Exam #6: Limbic System Flashcards
What is emotion? How would you define emotion?
Emotion is defined as “powerful subjective feelings & their associated physiological states”
**This implies that there are neurobiological connections between the cortex (subjective feeling) & systems that produce corresponding physiological states (endocrine)
What are the major functions of the limbic system?
1) Production of emotional responses
2) Memory
3) Homeostasis
What are the functions of the hypothalamus?
1) Governing/ monitoring internal homeostasis
2) Mediates raw & reflexive emotionality via the ANS
What are the functions of the amygdala?
- Fear
- Interpretation of facial expression
- Motivation & emotion
- Learning & memory (some)
Integrative center for emotions, emotional behavior, and motivation
What is the function of the limbic cortex?
Governs the efficient, effective, & safe satisfaction of limbic needs
What structures compose the limbic cortex?
- Anterior cingulate cortex (Acc)
- Orbitofrontal cortex
- Medial prefrontal cortex (mPFC)
- Insula
What are the functions of the hippocampus?
Memory
- Contextual influences on emotion
What is the function of the nucleus accumbens?
Motivation and reinforcement
How does the amygdala interact with the cerebral cortex to produce emotional behaviors?
The mPFC regulates the amygdala e.g. preventing yourself from losing your temper
Describe fear conditioning.
This is an experimental procedure in rats with 2 phases:
1) Habituation
2) Conditioning–shock paired with sound (conditional stimulus)
3) Testing–presentation of CS (sound) only
*****Fear responses are seen in response to the sound only
What is the reward system?
This is the Limbic Loop of the Basal Ganglia
- DA from the VTA to NAcc serves are a reward signal
- Normally promotes motor progams to acquire beneficial rewards e.g. food, water, sex, love…etc.
What is the neurobiological basis of drug addiction?
Drugs of abuse target the dopaminergic reward pathways and damped the reward response to natural stimuli, simultaneously increasing the response to addictive drugs
What does a lesion to the amygdala result in?
Flat affect & docile behavior
What is the primary output of the limbic system?
Hypothalamus
Where is dopamine produced in the limbic system? Where do dopaminergic neurons project in the limbic system?
DA is produced in the mesolimbic system; primary projections include:
1) Ventral Tegmental Area
2) Nigrostriatal pathway
What is the Ventral Tegmental Area (VTA)?
NAcc, mPRC & Septal Nuclei
What is the Nigrostriatal pathway?
SN to striatum
What are two unique characteristics of the hypothalamus?
1) Exerts influence through both synaptic & circulatory connections
2) Exhibits sexual dimorphism i.e. different functions/hormones in different sexes
What are the three major components of the amygadala?
Basolateral
Central
Corticomedial
What is the biggest part of the amygdala & why?
Basolateral region is biggest in humans
*****This is the input region–it has to be large to accommodate all of the information coming in from the cortices
What are the neural mechanisms underlying fear conditioning?
US
1) US sensation is carried via sensory pathways to somatosensory cortex
2) Somatosensory cortex projects to the amygdala
3) Amygdala’s connections with:
- CG= freezing
- LH= autonominc resoponse
- PVC= hormones
CS
1) Sensation of CS to amygdala
2) Pairing with US
- ->Same responses
What is the neural basis for empathy?
Mirror neurons
Describe the presentation of an mPFC lesion.
- Apathetic
- Impulsive
- Poor judgement
- Depressive behavior
- Mania
