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Functional Neurology
Published in James Crossley, Functional Exercise and Rehabilitation, 2021
Neuroscience has found evidence that certain movement patterns are so deeply embedded within the nervous system of humans and other animals, that they can control movements with negligible input from higher centers of the brain. Fish can swim, hamsters chew, snakes crawl and humans can walk, almost subconsciously, with little input from higher, conscious areas of the brain. Neuroscientists refer to these fundamental templates as ‘central pattern generators’ (CPG). CPGs act from within the spinal cord and brain stem, coordinating rhythmic movement patterns to such an extent they can almost take care of themselves. You might have seen gruesome films of decapitated frogs still kicking their legs as if they are swimming. We also retain templates for basic movement patterns like walking, running and crawling.
Control of Movement and Posture
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Rhythmic behavior such as chewing, breathing, and locomotion is controlled by specialized neuronal circuits, referred to as central pattern generators (CPGs), which are mainly responsible for generating the rhythm and pattern of the rhythmic activity. More complex CPGs are involved in organized, stereotyped behavior such as swallowing, coughing, and sneezing and which require coordination of many different muscles. In some continuous rhythmic behavior, the periodicity is generated by neurons having pacemaker properties, as in the case of the heartbeat.
Transmitter/Peptide Interactions in NTS Neuronal Circuits
Published in I. Robin A. Barraco, Nucleus of the Solitary Tract, 2019
Modulators also interact with membrane potential changes related to the activity of central pattern generators. Modulators in the NTS control voltage and chemically gated currents which, like IM, are inactive near the resting membrane potential and activate with a slow time constant upon de- or hyperpolarization by a few millivolts. These currents probably operate in vivo during periodic depolarizations of respiratory neurons because (1) muscarinic excitation of respiratory neurons has been described in vivo,46 and (2) the few millivolts required for the activation of IM are compatible with the amplitude of respiratory synaptic potentials.2 Intracellular injections of blockers in vivo appears to be a promising method to investigate how messenger-controlled currents interact with function-related potentials in the brainstem.47
Control strategy for intraspinal microstimulation based on central pattern generator
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Xiongjie Lou, Yan Wu, Song Lu, Xiaoyan Shen
The central pattern generator (CPG) is a motor neuronal network located in the spinal cord that can generate rhythmic control output to stimulate muscle movement and control the rhythmic movement of hindlimbs (Rybak et al. 2006; Asadi and Erfanian 2011). Therefore, by electrically stimulating the site of CPG on the spinal cord, we can use a small number of electrodes to restore the movement of the paralyzed lower limbs in a way that is closer to the physiological state. Previous studies have demonstrated that the polarity reversal of stimulation signals reverses the alternating motor pattern in the spinal cord CPG site (Shen et al. 2022). The positive pulse stimulates this CPG site to induce forward and backward movements of the left and right hindlimbs, respectively. Once the polarity of the stimulation signal is reversed, negative pulse stimulation is used to induce backward and forward movements of the left and right hindlimbs, respectively. Therefore, we can realise a complete alternating movement of the rat hindlimbs by combining the two pulse signals with opposite polarities in a certain time sequence.
Treatment with the essential amino acid L-tryptophan reduces masticatory impairments in experimental cerebral palsy
Published in Nutritional Neuroscience, 2021
Diego Cabral Lacerda, Raul Manhães-de-Castro, Henrique José Cavalcanti Bezerra Gouveia, Yves Tourneur, Barbara Juacy Costa de Santana, Renata Emmanuele Assunção Santos, Jacques Olivier-Coq, Kelli Nogueira Ferraz-Pereira, Ana Elisa Toscano
Rhythmical oral motor activity such as sucking and chewing is under the control of a network of brainstem neurons [11]. The regulation of these activities occurs in the brainstem, particularly in the central pattern generators (CPGs)[12,13]. Sucking and chewing CPGs extend from the rostral poles of the trigeminal motor nucleus (TMN) to the rostral pole of the facial nucleus[12]. In addition, the maturation of sucking and chewing involves neurotransmitter systems, including serotonin (5-HT)[14]. Several studies demonstrate that the serotonergic system is crucial to control TMN activities[14–16]. The TMN receives a dense serotonergic input and contains serotonergic receptors[14], which facilitate the discharges of trigeminal motoneurons. Moreover, 5-HT is involved in the morphogenesis of the craniofacial, dental, bone and muscle structures of the stomatognathic system [17,18], and all 5-HT receptor subtypes are expressed in the developing craniofacial structures as well [18]. Thus, an intact serotonergic system is necessary for the maturation of the neural structures involved in sucking and chewing.
Spinal cord injury and diaphragm neuromotor control
Published in Expert Review of Respiratory Medicine, 2020
Matthew J. Fogarty, Gary C. Sieck
There is considerable regenerative neuroplastic capacity in the neural inputs onto phrenic motor neurons following spinal cord injury. These involve inputs from contralateral bulbospinal projections, local segment interneurons and ascending projections from more caudal regions of the spinal cord [52,99,101–104,109,111,117–119]. In cases where ventilatory behaviors are impaired, such as in the cervical spinal hemisection model, synaptic stripping occurs for the axotomized inputs, with a marked reduction in the number of excitatory glutamatergic pre-synaptic terminals remaining on phrenic motor neurons [120]. In a preliminary study from our group, we found that following unilateral cervical spinal hemisection, the extent of loss of glutamatergic presynaptic terminals (synaptic stripping) is much greater on smaller phrenic motor neurons. This observation confirms that descending inspiratory presynaptic drive for ventilatory behaviors is primarily ipsilateral [49–55] and further suggests this drive is distributed disproportionately to smaller phrenic motor neurons. It is possible that a significant proportion of presynaptic drive for expulsive/straining behaviors does not emanate from a supraspinal origin. In limb locomotor control, the central pattern generator and presynaptic neurons are located segmentally in the spinal cord [1]. This may also be the case for expulsive/straining behaviors of the diaphragm [11,13,17–19,68], particularly those that involve co-activation of chest wall and abdominal muscles (Figure 3).