L48 - Limbic system and central autonomic function Flashcards
<p>List some primary and secondary emotions</p>
<p>Primary (reflexive) : Fear, anger, surprise, disgust, happiness, sadness.
Secondary (cognitive) : Envy, shame, guilt, etc.</p>
<p>What modulates emotions and drive motivated bahaviors?</p>
<p>Rewards, both good and bad</p>
<p>List general brain regions involved in the limbic system.</p>
Prefrontal and association cortex
Cingulate gyrus
Hippocampal formation
Mamillary body of hypothalamus & Hypothalamus
Anterior nucleus of Thalamus
Amygdala
<p>Function of the limbic system?</p>
<p>integrate information about sensory stimuli, memories, and cognitive plans
>> produce emotional learning and experience</p>
> > modulate emotional responses
Role of the hypothalamus in the limbic system?
Modulate autonomic output in emotional responses
Generation of aggressive behavior patterns **
Describe the connection between neocortex and hippocampus?
<p>Via Entorhinal area</p>
Describe the brain regions involved in the Papezcircuit?
Hippocampal formation >> fornix (connect temporal lobe to diencephalon) >> Mamillary body of hypothalamus >> Mammilothalamic tract >> Anterior nucleus of thalamus >> Cingulate gyrus >> Cingulum (tract) >> Entorhinal cortex >> Hippocampal formation
Role of Amygdala in the limbic system?
1) Key coordinator: Linking cortical processing to the hypothalamus and other subcortical brain structures
2) expression of fear, anxiety, stress
3) Response to emotional facial expression + emotional arousal
List some functions of primary reflexive emotions?
Aid survival:
- Fear = danger, fleeing, fast escape
- Anger = fight
- Surprise = response to novel stimuli and prepare for reaction
- Disgust = avoid poisoning, infection (limbic system connected to olfactory bulb)
- Joy = motivator, drive
Changes in behavior due to amygdala damage? ( Kluver-Bucy syndrome )
- Tame, loss of fear, blunted emotions, less aggression
- Forget rapidly
- Increase oral activity and sexual behavior
Describe the 2 neural pathways for processing emotional stimulus into emotional response?
For evaluating emotions, long-term memory:
- Central/ Indirect pathway: Thalamus > Cortex > Amygdala > descending efferent output
For autonomic responses:
- Peripheral/ Direct pathway: Thalamus > Amygdala > descending efferent output
List some autonomic responses triggered by the posterior** hypothalamus after emotional stimuli?
- Sympathetic- like responses:
Increase BP, shivering
GI stimulation: hunger and thirst, feeding reflexes
Rage
List some autonomic responses triggered by the anterior** hypothalamus after emotional stimuli?
Parasympathetic-like response:
- Oxytocin release
- Decrease BP, HR
- Bladder contraction
- Panting, sweating
Which brain region is responsible for eliciting hunger, thirst and feeling of fullness (satiety)?
Lateral hypothalamus: feeding/ hunger center
Consequences of lateral hypothalamus lesion?
Lesion in Ventromedial hypothalamus?
Lesions in lateral hypothalamus (feeding / hunger center) :
- Hypophagia (decrease in food intake) / aphagia (lack of eating)
- Adipsia (absence of thirst)
Lesions of ventromedial hypothalamus (satiety center) = loss of satiety
Describe the output of the amygdala for modulating autonomic emotional expression/ response?
2 tracts to reach branstem nuclei:
1) Indirect: Central nucleus in amygdala»_space; Hypothalamus (medial and lateral)»_space; Brainstem nuclei
2) Direct: Central nucleus in amygdala»_space; brain stem nuclei
Both tracts output to modulate sympathetic and parasym. neurons = change emotional response
Which sensory input can directly impact the autonomic output of the amygdala for emotional response?
1) visceral organs and taste** receptors»_space; solitary nucleus»_space; brain stem
2) Olfactory system > directly to amygdala > brain stem
Modulate emotional response through changing sympathetic and parasym. output
Which brain region is associated with euphoria and pleasant sensations?
Septal region: pleasure centre
Closely connected with the dopaminergic limbic system
Describe the sequence of structures in the mesolimbic pathway.
mesolimbic pathway:
septal area»_space; dopaminergic connection» ventral tegmental area**»_space; Nucleus accumbens
(Pathway through lat. hypothalamus to reach frontal cortex is mesocortical pathway)
Which brain region is associated with reward and addiction?** (not euphoria/ pleasure)
Nucleus accumbens
Which brain area forms most of the mesolimbic system?
Ventral tegmental area
mesolimbic and mesocortical projections involved in reward by dopamine release
Describe the autonomic output when fear stimuli activates the amygdala (corticomedial area)?
Amygdala: indirect or direct output to brainstem, trigger sympathetic activation (fight-or-flight response):
Tachycardia Sweating Paleness Pupil dilation Piloerection Adrenal release of adrenaline
How is the olfactory system connected to the limbic system?
Olfactory system > Medial amygdala group > hypothalamus
What is the role of the Ventral Tegmental area? What emotions/behavior does it regulate?
Form most of mesolimbic/ mesocortical pathways: for REWARD ANTICIPATION:
- VTA neurons provide a learning signal that reflects reward expectation
- i.e. seeing reward cause VTA neurons to fire in prediction and anticipation of getting the reward
Input and output of the nucleus accumbens?
Input: dopaminergic input from midbrain dopamine neurons (e.g. septal area for euphoria)
Output: hypothalamus and limbic structures mediating emotional responses
Which brain region is affected by addictive drugs i.e. Cocaine and amphetamines? explain the physiological effects?
Medial Forebrain Bundle that innervates the Ventral Tegmental Area: especially Nucleus Accumbens***:
- increase dopamine release in shell of the nucleus accumbens
- Block dopamine reuptake at synapses
- Enhance dopamine release by acting on presynaptic cholinergic receptors (Nicotine)
> > Enhance pleasure
List functions of the Dopamine pathways?
Nigrostriatal, mesolimbic, tuberoinfundibular:
- Reward (motivation)
- Pleasure, euphoria
- Motor function (fine tuning)
- Compulsion
- Perseveration
List functions of the serotonin pathways?
- Mood
- Memory processing
- Sleep
- Cognition
Define the parasympathetic tracts/ CN nuclei that are modulated to produce emotional responses?
CN 3,8,9,10 + Sacral outflow tracts
Which brain area has increased firing activity in the learned anticipation of reward?
VTA
What is the function of the VTA in the mesolimbic system?
VTA neurons provide a learning signal that reflects reward expectation
> > guide behavior and to modulate emotional responses to reward-predicting stimuli.
Which area in the mesolimbic system uses NE as neurotransmitter?
Locus coeruleus
Which area in the mesolimbic system uses Dopamine as neurotransmitter?
VTA, Substantia nigra
Which area in the mesolimbic system uses Serotonin as neurotransmitter?
Raphe Nucleus
Which area in the mesolimbic system uses Ach as neurotransmitter?
Basal forebrain
List the structures that make up the hippocampal formation?
(dentate gyrus, hippocampus, subiculum)
