A.6 Ethology

Testing a hypothesis—experiments to test hypotheses on the migratory behaviour of blackcaps have been carried out.

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Male blackcap warbler (Bird fieldguide)

In the 1950s, blackcap warblers (Sylvia atricapilla), a small European songbird, began to be observed wintering in Great Britain, instead of North Africa. These observations led to the formation of hypotheses regarding blackcap migratory behaviour: were the changes due to inherited (innate) factors, was it a response to the environment or did the birds simply lose the ability to migrate normally?

To test these hypotheses, it was necessary to use experimental methods, as fieldwork would have been unfeasible.  The birds were kept in specially designed cages that could register if birds began to become restless during the migratory season and then what direction they tried to orient towards.

The results showed that the offspring of birds that migrated to Britain oriented consistently in a NW direction, despite being raised in isolation from their parents. Follow-up genetic analysis showed a strong heritability for this trait in both British wintering blackcaps and those from other parts of Europe.  The authors were led to suggest that:

“Under moderate selection intensities and environmental conditions similar to those presented in this study, the southern German blackcap population could evolve into a short-distance migrant in 10-20 generations.” (Berthold and Pulido; p311)

These results represent rapid evolutionary changes in behaviour- it is worth considering what selection pressures are working to promote these changes.  Can you relate this back to the Evolution/Natural Selection topics (5.1/5.2)?

Sources:

Berthold, P and Pulido, F. Heritability of Migratory Activity in a Natural Bird Population.
Proc. R. Soc. Lond. B. 257. 1994. 311-315. Web. Mar 15, 2016. Full text available: at https://www.researchgate.net/profile/Francisco_Pulido/publication/216768532_Heritability_of_migratory_activity_in_a_natural_bird_population/links/0fcfd50c5c5adc29c9000000.pdf

Berthold, P. et al. Rapid microevolution of migratory behaviour in a wild bird species. Nature. 360.  1992. Web. Mar 15, 2016.

“Identify A Blackcap, Sylvia Atricapilla”. Birdfieldguide.co.uk. N. p., 2016. Web. 15 Mar. 2016.

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A.5 Neuropharmacology

Assessing risks associated with scientific research—patient advocates will often press for the speeding up of drug approval processes, encouraging more tolerance of risk.

Another NOS with great links to TOK (though this might be too late in the course for some G12 students!) Testing experimental drugs on humans is incredibly important for the development of new drugs but it does raise several ethical concerns.  One is the tension that exists between the need to rigorously ensure that the drug is effective and safe (which can take years) and the needs of patients requiring treatment.  This can be especially acute if patients have terminal or incurable conditions and they are desperate for a possible cure.

In the US, the Food and Drug Administration (FDA) has the responsibility to review and approve drugs for use.  There are four pathways for faster approval, shown in the graphic below:

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Pathways to faster approval of drugs (FDA)

 A recent example of this dilemma was the Ebola outbreak in West Africa in 2014-15.  There were minimal supplies of an experimental drug called ZMapp and it was perceived to have helped the recovery of two American aid workers.  However, the drug was still in the experimental stages and doctors did not know if the drug really helped the Americans or if there were other factors involved.  In the case of an emerging epidemic where there are few medical treatments available, it can be tempting to fast-track any drug in development.  But the risks of unknown, harmful side-effects cannot be ignored and this places public health officials in a difficult situation.  What might be your approach using the different schools of ethical thought here? How does reason and emotion influence your opinion of this?

“Fast Track, Breakthrough Therapy, Accelerated Approval, Priority Review”. Fda.gov. N. p., 2016. Web. 15 Mar. 2016.

Pollack, Andrew. “Ebola Drug Could Save A Few Lives. But Whose?”. Nytimes.com. N. p., 2014. Web. 15 Mar. 2016.

A.4 Innate and learned behaviour

Looking for patterns, trends and discrepancies—laboratory experiments and field investigations helped in the understanding of different types of behaviour and learning.

Both laboratory experiments and field investigations have been essential in understanding animal behaviour and learning.  Both forms of investigation are necessary: lab experiments allow for the precise control and manipulation of variables, but provide an artificial setting; field investigations provide the natural setting required but can face challenges in controlling the boundaries of the experiment.

A classic 1950s lab study investigated mimicry in butterflies in the lab by providing caged birds with different species and recording their feeding behaviour (van Zandt Brower, 1958). This was based on the observed toxicity of monarch butterflies (Danaus plexippus) and its presumed mimic, the viceroy butterfly (Limenitis archippus). The butterflies were prevented from flying by folding the wings together and then presented to the birds. Control butterflies that did not mimic the coloration of the monarchs  were eaten in every trial by all birds. The monarch was not eaten in any of the trials and the butterfly that mimicked the coloration of the monarch (the Viceroy) was similarly avoided.  The study helped expand our understanding of mimicry and bird foraging behaviour in a very controlled setting.

In contrast, field studies have a range of challenges in ensuring that the behaviour observed is free of bias or manipulation by the presence of the observers. One recent interesting study investigates foraging behaviour of harbour seals in Alaska (Womble et al.). Dive duration and depth were inversely correlated with prey density, which depended on the habitat of the seals (glacial or terrestrial). As part of the investigation, seals had to be captured, sedated, weighed and fitted with data logging devices to record temperature, time and depth. They were then released and the data provided by the devices used to determine their foraging strategy. Obviously, there is some invasiveness in this method, but it does enable the researchers to then collect data on the natural feeding behaviour of the seals.  Field studies regularly involve such trade-offs. Similarly to lab experiments, they must also acknowledge the potential ethical concerns of these studies.

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Data from Womble et al. (2014; p1368)

Extension: Using the graph above, consider the following possible DBQ-style questions:

  1. State the average dive depth for both locations at hour 12. (1)
  2. Compare and contrast the data for terrestrial and glacial seals over the 24 hour period. (2)
  3. Using the data, evaluate the hypothesis that glacial seals spend more time foraging than terrestrial seals. (3).

Sources

Jane van Zandt Brower. “Experimental Studies of Mimicry in Some North American Butterflies: Part I. The Monarch, Danaus Plexippus, and Viceroy, Limenitis Archippus Archippus”. Evolution 12.1 (1958): 32–47. Web. Mar 15, 2016.

Womble, J.N. et al. “Linking marine predator diving behavior to local prey fields in contrasting habitats in a subarctic glacial fjord.” Marine Biology 161. (2014): 1361–1374. Web. Mar 15, 2016. Full-text available for download at: https://www.researchgate.net/publication/261870558_Linking_marine_predator_diving_behavior_to_local_prey_fields_in_contrasting_habitats_in_a_subarctic_glacial_fjord 

A.3 Perception of stimuli

Understanding of the underlying science is the basis for technological developments—the discovery that electrical stimulation in the auditory system can create a perception of sound resulted in the development of electrical hearing aids and ultimately cochlear implants.

Research into the auditory nerve and cochlea over the mid-20th century helped develop our understanding of how we detect and process hearing. As scientific understanding improved, scientists were able to move beyond the hearing aid, which merely amplifies sounds, to developing the cochlear implant, which is a far more sophisticated device.

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NIH Medical Art (NIDCD)

It works in the following way:

  1. The microphone collects sound from the environment
  2. The speech processor arranges these sounds
  3. The transmitter and receiver/stimulator send signals from the speech processor and convert them into electric impulses.
  4. The electrode array takes this impulses and sends them to the auditory nerve.

Hearing through such a device sounds like this.

This device does not restore normal hearing, but is able to approximate the sounds from the natural environment and allow the patient to understand speech.  It is most effective typically when implanted in early childhood (for congenitally deaf babies) as the brain is yet to develop all the neural pathways associated with hearing and language.

As of December 2012, approximately 324,200 people worldwide have been fitted with cochlear implants, including 38,000 children in the US alone.

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Baby with a newly fitted cochlear implant. Image from Ringo.

There is an interesting TOK extension here.  Parts of the deaf community rally against cochlear implants because the medical profession treats deafness as a disability or illness to be cured.  There is a worry that using cochlear implants will erode the importance of sign language as the medium of communication between deaf people and thus affect their community and culture.  “The debate stems from a fundamental disagreement: one group sees deafness as a disability, and the other group sees it as a culture.” (Ringo).

This could be an interesting example with which to extract a knowledge question and discuss different perspectives.  A couple to start with might be:

To what extent is culture influenced by sense perception?
In what ways is our use of language influenced by sense perception?

Sources:

Auditory Neuroscience,. “What Do Cochlear Implants Sound Like? – 1: Speech”. N. p., 2016. Web. 11 Feb. 2016.

National Institute of Deafness and other Communication Disorders (NIDCD). “Cochlear Implants “. NIDCD, 2014. Web. 11 Feb. 2016.

Ringo, Allegra. Cochlear Implants In A Baby.2013. Web. 16 Feb. 2016.

Ringo, Allegra. “Understanding Deafness: Not Everyone Wants To Be ‘Fixed'”. The Atlantic. N. p., 2013. Web. 16 Feb. 2016.

A.2 The human brain

Use models as representations of the real world—the sensory homunculus and motor homunculus are models of the relative space human body parts occupy on the somatosensory cortex and the motor cortex.

This follows on from A.1 Neural Development as another example of models in science – perhaps this tells us something about neurobiology?  These models are used to represent the relative amount of cerebral cortex that either receive sensory input or send motor signals out.  What is particularly interesting is that some parts of the body have a much greater amount of cortex dedicated to their sensory or motor information.  These differences have been expressed in the form of a “homunculus” – Latin for “Little man”.

 

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The sensory and motor and homunculi, Penfield and Rasmussen (1950) in Schott (1993).

As you can see in the image above, The largest sections of both sensory and motor cortexes are concerned with the hands, lips and other parts of the face. This can be transferred to a model as in the image below:

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You can check out more interesting information on the homunculus in the eponymous Crash Course Psychology Episode 6

This can manifest itself in some interesting complications.  For instance, you will notice that in the sensory cortex, the region receiving information from the face is directly under the face.  The neuroscientist V.S. Ramachandran, investigating the phenomenon of phantom limbs in patients with amputations, found that when he stroked the cheek of a patient, the patient felt the stroking happening in his phantom hand. The sensory neurons from the facial region had moved into the adjacent area for the hand, which was no longer receiving any input.  This, and other investigations into phantom limbs, helped establish the plasticity of the brain neurons (Topic A.1) and developed treatments for amputees suffering from phantom limb syndrome.

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Points that yielded referred sensations in the phantom hand – both on the face and the upper arm. The numbers refer to the digits on the hand.  When these points are touched, it is felt in the phantom hand as well. (Ramachandran and Blakeslee, p30)

Source

Andrews, M. “How To Refresh Your Inner Gollum: Health And The Homunculus”. N. p., 2014. Web. 7 Feb. 2016.

Ramachandran, V. S, and Sandra Blakeslee. Phantoms In The Brain. New York: William Morrow, 1998. Print.

Schott, G D. “Penfield’s Homunculus: A Note on Cerebral Cartography.”Journal of Neurology, Neurosurgery, and Psychiatry 56.4 (1993): 329–333. Print.`

The Motor Homunculus. 2014. Web. 7 Feb. 2016.

A.1 Neural Development

Use models as representations of the real world—developmental neuroscience uses a variety of animal models.

Animal models are crucial in developmental biology, as they allow observations and experiments that would not be possible, feasibly or ethically, with humans. One example of a model organism is Xenopus sp. collectively known as the African clawed frogs.  The guide asks you to label developmental images from this animal and it is one of the most important model organisms used in embryological research.

Besides, Xenopus sp. there are a range of other model organisms used in research. Here’s how they compare in terms of their importance to scientists:

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C. elegans is a nematode worm and Drosophila sp. refers to the fruit fly, so important in genetic studies.  Each has its advantages and disadvantages. For instance, C. elegans has a fixed number of cells as an adult (959), which makes it very useful for studying cell differentiation. The zebrafish (Danio rerio) produces almost transparent tissues.

The relative evolutionary relatedness of these organisms to humans can be seen here (and a good chance to review Cladograms!):

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You can see the importance of Xenopus sp. as a model organism – here is the summary of this:

  1. Easy to maintain in the laboratory
  2. They produce eggs throughout the year
  3. The eggs are a reliable and flexible material for research
  4. The eggs themselves are very large, making manipulation and observation much easier
  5. The embryos are a good model for vertebrate development
  6. Genetically similar to humans and so a good model for human disease

Points 4 and 5 are particularly relevant for studying neural development.

The source listed below on Xenbase.org is a wonderful resource for all things African clawed frog – especially developmental imaging.

The use of model organisms, of course, has ethical considerations, as we have discussed previously on this blog.

Sources

Cbs.umn.edu,. “What Is C. Elegans? | College Of Biological Sciences”. N. p., 2015. Web. 1 Feb. 2016. http://cbs.umn.edu/cgc/what-c-elegans

Xenbase.org,. ” Introduction To Xenopus – Xenbase | A Xenopus Laevis And Xenopus Tropicalis Resource “. N. p., 2016. Web. 1 Feb. 2016. http://www.xenbase.org/anatomy/intro.do