Nicotinic alteration of functional thalamocortical topography

Abstract

The thalamocortical pathways form highly topographic connections from the primary sensory thalamic nuclei to the primary cortical areas. The synaptic properties of these thalamocortical connections are modifiable by activation from various neuromodulators, such as acetylcholine. Cholinergic activation can alter functional properties in both the developing and mature nervous system. Moreover, environmental factors, such as nicotine, can activate these receptors, although the circuit-level alterations resulting from such nicotinic activation of sensory neural circuits remain largely unexplored. Therefore, we examined alterations to the functional topography of thalamocortical circuits in the developing sensory pathways of the mouse. Photostimulation via uncaging of glutamate was used to map these functional thalamocortical alterations in response to nicotinic receptor activation. As a result, we found that activation of forebrain nicotinic acetylcholine receptors results in an expansion and enhancement of functional thalamocortical topographies as assessed in brain slice preparations using laser-scanning photostimulation via uncgaing of glutamate. These physiological changes were correlated with the neuroanatomical expression of nicotinic acetylcholine receptor subtypes (α7 and β2). These circuit level alterations may provide a neural substrate underlying the plastic development and reshaping of thalamocortical circuitry in response to nicotinic receptor activation.

Wisteria Floribunda Agglutinin-Labeled Perineuronal Nets in the Mouse Inferior Colliculus, Thalamic Reticular Nucleus and Auditory Cortex

“…Moreover, we utilized a transgenic mouse line that expressed the Venus-fluorescent protein in presumed inhibitory neurons of these auditory structures, i.e. , the vesicular GABA transporter (VGAT)-Venus transgenic mouse line [ 36 , 37 ], which we have employed in previous studies of the auditory system [ 26 , 38 ]. This mouse line is particularly useful for the expeditious identification of gamma-amino butyric acid (GABA)-ergic inhibitory neurons throughout the nervous system, since it expresses an enhanced form of yellow-fluorescent protein natively in nearly all GABAergic inhibitory neurons [ 36 , 37 ].…”

Functional Topography and Development of Inhibitory Reticulothalamic Barreloid Projections

“…Our preparation takes advantage of transgenic-labeling of VGAT-positive inhibitory neurons, i.e., the VGAT-Venus mouse line (Wang et al, 2009 ). VGAT-Venus mice have been widely used to identify inhibitory neurons with Venus-labeled neuronal somata in various studies (Inada et al, 2011 ; Arami et al, 2013 ; Henderson et al, 2014 ; Bolton et al, 2015 ; Lee et al, 2015a , b ). In addition, Venus is expressed in inhibitory axonal projections (Saito et al, 2015 ).…”