Warning: file_get_contents(https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=27092057
&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 215
Serotonin, Amygdala and Fear: Assembling the Puzzle
#MMPMID27092057
Bocchio M
; McHugh SB
; Bannerman DM
; Sharp T
; Capogna M
Front Neural Circuits
2016[]; 10
(?): 24
PMID27092057
show ga
The fear circuitry orchestrates defense mechanisms in response to environmental
threats. This circuitry is evolutionarily crucial for survival, but its
dysregulation is thought to play a major role in the pathophysiology of
psychiatric conditions in humans. The amygdala is a key player in the processing
of fear. This brain area is prominently modulated by the neurotransmitter
serotonin (5-hydroxytryptamine, 5-HT). The 5-HT input to the amygdala has drawn
particular interest because genetic and pharmacological alterations of the 5-HT
transporter (5-HTT) affect amygdala activation in response to emotional stimuli.
Nonetheless, the impact of 5-HT on fear processing remains poorly understood.The
aim of this review is to elucidate the physiological role of 5-HT in fear
learning via its action on the neuronal circuits of the amygdala. Since 5-HT
release increases in the basolateral amygdala (BLA) during both fear memory
acquisition and expression, we examine whether and how 5-HT neurons encode
aversive stimuli and aversive cues. Next, we describe pharmacological and genetic
alterations of 5-HT neurotransmission that, in both rodents and humans, lead to
altered fear learning. To explore the mechanisms through which 5-HT could
modulate conditioned fear, we focus on the rodent BLA. We propose that a
circuit-based approach taking into account the localization of specific 5-HT
receptors on neurochemically-defined neurons in the BLA may be essential to
decipher the role of 5-HT in emotional behavior. In keeping with a 5-HT control
of fear learning, we review electrophysiological data suggesting that 5-HT
regulates synaptic plasticity, spike synchrony and theta oscillations in the BLA
via actions on different subcellular compartments of principal neurons and
distinct GABAergic interneuron populations. Finally, we discuss how recently
developed optogenetic tools combined with electrophysiological recordings and
behavior could progress the knowledge of the mechanisms underlying 5-HT
modulation of fear learning via action on amygdala circuits. Such advancement
could pave the way for a deeper understanding of 5-HT in emotional behavior in
both health and disease.
free
free
free
