Unit 11 - Emotion Flashcards
neural circuit of the limbic system
cerebral cortex (cingulate, parahippocampal gyrus, frontal lobes)
hypothalamus (mamillary body, lateral nuclei)
amygdala
septal nuclei
striatum (nucleus accumbens - caudate and putamen for movement)
RICH INTERCONNECTIONS
important aspects of limbic neural circuit
circuit hypothesis based on
emotions reach consciousness
thoughts can affect emotions
e.g. if you’re embarrassed you cannot stop blushing by talking to yourself
nervousness - GI implications
hypothalamus
active from…
hypothalamus - men vs women
age
what does it control
functional at birth - As we develop in utero, grown at 3 months - babies have same neurogenesis when they’re born as they were in utero - especially up to 2, but generally until 4 HOWEVER thermoregulation is poor
dissimilar in men and women
ancient phylogenetically
control over autonomic responses, eating, drinking and expression of primitive emotions
hypothalamus - influence on emotion
primitve, undirected, short-lived response (cerebral cortex input is limited)
stimulation of hypothalamus in cats ⇒ attack behaviour
electrical stimulation of hypothalamus in humans ⇒ feelings of pleasure
tumours in hypothalamus
produce sham mirth or rage
lateral hypothalamic nuclei
destruction ⇒ severe attenuation of emotional responsiveness and experience
stimulation ⇒ can induce extremes in emotionality
medial hypothalamic nuclei
stimulation ⇒ termination of behaviour
amygdala involved in
higher order emotional and motivational activities
stronger connection to cerebral cortex
involved with expression and perception of emotion
sexually dimorphic (differences between males and females)
medial nuclei of amygdala
stimulation of central nucleus - cessation of behaviour
lateral nuclei of amygdala
primates
emotional significance is assigned
amygdala can overwhelm neocortex
Amygdala is a NEWER structure, specifically lateral nuclei
amygdaloid stimulation ⇒
fear response
anger, pleasure
involved in more sophisticated emotions e.g. disappointment, surprise
temporal lobe epileptic seizures
feelings of depression, pleasure, fear
crying, tantrum, laughing, sexual behaviour
directed, long lasting emotional response of amygdala is due to
strong interactions with cerebral cortex
role in mood and affective disorders
(hypothalamus is short lasting, so not implicated in affective disorders)
Kluver-Bucy syndrome - amygdaloid lesion
tameness
visual agnosia - difficulty recognising things
fear conditioning is affected
social impairment (hyperactivity, hypersexuality, hyperorality)
Urbach-Wiethe disease - amygdaloid lesion
failure to discern facial expressions, especially fear
can be specific to fear recognition
less likely to be fearful
other roles of amygdala
social drive
perception of social signals
interpretation of emotion in faces
memory and learning - faces
attention and abstract anticipation
threat detection
motivation to vocalise
interpretation of emotive sounds
septum
age
function
phylogenetically new
dampening influence on arousal and limbic system functioning
dampens socialising tendencies and emotions
septum and amygdala have an antagonistic relationship - counterbalance
destruction results in increased aggressive behaviour and rage - generalised tendency to over-respond persists
destruction also causes a persistent drive for social and physical contact
septum and amygdala
antagonistic relationship - counterbalance
destruction of septum
a persistent drive for social and physical contact
role of nucleus accumbens
increasing dopamine in the NA is associated with reward
pleasurable
enhanced likelihood of repeat of behaviour
reward pathway
mesolimbic pathway
dopaminergic projections
ORIGIN = ventral tegmental area of brainstem
dopamine released in the NA
signal sent from NA to the cerebral cortex via globus pallidus and thalamus
cingulate cortex
motivation, emotion, self control
prefrontal and anterior cingulate cortices
response selection, decision making, volitional behaviour (self control)
planning
response to punishment
manners
concern for others
recognition of faux pas
hunches
self control
anterior cingulate cortex
important response selection, decision making based on emotion, self control
lesions in prefrontal and anterior cingulate cortices
impaired social function in primates
what is implicated in depression and anxiety
overactivation of amygdala
underactivation of prefrontal and altered activity in cingulate gyrus cortical areas
reduced GM volume in amygdala, prefrontal cortex and cingulate gyrus
what can stress do
block neurogenesis in the dentate gyrus of hippocampus
in depression -
structural alterations in hippocampus
decreased cell proliferation in granule cell layer
atrophy of CA3 pyramidal neurons
reversed by antidepressants
time course consistent with therapeutic effect
increased cell proliferation/block of atrophy
neurotrophic factors implicated e.g. BDNF
