SED Task 2. Fear and Williams syndrome
Learning goals
1. What are the 2 pathways (Ledoux)
2. Williams syndrome and symptoms (visuospatial and social)
3. Causes of Williams Syndrome
4. Relation with fear (pathways)
Ledoux: emotion circuits in the brain
The behavioral paradigm of fear conditioning has offered new insights in emotions. The fear
system is seen as a set of processing circuits that detect and repons to danger, rather than as a
mechanism through which subjective states of fear are experienced. Fear is operationalized
and easier to experiment with. Some limbic areas are involved, but the limbic system theory
that was most popular before, could not explain the exact brain areas involved.
Fear conditioning
An initially neutral stimulus [a conditioned stimulus (CS)] can acquire affective properties on
repeated temporal pairings with a biologically significant event [the unconditioned stimulus
(US)]. As the CS-US relation is learned, innate physiological and behavioral responses come
under the control of the CS. In fear conditioning, first a neutral CS is presented (light or tone)
and then an unpleasant US (like a shock) so eventually, when the CS is presented, one will
react in fear (of the shock). The CS now elicits a wide range of behavioral and physiological
responses that characteristically occur when an animal encounters a threatening or fear-
arousing stimulus, like defensive behavior, autonomic arousal, hypoalgesia, reflex
potentiation and stress hormones.
Neuroanatomy of FC
Conditioned fear is mediated by the transmission of information about the CS and US to the
amygdala, and the control of fear reactions by way of output projections from the amygdala to
the behavioral, autonomic, and endocrine response control systems located in the brainstem.
The amygdala consists of 12 different regions, which consist of subregions. The most
important ones for FC (in primate and rat brains) are the lateral (LA), basal (B), accessory
basal (AB), and central (CE) nuclei and the connections between these. In brief, LA projects
to B, AB, and CE, and both B and AB also project to CE. However, it is important to
recognize that the connections of these areas are organzied at the level of subnuclei within
each region rather than at the level of the nuclei themselves.
CS pathways: Auditory and other sensory inputs to the amygdala terminate mainly in LA, and
damage to LA interferes with fear conditioning to an acoustic CS. Auditory inputs to LA
come from both the auditory thalamus and the auditory cortex, and fear conditioning to a
simple auditory CS can be mediated by either of these pathways. It appears that the projection
to LA from the auditory cortex is involved with a more complex auditory stimulus pattern.
The cortical pathway learns more slowly that the thalamic pathway, so plasticity in the
amygdale occurs intitially through the (direct) thalamic pathway.
Learning goals
1. What are the 2 pathways (Ledoux)
2. Williams syndrome and symptoms (visuospatial and social)
3. Causes of Williams Syndrome
4. Relation with fear (pathways)
Ledoux: emotion circuits in the brain
The behavioral paradigm of fear conditioning has offered new insights in emotions. The fear
system is seen as a set of processing circuits that detect and repons to danger, rather than as a
mechanism through which subjective states of fear are experienced. Fear is operationalized
and easier to experiment with. Some limbic areas are involved, but the limbic system theory
that was most popular before, could not explain the exact brain areas involved.
Fear conditioning
An initially neutral stimulus [a conditioned stimulus (CS)] can acquire affective properties on
repeated temporal pairings with a biologically significant event [the unconditioned stimulus
(US)]. As the CS-US relation is learned, innate physiological and behavioral responses come
under the control of the CS. In fear conditioning, first a neutral CS is presented (light or tone)
and then an unpleasant US (like a shock) so eventually, when the CS is presented, one will
react in fear (of the shock). The CS now elicits a wide range of behavioral and physiological
responses that characteristically occur when an animal encounters a threatening or fear-
arousing stimulus, like defensive behavior, autonomic arousal, hypoalgesia, reflex
potentiation and stress hormones.
Neuroanatomy of FC
Conditioned fear is mediated by the transmission of information about the CS and US to the
amygdala, and the control of fear reactions by way of output projections from the amygdala to
the behavioral, autonomic, and endocrine response control systems located in the brainstem.
The amygdala consists of 12 different regions, which consist of subregions. The most
important ones for FC (in primate and rat brains) are the lateral (LA), basal (B), accessory
basal (AB), and central (CE) nuclei and the connections between these. In brief, LA projects
to B, AB, and CE, and both B and AB also project to CE. However, it is important to
recognize that the connections of these areas are organzied at the level of subnuclei within
each region rather than at the level of the nuclei themselves.
CS pathways: Auditory and other sensory inputs to the amygdala terminate mainly in LA, and
damage to LA interferes with fear conditioning to an acoustic CS. Auditory inputs to LA
come from both the auditory thalamus and the auditory cortex, and fear conditioning to a
simple auditory CS can be mediated by either of these pathways. It appears that the projection
to LA from the auditory cortex is involved with a more complex auditory stimulus pattern.
The cortical pathway learns more slowly that the thalamic pathway, so plasticity in the
amygdale occurs intitially through the (direct) thalamic pathway.
