Weaknesses

• Causation is an issue within these investigations
• observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay
• A further problem is that post-mortem studies raise ethical issues of consent from the patient before death
• Patients may not be able to provide informed consent for example in the case of HM who lost his ability to form memories and was not able to provide such consent- nevertheless postmortem research has been conducted on his brain