Appellant-defendant was found guilty of aggravated assault without dangerous weapon in violation of § 6—4—506(a), W.S.1977,1 by the district court sitting without a jury. While appellant characterizes the issues on appeal differently, we believe the issues to be:
1) Is it necessary for a defendant to plead “not guilty by reason of mental illness or deficiency” before evidence of unconsciousness can be presented?
2) Was there sufficient evidence to sustain appellant’s conviction?
We will affirm.
On November 17, 1979, the appellant consumed seven or eight shots of whiskey over a period of four hours in a Torrington bar, and had previously had a drink at home.
Appellant claims he got in a fight in the bar restroom, then left the bar to find a friend. According to his testimony, the last thing he remembers until awakening in jail, is going out of the door at the bar.
Appellant and his friend were found lying in the alley behind the bar by a police officer who noted abrasions on their fists and faces. Appellant and his friend swore, were uncooperative, and combative. They were subsequently booked for public intoxication and disturbing the peace. During booking appellant continued to swear, and said he and his friend were jumped by a “bunch of Mexicans.” Although his speech was slurred, he was able to verbally count his money, roughly $500 to $600 in increments of $20, and was able to walk to his cell without assistance.
Appellant was placed in a cell with one Martin Hernandez who was lying unconscious on the floor of the cell. After the jailer left the cell, he heard something that sounded like someone being kicked. He ran back to the cell and saw appellant standing by Hernandez. When the jailer started to leave again, the kicking sound resumed, and he observed appellant kicking and stomping on Hernandez’s head. Appellant told the officer Hernandez had fallen out of bed. Hernandez was bleeding profusely and was taken to the hospital for some 52 stitches in his head and mouth. He had lost two or three teeth as a result of the kicking.
Appellant was released later in the day, November 18, 1979, and went home. He went back to Torrington on November 22, 1979, to see a doctor. Appellant testified that the doctor diagnosed he had a concussion, although there is no evidence in the record of medical treatment.
At his arraignment in district court, appellant first entered a plea of “not guilty by reason of temporary mental illness.” Upon being advised by the trial judge that he would have to be committed for examination pursuant to § 7-11-304, W.S.1977, he withdrew that plea and entered a plea of not guilty.
In preparation for trial, appellant was examined by Dr. Breck LeBegue, a forensic *144psychiatrist. The doctor reviewed the police report and conducted a number of tests.
At the trial Dr. LeBegue testified that in his expert medical opinion appellant suffered brain injury and was in a state of traumatic automatism at the time of his attack on Hernandez. Dr. LeBegue defined traumatic automatism as the state of mind in which a person does not have conscious and willful control over his actions, and lacks the ability to be aware of and to perceive his external environment. Dr. Le-Begue further testified that another possible symptom is an inability to remember what occurred while in a state of traumatic automatism.
Dr. LeBegue was unable to state positively whether or not appellant had the requisite mental state for aggravated assault and battery, but thought appellant did not because of his altered state of mind. He could not state, however, that the character of an act is devoid of criminal intent because of mind alteration.
After the record on appeal had been filed in this court, defense counsel and the prosecuting attorney for Goshen County attempted to supplement the record by entering into a stipulation.2 We hold that the stipulation was an improper attempt to supplement the record.
The Attorney General refused to approve the stipulation prior to its execution. He may not be bypassed, for once a case is in this court the Attorney General has complete charge of the State’s case. Section 9-2-205(a), W.S.1977.3 The county and prosecuting attorney is not the attorney of record for the State in this appeal. The stipulation, therefore, will not be considered by this Court. See also, Hayes v. State, Wyo., 599 P.2d 569 (1979) and Tobin v. Purcel, Wyo., 539 P.2d 361 (1975).
I
We hold that the trial court properly received and considered evidence of unconsciousness absent a plea of “not guilty by reason of mental illness or deficiency.”4
*145The defense of unconsciousness perhaps should be more precisely denominated as the defense of automatism. Automatism is the state of a person who, though capable of action, is not conscious of what he is doing. While in an automatistic state, an individual performs complex actions without an exercise of will. Because these actions are performed in a state of unconsciousness, they are involuntary. Automa-tistic behavior may be followed by complete or partial inability to recall the actions performed while unconscious. Thus, a person who acts automatically does so without intent, exercise of free will, of knowledge of the act.
Automatism may be caused by an abnormal condition of the mind capable of being designated a mental illness or deficiency. Automatism may also be manifest in a person with a perfectly healthy mind. In this opinion we are only concerned with the defense of automatism occurring in a person with a healthy mind. To further narrow the issue to be decided in this case, we are concerned with alleged automatism caused by concussion.
The defense of automatism, while not an entirely new development in the criminal law, has been discussed in relatively few decisions by American appellate courts, most of these being in California where the defense is statutory. Some courts have held that insanity and automatism are separate and distinct defenses, and that evidence of automatism may be presented under a plea of not guilty. Some states have made this distinction by statute. In other states the distinction is made by case law. People v. Hardy, 33 Cal.2d 52, 198 P.2d 865 (1948); People v. Martin, 87 Cal.App.2d 581, 197 P.2d 379 (1948); People v. Taylor, 31 Cal.App.2d 723, 88 P.2d 942 (1939); People v. Grant, 46 Ill.App.3d 125, 4 Ill.Dec. 696, 360 N.E.2d 809 (1977); Carter v. State, Okl.Cr., 376 P.2d 351 (1962); 21 Am.Jur.2d § 29, Criminal Law, p. 115 (1965).
“A defense related to but different from the defense of insanity is that of unconsciousness, often referred to as automatism: one who engages in what would otherwise be criminal conduct is not guilty of a crime if he does so in a state of unconsciousness or semi-consciousness. * * * ” LaFave & Scott, Criminal Law, § 44, p. 337 (1972).
“The defenses of insanity and unconsciousness are not the same in nature, for unconsciousness at the time of the alleged criminal act need not be the result of a disease or defect of the mind. As a consequence, the two defenses are not the same in effect, for a defendant found not guilty by reason of unconsciousness, as distinct from insanity, is not subject to commitment to a hospital for the mentally ill.” State v. Caddell, 287 N.C. 266, 215 S.E.2d 348, 360 (1975).
The principal reason for making a distinction between the defense of unconsciousness and insanity is that the consequences which follow an acquittal will differ. The defense of unconsciousness is usually a complete defense.5 State v. Mercer, 275 N.C. 108, 165 S.E.2d 328, 334 (1969). State v. Caddell, supra; 21 Am.Jur.2d, Criminal Law, § 29, p. 115 (1965). That is, there are no follow-up consequences after an acquittal; all action against a defendant is concluded.
However, in the case of a finding of not guilty by reason of insanity, the defendant is ordinarily committed to a mental institution.
*146“ * * * [0]ne of the purposes served by the insanity defense is that it makes possible the commitment of some persons, not as an alternative to conviction and imprisonment, but rather as an alternative to outright acquittal. That is, if the defendant did not commit the acts with the mental state required for conviction of the crime charged, but this is because he was suffering from a mental disease or defect, the result is likely to be a finding of not guilty by reason of insanity followed by commitment rather than a mere finding of not guilty followed by release * * * .” LaFave and Scott, supra, at 338.
In some states the commitment is automatic after a finding of not guilty by reason of insanity. In Wyoming the trial judge may commit a defendant based on evidence produced at trial or the commitment may be by separate proceedings.6
The mental illness or deficiency plea does not adequately cover automatic behavior. Unless the plea of automatism, separate and apart from the plea of mental illness or deficiency is allowed, certain anomalies will result. For example, if the court determines that the automatistic defendant is sane, but refuses to recognize automatism, the defendant has no defense to the crime with which he is charged. If found guilty, he faces a prison term. The rehabilitative value of imprisonment for the automatistic offender who has committed the offense unconsciously is nonexistent. The cause of the act was an uncontrollable physical disorder that may never recur and is not a moral deficiency.
If, however, the court treats automatism as insanity and then determines that the defendant is insane, he will be found not guilty. He then will be committed to a mental institution for an indefinite period. The commitment of an automatistic individual to a mental institution for rehabilitation has absolutely no value. Mental hospitals generally treat people with psychiatric or psychological problems. This form of treatment is not suited to unconscious behavior resulting from a bump on the head.
It may be argued that evidence of unconsciousness cannot be received unless a plea of not guilty by reason of mental illness or deficiency is made pursuant to Rule 15, W.R.Cr.P. We believe this approach to be illogical.
“ * * * Insanity is incapacity from disease of the mind, to know the nature and quality of one’s act or to distinguish between right and wrong in relation thereto. In contrast, a person who is completely unconscious when he commits an act otherwise punishable as a crime cannot know the nature and quality thereof or whether it is right or wrong. * * * ” State v. Mercer, supra, 165 S.E.2d at 335.
It does not seem that the definition of “mental deficiency” in § 7—11—301(a)(iii),7 W.S.1977, which includes “brain damage,” encompasses simple brain trauma with no permanent aftereffects. It is our view that the “brain damage” contemplated in the statute is some serious and irreversible condition having an impact upon the ability of the person to function. It is undoubtedly something far more significant than a temporary and transitory condition. The two defenses are merged, in effect, if a plea of “not guilty by reason of mental illness or deficiency” is a prerequisite for using the defense of unconsciousness.
The committee that drafted Wyoming Pattern Jury Instructions Criminal, apparently recognized mental illness or deficiency and unconsciousness as separate and distinct defenses. See § 4.301, Wyo. P.J.I.Cr. A copy is attached hereto as Appendix A. *147Admittedly the instructions in Wyo. P.J.I.Cr. are not authoritative, because they were not approved by the Wyoming Supreme Court, and this was a matter of design. Still they are the product of a distinguished group of legal scholars, including judges, attorneys and teachers of the law. The comment to this pattern jury instruction notes that it is limited to persons of sound mind, and the comment distinguishes persons suffering from “mental deficiency or illness.” In this respect, it tracks the case law from other jurisdictions, which authorities hold that unconsciousness and insanity are completely separate grounds of exemption from criminal responsibility. People v. Conley, 64 Cal.2d 310, 49 Cal.Rptr. 815, 411 P.2d 911 (1966); Carter v. State, supra; State v. Mercer, supra.
Although courts hold that unconsciousness and insanity are separate and distinct defenses, there has been some uncertainty concerning the burden of proof. We believe the better rule to be that stated in State v. Caddell, supra, 215 S.E.2d at 363:8
“We now hold that, under the law of this state, unconsciousness, or automatism, is a complete defense to the criminal charge, separate and apart from the defense of insanity; that it is an affirmative defense; and that the burden rests upon the defendant to establish this defense, unless it arises out of the State’s own evidence, to the satisfaction of the jury.” (Emphasis added.)
The rationale for this rule is that the defendant is the only person who knows his actual state of consciousness. Hill v. Baxter 1 All E. R. 193 (1958), 1 Q. B. 277.
Our ruling on the facts of this case is that the defense of unconsciousness resulting from a concussion with no permanent brain damage is an affirmative defense and is a defense separate from the defense of not guilty by reason of mental illness or deficiency.
II
The appellant’s conviction must, nevertheless, be affirmed. Dr. LeBegue was unable to state positively whether or not appellant had the requisite mental state for aggravated assault. He could not state that the character of the act was devoid of criminal intent because of the mind alteration. The presumption of mental competency was never overcome by appellant and the evidence presented formed a reasonable basis on which the trial judge could find and did find that the State had met the required burden of proof.
Further, the trial judge was not bound to follow Dr. LeBegue’s opinion. The trier of the facts is not bound to accept expert opinion evidence in the face of other substantial and credible evidence to the contrary. State v. Peterson, 24 N.C.App. 404, 210 S.E.2d 883 (1975). Cf., Reilly v. State, Wyo., 496 P.2d 899 (1972), reh. denied, 498 P.2d 1236 (1972). There was an abundance of other credible evidence that appellant was not unconscious at the time of the assault and battery for which he was convicted.
Affirmed.
APPENDIX A
4.S01 UNCONSCIOUS ACTS
Where a person commits an act without being conscious thereof, such act is not criminal even though, if committed by a person who was conscious, it would be a crime.
This rule of law applies only to cases of the unconsciousness of person of sound mind, in which there is no functioning of the conscious mind.
Use Note-
Specific examples of where this instruction would apply include: sleep walkers or persons suffering from the delirium of fever, epilepsy, a blow on the head or the involuntary taking of drugs or intoxicating liquor.
*148 Comment-
CALJIC 4.30.
Unconsciousness is a complete, not a partial, defense to a criminal charge. People v. Wilson, [66 Cal.2d 749, 59 Cal.Rptr. 156,] 427 P.2d 820, 828 (Cal.1967).
There can be no criminality in the absence of criminal intention, and one who acts while unconscious lacks criminal intention. Fair v. Commonwealth, 78 Ky. 183 [39 Am.Rep. 213] (1879).
Wyoming has no statutory or case law in this area. Two theories have been used to support this defense in jurisdictions recognizing it. The first is that unconsciousness or semi-consciousness is a defense because one who acts while in such a condition does not have the requisite mental state for commission of a crime. The second, which is the rationale used by the Model Penal Code, § 2.01 (1962), and favored by LaFave and Scott, Criminal Law, § 44 (1972), is that commission of a crime requires a voluntary act or omission, and one who acts while in a state of unconsciousness or semi-consciousness has not engaged in a voluntary act.
The above instruction does not favor either of these theories because California’s unconsciousness defense, from which this instruction is taken, is statutorily based. When a case involving an unconsciousness defense arises, either rationale can be adopted under the instruction as it is written.
The second paragraph of the instruction limits the availability of the unconsciousness defense to persons of sound mind. People who commit similar acts but are of unsound mind are suffering from mental illness or deficiency and are covered by the laws and instructions concerning the insanity defense.
. Section 6—4—506(a), W.S.1977:
"(a) If any person shall unlawfully and maliciously inflict upon another person, any grievous bodily harm the person so offending shall be fined not more than one thousand dollars ($1,000.00) or be confined in the county jail not more than one (1) year, or both.”
. The substance of the stipulation:
“COME NOW the parties in the trial Court, the defendant, Robert Brian Fulcher, by and through his attorney, Robert T. Moxley, the State of Wyoming by and through Goshen County and Prosecuting Attorney, Lowell H. Fitch, and make the following Stipulation of Facts for the purpose of clarifying the record on appeal;
“1. At the time of the commission of the crime charged, on November 18, 1979, the defendant was suffering from a cerebral concussion;
“2. At the time of the commission of the crime, the defendant was in an altered mental state, clinically defined as ‘traumatic automatism’, brought on and caused by said cerebral concussion;
“3. That the outstanding clinical feature of said traumatic automatism is defined as ‘traumatic amnesia’;
“4. That the defendant is suffering from amnesia and does not remember the occu-rance [sic] of the crime.”
. Section 9-2-505, W.S.1977:
“(a) The attorney general shall prosecute and defend all suits that may be instituted by or against the state of Wyoming, the prosecution and defense of which is not otherwise provided for by law, and he shall represent the state in all criminal cases in the supreme court, and shall defend all suits brought against the state officers in their official relations, except suits brought against them by the state. He shall be required to attend to the interests of the state in all suits, actions or claims in which the state is or may become interested in either the supreme court of the state, or in any of the United States courts. * * * ” (Emphasis added.)
.Formerly under Wyoming law a defendant could enter a plea of “not guilty by reason of insanity.” Section 7-240, W.S.1957, repealed by Ch. 191, § 2, S. L. of Wyoming 1975. Under present law a defendant may enter a plea of “not guilty by reason of mental illness or deficiency.” Rule 15, W.R.Cr.P.
In this opinion we will use the terms insanity and mental illness or deficiency interchangeably and as having the same meaning. The issues in this case do not require that a distinction be made. It would add nothing to the opinion to explain the difference in the two terms and may, in fact, obscure the issues in this case. The case law and treatises that we will cite generally use the term, “insanity.” The rationale for distinguishing the defenses of unconsciousness and insanity is substantially the same as the rationale for distinguishing the defenses of unconsciousness and mental illness or deficiency.
. Unconsciousness is not a complete defense under all circumstances. An incomplete list of situations will illustrate. In California, “unconsciousness produced by voluntary intoxication does not render a defendant incapable of committing a crime.” People v. Cox, 67 Cal.App.2d 166, 153 P.2d 362 (1944), and cases cited. In Colorado a person who participates in a fracas and as a result is hit on the head and rendered semi-conscious or unconscious cannot maintain that he is not criminally responsible. Watkins v. People, 158 Colo. 485, 408 P.2d 425 (1965). In Oklahoma a motorist is guilty of manslaughter if he drives an automobile with knowledge that he is subject to frequent blackouts. Carter v. State, Okl.Cr., 376 P.2d 351 (1962). See also, Smith v. Commonwealth, Ky., 268 S.W.2d 937 (1954). As to somnambulism, see Fain v. Commonwealth, 78 Ky. 183, 39 Am.Rep. 213 (1879); and Lewis v. State, 196 Ga. 755, 27 S.E.2d 659 (1943). See also § 6-1-116, W.S. 1977.
. Section 7-11-306(a):
“After entry of a judgment of not guilty by reason of mental illness or deficiency excluding responsibility, the court shall, on the basis of evidence given at trial or at a separate hearing, make an order as provided in subsection (b), (c) or (d) of this section.”
. Section 7—11—301(a)(iii):
“ ‘Mental deficiency’ means a defect attributable to mental retardation, brain damage and learning disabilities.”
. State v. Mercer, 275 N.C. 108, 165 S.E.2d 328, 335 (1969), held that “unconsciousness is never an affirmative defense.” State v. Caddell, 287 N.C. 266, 215 S.E.2d 348, 363 (1975), overruled Mercer, supra, and stated that “it [unconsciousness] is an affirmative defense.”