged.