Emotional States 2 Flashcards
(27 cards)
Cannon and Bard exp - decorticate cats exhibit ?
lesion / remove hypothalamus ?
surmised ?
sham rage
no emotion
Hypothalamus is critical for expression of emotional
responses to stimuli (in this case, aggression)
Cortex functions to inhibit and direct these responses
James Papez propsed emotional behaviours depend on ?
group of interconnected forebrain
structures (“Papez circuit”)
Paul MacLean called this circuit what ?
and proposed three layer brain structure ?
limbic system
brainstem - routine maintenance
(ii) limbic system - primitive functions
(iii) cortex - rational thought
difference between papez and mclean circuits ?
mclean introduced higher structures i.e cortex
Kluver & Bucy (1937) showed lesion of temporal lobe in monkeys causes
behavioural
changes (tameness, lack of fear and aggression,
strong oral tendencies, hypersexuality)
“Kluver-Bucy syndrome is exhibited when ?
thus ?
bilateral lesions of amygdala
thus amygdala is critical for emotion
Amygdala is reciprocally connected to
hypothalamus,
hippocampal formation, neocortex and thalamus.
amygdala damage leads to impaired what ?
recognition of emotional facial expression
what stimuli have been shown to activate amygdala in fMRI studies ?
fearful stimuli
flash scary pictures in front of patients - subconscious activation of amygdala
what is fear conditioning ?
rats trained to associate sound with a foot shock
when they hear the sound alone they exhibit ith motor
(freezing, startle), endocrine, sympathetic (h.r., b.p.) changes associated with fear
what blocks fear conditioning ?
Bilateral lesion of either
medial geniculate nucleus of thalamus (auditory relay nuc.)
or of amygdala blocks this fear conditioning
what nuc in the amygdala is responsible for emotional response ?
central nucleus
LeDoux mapped the neural circuit of auditory fear
conditioning
lmedial geniculate nuc of thalamus - lateral amygdala - basolateral and basomedial amygdala and then central nuc
emotional significance of sound is assessed in amygdala based on previous experiences
two pathways from MGN - lateral amygdala ?
“Low road” (Direct) -
delivers crude sensory info, allowing an early
conditioned fear response
“High road” (Indirect)
via primary sensory areas of cortex, allowing a more complex analysis and slower conditioned
emotional response
efferent pathways from central nuc of amygdala ?
i) stria terminalis
(ii) ventral amygdalofugal pathway
stria terminalis
hypothalamus (autonomic responses)
nuc. of stria terminalis (neuroendocrine resp.)
brain stem nuclei (conditioned resp. eg. freezing)
ventral amygdalofugal pathway
nucleus accumbens in ventral striatum (motor resp.)
brain stem nuclei (conditioned resp. eg. freezing)
cingulate gyrus (storage and recall)
higher cortical centres (cognitive effects)
what is Fear-potentiated startle?
what is it a good model for ?
amplification of startle response by a fear stimulus
PTSD
FPS is mediated by the amygdala through two pathways?
central amygdalo-tegmental-pontine
medial amygdalo-hypothalamo-periaqueducto-pontine
how is the FPS affected in people with anxiety disorders
its increased?
How does damage to the amygdala effect FPS?
Patients with damage to amygdala display no (or
reduced) fear-conditioning / fear-potentiated startle
responses
In neuroimaging studies, people with PTSD exhibit?
increased activity in amygdala, insular cortex and
dorsal anterior cingulate cortex
- decreased activity in ventromedial prefrontal cortex
role of amygdala in emotion ? (3)
processing social signals of emotion (esp. fear)
- emotional conditioning
- consolidation of emotional memories
what is the insular cortex ?
somatosensory area
brings auditory, visual, tactile info and integrates it
