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Notes and Peer Reviewed Resources on Snake Training, Brains, and Cognition

Posted by on August 30, 2020 at 4:45 AM

Notes and Resources on Snake (and other reptiles) Training, Brains and Cognition

When I decided to share my home with snakes again after more than twenty years without one I took on that responsibility with an understanding of animal behavior and training that I did not have the first time. From years of education in behavior science and the laws governing how animals learn to many years of hands-on experience training animals, I ventured into snake keeping with an interest in relationship building and communication I had ignorantly not thought possible before. I was still hearing the same narrative being spun by breeders and snake keepers that I had heard twenty years before, which was that snakes were not intelligent, that they were primitive and just functioned on instinct, that they weren’t very active and preferred small spaces, and that they could not be trained. This rhetoric was not what I was actually observing in my snakes’ behavior.

One of the snakes I added to my family was shy and fearful. I wanted us to develop a positive and trusting relationship and be able to communicate effectively since she would be with me for her lifetime. I told myself that I was an animal trainer and should be able to train her as I would any other animal. I asked myself how I would handle this situation if it was a horse or dog. From that moment on, I began working with her using passive habituation and gradual desensitization, along with training that combined classical and operant conditioning. This was tremendously successful and went so smoothly I began to research snake training, cognition, and learning to prove to myself that I was not imagining that the training and behavior modification I was doing with her was actually working.

What I learned was that there were people, mainly in the zoo world and scientific community, who had been training reptiles, including snakes for several years. I learned that snakes have the same basic brain plan as other vertebrates, and that scientific studies into reptile neuroanatomy, cognition, emotion, and brain chemistry support that reptiles have the same or homologous brain structures as mammals, produce dopamine, and have emotional lives.

Do not take my word for this. I encourage you to read the literature for yourselves and draw your own conclusions from what the researchers have documented. I spent a lot of time and effort searching for information about snake brain structure, cognition, and training. The following are some of the relevant papers I was able to find, there are more out there. Some of these are so amazing I cannot believe they are not well known in herpetoculture.

1. Using Operant Conditioning and Desensitization to Facilitate Veterinary Care with Captive Reptiles (Hellmuth, Heidi; Augustine, Lauren, et al., Veterinary Clinics: Exotic Animal Practice, Volume 15, Issue 3, 425 – 443)

Key Points listed in this paper are:

• In addition to being a large component of most zoological collections, reptile species are also becoming more and more popular as family pets.

• Reptiles have the cognitive ability to be trained in order to facilitate daily husbandry and veterinary care.

• Desensitization and operant conditioning can alleviate some of the behavioral and physiological challenges of treating these species.

• A survey of reptile training programs at zoos in the United States and worldwide reveals that there are many successful training programs being used in zoological settings to facilitate veterinary care and minimize stress to the animal.

• Many of the techniques being used to train reptiles in zoological settings are transferable to the exotic pet clinician.

• These techniques are useful for improving veterinary care in private herpetological collections and for the family pet.

2. Predators in Training: Operant Conditioning of Novel Behavior in Wild Burmese Pythons (Emer SA, Mora CV, Harvey MT, Grace MS. Predators in training: operant conditioning of novel behavior in wild Burmese pythons (Python molurus bivitattus). Anim Cogn. 2015;18(1):269‐278. doi:10.1007/s10071-014-0797-1)

Key Points listed in this paper are:

• Large pythons and boas comprise a group of animals whose anatomy and physiology are very different from traditional mammalian, avian and other reptilian models typically used in operant conditioning.

• Investigators used a modified shaping procedure involving successive approximations to train wild Burmese pythons to approach and depress an illuminated push button in order to gain access to a food reward.

• Results show that these large, wild snakes can be trained to accept extremely small food items, associate a stimulus with such rewards via operant conditioning and perform a contingent operant response to gain access to a food reward.

• The shaping procedure produced robust responses and provides a mechanism for investigating complex behavioral phenomena in massive snakes that are rarely studied in learning research.

3. Environmental Enrichment Alters the Behavioral Profile of Ratsnakes (Almli LM, Burghardt GM. Environmental enrichment alters the behavioral profile of ratsnakes (Elaphe). J Appl Anim Welf Sci. 2006;9(2):85‐109. doi:10.1207/s15327604jaws0902_1)

Key Points listed in this paper are:

• This study demonstrated that housing conditions can affect the behavior of captive snakes and produce improvements in behavior similar to those seen in mammalian enrichment studies.

• In a problem-solving task, snakes housed in enriched environments (EC) exhibited shorter latencies to the goal as compared to snakes housed in standard conditions (SC).

• In an open field task, EC snakes tended to habituate more quickly than SC snakes with repeated testing.

• A discriminant function analysis correctly assigned all snakes to their appropriate housing treatment groups, based on the responses in each of the behavioral tasks.

• EC snakes were more behaviorally adaptive than SC snakes.

4. The Reptilian Brain (Naumann RK, Ondracek JM, Reiter S, et al. The reptilian brain. Curr Biol. 2015;25(8):R317‐R321. doi:10.1016/j.cub.2015.02.049)

Key Points listed in this paper are:

• Identification of conserved brain subdivisions demonstrates that all of the general brain regions found in mammals, including the cerebral cortex, have homologies in reptiles.

• Although pallial structures exist in amphibians and fish, reptiles and mammals are the only vertebrates to have a cerebral cortex with a clear, three-layered structure, similar to that of mammalian allocortex.

• The reptilian ventral pallium gives rise to the dorsal ventricular ridge, a structure that dominates the bird pallium and contributes to the complex cognitive abilities of birds.

• Reptiles express a number of complex behaviors normally attributed to mammals. They can, for example, learn to navigate mazes as well as birds or mammals do and likely use a hippocampal structure to do so.

• Mammalian and reptilian brains share both ancestry and a large number of functional attributes.

5. Variation in Reptilian Brains and Cognition (Northcutt RG. Variation in reptilian brains and cognition. Brain Behav Evol. 2013;82(1):45‐54. doi:10.1159/000351996)

Key Points listed in this paper are:

• Studies of spatial and visual cognition in nonavian reptiles reveal that they learn mazes and make visual discriminations as rapidly as most birds and mammals.

• Studies of social cognition and novel behavior, including play, reveal levels of complexity not previously believed to exist among nonavian reptiles.

• Given this level of neural and cognitive complexity, it is possible that consciousness has evolved numerous times, independently, among reptiles.

6. Homology in the Evolution of the Cerebral Hemispheres. The Case of Reptilian Dorsal Ventricular Ridge and Its Possible Correspondence with Mammalian Neocortex (Aboitiz F. Homology in the evolution of the cerebral hemispheres. The case of reptilian dorsal ventricular ridge and its possible correspondence with mammalian neocortex. J Hirnforsch. 1995;36(4):461‐472.)

Key Points listed in this paper are:

• It is likely that the Dorsal Ventricular Ridge (DVR) is a derived character of reptiles while the neocortex is a derived character of mammals and that the two structures may originate from the same primordial anlage in the common ancestor.

• Lateral cortex is similarly localized in reptiles and mammals.

• Regardless of whether DVR and extrastriate neocortex can or cannot be considered phylogenetic homologues, some of the integrative functions performed by them might have a common evolutionary origin, that became localized in reptilian DVR and in mammalian extrastriate neocortex.

7. Neuroanatomy and Neurological Diseases of Reptiles (Seminars in Avian and Exotic Pet Medicine, Volume 5, Issue 3, July 1996, Pages 165-171)

Key Points listed in this paper are:

• Reptiles and mammals share structural similarities, including nervous systems with many common features.

• The brain of reptiles, like mammals, is divided into the forebrain, the midbrain, and the hindbrain.

• The forebrain of reptiles, like mammals, consists of the telencephalon and the diencephalon.

• The telencephalon includes the olfactory lobes, basal nuclei or corpus striatum, cerebral hemispheres, and the olfactory bulbs.

• The diencephalon includes the epithalamus, thalamus, and the hypothalamus. The telencephalon of reptiles includes an additional structure, the dorsal ventricular ridge (DVR).

• The nature of the pathways leading to and from the DVR suggest that it is functionally analogous to, and possibly homologous with, the neocortex of mammals.

8. Distribution of Dopamine Immunoreactivity in the Forebrain and Midbrain of the Snake Python Regius (Smeets WJ. Distribution of dopamine immunoreactivity in the forebrain and midbrain of the snake Python regius: a study with antibodies against dopamine. J Comp Neurol. 1988;271(1):115‐129. doi:10.1002/cne.902710112)

Key Points listed in this paper are:

• Dopamine-containing cell bodies were found around the glomeruli and in the external plexiform layer of both the main and accessory olfactory bulb.

• In the diencephalon, Dopamine (DA) cells were observed in several parts of the periventricular hypothalamic nucleus, in the periventricular organ, the ependymal wall of the infundibular recess, the lateral hypothalamic area, the magnocellular ventrolateral thalamic nucleus, and the pretectal posterodorsal nucleus.

• In the midbrain, DA cells were found in the ventral tegmental area, the substantia nigra, and the presumed reptilian homologue of the mammalian A8 cell group.

• Dopaminergic fibers and varicosities were observed throughout the whole brain, particularly in the telencephalon and diencephalon.

9. Phasic Dopamine Signals in the Nucleus Accumbens that Cause Active Avoidance Require Endocannabinoid Mobilization in the Midbrain (Jennifer M. Wenzel, Erik B. Oleson, Willard N. Gove, Anthony B. Cole, Utsav Gyawali, Hannah M. Dantrassy, Rebecca J. Bluett, Dilyan I. Dryanovski, Garret D. Stuber, Karl Deisseroth, Brian N. Mathur, Sachin Patel, Carl R. Lupica, Joseph F. Cheer. Current Biology, 2018; DOI: 10.1016/j.cub.2018.03.037)

Key Points listed in this paper are:

• Dopamine is a neurotransmitter involved in actions associated with the pursuit of rewards.

• Dopamine plays a key role in driving behavior related to pleasurable goals, such as food, sex and social interaction.

• Increasing dopamine boosts the drive toward pleasurable stimuli; however, it also drives animals to avoid unpleasant or painful situations and stimuli.

• Using optogenetics, researchers controlled the amount of dopamine released by neurons in the nucleus accumbens.

• Animals with high levels of dopamine in the nucleus accumbens brain region learned to avoid aversive stimuli more quickly and more often than animals that had a lower level of dopamine in this region.

10. Spatial Learning of an Escape Task by Young Corn Snakes (Holtzman DA, Harris TW, Aranguren G, Bostock E. Spatial learning of an escape task by young corn snakes, Elaphe guttata guttata. Anim Behav. 1999;57(1):51-60. doi:10.1006/anbe.1998.0971)

Key Points listed in this paper are:

• Spatial learning is critical to most animals for many behaviors necessary to survival.

• 17 young corn snakes were trained to find one open shelter in an eight-hole arena with the entrance not visible from the arena surface.

• Over a 4-day training period of 16 trials the snakes showed a significant decrease in the mean latency to the goal hide.

• They showed a significant decrease in the mean total distance traveled.

• They showed a significant increase in the the percentage of the total distance traveled in the quadrant containing the goal hide.

• They showed a significant increase in movement in the goal quadrant above chance.

• Overall, this study shows that snakes can learn a spatial-escape task rapidly when it is relevant behaviorally and that attaining the goal reinforces learning.

11. Conditioned Responses to Airborne Odorants by Garter Snakes (Begun D, Kubie JL, O'Keefe MP, Halpern M. Conditioned discrimination of airborne odorants by garter snakes (Thamnophis radix and T. sirtalis sirtalis). J Comp Psychol. 1988;102(1):35-43. doi:10.1037/0735-7036.102.1.35)

Key Points listed in this paper are:

• This study demonstrated snakes can learn a task with airborne odors as discriminative stimuli.

• This study was comprised of two experiments.

• Experiment one:

o 7 Plains Garter Snakes were trained in a 2-choice apparatus to move into a compartment containing lemon-scented chips to obtain a food reward.

o All snakes improved in performance when comparing the first ten tries to the final ten tries when 100 trials were compared.

o Upon completion of the initial part of the trial, 4 of the snakes were retrained to move away from the scented compartment and into the unscented compartment; these 4 snakes rapidly learned the new criteria and made the reversal.

• Experiment two:

o 7 Common Garter Snakes were trained to traverse a 2-choice maze with the presence or absence of amyl acetate odor as a conditioned stimulus.

o The snakes were initially tested for their odor preference and trained to go to their non-preferred odor.

o 5 of 7 snakes achieved criteria predetermined by the researchers.

12. Maze learning in water snakes (Kellogg, W. N., & Pomeroy, W. B. (1936). Maze learning in water snakes. Journal of Comparative Psychology, 21(3), 275 295.

Key Points listed in this paper are:

• 12 water snakes were trained to traverse a T-maze with two blind alleys.

• Warm water (versus cold water) was used as the discriminative stimulus.

• The water snakes learned to navigate the maze with heat being the positive reinforcer.

13. A learning experiment with snakes (Takemusa, T. and Nakamura, K., 1935; Kyoiku Shinri Kenkyu, 10, 575-581)

Key Points listed in this paper are:

• This study demonstrated snakes can learn to efficiently escape confinement in a box.

• Note this paper was not available in electronic format for further review.

14. Emotion and Phylogeny (Cabanac M. Emotion and phylogeny. Jpn J Physiol. 1999;49(1):1-10. doi:10.2170/jjphysiol.49.1)

Key Points listed in this paper are:

• Based on emotional fever and emotional tachycardia results during gentle handling of mammals, lizards, frogs, and fish; the results being that emotional fever and emotional tachycardia were produced by gentle handling of mammals and reptiles but not fish and amphibians, this research suggests that emotion emerged in the evolutionary lineage between amphibians and reptiles.

• This research suggests that reptiles possess consciousness along with its characteristic affective dimension of pleasure.

• The role of sensory pleasure in decision-making was verified in lizards placed in emotional conflict.

15. The Emergence of Consciousness in Phylogeny (Cabanac M, Cabanac AJ, Parent A. The emergence of consciousness in phylogeny. Behav Brain Res. 2009;198(2):267-272. doi: 10.1016/j.bbr.2008.11.028)

Key Points listed in this paper are:

• The brains of Amniota (reptiles, birds, and mammals) show chemical, anatomical, and functional differences from anamniotes (fishes and amphibians).

• Play behavior, capacity to acquire taste aversion, sensory pleasure in decision making, expression of emotional tachycardia and emotional fever evolutionarily began to be displayed by Amniota.

• Researchers concluded that emotion and consciousness evolutionarily emerged in early Amniota and that consciousness is characterized by a common mental pathway using pleasure and displeasure as a way to optimize behavior.



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