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NEUROSCIENCE OF PSYCHOACTIVE SUBSTANCE USE AND DEPENDENCE

Ethical principles in medicine and human rights both embody injunctions
to behave in specific ways but they differ in to whom they apply (Mann, 1999).
Ethical principles typically apply to individuals, usually health care workers
and researchers, whereas human rights impose obligations on states and
governments to promote and protect the rights of their citizens from
infringements by the state or by others (Mann, 1999). Human rights are most
relevant to the way in which treatments and interventions derived from
neuroscience research are used to treat and prevent substance dependence.
This is because treatment and prevention may involve the use of the coercive
powers of the state to threaten the human rights of persons who are
dependent on psychoactive substances (Gostin & Mann, 1999).

Ethics of animal experimentation in neuroscience research
The use of animals in biomedical research has traditionally been justified
by the argument that the harm inflicted upon animals in the course of
research is outweighed by the gains in scientific knowledge to humans (and
animals) (Resnik, 1998). The scientific community has generally accepted
this defence, but it has not received similar support from the public as a
result of media reporting of controversial examples of animal experimen-
tation (Brody, 1998).
Animal research has provided some significant benefits to humans, for
example, the identification of mechanisms that cause disease and the
improvement of treatments (Naquet, 1993).
Although there are alternatives to animal models in some situations, such
as tissue cultures and computer simulation (Resnik, 1998), these models
cannot replace the use of animals in research because they cannot model
the rich behavioural and physiological environment of live animals (American
Psychological Association Science Directorate, 2001).
A criticism of animal experimentation is that the animals used do not
provide good models of human biology, physiology and psychology (Resnik,
1998). For example, research has shown that cortical organization in the brain
varies between species and that some primates lack characteristics found in
humans (Preuss, 2000). It has also been argued that the psychology and
neurobiology of substance dependence are not well-modelled in commonly
used animals such as mice and rats (Resnik, 1998), and that non-human
primate models are more desirable because the cortical anatomy and
behavioural repertoire of primates more closely resembles those of humans
(National Academy of Science, 1996). However, much of the current
knowledge regarding the neuroscience of substance dependence has come
from animal experimentation using a number of different species. Genetically
engineered mice, for example, have been used to identify initial targets for
drugs, such as the CB1 cannabinoid receptor, and biochemical pathways
involved in cocaine metabolism have been investigated (Nestler, 2000). Rats
and other non-primate species have provided good models for certain aspects

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