bio 210a presentation

8/8/2019 Bio 210A Presentation

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Conditioned Taste Aversion

Kevin Nahler Kevin Nahler

Tony Norton National Geographic


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I. Conditioned Taste Aversion (CTA)

A. Definition

B. Evolutionary Basis

II. CTA at the Organ System Level

A. Brain Stem Activity

B. Role of the Amygdala

III. Molecular Processes Behind CTA

A. CREB

B. c-FosC.Metabotropic Glutamate Receptors

IV. Substances that produce CTA

A. Lithium Chloride

B. Estrogen

C. Thiabendazole

V. Practical Application of CTA

A. Reduction of Livestock and Crop Losses

B. Conservation of Endangered Species and Other Wildlife

C. Drug and Radiation Therapies for Humans

VI. References

Tony Norton


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Conditioned Taste Aversion (CTA) is a form of

associative learning and classical conditioning

in which an animal avoids and acts aversivelyto the taste of a food that has previously been

paired with illness. (Houpt)

Why would such a phenomenon exist innature?

University of FloridaKevin Nahler


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CTA in the Brain Stem (Short Term Memory and Physiological Response)

Brain stem receives input regarding internalconditions in the body; controls involuntary functions

such as digestion, respiration, and circulation; food

preference learning takes place at least partially in the

brain stem

The Nucleus of the Solitary Tract in the medulla

(emetic center) junction of nerves from tongue thatbring taste sensations with the vagus nerve that

brings sensory impulses from the upper GI tract

If digestion and absorption results in nutrients being

replenished in the body, the brain remembers that

food choice as a good one; if food contains poison of

some kind, the brain stem receives signals from thedigestive tract and send signals back that result in

vomiting and other detoxifying processes

The brain remembers the external cues surrounding

the food that produced the illness and will not

tolerate the scent and taste of that food in the future

(taste-illness pairing also results in association of non-taste cues such as scent or appearance of food)


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CTA in the Amygdala and Gustatory Cortex

(Long Term Memory and Behavioral Response)

The gustatory cortex (in the

cerebrum) processes and retains

memory of taste while the amygdala

plays a crucial role in the integration

and expression of CTA behavior (i.e.the formation of long term memories

and patterns of behavior of CTA)

The memory of CTA produced in the

brain stem only remains effective if

certain genes are expressed in theamygdala

The amygdala has been shown to be

responsible for many types of aversive

and emotional learning


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Molecular Mechanisms of CTA cAMP Response Element-Binding Protein (CREB)

cAMP = second messenger that regulates ion channels(Ca2+) (among other functions)

CREB = transcription factor that binds to cAMP responseelements on DNA to increase or decrease transcription

Genes regulated by cAMP Response Elements (CRE-regulated genes) produce long term changes in theamygdala that enable retention of CTA-relevantinformation

Must be functioning properly for long term CTA memoryto be produced (does not affect short term memory orretrieval of long term memory once it has been formed)

c-Fos Proto-oncogene; transcription factor; immediate early

gene family

Among other functions, c-Fos controls genes that controlsome immune responses (c-Fos genes are expressed aftersensory stimulation, such as light exposure, food intake, ortoxin intake)

c-Fos-like immune (c-FLI) proteins were used todemonstrate the relationship between c-Fos and CTA (i.e.ingestion of LiCl resulted in expression of c-Fos)

c-Fos is found in brain tissue during all CTA responses

Metabotropic Glutamate Receptors (mGluRs) Affect second messengers and ion channels via G-proteins

mGluR7 (one of eight subtypes of mGluRs) is expressed inthe amygdala, among other areas of the central nervoussystem (localized at presynaptic axon terminals); plays arole in amygdala-dependent averse responses; coupledwith inhibition of cAMP cascade

mGluR7 must be functioning properly for CTA to occur


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Some CTA-inducing CompoundsLithium Chloride (LiCl)Naturally occuring salt

Produces a strong, long-lasting CTA

EPA has found some potentially negative environmental

impacts associated with use in untargeted baits

Estrogen (estradiol) (C18H24O2)Includes both naturally occurring and synthetic hormones

Produces the strongest, longest-lasting CTA

Because it is a hormone, its use may affect development

and reproduction in some vertebrates

Thiabendazole (TBZ) (C10H7N3S)Has also been used as an anti-fungal, a preservative food

additive, and a chelating agent to treat heavy metal

poisoning

Produces moderate CTA with minimal side effects

May be a safe alternative to other compounds but more

testing is needed


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Practical Applications of CTA

Reduction of Livestock and Crop Losses

Economic impact

Socio-political impact

Human health impact

Conservation of Endangered Species and OtherWildlife

Reduced depredation and crop destructionresult in greater survival and reproductive ratesfor wildlife (particularly critical for endangeredand threatened species)

Drug and Radiation Therapies for Humans

Understanding CTA could lead to improvedtreatments for a variety of diseases whosetreatments currently involve debilitating sideeffects

Tony Norton

afssa.fr

fluofarma.com


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References "Amygdala." Wikipedia, The Free Encyclopedia. 5 Dec 2008, 08:29 UTC. 10 Dec 2008

.

Gill, Elaine L., Anne Whiterow, and David P. Cowan. A Comparative Assessment of Potential Conditioned Taste

Aversion Agents for Vertebrate Management. Applied Animal Behaviour Science. Volume 67, Issue 3, April 3,

2000, pp. 229-240.

Houpt, Thomas A., et al. Increased c-fos Expression in Nucleus of the Solitary Tract Correlated with Conditioned

Taste Aversion to Sucrose in Rats. Neuroscience Letters. Issue 172, February 18, 1994, pp. 1-5.

Lamprecht, Raphael, and Yadin Dudai. Transient Expression of c-fos in Rat Amygdala During Training is Required

for Encoding Conditioned Taste Aversion Memory. Learning Memory. Volume 3, 1996, pp. 31-41.

Lamprecht, Raphael, Shoshi Hazvi, and Yadin Dudai. cAMP Response Element-Binding Protein in the Amygdala is

Required for Long- but not Short-Term Conditioned Taste Aversion Memory. The Journal of Neuroscience.

Volume 17, Number 21, Issue of November 1, 1997, pp. 8443-8450.

Massei, Giovanna, and David P. Cowan. Strength and Persistence of Conditioned Taste Aversion in Rats:

Evaluation of 11 Potential Compounds. Applied Animal Behaviour Science. Volume 75, Issue 3, January 23, 2002,

pp. 249-260.

Masugi, Miwako, et al. Metabotropic Glutamate Receptor Subtype 7 Ablation Causes Deficit in Fear Response

and Conditioned Taste Aversion. The Journal of Neuroscience. Volume 19, Number 3, Issue of February 1, 1999,

pp. 955-963.

Nicolaus, Lowell. Predation Politics: The Sad Story of Wolves, Conditioned Taste Aversion, and the Wildlife

Management Hierarchy. [Online] Available http://www.conditionedtasteaversion.net/index.html, March 2008.

"Solitary nucleus." Wikipedia, The Free Encyclopedia. 20 Aug 2008, 05:25 UTC. 10 Dec 2008

.

Ternent, M.A., and D.L. Garshelis. Taste Aversion Conditioning to Reduce Nuisance Activity by Black Bears in a

Minnesota Military Reservation. Wildlife Society Bulletin. Volume 27, Number 3, 1999, pp. 720-728.

Images of CTA-inducing compounds and cAMP downloaded from Wikipedia; images of brain found using Google

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