Fear Conditioning: Integrated Behavior
USD
Behavioral Neuroscience
Summers
Fear
Afferent Path for Fear
Amygdala
Fear Conditioning
Pavlovian potentiated startle Afferent Shock (US) Pathway
Efferent Output
Neuromuscular Production of Fear Potentiated Startle
Integration of Fear Conditioning
BDNF
Substance P
ACh
Fear figures
Fear Conditioning Circuitry
end     Acronyms/Abbreviations

Fear Conditioning
IX. Integration of Fear Conditioning  

A. Acoustic Startle Circuit 1. Loud sudden Sound 2. Ear a. Cochlear Root Neurons (CRN) in VIIIth nerve i. Glu: Carry Acoustic information (1) not for hearing purposes (a) hearing: not necessary for startle i) not missing ii) affects startle via PPI 3. Reticular caudal Pontine nucleus (PnC = pontis caudalis reticularis) a. AMPA/NMDA b. can be potentiated by additional Glu inputs i. from CeA, Deep SC, reticular nucleus, and PAG 4. Spinal motor neurons: ACh a. PnC potentiation can recuitment of motor neuons 5. muscles a. Nicotinic Receptors 6. Jump
B. Fast Fear Circuit 1. Foot Shock 2. Nociceptors a. bare sensory receptors in the skin of the foot i. soma in DRG (dorsal root ganglion) b. terminals in the dorsal horn (gray) of the spinal cord i. Glu AMPA/NMDA ii. some may colocalize SP 3. Nociceptive information to Posterior Intralaminar Nucleus (PIN) a. Glu AMPA/NMDA 4. Basolateral Amygdala 5. BLA Glu AMPA/NMDA Central Amygdala 6. CeA Glu AMPA/NMDA PnC a. CRF too?
C. Slower Fear Cicuit - modulated 1. Foot shock Nociceptors Spinal Dorsal horn 2. decussation spinothalamic tract in anteriolateral column Thalamus 3. Thalamic PIN + VPNGlu AMPA/NMDAPosterior Insular Cortex (PIC) a. Thalamic nociceptive neurons: VPNGlu AMPA/NMDASomatosensory CortexGlu AMPA/NMDAPIC 4. PIC Glu AMPA/NMDA LA BLA
D. Visual Conditioned Stimulus Circuit 1. light presented just before/during foot shock 2. Eye a. Retina Glu AMPA/NMDA thalamic LGN b. LGNGlu AMPA/NMDAvisual 1o ctx temporal ctx perirhinal ctx i. temporal ctxGlu AMPA/NMDALAGlu AMPA/NMDABLA ii. perirhinal ctxGlu AMPA/NMDALA AMPA/NMDABLA c. Retina Glu AMPA/NMDA thalamic LPN i. LPNGlu AMPA/NMDAvisual 1o ctx / temporal ctx / perirhinal ctx and LA
E. Fear Learning Circuit 1. light (1. temporal cortex/ 2. perirhinal cortex/ 3. LPN) + shock (4. PIN / 5. PIC) LA 2. light LAGlu signals + painGlu siganals converge LA BLA neuroplasticity a. Acquisition i. Glu potentiation 1) Glu NMDA with GluN2B (NR2B) MEK/ERK 2) BDNF - TrKB PI3K; ERK nucleus a) CREB CRE
b. Consolidation i. BLA gephyrin GABAA 1) GABAA LTP a) BDNF - TrKB
F. Expression (Light + Loud sudden Sound = Conditioned Fear + Startle) 1. BLA AMPA NMDA with GluN2A (NR2A) 2. BLA MeA AMPA NMDA with GluN2A a. MeAGlu/Enk/SP AMPA/NMDA/m/NK1VMHEnk/SP m/NK1PAG 3. BLA CeA AMPA NMDA with GluN2A a. CeA Glu PnC AMPA/NMDA 4. Convergence of CRN, PAG, CeA PnC a. Glu potentiation i. CRF from longer term stress PnC Glu potentiation ii. #neurons firing + rate b. PnC spinal cord ventral horn motor neuron ACh c. quadriceps femoris + gastrocnemius muscles d. jump

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