Action for Primates
Below are samples of recent publications from laboratories in which non-human primates were used in experiments (see previous entries in our archives). Our intention is to provide details of the types of research to which non-human primates are being subjected. Bear in mind that what we list here is only a tiny example of the dozens of experiments published each week.
Although we emphasise welfare issues with respect to how the research impacted on the animals, please bear in mind that the non-human primates used were all essentially wild animals, even if bred in captivity. Because of this, the suffering and stress of being in captivity was inherent in every case.
The work was carried out at Charles River in Canada, but involved researchers from Southwest Research Institute in Texas, Emergent BioSolutions in Maryland and the US Department of Health and Human Services. See our take action alert.
It was approved by the Office of Laboratory Animal Welfare/Vertebrate Animal Section (OLAW/VAS) in the US, and publicly funded in whole or in part by the Department of Health and Human Services. It was also approved by the Canadian Council on Animal Care, who claim that they ensure
...humane treatment... of animals.
Cyanide is one of the most lethal poisons known and death can occur within minutes following exposure. According to the authors of the research reported here, the objective was to demonstrate the effectiveness of isoamyl nitrite, a cyanide antidote, against lethal potassium cyanide given intravenously in conscious non-human primates. This is despite the fact that amyl nitrite has been used as a cyanide antidote in people for decades.
Twenty-two rhesus macaques were used (11 females, 11 males). They were anaesthetised and subjected to major surgery to have telemetry devices implanted into the abdominal cavity to monitor cardiovascular and lung functions; a pressure catheter implanted into the femoral artery; electrocardiography (ECG) leads implanted into the jugular vein to the heart and diaphragm; a pressure catheter implanted into the left ventricle of the heart and respiratory function leads implanted inside the animals, near the seventh rib.
Following recovery from this surgery, the conscious macaques were placed on a sling and given potassium cyanide intravenously. Some individuals were then treated with intranasal isoamyl nitrite at different doses and different times. The others were not treated with the isoamyl nitrite. According to the researchers, the
...monkeys were monitored for survival, clinical signs, respiratory and cardiovascular changes via continuous telemetry recording.
Shortly after the injection of potassium cyanide, all monkeys showed clinical signs
...leading to a serious deteriorating condition or death. Within three minutes, the macaques had salivation, drooping of eyelids (ptosis), agitation, decreased activity, skin paleness and vomiting. Within the next 3-4 minutes, they had difficulty breathing, were gasping, their eyes were moving involuntarily (nystagmus), their pupils were dilated, they had involuntary muscle spasms and some were convulsing. For some of the animals, the antidote resulted in an improvement in clinical signs with
...complete recovery within an hour post-dose. Those individuals who were not treated or who were treated with a low dose of isoamyl nitrite, however, continued to deteriorate until they died within 10-15 minutes of being poisoned with potassium cyanide. Two macaques
...survived the challenge, but remained lying on the cage floor without any signs of recovery... and were killed, but not until three or five hours after treatment!
This 'research' was exceptionally appalling and barbaric. It is unquestionable that all the macaques even those treated with the antidote suffered substantially. In many studies in which it is known that the animals will suffer, the researchers develop guidelines to decide at what point the animals should be killed the so-called 'humane endpoint'. The researchers in the present study, however, did not even provide for this situation. Instead, some of these macaques were allowed to die with no relief provided to ease the pain and profound suffering from cyanide poisoning. The only ones who were killed out of concern for 'humaneness' were allowed to suffer for up to five hours first.
Scientists routinely try to justify their use and killing of unquestionably non-consenting and unwilling individuals, such as the rhesus macaques in this 'study', by stating that they only do this when absolutely necessary and only to further medical benefits to people. This study, however, shows unequivocally that such pronouncements are not only untrue, there are also no moral boundaries that some scientists will not cross. Moreover, it is difficult to understand how an agency concerned with humanity Health & Human Services could fund such work. Even more demoralising is that the federal agency whose obligation is to ensure the
humane care and
welfare of non-human animals used in research, funded by US tax payers and comprised of veterinarians Office of Laboratory Animal Welfare could allow such brutal treatment of non-human primates.
Twelve adult male rhesus macaques were used in this research carried out at Wake Forest School of Medicine, North Carolina, US, which was approved by the Animal Care and Use Committee of Wake Forest University and funded entirely with public funds via National Institute on Drug Abuse (NIDA; a branch of the NIH) grant DA039953. See our take action alert.
The rhesus macaques were used in an attempt to determine whether alcohol causes more sensitivity to cocaine, as if this might answer the same question in people who abuse both drugs. To prepare them for this ordeal, the macaques were subjected to surgery to keep a catheter permanently inside a vein so that they could self-administer the cocaine. They were also fitted with an aluminium collar and restrained in an apparatus euphemistically referred to as a
primate chair, produced by Primate Products (see photo for example of one of their 'primate chairs').
Six of the macaques were coerced to drink ethanol (alcohol). A solution of 4% (w/v) ethanol in 5% Tang® was given to them via an 800-mL drinking bottle attached to each individual's cage for one hour per day, five days per week. By 18 days, the macaques
...drank enough to equal an intake of 2.0 g/kg ethanol during the one-hour period, the equivalent of eight drinks. The researchers called this a
binge-like pattern, and continued this five days a week for about nine months before the start of cocaine self-administration. The other six macaques the
control group were treated exactly the same except that Tang® solution did not contain ethanol.
The cocaine-self administration began with the macaques restrained in the apparatus inside a sound-attenuating chamber. For five mornings per week, they were rewarded with banana-flavoured food pellets if they responded 'correctly' to a specific stimulus. Once a macaque reliably responded and received 30 pellets in a session (which lasted up to an hour), the catheter was implanted. Cocaine was then infused into the bloodstream and testing, in the apparatus, including food rewards, was done to see what effect the cocaine had. The macaques continued to drink an ethanol (alcohol) solution every day after they were returned to their cages.
The researchers did not say anything about the ultimate fate of the macaques, including what happened when the alcohol and cocaine was presumably taken away at the end of the research.
This project is just one more in a continuing series of publicly-funded projects in which non-human primates are forced to consume addictive substances by coercion, in the misguided notion that this will somehow provide answers to substance abuse in people. Drug addiction in people, however, involves considerably more than simply abusing certain substances. The complex combination of factors at play, such as genetics, emotional and personal experiences, and socioeconomic aspects, can never be simulated or resolved through non-human primate research. The millions of tax dollars squandered each year on 'animal models' of drug addition could be better used to directly help the millions of people who suffer from substance abuse.
The daily use of marijuana is apparently rising in human adolescents, along with the use of high potency marijuana products such as tetrahydrocannabinol (THC). This research subjected black-capped squirrel monkeys to daily injections of cannabis for four months in an attempt to 'understand' the long-term effects of the daily consumption of a high dose of THC in adolescents and whether a therapeutic dose of cannabidiol (CBD) has a modifying effect on the THC. See our take action alert.
Tetrahydrocannabinol is the psychoactive substance that produces the 'high' associated with smoking marijuana and can also lead to central nervous system depression. Cannabidiol is a major component of the active ingredients of marijuana and is used in medical marijuana.
Twelve adolescent male black-capped squirrel monkeys were used in this research carried out at McLean Hospital (part of Harvard University), with collaboration by the University of Toronto. The research was approved by the Institutional Animal Care and Use Committee at McLean Hospital and supported by public funds (NIH grant) and Harvard University.
The monkeys were divided into three groups, one of which was a 'control' group not given the drugs. The remaining monkeys were injected intramuscular daily for four months, receiving an increasing amount of either THC or a combination of THC and CBD, eventually reaching the equivalent of one
marijuana joint equivalent per day.
During the first three weeks, the monkeys underwent
training on a touchscreen. There were
90-training trials during at least five daily sessions. During these sessions, the monkeys were held in a small Plexiglass chamber which was in a sound- and light-attenuating enclosure.
In week four, when the highest dose of drugs was injected, the monkeys were tested using the touchscreen to see the effects of the drugs on their ability to do the task. Some of the monkeys carried out hundreds of trials. The fate of the monkeys was not stated.
The authors concluded:
Whether our observations are relevant to a broader range of cognitive tasks vital for daily function in humans, especially those known to be compromised by marijuana use in human adolescents (i.e., learning and memory, processing speed, complex attention, executive function, impulse control and decision-making) is uncertain. Long term marijuana use initiated during adolescence is associated with a broad spectrum of adverse effects (e.g. cognitive impairment, anxiety, psychosis, amotivation, addiction, accidents) some of which are not identifiable in laboratory housed non-human primates.
As common sense would have foretold, the authors acknowledge that the work subjecting these non-consenting beings to forced captivity, drugs and testing, may have no relevance to people. The authors also concluded that using CBD in addition to THC in the monkeys did not change the outcome.
Drug use is a major public health issue, and there is already a wealth of data on its impact. Testing could easily be carried out using morally-defensible studies in human volunteers and relevant data obtained. Despite this and while the scientific community claims repeatedly that they only use
absolutely necessary, researchers such as these continue to deliberately inflict misery and suffering by forcing drugs into non-human primates. None of these studies, however, can nor could they ever get to the root issues surrounding drug abuse in people, which comprise a complex combination of factors such as genetics, emotional and personal experiences, and socioeconomic issues. While millions of dollars usually paid for by the US tax payer are spent every year to make non-human primates 'drug addicts', people who might actually benefit from these funds and resources continue to suffer.
Rhesus macaques were subjected to an appalling ordeal lasting many months during research to deliberately damage the part of their ear involved in balance. See our take action alert.
The vestibular system (inner ear balance mechanism) is a sensory system that contributes to the sense of balance and spatial orientation for the purpose of coordinating movement. It works with the visual system (eyes, relevant muscles and parts of the brain) to stop objects blurring when the head moves. People with vestibular damage experience impaired vision, spatial perception and balance.
The work was done at the Massachusetts Eye and Ear Infirmary, Boston, Massachusetts (a teaching hospital of Harvard Medical School), and was approved by the Massachusetts Eye and Ear Infirmary Animal Care and Use Committee. It was publicly funded with NIH (NIDCD) grants and privately with a grant from MED EL Corp, a company that produces cochlear implants for hearing issues.
Two female rhesus macaques were used, called
M2 by the authors. They were
...trained to perform a psychophysical task that assayed their perception of head orientation relative to gravity... [authors' emphasis] The 'training', which took six months, was not described, so it is not known whether the monkeys were deprived of food or liquids to 'motivate' them, as usually happens with this type of 'training'.
The monkeys were then subjected to four surgical procedures under anaesthesia:
tunneled subcutaneously to the headcap
Running wires subcutaneously under the skin to the headcap would have involved tearing a path through the tissues beneath the skin, adding to postoperative pain for the monkeys.
The researchers then attempted to carry out a
vestibular ablation, destroying the ability of the monkeys to orient themselves. Monkey
M1 was injected 10 times in each ear with a drug that is toxic. Despite this, the desired loss of function did not occur, leading the researchers to conclude that
Rhesus monkeys appeared to be fairly resistant to this mode of ablation, however, as ten bilateral...injections in M1 only modestly reduced... function. The researchers then tried giving a different drug that is known to be toxic to the ear. They gave two courses of this drug intramuscularly, but this also did not result in the desired loss of function. It was not stated how frequently all these injections were made, whether
M1 was awake or anaesthetised each time and what effects they had on her. Eventually, the researchers gave the original toxic drug directly into a specific part of one ear while implanting electrodes. This was also done in one ear of
M2. In both macaques, the other ear was subjected to a separate surgery:
...the contralateral ear was destroyed with a labyrinthectomy. This resulted in
...complete loss of vestibular function on the non-implanted side and severe damage in the implanted ear...
After subjecting these monkeys to such brutal mutilation, the testing began. The researchers admitted, however, that
Due to delays associated with vestibular ablation and surgical recoveries, testing in the different states was separated by substantial periods of time. As a result, the testing took place over many months. The monkeys had to carry out the task in the dark, immobilised in a restraint apparatus with their heads further immobilised by the head bolt. They had
to rotate a light bar about the roll...axis using a small steering wheel with the goal of aligning the light bar parallel to gravity. Their eye movements were measured. Tilting the chair to see the monkeys' responses was part of the testing process.
There was no information provided on the outcome for the monkeys, their physical condition, their behaviour, how they managed in their cages following such severe disruption to their coordination and orientation. We wrote to the corresponding author of the paper and to the Editor-in-Chief of the journal and asked specifically about the fate of the monkeys. Neither provided us with this information, suggesting that they did not think it was important to include in the publication. We know that damage to a human's vestibular system can cause a person to experience symptoms such as sudden, severe vertigo (spinning/swaying sensation); dizziness; balance problems; lack of coordination; blurred or 'bouncing' vision; hearing abnormalities; anxiety; nausea and vomiting. There is nothing to suggest that monkeys do not experience the same effects. These would unquestionably be extremely frightening to a monkey who cannot understand what is happening to them and who is highly mobile and depends on their agility to survive in their environment.
This research was basic science to learn more 'details' about how balance is controlled in rhesus macaques, but may have no applicability to people. The authors stated that
Considerable work remains before the VI [vestibular implant] can be optimized as a clinical therapy. They also stated that
Human implantation has been initiated by three groups... [authors' emphasis] and that the results are promising. This calls into question, therefore, why macaques were subjected to such an arduous ordeal and mutilation. Despite this, the researchers called for more macaque research.
This experiment carried out on Japanese macaques at Osaka University in Japan, involved using the monkeys as a 'model' for central poststroke pain, which is caused by damage to the brain. The monkeys were deliberately subjected to pain and then the researchers tracked changes in the animals' pain threshold using a behavioural experiment and tracking anatomical and functional changes in the brain by using magnetic resonance imaging (MRI). See our news report.
In two adult male snow monkeys, a specific part of the brain was damaged to create
central poststroke pain (CPSP). Under anaesthesia, part of the scalp was removed and a recording chamber was screwed to the skull with at least one hole into the brain for injecting the compound that would cause the artificial stroke and for making recordings. Head posts were also implanted into the monkeys' skulls. For recordings, the monkeys were forced to sit in a device made of acrylate glass with their lower backs and heads immobilised. Their wrists were also fixed in place to keep their palms facing downwards. An eyeshield was used so that the monkeys could not see their hands and stimulators during the experiment. The monkeys had to do certain tasks and respond to painful stimuli. They were deliberately subjected to pain through a hot stimulus (45-50°C) and a cold stimulus (5-15°C). In their Supplementary Information document, the authors stated that
To avoid burns, each trial took less than 1 minute. ... Monkeys could get a food reward if they could endure the stimulus for 1 minute.
The fate of the macaques was not stated.
The authors acknowledged there were major limitations to their research, in design and results. This raises questions as to why the study was approved, subjecting the snow monkeys to this brutal research. Among the limitations listed were 1) the type of artificial brain damage was different to that in people with stroke, 2) the pain induced by the stimulations was not the same as the persistent pain experienced by people suffering from CPSP, and 3) the pain rating scale commonly used for people suffering from CPSP was not used because such
subjective measures could not be obtained from the monkeys. These and the other limitations acknowledged by the researchers reinforce our recurring argument that using non-human primates to study human illnesses is not only morally reprehensible, it also lacks scientific validity.
Thirty-four rhesus macaques were used and killed in this recently published research carried out at Boston University School of Medicine in the US. Not only was it approved by their
...Institutional Animal Use and Care Committee (IACUC)..., it was funded entirely by public funds through the National Institutes of Health (NIH). See our take action alert.
The aim of the research was to look at impairments in learning, memory, executive function, and processing speed using the research group's rhesus macaque as a
model of ageing for humans.
The macaques were between five and 30 years old and were used simply to see what changes occurred in their learning ability and their brains with age. They were subjected to a series of behavioural tests to assess learning, memory and executive functions. The testing was carried out five days a week, but for how many hours a day or how many days or weeks was unclear. When the period of testing was completed, the macaques were killed to get their brains, or in the sanitised language of the authors, the
...brains were harvested.... The animals were anaesthetised before being bled to death.
According to the researchers, the macaques exhibit age-related cognitive impairment and can serve as a
model for studying ageing in people. These macaques, however, are essentially wild animals imprisoned in captivity. They will experience severe stresses caused by artificial experimental conditions, something that surely would have an unknown and unmeasurable impact on the their cognitive processes. From a scientific perspective, the findings in the captive macaques would have little, if any, applicability to ageing in people whose lives are fundamentally different and considerably more complex with respect to stressors. The most appropriate species to use to study people is people! More importantly, there are already data on the effects of ageing in people, as acknowledged by the authors, and more can be easily derived from humane and morally defensible studies in people.
This research comprises and exemplifies an appalling waste of life, the work obviously designed just to produce a 'library' of findings to use in future work involving rhesus macaques as a
model. It demonstrates, yet again, that the much-touted refrain of the research community of using 'animals' only when absolutely necessary is just meaningless and disingenuous.
Boston University School of Medicine claims that
The humane care and involvement of animals in research is a serious responsibility shared by the entire research community. In what way was this senseless 'research'
The research was carried out at the University of Fribourg in Switzerland (1). Funding was from several sources, including the European Union's Horizon 2020 research and innovation programme, and the research was approved by the local veterinary authorities of the Canton of Fribourg. The researchers declared the following
Competing interests: three were shareholders and founders of GTX medical, a company producing spinal cord stimulation technologies and who provided part of the research funding, and five were inventors of multiple patent applications and had been granted patents covering parts of this work. See our take action alert.
Five long-tailed macaques were used and were subjected to deliberate spinal cord damage. This involved major surgery to remove parts of their vertebrae to implant spinal electrodes as well as to have muscle electrodes implanted. Electrical stimulation was then applied to parts of their spinal cord to study arm and hand movements. Three of the macaques were used in
terminal procedures and underwent electrophysiological tests. They were killed before waking up from the surgery. The other two macaques were used for
acute procedures in which they were anaesthetised, underwent electrophysiological tests and were then allowed to recover. The researchers state that one of the monkeys had been
trained (although they do not describe how) to reach, grasp and pull an object using a robotic framework designed by the researchers.
Human patients with similar spinal surgeries were also tested.
Despite the authors' assertion that
All procedures were carried out in accordance to...the principle of the 3Rs...,** essentially similar or at least clinically relevant data were obtained from people who had spinal surgery. The authors also cited numerous studies on people with spinal cord injury, studies that have resulted in considerable knowledge about spinal cord injury in people.
Thirty male long-tailed macaques were used in this research carried out to evaluate the different stages of liver fibrosis (scarring of liver tissue) in long-tailed macaques.
Eight of these individuals died before the study was completed. The work was done at The Third Affiliated Hospital of Guangxi Medical University in China, approved by the medical ethics committee and experimental animal ethics committee, and funded by various sources within China. See our news report.
The macaques were injected subcutaneously with carbon tetrachloride twice a week. Carbon tetrachloride is used as a solvent for oils and fats, as a refrigerant and as a dry-cleaning agent. It is highly toxic and carcinogenic. Presumably to add to the liver damage suffered by these monkeys, they were also fed a high-fat diet supplemented with about 35% cholesterol and the only source of fluids given to them was an ethanol (alcohol) solution (10% in water). Every four weeks after the injection with carbon tetrachloride, the macaques were anaesthetised with ketamine in order to get liver tissue via needle aspiration. The animals were also subjected to magnetic resonance imaging (MRI). After 20 weeks, the macaques were anaesthetised with ketamine and killed by injecting air into an ear vein. Liver tissue was collected for examination.
Eight of the macaques died during the study. The remaining 22, who were killed, were all found to have fibrosis of the liver, most with severe damage. The authors of the paper provide no details of the clinical condition of the monkeys, especially those individuals who died during this appalling 'experiment'.
The aim of the work was to develop a
model of liver fibrosis in the long-tailed macaque. The artificial nature of the research, the lack of application to people who suffer liver damage caused by a variety of factors (and not by injecting themselves with a solvent!) and the infliction of such severe suffering on sentient beings is morally and scientifically unacceptable. It leaves us wondering what working definition of
ethics was used by the institution's
medical ethics committee and experimental animal ethics committee.
Young monkeys were deliberately subjected to extremely cruel and barbaric treatment in an attempt to simulate human teenage depression. Although this recently published research was done at Chongqing Medical University in China and supported mostly with Chinese funding, there are two US authors, one from Wake Forest School of Medicine and another from Virginia Commonwealth University. The work was approved by the Ethics Committee of Chongqing Medical University, but there is no mention of any oversight or decisions by ethics committees at either of the US facilities. The latter is disturbing in and of itself. See our take action alert.
In the research, ten male adolescent long-tailed macaques, some less than two years old, were used. They were housed singly in cages. The 'experimental' group (as opposed to those serving as 'controls') were subjected to
chronic unpredictable mild stress for seven days, and then observed for four days. This cycle was repeated four more times. The stressors the monkeys were subjected to, in some cases lasting 24 hours, included:
Noise: A buzzer with a 100 decibel shrill chirp was placed in the monkeys' room for 12 hours from 8:00 PM to 8:00 AM the following day. According to the US Centers for Disease Control and Prevention (CDC) noise above just 70 decibels over a prolonged period of time may start to damage your hearing.
Water deprivation: The monkeys were deprived of water for 12 hours from 8:00 PM to 8:00 AM the following day.
Food deprivation: The monkeys were deprived of food for 24 hours from 8:00 AM to 8:00 AM the following day.
Space restriction: The cage space of the monkeys was restricted by a push-pull device for four hours from 8:00 AM to 12:00 PM.
Cold stress: The monkeys were sprayed with 10°C water for ten minutes. Although long-tailed macaques are known for their affinity for water, the natural conditions do not involve such cold water nor for such an extended period. Further, under natural conditions, the macaques emerge into a warm and usually sunny environment so that they can dry off quickly.
Exposure to stroboscope: Flashing stroboscopes were placed facing the monkey cages for 12 hours from 8:00 PM to 8:00 AM the following day. Flicker causes disturbance and can cause physiological effects such as headaches, at least in people.
Inescapable foot shocks: The monkeys were exposed to foot shocks by an electric shock stick from which they could not escape. The shock was 6 volts lasting 10-15 seconds with intervals of ten seconds. The monkeys received 3-4 rounds of this.
Two different stressors were used each day. The macaques' behaviour was observed and recorded, their weight was recorded and certain standard 'tests' were done to see the difference between 'controls' and stressed individuals. The researchers were looking for both depressive-like behaviours and anxiety-like behaviours, such as a huddle posture, self-clasping with head at or below the shoulders.
This is a shocking and damning indictment of the appalling way in which non-human primates are abused in the name of science. The mental anguish and torment these monkeys must have suffered is unimaginable. As a gesture to
ethics, the researchers provided the monkeys with an eight-hour window each day when they allowed the animals social contact with each other, toys (already scientifically proven to be of only transient value) and fruit and vegetables (apart from those of food deprivation)
...to meet experimental requirements set by the institutional animal care and use committee..., which they admit may have influenced the outcome of the study.
The researchers were trying to establish a non-human primate 'model' for human adolescent depression, and yet their paper states that
...youth with depression experience more serious impairments in global functioning, an increased risk of tobacco smoking and other substance abuse2. Moreover, suicide is the third leading cause of death in adolescents; and among depressed youth, 29% experience suicidal thoughts and 11% attempt suicide4. All these depressive behaviours, critical in understanding and helping troubled human adolescents, are not reproducible in non-human primates, rendering the authors' abjectly inhumane 'model' of no relevance.
The researchers stated that they were able to
...induce depressive-like and anxiety-like behaviors... in macaques. By using such terms, however, the authors clearly acknowledge that their 'model' is only superficially similar to the situation seen in adolescent human teenagers. Despite this, the researchers conclude that subjecting macaques to chronic stress provides
...a promising model to study the mechanisms underlying adolescent depression. No amount of artificial and cruel stressors inflicted on macaques can compare with the complex emotional, genetic and environmental stressors that cause mental illness and depression in human teenagers.
The Wake Forest School of Medicine claims that the goal of their Animal Welfare Program
...is to ensure that animals at Wake Forest are always treated ethically and humanely. Virginia Commonwealth University states that their Animal research program places
...the ethical treatment of animals as a primary responsibility and the founding principal [sic] of our animal care and use program and that they employ the
...ethical mandates, known as 'The Three Rs' of animal research (Reduction, Replacement and Refinement). Did these institutions approve the involvement of their representatives in research that was not only extremely cruel, but also of no scientific merit? Would they consider the research they endorsed, albeit indirectly, to be 'humane'?
Tragically for the common marmoset (Callithrix jacchus), researchers are looking to this species as a new non-human primate 'model' to be used in neurophysiology, for visual processing and behaviour.
This research was carried out at Monash University, Australia, approved by the Monash Animal Research Platform Animal Ethics Committee and publicly funded by the Australian Research Council and by the National Health and Medical Research Council of Australia. See our take action alert.
Five adult common marmosets were used (one female, four males). They were anaesthetised and subjected to invasive surgery: a tracheotomy (an incision into the windpipe), vein cannulation and craniotomy (opening up the skull) to implant electrodes into their brains. Once the surgical procedures were done, while still anaesthetised, the animals were given pancuronium bromide, which is a neuromuscular blocking agent that paralyses the animals, prevents breathing (they must be artificially ventilated) and potentially can allow them to feel pain without being able to show this by moving. The monkeys were artificially ventilated with a mixture of nitrous oxide (commonly known as laughing gas) and oxygen; there was no mention of any further anaesthetic. Recordings were made while visual stimuli were presented to the paralysed animals. The recordings went on for 2-3 days, after which the animals were killed by being given a lethal dose of sodium pentobarbital.
In addition to the inhumanity of keeping marmosets in captivity and subjecting them to research, we are concerned that, following painful surgery, the marmosets were paralysed and kept alive for up to three days. Nitrous oxide was the only anaesthetic used during this period, but it is a very weak general anaesthetic that might not have been sufficient to render the marmosets insensitive not only to the damage done by the surgeries, but also to the serious problems cause by being paralysed. It is well known that people who receive neuromuscular blocking agents for medical reasons experience a visceral reaction of extreme fear and distress even though they are being artificially respirated. They, of course, would understand that they were in no harm, something not possible in the marmosets under similar circumstances. Although it was alleged that the marmosets were
continuously monitored, because they were kept paralysed, there is no unequivocal way of knowing they did not experience fear or pain.
This experiment was basic research with no particular human benefit. The authors clearly want to continue using the marmoset as a 'model' for human brain function, as evidenced by their statement:
The marmoset offers exciting new opportunities to study links between brain physiology and behavior, but the functions of frontal cortex areas are still being identified in this species. Here, we provide the first evidence of visual receptive fields in the marmoset dorsolateral frontal cortex, an important step towards future studies of visual cognitive behavior. This does not bode well for marmosets at Monash University.