Classification of projection neurons and interneurons in the rat lateral amygdala based upon cluster analysis

Abstract

Neurons in the rat lateral amygdala in situ were classified based upon electrophysiological and molecular parameters, as studied by patch-clamp, single-cell RT-PCR and unsupervised cluster analyses. Projection neurons (class I) were characterized by low firing rates, frequency adaptation and expression of the vesicular glutamate transporter (VGLUT1). Two classes were distinguished based upon electrotonic properties and the presence (IB) or absence (IA) of vasointestinal peptide (VIP). Four classes of glutamate decarboxylase (GAD67) containing interneurons were encountered. Class III reflected "classical" interneurons, generating fast spikes with no frequency adaptation. Class II neurons generated fast spikes with early frequency adaptation and differed from class III by the presence of VIP and the relatively rare presence of neuropeptide Y (NPY) and somatostatin (SOM). Class IV and V were not clearly separated by molecular markers, but by membrane potential values and spike patterns. Morphologically, projection neurons were large, spiny cells, whereas the other neuronal classes displayed smaller somata and spine-sparse dendrites.

Networks of Parvalbumin-Positive Interneurons in the Basolateral Amygdala

“…The presence of mRNA for parvalbumin in ϳ7% of projection neurons in the BLA was recently reported based on single-cell PCR (Sosulina et al, 2006). However, the presence of parvalbumin was not confirmed in these neurons.…”

“…Interneurons can be separated into distinct populations based on their electrophysiological properties and expression of different calcium-binding proteins and peptides (Gupta et al, 2000;Kawaguchi and Kondo, 2002;Markram et al, 2004;Hestrin and Galarreta, 2005). Within the BLA, interneurons have previously been separated into four types based initially on immunohistochemical markers , but more recently on mRNA expression profiles (Sosulina et al, 2006) and electrophysiological parameters (Rainnie et al, 2006). Electrophysiological recordings from BLA interneurons expressing PV have indicated the presence of two subtypes (Rainnie et al, 2006).…”

Differential Effects of Corticosterone on the Slow Afterhyperpolarization in the Basolateral Amygdala and CA1 Region: Possible Role of Calcium Channel Subunits

“…Their overall morphological features under the recording microscope (more specifically the pyramidal-shaped cell body and number of primary branches) could not be distinguished from those of the other cells. This is reminiscent of projection neurons in the lateral amygdala, which also display two subclasses of pyramidal-shaped neurons, i.e., a prevalent subclass of cells with an average membrane resistance of 270 M⍀ and an infrequently encountered subclass of cells with an average membrane resistance of 645 M⍀ (Sosulina et al 2006). If the high-inputresistance cells were included in our analysis, the control group had on average a larger sAHP amplitude and spike-frequency accommodation than those of the corticosterone-treated cells, similar to what was reported in the afore-mentioned recent paper (Duvarci and Paré 2007).…”

Glutamic Acid Decarboxylase 65: A Link Between GABAergic Synaptic Plasticity in the Lateral Amygdala and Conditioned Fear Generalization

“…Coronal slices were prepared and whole-cell patch clamp recordings were obtained from principal neurons (PNs) in the lateral amygdala (LA) (Sah et al, 2003), as described previously (Sosulina et al, 2006; for details, see Supplementary Information). After assessing membrane properties, postsynaptic responses were recorded under current-or voltage-clamp conditions, as previously described (Chauveau et al, 2012; for details, see Supplementary Information).…”