Many people are unaware that primate experimentation is still being conducted in Australia. Here, we continue our series of snapshots of current experiments being conducted in Australia.
A (2024) publication (1) has revealed invasive procedures carried out on macaques at Monash University, Australia. The study subjected, intelligent monkeys to invasive brain surgeries, prolonged captivity, and cognitive testing that likely caused significant distress.
Research Aim
This study looked at how a part of the brain called the frontopolar cortex helps primates (like humans and monkeys) decide when to act and when to stop an action. The goal was to better understand how the brain controls decision-making when either choosing to do something or holding back.
Definitions:
• Frontopolar cortex: A region at the very front of the brain, involved in complex thinking, planning, and decision-making.
• Action inhibition: The ability to stop or control an action before it happens.
• Response execution: The process of carrying out an action or movement.
Invasiveness of the Procedures
The study intentionally inflicted brain damage on 4 macaque monkeys by performing bilateral frontopolar cortex lesions. This required cutting out a section of the skull, surgically exposing the brain and removing sections of the frontopolar cortex. Then, the exposed brain segments and wounds were sewn back together.
The monkeys were subjected to this surgery under general anaesthesia and their peri-operative pain was adequately managed. However, there were inconsistencies in the model used for the post-operative period. Namely, it is unclear if the monkeys received any pain relief beyond the day of the surgery. Given the highly invasive nature of this procedure and the various kinds of tissues involved (skin, muscle, bone and brain), the associated pain and discomfort would likely have continued for several weeks (the monkeys were only allowed 2 weeks to recover). Furthermore, headaches are not something that can be diagnosed in animal patients, so any perceived pain was probably underestimated. Safe and affordable pain relief medications were readily available but may not have been used. Thus, the monkeys may have suffered significantly throughout the recovery period
Similarly, antibiotics were used on the day of the surgery preventatively, but there is inconsistency in the reporting of infection prevention or management in the days that followed.
Captive Conditions
The monkeys were housed in an experimental facility, deprived of their natural environment. They underwent extended training to perform cognitive tasks, likely under food restriction, as they were rewarded with food. Repeated cognitive testing —using failure signals, reward-based conditioning, and isolation—can cause distress for intelligent, social primates. These conditions may have led to frustration, anxiety, and stress.
The research publication notes “These monkeys were provided by the National Non-Human Primate breeding and experimental facility, and group-housed in the experimental facility”. Below is an image of a primate housing unit located at the facility which AFSA obtained under FOI.
The Testing Procedures
These intelligent animals were transferred from their research facility to an experimental room in a test cage with open bars at the front, allowing access to a switch and touchscreen. While in the cage, they performed cognitive tasks, with their daily food allowance positioned next to the touchscreen, automatically opening upon task completion.
Initially they were trained to match visual items (colour and shape) in a task called “Go trials”. These required the monkeys to press a switch, prompting two visual items to appear on the touchscreen. When a matching central image was displayed, they had to release the switch and select the corresponding item within 1300 milliseconds. In a separate task called “Stop trials”, monkeys had to inhibit their response after a delay, signalled by a red cross. To receive a reward, they had to continue holding the switch for at least 1200 milliseconds until all items disappeared. Correct responses were rewarded with a banana-flavoured pellet, while incorrect ones triggered an error signal and no reward
After learning the stop-signal task, the monkeys underwent 15 pre-lesion testing sessions to collect baseline data (initial measurements). They then underwent surgical frontopolar cortex lesions and were given a two-week recovery period before post-lesion data collection. Then, lesions into the frontopolar cortex were surgically induced and followed by a two-week recovery period. After this, their performance was assessed over 15 additional daily testing sessions to evaluate the effects of the lesions on their decision-making.
Their fate at the end of the experiments is unknown. Despite their lasting injuries and associated pain, they were likely to have been used in further invasive experiments or quoted in further research publications. In this experiment they are simply referred to as M157, M51, M62 and M71.
Ethical Implications
Non-human primates have advanced cognitive abilities and emotional depth, making them particularly vulnerable to suffering in such experiments.
Further, the study, also involved 58 humans who performed computerised stop-signal tasks with the purpose of comparing the pattern of behavioural adjustments in both species. The effects of selective and bilateral lesions of frontopolar cortex were examined by comparing monkeys’ performance before (pre-lesion testing) and after frontopolar lesions (post-lesion testing).
Insufficient social value in these experiments
There is insufficient social value from these experiments to warrant the use of the primates. The extra knowledge from this study has no significant medical or scientific benefit. It is already known that frontopolar cortex has these cognitive functions, and the study does not in any way facilitate medical progress. AFSA consulted Jan Lauwereyns, Professor of Bioethics and Senior Vice President at Kyushu University, Japan. Although Professor Lauwereyns previously conducted research involving monkeys, he no longer engages in such practices.
“This detailed lesion study is an unremarkable achievement, equivalent to a colouring exercise in a drawing where the contours are already known”.
Prof Jan Lauwereyns, Professor of Bioethics and Senior Vice President at Kyushu University, Japan
Funding
According to the publication, this experiment was funded by the Australian Research Council (using taxpayer dollars) through its Centre of Excellence for Integrative Brain Function and an ARC Discovery project grant.
Further information about primate experimentation in Australia refer to our ‘Ending Primate Experiments’ page and to see what you can do to make a difference, please see our page ‘What you can do’
References
1. Feizpour, A. et al The role of frontopolar cortex in adjusting the balance between response execution and action inhibition in anthropoids Progress in Neurobiology (2024) 102671
https://pubmed.ncbi.nlm.nih.gov/39369837