scholarly journals Parvalbumin-positive interneurons mediate neocortical-hippocampal interactions that are necessary for memory consolidation

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Frances Xia ◽  
Blake A Richards ◽  
Matthew M Tran ◽  
Sheena A Josselyn ◽  
Kaori Takehara-Nishiuchi ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Fear Conditioning ◽  
Medial Prefrontal Cortex ◽  
Memory Consolidation ◽  
Fear Memory ◽  
Contextual Fear Conditioning ◽  
Contextual Fear ◽  
Contextual Fear Memory ◽  
Spiking Activity

Following learning, increased coupling between spindle oscillations in the medial prefrontal cortex (mPFC) and ripple oscillations in the hippocampus is thought to underlie memory consolidation. However, whether learning-induced increases in ripple-spindle coupling are necessary for successful memory consolidation has not been tested directly. In order to decouple ripple-spindle oscillations, here we chemogenetically inhibited parvalbumin-positive (PV+) interneurons, since their activity is important for regulating the timing of spiking activity during oscillations. We found that contextual fear conditioning increased ripple-spindle coupling in mice. However, inhibition of PV+ cells in either CA1 or mPFC eliminated this learning-induced increase in ripple-spindle coupling without affecting ripple or spindle incidence. Consistent with the hypothesized importance of ripple-spindle coupling in memory consolidation, post-training inhibition of PV+ cells disrupted contextual fear memory consolidation. These results indicate that successful memory consolidation requires coherent hippocampal-neocortical communication mediated by PV+ cells.

scholarly journals Differential involvement of the medial prefrontal cortex across variants of contextual fear conditioning

2017 ◽  
Vol 24 (8) ◽  
pp. 322-330 ◽  
Author(s):  
Nicholas A. Heroux ◽  
Patrese A. Robinson-Drummer ◽  
Hollie R. Sanders ◽  
Jeffrey B. Rosen ◽  
Mark E. Stanton
Keyword(s):  
Prefrontal Cortex ◽  
Fear Conditioning ◽  
Medial Prefrontal Cortex ◽  
Contextual Fear Conditioning ◽  
Contextual Fear ◽  
Differential Involvement

scholarly journals Contextual Fear Memory Maintenance Changes Expression of pMAPK, BDNF and IBA-1 in the Pre-limbic Cortex in a Layer-Specific Manner

2021 ◽  
Vol 15 ◽  
Author(s):  
Nicholas Chaaya ◽  
Joshua Wang ◽  
Angela Jacques ◽  
Kate Beecher ◽  
Michael Chaaya ◽  
...  
Keyword(s):  
Fear Conditioning ◽  
Fear Memory ◽  
Contextual Fear Conditioning ◽  
Mitogen Activated Protein Kinase ◽  
Limbic Cortex ◽  
Pavlovian Fear Conditioning ◽  
Bdnf Expression ◽  
Contextual Fear ◽  
Contextual Fear Memory

Post-traumatic stress disorder (PTSD) is a debilitating and chronic fear-based disorder. Pavlovian fear conditioning protocols have long been utilised to manipulate and study these fear-based disorders. Contextual fear conditioning (CFC) is a particular Pavlovian conditioning procedure that pairs fear with a particular context. Studies on the neural mechanisms underlying the development of contextual fear memories have identified the medial prefrontal cortex (mPFC), or more specifically, the pre-limbic cortex (PL) of the mPFC as essential for the expression of contextual fear. Despite this, little research has explored the role of the PL in contextual fear memory maintenance or examined the role of neuronal mitogen-activated protein kinase (pMAPK; ERK 1/2), brain-derived neurotrophic factor (BDNF), and IBA-1 in microglia in the PL as a function of Pavlovian fear conditioning. The current study was designed to evaluate how the maintenance of two different long-term contextual fear memories leads to changes in the number of immune-positive cells for two well-known markers of neural activity (phosphorylation of MAPK and BDNF) and microglia (IBA-1). Therefore, the current experiment is designed to assess the number of immune-positive pMAPK and BDNF cells, microglial number, and morphology in the PL following CFC. Specifically, 2 weeks following conditioning, pMAPK, BDNF, and microglia number and morphology were evaluated using well-validated antibodies and immunohistochemistry (n = 12 rats per group). A standard CFC protocol applied to rats led to increases in pMAPK, BDNF expression and microglia number as compared to control conditions. Rats in the unpaired fear conditioning (UFC) procedure, despite having equivalent levels of fear to context, did not have any change in pMAPK, BDNF expression and microglia number in the PL compared to the control conditions. These data suggest that alterations in the expression of pMAPK, BDNF, and microglia in the PL can occur for up to 2 weeks following CFC. Together the data suggest that MAPK, BDNF, and microglia within the PL of the mPFC may play a role in contextual fear memory maintenance.

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