Brain Manipulations
In the lab we use stereotaxic surgical approaches to implant probes chronically or infuse chemicals into select brain regions. By doing this we are able to selectively manipulate neural circuits. Below we describe how we used these stereotaxic approaches in our research.
Model 902 Stereotaxic frame
This is the Model 902 stereotaxic surgical frame. This frame has a rotation of 100um, but can have a resolution as small as 10um. The frame also has two manipulating arms (images currently display one) that can be used to simultaneously place two probes into the brains of rats. For more details about this device please see http://kopfinstruments.com/product/model-902-dual-small-animal-stereotaxic-instrument/.
Studies using permanent cholinergic lesion
In these studies we used stereotaxic surgerical methods to target clusters of basal forebrain cholinergic neurons and examine the role of these neurons in fear and extinction memory. The above image shows loss of AChE in the efferent fields of basal forebrain cholinergic neurons in the nbm and MS/DBB
References
Knox, D. and Keller, S.M.* (2016). Cholinergic neuronal lesions in the medial septum and vertical limb of the Diagonal Bands of Broca induce contextual fear memory generalization and impair acquisition of fear extinction. Hippocampus 26(6): 718-726. Citations – 24.
Staib, J.M.·, DellaValle, R.*, and Knox, D. (2018). Medial septum and diagonal bands of Broca cholinergic projections to the ventral hippocampus facilitate auditory fear memory. Neurobiology of Learning and Memory 152: 71-79. Citations – 8.
Studies using PI3K-Akt inhibition
In this study we infused a PI3K inhibitor into the BLA and examined the effect this has on fear memory in stressed and control rats. The above image shows a cannula and infusion site within the BLA
References
Knox, D., Della Valle, R*. Mohammadmirzaei, N.*, Shultz, B.*, Biddle, M., Farkash, A. ·, Chamness, M., and Moulton, E ·. (2021). PI3K-Akt signaling in the basolateral amygdala facilitates traumatic stress enhancements in fear memory. International Journal Of Neuropsychopharmacology. 24(3):229-238. Citations - 2
Expression of DREADDs in Chat;;cre rats
In this experiment we used stereotaxic surgical methods to infuse a viral vector that expresses the inhibitory DREADD (hM4Di) in cholinergic neurons in the nbm
References
Shultz, B.*, Mohammadmirzaei, N.*, and Knox, D. (2019). Role of nucleus basalis cholinergic neurons in contextual fear memory. Addgene Report. https://doi.org/10.57733/addgene.88hyvn.