Posttraining optogenetic manipulations of basolateral amygdala activity modulate consolidation of inhibitory avoidance memory in rats

Abstract

Memory consolidation studies, including those examining the role of the basolateral amygdala (BLA), have traditionally used techniques limited in their temporal and spatial precision. The development of optogenetics provides increased precision in the control of neuronal activity that can be used to address the temporal nature of the modulation of memory consolidation. The present experiments, therefore, investigated whether optogenetically stimulating and inhibiting BLA activity immediately after training on an inhibitory avoidance task enhances and impairs retention, respectively. The BLA of male Sprague-Dawley rats was transduced to express either ChR2(E123A) or archaerhodopsin-3 from the Halorubrum sodomense strain TP009 (ArchT). Immediately after inhibitory avoidance training, rats received optical stimulation or inhibition of the BLA, and 2 d later, rats' retention was tested. Stimulation of ChR2 (E123A)-expressing neurons in the BLA using trains of 40-Hz light pulses enhanced retention, consistent with recording studies suggesting the importance of BLA activity at this frequency. Light pulses alone given to control rats had no effect on retention. Inhibition of ArchT-expressing neurons in the BLA for 15 min, but not 1 min, significantly impaired retention. Again, illumination alone given to control rats had no effect on retention, and BLA inhibition 3 h after training had no effect. These findings provide critical evidence of the importance of specific frequency patterns of activity in the BLA during consolidation and indicate that optogenetic manipulations can be used to alter activity after a learning event to investigate the processes underlying memory consolidation.

Resolving the neural circuits of anxiety

“…Tonic activity in a subset of BLA neurons has been shown to track with anxiety-like behavior in the EPM and OFT 79 . Moreover, photoactivation of BLA somata increases measures of innate anxiety 33 as well as learned inhibitory avoidance 80 . Targeted photostimulation of BLA inputs to CeL, by contrast, is anxiolytic, presumably via enhanced inhibition over CeM projection neurons 33 .…”

Basolateral amygdala projections to ventral hippocampus modulate the consolidation of footshock, but not contextual, learning in rats

“…An insulated optical fiber connected the commutator to the appropriate laser source (DPSS, 300 mW, 473 nm for ChR2(E123A) or 561 nm for eArchT3.0), with a multimode fiber coupler for an FC/PC connection. Light output was adjusted to allow for 10 mW at the fiber tip based on previous work (Gradinaru et al 2009;Yizhar et al 2011;Deisseroth 2012;Huff et al 2013), as measured by an optical power meter. In all cases, the comparison control was a "sham-control" that had opsin expression but for which no illumination was provided except for one case (see below).…”

Superior temporal resolution of Chronos versus channelrhodopsin-2 in an optogenetic model of the auditory brainstem implant

“…In contrast to INS, optogenetics uses visible light from the visible spectrum to stimulate the nervous system, and it has been used to investigate a host of neural systems (Ayling et al , 2009; Boyden et al , 2005; Huff et al , 2013; Rolls et al , 2011). Viral -mediated infection is a common approach to deliver light-sensitive microbial opsin genes and enable neurons to respond to optical stimulation.…”