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There are significant age-related changes in autonomic nervous system function that are responsible for an impaired ability to adapt to environmental or intrinsic visceral stimuli in the elderly. We review data on changes in autonomic nervous system regulation of cardiovascular and urinary function, as well as data on strategies to improve function. There are data showing alterations in peripheral and central autonomic nerve activity, and decreases in neurotransmitter receptor action that lead to diminished autonomic reactivity (e.g. blood pressure and cerebral blood flow regulation) and poorly coordinated autonomic discharge (e.g. bladder function). Simple strategies for autonomic function improvement and increasing cortical blood flow include walking and somatic afferent stimulation (e.g. stroking skin or acupuncture) to increase sympathetic, parasympathetic and central cholinergic activity. Geriatr Gerontol Int 2010; 10 (Suppl. 1): S127-S136.

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The intracranial neural vasodilative system of cholinergic fibers projecting from the basal forebrain to the cortex was discovered by Biesold, Inanami, Sato and Sato (Biesold, D., Inanami, O., Sato, A., Sato, Y., 1989. Stimulation of the nucleus basalis of Meynert increases cerebral cortical blood flow in rats. Neurosci. Lett. 98, 39-44) using laser Doppler flowmetry in anesthetized rats. This cholinergic vasodilative system, which operates by increasing extracellular ACh release, relies upon activation of both muscarinic and nicotinic cholinergic receptors in the parenchyma of the cortex. Further, the involvement of nitric oxide in this cholinergic vasodilation, indicates the necessity to this system of neurons, which contain nitric oxide synthase. The increase in cortical blood flow elicited by this cholinergic vasodilative system is independent of systemic blood pressure and is not coupled to cortical metabolic rates. This cholinergic vasodilative system may be activated by somatic afferent stimulation. Most of the data presented here were obtained in anesthetized animals.

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Differential vulnerability among motor neuron (MN) subtypes is a fundamental feature of amyotrophic lateral sclerosis (ALS):Amyotrophic lateral sclerosis (ALS) is an adult-onset, fatal neurodegenerative disease characterized by progressive degeneration of motor neurons (MNs) and skeletal muscle denervation and atrophy. However, strong evidence suggests the MN pools involved in eye movement and pelvic sphincter control are largely spared in ALS 1,2 . Moreover, within a given MN pool, differences in vulnerability between MN subtypes (e.g. alpha/gamma or fast/ slow) are a fundamental but unexplained feature of ALS. α -MNs are divided into three subtypes: fast-twitch fatigable (FF), fast-twitch fatigue-resistant (FR) and slow-twitch fatigue-resistant (S). The large-diameter low-excitability FF MNs innervate type IIB muscle fibers and degenerate early in the ALS disease course, while medium-excitability FR MNs innervating type IIA muscle fibers follow after that. The high-excitability S MNs innervating type I muscle fibers are largely resistant to degeneration and are preserved, even late in the disease course. Although molecular markers for MNs have been available for several years [3][4][5][6] , the absence of markers that distinguish FF from FR MNs has hindered analysis of the early selective degeneration of MN subtypes.

Using single unit nerve recording techniques in rats, the present experiment aimed to determine which specific population of afferent nerve fibers (groups I, II, III and IV) in the dorsal roots at the 4th or 5th lumbar segments (L4 or L5) are activated during manual acupuncture needle stimulation. An acupuncture needle 300-340 microm in diameter was inserted into the skin and underlying muscles around the Zusanli acupoint (ST36) area in the hindlimbs, and was manually rotated right and left at a frequency of about 1 Hz for 1 min. The dorsal root of the L4 and L5 spinal nerve was cut close to the entrance into the spinal cord after laminectomy and dissected free to record unitary afferent nerve activity. A single afferent fiber activated by acupuncture stimulation was identified by the identical shape of the discharge spikes during stimulation and during electrically evoked action potentials induced by single pulse electrical stimulation of the sciatic nerve. The conduction velocity of the afferent fiber was calculated by the latency of the electrically evoked action potential. A total of 35 units were intentionally recorded from all animals in order to include all 4 afferent fiber groups. Units were spontaneously silent in the absence of stimulation, while all units responded to ipsilateral manual rotation of the acupuncture needle. The conduction velocity of all 35 units ranged between 0.8 and 86.0 m/s, thus belonging to groups I-V fibers. Mean conduction velocity of groups I, II, III and IV were 57.9 m/s (n = 13), 42.9 m/s (n = 11), 10.3 m/s (n = 6) and 1.2 m/s (n = 5), respectively. Mean discharge rates during acupuncture stimulation of groups I, II, III and IV afferents were 7.4 Hz, 6.2 Hz, 4.7 Hz and 0.4 Hz, respectively. Discharge rates of group IV afferent fibers were significantly lower than those of groups I, II and III afferents. It was concluded that manual acupuncture needle stimulation to the hindlimbs activated afferent nerve fibers belonging to all four groups of afferents in rats. It is suggested that all four groups of somatic afferents activated by manual acupuncture stimulation will elicit various effects when action potentials are delivered to the central nervous system.