“Glutamate receptors in the basolateral complex of the amygdala (BLA) are essential for the acquisition, expression and extinction of Pavlovian fear conditioning in rats. Recent work has revealed that glutamate receptors
in the central nucleus of the amygdala (CEA) are also involved in the acquisition of conditional fear, but it is not known whether they play a role in fear extinction. Here we examine this issue by infusing Z VAD FMK glutamate receptor antagonists into the BLA or CEA prior to the extinction of fear to an auditory conditioned stimulus (CS) in rats. Infusion of the α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor antagonist, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX), into either the CEA or BLA impaired the expression of conditioned freezing to the auditory CS, but did not impair the formation of a long-term extinction memory to that CS. In contrast, infusion of
the N-methyl-d-aspartate (NMDA) receptor antagonist, d,l-2-amino-5-phosphonopentanoic acid (APV), into the amygdala, spared the expression of fear to the CS during extinction training, but impaired the acquisition of a long-term PD0325901 cost extinction memory. Importantly, only APV infusions into the BLA impaired extinction memory. These results reveal that AMPA and NMDA receptors within the amygdala make dissociable contributions to the expression and extinction of conditioned fear, respectively. Moreover, they indicate that NMDA receptor-dependent processes involved in extinction learning are localized
to the BLA. Together with previous work, these results reveal that NMDA receptors in the CEA have a selective role acquisition of fear memory. “
“The sight of a hand can bias the distribution of spatial attention, and recently it has been shown that viewing both hands simultaneously can facilitate spatial selection between tactile events at the hands when these RAS p21 protein activator 1 are far apart. Here we directly compared the electrophysiological correlates of within-hand and between-hands tactile–spatial selection to investigate whether within-hand selection is similarly facilitated by viewing the fingers. Using somatosensory event-related potentials, we have shown that effects of selection between adjacent fingers of the same hand at early somatosensory components P45 and N80 were absent when the fingers were viewed. Thus, we found a detrimental effect of vision on tactile–spatial within-body part (i.e. hand) selection. In contrast, effects of tactile–spatial selection between hands placed next to each other, which were first found at the P100 component, were unaffected by vision of the hands. Our findings suggest that (i) within-hand and between-hands selection can operate at different stages of processing, and (ii) the effects of vision on within-hand and between-hands attentional selection may reflect fundamentally different mechanisms.