Problem 2 Flashcards
Affective neuroscience
Aims to better understand emotion + mood at neurobiological + psychological levels and their interface
–> uses functional neuroimaging, electrophysiological recordings, lesion studies
Darwins first notion on emotion
Animal emotions are homologous for human emotion
James-Lange theory of emotion
Emotions are no more than the experience of sets of bodily changes that occur in response to emotive stimuli
e.g. if we meet a bear, we don’t run because we are frightened but because of prior experience
Darwins second notion on emotion
A limited set of fundamental/”basic” emotions are present across species + cultures
e.g. anger, fear, surprise, sadness
THUS: the embodiment of emotions
How did Canon challenge James langes theory ?
He pointed out that
- surgical separation of the viscera from the brain did not impair emotional behavior
- bodily changes are too slow to generate emotions
- artificial hormonal activation of bodily activity is insufficient to generate emotion
- bodily activity cannot differentiate different emotional states
BUT: claims were on some points rejected
Sham rage
Refers to an outburst of motor activity due to sudden aggressiveness or fear
–> seen in cats
Cannon-Bard theory of emotion
We feel emotions and physiological reactions simultaneously
How does cannon bards theory explain sham rage ?
Removal of the cortex frees the hypothalamic circuit from top-down control
Elaborate on the Cannon-bard theory on a neuronal level.
What was their main hypothesis ?
Argued that the hypothalamus is the brain region involved in emotional response to stimuli
–> such responses are inhibited by evolutionarily more recent neocortical regions
Papez circuit
Suggests that sensory input into the thalamus diverges into upstream + downstream
–> separate streams of thought + feeling
Thought stream
Upstream/cold
Is transmitted from thalamus to sensory cortices
–> sensation are turned into perceptions, thoughts and memories
Feeling stream
Downstream/hot
Is transmitted from the thalamus to mammillary bodies
–> to generate emotions via anterior thalamus to cingulate cortex
Triune architecture
MacLeans limbic system
Consists of the
- Ancient reptilian brain
a) Striatal complex + basal ganglia
b) seat for primitive emotions
- -> fear + aggression
- Old mammalian brain
a) Papez circuit, amygdala, PFC, hippocampus, Thalamus, Hypothalamus
b) augments primitive reptilien emotional responses
- New mammalian brain
a) neocortex
b) exerts top-down control over the emotional responses
McLeans theory of emotion
Emotional experiences involve the integration of sensations from the world with info from the body
–> THUS:
- events in the world lead to bodily changes
- brain integrates these changes
- emotional experience is generated
Kluver-Bucy syndrome
Is characterized by diminished fear responses and unusually low aggression
–> lesions to both temporal cortices
Direct thalamo-amygdala route
Processes crude sensory aspect of incoming stimuli + directly relays this info to the amygdala
THUS: an easy conditioned fear response is elicited
Indirect thalami-cortico-amygdala route
Allows more complex analysis of the incoming stimulus, then delivers a slower, conditioned emotional response
Name the 3 main roles of the amygdala
- Consolidation of LT emotional memory
- Fear conditioning
- Top-down processing of emotion
Right hemisphere hypothesis
Mills
Suggests that the right hemisphere has a specialized role in the aspects of
- perception
- Expression of emotion
Multiple systems models
Suggests that a small set of discrete emotions are underpinned by relatively separable neural systems in the brain
Traditional fear center model
In the presence of threat, this system generates
- conscious feeling of fear
- physiological responses typical of such experiences
–> mammalian brain = fear system
Two system framework/model
Suggests that one set of circuits generates conscious feelings, whereas the other the physiological response
–> opposition to fear system
How is a fear response elicited through the amygdala ?
Innate fear circuit view
An immediately present threat activates the lateral nucleus of the amygdala
–> this initiates the expression of defensive behavioral reactions
e.g. freezing,
What is the anxiety center/Anxiety circuit hub ?
BNST - stria terminals
- ->
1. it is engaged when threats are uncertain
- uses similar output pathways that are also used by amygdala to control responses
Name the main problems with the subcortical fear + anxiety center/circuit views
- Subjective experiences of fear and anxiety do not correlate well with measures of behavioral and physiological responses
- Patients with amygdala damage still can feel fear, panic and pain
- Threats presented subliminally increase amygdala activity and trigger peripheral physiological responses
- Blindsight patients lose their ability to consciously experience stimuli presented to the LVF
- -> exhibit threat-elicited amygdala activity and defensive responses
THUS: The BNST and amygdala contribute indirectly to fear and anxiety
Advantage of the 2 systems view
- Makes it easier to understand the role language and culture play in shaping our experience
- Explain why infants react emotionally long before they report emotions
Higher order association cortex
Is responsible for cognitive processes such as attention + WM
- Lateral and medial PFC
- ->conscious awareness - Insula
- -> conscious experience of somatic sensations - Parietal neocortex
THUS: cuirtuis are engages when one is ware of visual stimulus
What is the fear network comprised of ?
- ACC
- Anterior insula
- Amygdala
- -> but decreases over time which indicates habituation
Fear extinction
- Previously neutral stimulus is repeatedly presented without the aversive stimulus
- Conditioned fear response is gradually eliminated
–> Fear network active during extinction as well, so you learn a new conditioning response that is hopefully now more dominant
PTSD patients neuronal diysfunctions
- Amygdala hyperactivity
- -> persistent elevated fear response & hypoactivity in frontal regions suggests a reduced potential for top down regulation of fear and fear extinction - Medial PFC and cingulate cortex & acc hypoactivity
- -> reduced potential for top-down control and fear extinction - Reduced hippocampal activity
- -> difficulties in identifying safe contexts
Why is there a 2-way relationship in PTSD patients?
Some of the observed abnormalities, like reduced hippocampal volume can be a predisposing factor for the
development of PTSD
–> on the other hand it could also be a consequence of the disorder and show a further decrease over time
Neuronal dysfunctions in PTSD patients
- Amygdala hyperactivity
- -> persistent elevated fear response & hypoactivity in frontal regions suggests a reduced potential for top down regulation of fear and fear extinction - Medial PFC and cingulate cortex & ACC hypoactivity
- -> reduced potential for top-down control and fear extinction - Reduced hippocampal activity
- -> difficulties in identifying safe contexts
How can anxiety disorders be treated ?
- Exposure therapy
- -> related to fear extinction - Cognitive behavioral therapy
- Mindfulness based stress reduction therapy
- SSRI
Neuronal dysfunctions in OCD patients
- Orbitofrontal hyperactivity
- -> occurrence of intrusive thoughts - ACC hyperactivity
- -> compulsiveness + anxiety arising from these thoughts - Cortico-striatal pathway (primary caudate nucleus)
- -> abnormal functional connectivity and increased brain activity in orbitofrontal and ACC regions
Is the circuit of papez involved in emotions?
Previously it was thought to be involved in emotion but it turned out that it was more important for memory consolidation
–> for this the PFC was later on added
Anterior cingulate cortex
Associated with conflict monitoring
–> send signal to PFC, which can integrate this information
e.g. doing something you don’t really want to do
Thalamus
Is the relay center of sensory signals, including
- motor signals to the cerebral cortex
- regulation of consciousness, sleep, and alertness.[4]
Hypothalamus
Refers to a portion of the brain that contains a number of small nuclei with a variety of functions
–> links the NS to the endocrine system via the pituitary gland.
Functions of the Hypothalamus
- Regulation of certain metabolic processes + other activities of the autonomic NS
- Synthesizes and secretes certain neurohormones, which in turn stimulate or inhibit the secretion of hormones from the pituitary gland
- Controls body temperature, hunger, fatigue, sleep, and circadian rhythms
