Cortical neuron

ALS is a disorder of the motor neurons and the cortical neurons that provide their input. The disorder is characterized by rapidly progressive weakness and muscle atrophy. Most affected patients die of respiratory compromise and pneumonia after 2 to 3 years. There is prominent loss of motor neurons in the spinal cord and brainstem although the oculomotor neurons are spared. Large pyramidal motor neurons in layer V of motor cortex, which are the origin of the descending corticospinal tracts, are also lost. 

Pomes A, Rodriguez-Farre E, Sunol C. 1994. Disruption of GABA-dependent chloride flux by cyclodienes and hexachlorocyclohexanes in primary cultures of cortical neurons. J Pharmacol Exp Ther 271(3) 1616-1623. 

Tun C, Guo W, Nguyen H, Yun B, Libby RT, Morrison RS, Garden GA (2007) Activation of the extrinsic caspase pathway in cultured cortical neurons requires p53-mediated down-regulation of the X-linked inhibitor of apoptosis protein to induce apoptosis. J Neurochem 102 1206-1219... 

The neurons from which NTs are released number more than 7 billion in the human brain. Each (Fig. 1.2) consists of a cell body, the soma or perikaryon, with one major cytoplasmic process termed the axon, which projects variable distances to other neurons, e.g. from a cortical pyramidal cell to adjacent cortical neurons, or to striatal neurons or to spinal cord motoneurons. Thus by giving off a number of branches from its axon one neuron can influence a number of others. All neurons, except primary sensory neurons with cell bodies in the spinal dorsal root ganglia, have a number of other, generally shorter, projections running much shorter distances among neighbouring neurons like the branches of a tree. These processes are the dendrites. Their... 

Figure 2.14 Relation between the EEG recorded from an epileptic focus on the surface of the cerebral cortex (EEG) and the activity of a single cortical neuron recorded extracellularly (e.c.) and intracellularly (i.c.) during an experimental epilepsy induced by topical application of penicillin. Note that the large EEG excursions correspond to the large (synchronised) depolarisations of the neuron, not to action potential discharges. (Adapted from Brain Res. 52 Ayala, GF et al. Genesis of Epileptic Interictal Spikes. New Knowledge of Cortical Feedback systems suggests a Neurophysiological Explanation of Brief Paroxysms, 1-17 (1973) with permission from Elsevier Science)...

These opposing effects of tryptamine and 5-HT are also seen when they are applied directly to cortical neurons by iontophoresis. Tryptamine is predominantly depressant while 5-HT is mainly excitatory. Surprisingly, the 5-HT antagonist metergoline is more effective against tryptamine and the depressant effects. When the medial Raphe nucleus... 

A DA antagonist could certainly counter the increased mesolimbic activity and the positive symptoms. On the other hand, they would not be expected to reduce negative symptoms if these arise through an already inadequate DA influence. This fits with clinical experience because most of the neuroleptics are ineffective in treating negative symptoms. In fact if the negative symptoms do result from loss of the actual cortical neurons, rather than input to them, they will be difficult to reverse and much will depend on the precise role of DA in the DLPFC (see later). 

The more synchronised the activity of the cortical neurons, the greater the summation of currents and the larger and slower the EEG wave, as in the sleep pattern (Fig. 22.4). While there are some dissociations between EEG pattern and behavioural states, the EEG offers one way of determining experimentally the pathways (and neurotransmitters) that control arousal and sleep, and can be regarded as an important objective measurement of the cortical correlates of sleep and waking. 

More recently, another series of di-r-butyl phenol antioxidants represented by LY231617 has been developed. These compounds inhibit iron-dependent lipid j>eroxidation and antagonize hydrogen peroxide-induced cortical neuronal injury [at 5 /iM LY231617 increased neuron viability fiom 20% (untreated) to 70%]. Interestingly, LY231617 does not inhibit the key enzymes of... 

Two possible pathways for the biosynthesis of 2-AG have been proposed (1) a phospholipase C (PLC) hydrolysis of membrane phospholipids followed by a second hydrolysis of the resulting 1,2-diacylglycerol by diacylglycerol lipase or (2) a phospholipase Ai (PLA,) activity that generates a lysophospholipid, which in turn is hydrolyzed to 2-AG by lysophospholipase C (Fig. 5) (Piomelli, 1998). Alternative pathways may also exist from either triacylglycerols by a neutral lipase activity or lysophosphatidic acid by a dephosphorylase. The fact that PLC and diacylglycerol lipase inhibitors inhibit 2-AG formation in cortical neurons supports the contention that 2-AG is, at least predominantly, biosynthesized by the PLC pathway (Stella, 1997). However, a mixed pathway may also be plausible. 

Raff I m not aware that anyone has done it in that way, but it is an important question. Cortical neuron precursors in the mouse, for example, go through many fewer divisions than do cortical precursors in primates, which is why mice have a smaller cortex than primates. The question is why is the behaviour of the two types of precursors so different Is it because intrinsic timers are set differently Is it because the mitogens and growth factors that drive proliferation are around for longer in primates These are questions that could be addressed without a need for new technology. 

Noradrenaline acts on three types of receptor. The ai receptors mediate the main excitatory effects of noradrenaline upon wake-active neurons in the dorsal raphe, basal forebrain, and elsewhere (Vandermaelen Aghajanian, 1983 Nicoll, 1988 Fort et al., 1995 Brown et al., 2002). The a2 receptors mediate inhibitory effects of noradrenaline, e.g. on noradrenaline neurons themselves and on cholinergic brainstem neurons (Williams et al., 1985 Williams Reiner, 1993). The (3-receptors modulate neurons in a more subtle fashion, increasing excitability via blockade of afterhyperpolarizations in hippocampal and cortical neurons (Haas Konnerth, 1983). Activation of (3-receptors also promotes synaptic plasticity via activation of the cyclic-AMP-dependent kinase (PKA) and cyclic AMP response element binding protein (CREB) signal transduction pathway (Stanton Sarvey, 1987 Cirelli et al., 1996). 

The amino acid glutamate is the most widely used excitatory neurotransmitter in the central nervous system of mammals. Glutamate is the primary neurotransmitter used by the vast majority of reticular formation, thalamic and cortical neurons, which play a crucial role in the generation of the characteristic electrical activity as recorded in the electroencephalogram (for details see Steriade McCarley (2005)). The activity of these neurons is tightly regulated by the other neurotransmitters described in this chapter. 

Bayer, L., Serafin, M., Eggermann, E. et al. (2004). Exclusive postsynaptic action of hypocretin-orexin on sublayer 6b cortical neurons. J. Neurosci. 24, 6760-4. 

Mouse cortical neuron culture Ammonium formate On analytical column LCQ DECA XP SEQUEST (Yu et al., 2004)... 

FIGURE 1-7 A lipofiiscin granule from a cortical neuron shows membrane-bound lipid (dense) and a soluble component (gray). The denser component is lamellated. The lamellae appear as paracrystalline arrays of tubular profiles when sectioned transversely (arrow). The granule is surrounded by a single-unit membrane. Free ribosomes also can be seen. X96,000. 

Neuregulins are highly expressed in the nervous system by neuroblasts, cortical neurons, peripheral sensory ganglionic cells and spinal motor neurons as well as myelinforming glia. 

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