Inferior olive

Nach-mittag, m. afternoon, -miihlenol, n. inferior olive oil from the marc, -musterfarben, n. dyeing to pattern. 

Second, as in the ventricular muscle fibres of the heart, opening of L-type channels can generate sustained plateau potentials following the initial Na +-mediated action potential — for example, in the rhythmically firing neurons of the inferior olive (Fig. 2.7). 

Motor effects Harmaline produces a motor tremor (8-14 Hz) through activation of cells in the inferior olive, which is blocked by noncompetitive NMDA antagonists (Du et al. 1997 Stanford and Fowler 1998). Harmaline tremor is also reversed by benzodiazepine agonists (Robertson 1980). The tremor is initiated by synchronous rhythms in the olivocere-bellar system and red nucleus (Lorden et al. 1988 Gogolak et al. 1977 Batini et al. 1980). The tremor is associated with increased cGMP in the cerebellum, and tolerance with a relative normalization of cGMP (Lutes et al. 1988). Rapid tolerance develops to this effect with repeated doses. 

At the same time that the motor neurons send signals to the muscles, branches travel into other parts of the brain including the olivary nuclei, which send neurons into the cerebellum. The cerebellum acts as a kind of computer needed for fine tuning of the impulses to the muscles. Injury to the cerebellum leads to difficulty in finely coordinated motions. Input to the Purkinje cells arises from the climbing fibers, which originate in the inferior olive of the brain stem. Each climbing fiber activates a single Purkinje cell, but the dendrites of each Purkinje cell also form as many as 200,000 different synapses with parallel fibers that run across the cortex of the cerebellum (Fig. 30-15). 

Figure 30-15 (A) Diagram of the two-dimensional tree formed by dendrites of a single Purkinje cell of the cerebellum. From Llinas.404 (B) Schematic diagram showing input and output pathways for Purkinje cells. (C) Recordings of output from four different neurons of the inferior olive. These action potentials are thought to arise from oscillations that arise within the neurons or within arrays of adjacent neurons coupled by electrical (gap junction) synapses. These oscillations synchronize the generation of action potentials so that some cells oscillate in synchrony while others (e.g., cell 4 above) do not. From McCormick.412...

Haemorrhagic lesions are characteristic of experimental thiamine deficiency and WE in humans indicative of a breakdown of the blood-brain barrier (BBB). A study using immunoglobulin G (IgG) as an indicator of BBB integrity in thiamine-deficient rats revealed increased IgG immunoreactivity in the inferior colliculus and inferior olive prior to the onset of cell death in these regions (Calingasan et al.,... 

This disease is a late onset disorder of the cerebellum characterized by selective and progressive loss of Purkinje cells. Initially the disease was thought to be confined to the cerebellar cortex, dentate nucleus, and inferior olives, but more recent studies suggest more widespread cerebellar involvement (Seidel et al., 2009 Wang et al.,... 

IntPPC interposed cerebellar nucleus, posterior parvicellular part 66 InWh intermediate white layer of the superior colliculus 42-52, 80-84, 105, 107-114 lO inferior olive 79-81... 

---