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Full-Text Articles in Medicine and Health Sciences
Differential Expression Of Voltage-Gated K+ Currents In Medial Septum/Diagonal Band Complex Neurons Exhibiting Distinct Firing Phenotypes, Emilio R. Garrido-Sanabria, Miriam G. Perez-Cordova, Luis V. Colom
Differential Expression Of Voltage-Gated K+ Currents In Medial Septum/Diagonal Band Complex Neurons Exhibiting Distinct Firing Phenotypes, Emilio R. Garrido-Sanabria, Miriam G. Perez-Cordova, Luis V. Colom
Health & Biomedical Sciences Faculty Publications and Presentations
The medial septum/diagonal band complex (MSDB) controls hippocampal excitability, rhythms and plastic processes. Medial septal neuronal populations display heterogeneous firing patterns. In addition, some of these populations degenerate during age-related disorders (e.g. cholinergic neurons). Thus, it is particularly important to examine the intrinsic properties of theses neurons in order to create new agents that effectively modulate hippocampal excitability and enhance memory processes. Here, we have examined the properties of voltage-gated, K+ currents in electrophysiologically-identified neurons. These neurons were taken from young rat brain slices containing the MS/DB complex. Whole-cell, patch recordings of outward currents were obtained from slow firing, fast-spiking, …
Electrophysiological And Morphological Heterogeneity Of Slow Firing Neurons In Medial Septal/Diagonal Band Complex As Revealed By Cluster Analysis, E. R. Garrido-Sanabria, M. G. Perez, C. Banuelos, T. Reyna, S. Hernandez, María Teresa Castañeda Licón, Luis V. Colom
Electrophysiological And Morphological Heterogeneity Of Slow Firing Neurons In Medial Septal/Diagonal Band Complex As Revealed By Cluster Analysis, E. R. Garrido-Sanabria, M. G. Perez, C. Banuelos, T. Reyna, S. Hernandez, María Teresa Castañeda Licón, Luis V. Colom
Health & Biomedical Sciences Faculty Publications and Presentations
Slow firing septal neurons modulate hippocampal and neocortical functions. Electrophysiologically, it is unclear whether slow firing neurons belong to a homogeneous neuronal population. To address this issue, whole-cell patch recordings and neuronal reconstructions were performed on rat brain slices containing the medial septum/diagonal band complex (MS/DB). Slow firing neurons were identified by their low firing rate at threshold (< 5Hz) and lack of time-dependent inward rectification (Ih). Unsupervised cluster analysis was used to investigate whether slow firing neurons could be further classified into different subtypes. The parameters used for the cluster analysis included latency for first spike, slow afterhyperpolarizing potential, maximal frequency and action potential (AP) decay slope. Neurons were grouped into three major subtypes. The majority of neurons (55%) were grouped as cluster I. Cluster II (17% of neurons) exhibited longer latency for generation of the first action potential (246.5±20.1 ms). Cluster III (28% of neurons) exhibited higher maximal firing frequency (25.3±1.7 Hz) when compared to cluster I (12.3±0.9 Hz) and cluster II (11.8±1.1 Hz) neurons. Additionally, cluster III neurons exhibited faster action potentials at suprathreshold. Interestingly, cluster II neurons were frequently located in the medial septum whereas neurons in cluster I and III appeared scattered throughout all MS/DB regions. Sholl’s analysis revealed a more complex dendritic arborization in cluster III neurons. Cluster I and II neurons exhibited characteristics of “true” slow firing neurons whereas cluster III neurons exhibited higher frequency firing patterns. Several neurons were labeled with a cholinergic marker, Cy3-conjugated 192 IgG (p75NTR), and cholinergic neurons were found to be distributed among the three clusters. Our findings indicate that slow firing medial septal neurons are heterogeneous and that soma location is an important determinant of their electrophysiological properties. Thus, slow firing neurons from different septal regions have distinct functional properties, most likely related to their diverse connectivity.