Limbic System- OJ Flashcards
Limbic System
Girdle/ Border
hippocampus, amygdala, anterior thalamic nuclei, fornix, cingulate gyrus, parahippocampal gyrus, limbic cortex, and limbic midbrain areas.
how does brain create valence?
nociceptor connected via basic reflexes to withdraw from stimuli
Our circultry wants us to avoid noxious stuff
Appetitive reflexes
reflexive ingestion and enteric reflexes move some stimuli through enteric system, reject others
Enteric Nervous system
subdivision of the autonomic nervous system (ANS) that directly controls the gastrointestinal system.
____________ predict appetitive v. aversive events and engage more
complex behaviors accordingly
feedforward mechanisms
Emotion
• the complex psychophysiological experience of
an individual’s state of mind, interacting with
environmental influences.
emotion fundamentally involves
appetitive or aversive events, via links between:
–physiological arousal
–expressive behaviors (facial), actions, action
tendencies
–conscious experience (feelings), sensations,
perceptions
Autonomic Tendency
Anger
Flushing, “Heat” “Pressure”
Fear- Autonomic Tendency
Cold”, pallor, diaphoresis, t
Desire
Action Tendency
Approach
Insula
primary interoceptive cortex
Modern Ideas about the
Neurophysiology of Emotion
- The Amygdala
- Ventromedial Prefrontal (Orbitofrontal) Cortex
- Insula
- Ventral Striatum/Nucleus Accumbens
- Ventral Tegmental Area-Dopamine
MYTHS about the Neurophysiology
of Emotion
- The Amygdala is all about fear
- Ventral Tegmental Area-Dopamine is all about reward
- Neither is “true”
Inferior temporal cells
Integrates sensory input
Ganglionic eminences becomes
Amygdala
Striatum
Basolateral Amygdala complex does?
Input
Centromedial Amygdala complex does?
Output
Intercalated cells?
GABAnergic
?
Optogenetics
technique using light to control cells in living tissue, typically neurons, that have been genetically modified to express light-sensitive ion channels (rhodopsins= original study channels)
allowed for fundamental wiring discoveries
Optogenetics Discoveries
Fear Conditioning,
Fear Extinction,
Appetitive Conditioning
Mouse- Sound/ shock experiment
sound: Auditory thalamus, auditory cortex– amygdala
shock- somatosensory thalamus –> somatosensory cortex–> amygdala
Fire together, wire together: sound will lead to fear response
Mouse- Sound/ shock experiment timing
Shock does not need to be immediate
Ach give a “memory window” to relate an event
Half hour
Mouse- Sound/ shock –> sound/ neutral experiment
~EXTINCTION
EXTINCTION
Rodent can suppress fear response if sound is paired with something better (vs shock)
Temporary suppression, will revert to fear if neutral pairing stops
Needs intercalated cells for extinction
Nucleus Accumbens/
Ventral Striatum Potentiating
Basolateral group in amygdala can project to Nucleus Accumbens/ Ventral Striatum
Potentiate between neutral stimulus (sound) and appetite pairing
Ventromedial Prefrontal Cortex
(Orbitofrontal Cortex) and gambling
- High risk vs low risk card piles
- Control subject: did not “understand” the difference, but had ↑ Symp response when picking from high risk pile
-Brain damaged patient
Never responded to more risky pile
Iowa Gambling Task & Orbitofrontal
Cortex (VmOFC) Lesions
• Impairment in ability to estimate the risk/reward
associated with certain behaviors
• Impairment in ability to select behaviors based on risk/
reward calculations
Iowa Gambling Task & Orbitofrontal
Cortex (VmOFC) Lesions Implications
Implies “subconscious” “gut feeling” about the
implications of a given behavior
• Implies suppression of behaviors felt to be excessively
risky, esp. in context of social function
Phineas Gage
Problems estimating strategy esp. in social situations
Orbitofrontal damage
Dopaminergic Projections:
• Nigrostriatal • Mesolimbic • Mesocortical • Tuberoinfindibular: DA inhibits PRL release
VTA releases Dopamine in response to errors in predictions different subregions of VTA concerned with _____________________- subregions have different projections
REWARD, PUNISHMENT, or even SALIENCE, SURPRISE
Mesolimbic path
?
mesocortical pathway
?
