National Antivisection Society
Monkey Tests Exposed
Posted: 15 February 2008
An undercover investigation at the Weizmann Institute of Science in Israel by Let Animals Live, has highlighted the suffering of primates in brain research. It also reveals how, despite known species differences, invasive animal test methods continue to be used whilst superior, non-invasive, human study methods are employed elsewhere.
Monkeys were restrained for up to 8 hours a day and deprived of water in order to train them to perform tasks. Animals were seen grimacing in fear as they were handled for procedures. The purpose of the experiments was to improve upon an existing method of viewing conscious animal brain activity through a hole in the skull.
Three adult macaques were anaesthetised and a head holder and two cranial windows were cemented over the primary visual cortex. During a second operation months later, parts of the crania were removed, the dura mater resected and the brain exposed. Transparent material was placed over the brain so that dye (VSD) injected onto the brain surface could be viewed. The reaction of the dye to different stimuli was recorded.
As often as five times a week the head-chambers were opened and cleaned, whilst the animals were conscious. For each testing session, the monkeys were restrained, the chambers washed and dye washed over the cortical surface. Staining the cortex like this took 3-4 hours. Preparing the monkey for imaging took up to another hour to complete.
During imaging the monkey’s heads were anchored to a restraint and to further reduce any movement of the skull relative to the camera, this was connected to the monkey’s head holder. The hands were also restrained, and electrocardiogram recordings made.
Data was collected for 3-4 hours. The animals were severely restrained for up to 9 hours every testing day in an experiment that lasted approximately a year. Their reward for the correct test response was 0.2ml of water.
The workers admit that these experiments are repetition. Previous work is cited, which produced similar results: “In a recent work, we have already used long-term VSDI...” and some of the findings correspond to those in seven previous studies, spanning as far back as 1988.
This study’s measures of ocular dominance were similar to previous findings, and the workers assert that “It is important to repeat these experiments with higher time resolution."
One of the objectives of this project was to “facilitate the explorations of the spatial and temporal patterns underlying higher cognitive functions in the neocortex of behaving monkeys.” However, they also note, “The results of the present study are in line with previous findings …studied by VSDI in anaesthetised monkeys.”
Thus a key variation between this and the previous studies is that in the previous experiments, the animals were not subjected to the ordeal whilst conscious. It is disturbing that such a project would receive authorisation.
Perhaps more disturbing, is that the authors deemed it appropriate to subject highly intelligent, sensitive and social animals to such extreme experiments when they were already cognisant of key species differences. Neither do the authors discuss potential applications for their work.
The authors of this study should have been aware of the more advanced scientific methods available to replace the use of primates in such work. It should be inconceivable that anyone would be allowed to undertake a programme of work such as this, without first understanding the state of play in terms of the most advanced methods available. Those who authorise such work must be held responsible for ensuring that alternatives have been explored beforehand.
Species differences
Major problems, addressed in some studies, occur when applying results from animal brains to humans. Considering the large amounts of data created when mapping the brain: “The problem is compounded by individual variability in cortical structure and function. This variability includes pronounced differences in the pattern of folding, in the size and shape of cortical areas, and in their location relative to these folds."[1]
When discussing “visual” areas together they “occupy slightly more than half of the macaque neocortex whereas only 20-25% of the human neocortex is known to be visual in function. This 2-fold difference in relative extent of visual cortex impedes the evaluation of possible homologies, and the problem is exacerbated by the limited utility of geographical landmarks for interspecies comparisons” the authors then state “Although some areas have roughly the same location other candidate homologies differ considerably in location (e.g., the motion-related complex, which lies within the STS in the macaque but well posterior to it in humans)."
Further species differences are noted “The motion complex is relatively more posterior in human cortex compared with its position in the macaque.” Of another area, the authors write “In this and other regions, it is possible that human cortex contains areas that are altogether absent in the macaque”[1]
Information derived from another species is of no value: “Although it is well known that V1 normally extends over the depth and lips of the calcarine fissure, there is significant variability in the size, location, and shape of V1, and even more variability in the shape of the calcarine fissure. Thus in V1, as elsewhere in human visual cortex, the area boundaries need to be mapped in each individual subject-they cannot be safely generalised from other subjects or other studies, or even from the contralateral hemisphere of the same subject."[1]
Advanced Science
Studies into ocular dominance have been carried out non-invasively in humans. One study successfully mapped dominance fields of the human visual cortex reproducibly, over several days, with a high degree of accuracy, relative to expected spatial patterns from post mortem data.
This potentially paves the way for the study of the functional architecture of human sensory cortices and brain modules underlying specific cognitive processes.[2]
High end scanning enables the study of human subjects, providing data free of the impacts of repeated restraint, invasive surgery, and most significantly of all from the correct species.
These crude and rather unscientific experiments are a contrast to the bright, exciting work LDF is funding (p10-12).
As more and more ways of studying human conditions in the human brain open up across the world, it is unacceptable that ethically and scientifically poor research such as this is allowed to continue.
1. Van Essen, D.C. Drury H.A. Josh, S. and Miller, M.I (May 1997) (NAS Colloquium) Neuroimaging of Human brain Function: Functional and structural mapping of human cerebral cortex: Solutions are in the surfaces.
2. Yacoub, E 2007. Robust detection of ocular dominance columns in humans using Hahn Spin Echo BOLD functional MRI at 7 Tesla, Neuroimage, 37 (4):1161-1177
