Brain slices individual neurons

A variety of different types of tissue preparation are used to study neurosecretion and synaptic transmission. A classical preparation is the frog NMJ (discussed below). The brain slice has been used for many years for biochemical studies of CNS metabolism and is a useful preparation for electrophysiological studies of synaptic transmission in the CNS. Slices can be oriented to maintain the local neuronal circuitry and can be thin, 0.3 mm, to minimize anoxia. The transverse hippocampal slice is widely used as an electrophysiological preparation to study synaptic plasticity (see Ch. 53). Primary cultures of neurons from selected CNS areas and sympathetic ganglia are also frequently used. They permit excellent visual identification of individual neurons and control of the extracellular milieu, but the normal neuronal connections are disrupted. 

The immediate and reversible actions of dopamine are a combination of modulations of individual ion channels. The major ion channels expressed in spiny projection neurons are summarized in Table 2. Current understanding of the properties of these channels is mostly based on whole cell recordings from isolated cells, which have been recently reviewed by Nichola et al. (2000). The role of these channels in whole cell behavior has been studied using intracellular recordings in brain slices or anaesthetized animals. Many of the important cellular properties of spiny projection neurons can be accounted for in terms of ion channel activations occurring at different membrane potentials. 

Several lines of evidence pointed to a role for Rac in spine formation and/or maintenance and the control of spine morphology in different model organisms (Govek et al., 2005). These studies largely relied on imaging of individual, fluorescently labeled neurons expressing constitutively active (CA) and dominant-negative (DN) mutant forms of Rac. Expression of CA Racl in hippocampal brain slices resulted in the formation of multiple small spines (Nakayama et al., 2000 Tashiro et al.. 

The brain slices may be further treated to isolate individual neurons or may themselves be maintained in culture media for several weeks. For detailed descriptions of slice culture and neuronal isolation, please see Chapters 2 and 3. 

---