NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Human Biology
Unit 3: Neurobiology and
Communication
A Case Study into the
Limbic System
Teacher’s Notes
[HIGHER]
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Acknowledgement
Learning and Teaching Scotland gratefully acknowledges this contribution to the National
Qualifications support programme for Human Biology.
The publisher gratefully acknowledges permission to use the following sources: Figure 1 brain
connectivity graph from On the relationship between emotion and cognition by Luiz Pessoa
from Nature, Vol 9 February 2008, p. 152,
http://www.nature.com/nrn/journal/v9/n2/full/nrn2317.html, Reprinted by permission from
Macmillan Publishers Ltd: Nature Reviews Neuroscience 9, 148-158 (February 2008) © 2008
http://www.nature.com/nrn/index.html; Diagram c freezing, from fear conditioning induces
associate long term potentiation in the amygdala by Rogan Staubli and LeDoux from Nature,
Vol 390, December 1997, p. 605,
http://www.nature.com/nature/journal/v391/n6669/full/391818b0.html, Reprinted by
permission from Macmillan Publishers Ltd: Nature 391, 818 (19 February 1998 © 1998
http://www.nature.com/nature/index.html; Diagram from
http://www.dkimages.com/discover/previews/740/68987.jpg © Dorling Kindersley
Every effort has been made to trace all the copyright holders but if any have been inadvertently
overlooked, the publishers will be pleased to make the necessary arrangements at the first
opportunity.
© Learning and Teaching Scotland 2011
This resource may be reproduced in whole or in part for educational purposes by educational
establishments in Scotland provided that no profit accrues at any stage.
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A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
Contents
Introduction
4
Answers to activities
Activity 1
Activity 2
Activity 3
Activity 4
5
5
6
7
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A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
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TEACHER’S NOTES
Introduction
This case study aims to provide a deeper understanding of the limbic system
using the regulation of fear as an example. There are four activities:
1.
Labelling structures of the limbic system
2.
Connectivity of the amygdale
3.
Circuitry of fear regulation
4.
Fear conditioning as an experimental paradigm
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A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
TEACHER’S NOTES
Answers to activities
Activity 1
To complete this activity students should use the information given in the text
describing the location and function of each structure. Structures highlighted
in bold should be labelled. Label lines are included for some assistance.
This activity could be completed individually or in pairs. Answers can be
swapped between individuals/pairs for assessment . The correctly labelled
diagram from this pack could be photocopied and handed out for marking or
the answers discussed as a class.
Approximate duration of activity: 20 minutes
A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
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TEACHER’S NOTES
Activity 2
Brain structures
connected to the
amygdala
Functional contribution to emotional
response of fear
Hypothalamus
Enables an autonomic response of the HPA
axis, resulting in hormone modulation and
feedback, eg synthesis and release of stress
hormone and adrenaline prior to an exam.
Thalamus
Relays sensory information about the
surroundings to the rest of the brain and
contributes to the feeling of alertness before
beginning an exam.
Hippocampus
Involved in storing and retrieving memories.
Simply remembering that an exam can make us
stressed or anxious can trigger an emotional
response.
Prefrontal Cortex
Enables conscious and voluntary control over
fear such as attention and planning, eg
motivation to revise, planning a revision
strategy and keeping focused during the exam.
Sensory Cortex
Provides the perceived element of fear through
our senses, eg the smell of the exam hall,
hearing revision talk, seeing the exam paper on
the desk.
Brain Stem
Responsible for the body’s rapid physiological
response to fear, eg increased heart rate,
sweating, muscle contraction prior to an exam
etc.
Students will apply some of the information they have already learnt from
Activity 1 to complete this task – they apply knowledge about the function of
each structure to the emotional response of fear.
This activity could be completed in small groups and assessed as a class.
Everyone has a different emotional response to sitting an exam, so discussing
answers and examples as a class will open up ideas.
Approximate duration of activity: 20 minutes
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A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
TEACHER’S NOTES
Activity 3
This activity could be completed individually or in pairs and assessed by
small group discussion. All the information needed to complete the activity is
given in the text describing the circuitry of the amygdala.
Students must extract the relevant information from the text to complete the
flow diagram. A couple of boxes have already been filled in for assistance.
The red and blue arrows above indicate the short and long routes for
processing information, respectively.
Approximate duration of activity: 20 minutes
A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
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TEACHER’S NOTES
Activity 4
This activity could initially be discussed in small groups, but individual
answers should be also be written down by students – this is good practice in
science-style writing. Teacher-based marking is probably the most
appropriate form of assessment for this activity.
The number of marks per question is indicated below. Students receive a
mark per point covered in their answers based on the points raised in the
model answers below. A total of 15 marks is available.
What are the CS, US and CR?
CS: an acoustic tone coming from the loud speaker (1 mark)
US: a mild electric shock coming through the floor of the chamber (1 mark)
CR: amount of freezing measured in seconds (1 mark)
(Total 3)
What is happening at each stage in the experiment ( pre-training, training
and post-training?)
Rats were split into two groups: control and conditioned (1 mark).
In the pre-training session (sessions 1 and 2) the unconditioned stimulus (the
tone) was presented alone to both groups (1 mark). Conditioned and control
rats did not demonstrate fearful behavior to this stimulus (1 mark).
During the training phase (sessions 3–5) conditioned rats were presented
with the tone, but this time paired with a mild electric shock (the
unconditioned stimulus) (1 mark). Control rats received the electric shock
only after hearing the tone (ie not both simultaneously) (1 mark). Both groups
exhibited a freezing response during these sessions (1mark).
During the post-training phase (sessions 6 and 7) both groups were presented
with only the tone again (1 mark). In session 6 the conditioned group
displayed a freezing response for significantly longer than co ntrols (1 mark).
They were conditioned to associate the sound of a tone with a mild electric
shock and thus showed fearful behaviour to the tone alone (1 mark).
The control group still demonstrated some freezing towards the tone during
the second test phase, but because it was not presented paired with the shock
during training the effect was not as strong (1 mark).
(Total 10)
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A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
TEACHER’S NOTES
Why is there a drop in the freezing response of the conditioned group
between sessions 6 and 7?
The reduction in freezing in session 7 relative to session 6 is a result of
extinction of the CS–US association. Extinction is a memory process in which
a conditioned response (freezing to the sound of tone) gradually fades over
time as the rat learns to uncouple the CS (tone) fr om the US (shock).
During session 6, memory for the shock–tone pairing is strong and the
conditioned rats show a high level of freezing. However, a second
presentation of the tone weakens this association and the rats display less
freezing behaviour. The memory is quickly becoming extinct.
Students are not expected to know about the process of extinction. Simply
acknowledging that the fear memory is fading during the last session is
enough to explain the results graph (2 marks for a brief description and
explanation).
Approximate duration of activity: 40 minutes
A CASE STUDY INTO THE LIMBIC SYSTEM (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
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