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Pathophysiological mechanisms of chronic pain
Published in Jennifer Corns, The Routledge Handbook of Philosophy of Pain, 2017
Primary afferents may also make functional connections with descending neurons that traverse the cord from many areas of the brain including the cortex, midbrain, and brainstem. Thus the cord acts as a “selective hub” where sensory information is initially processed and modulated; peripheral inputs are not merely transmitted centrally.
Motor Cortex Control of a Complex Peripheral Apparatus: The Neuromuscular Evolution of Individuated Finger Movements
Published in Alexa Riehle, Eilon Vaadia, Motor Cortex in Voluntary Movements, 2004
Marc H. Schieber, Karen T. Reilly, Catherine E. Lang
From the viewpoint of neuromuscular evolution, many features of motor cortex organization become easier to understand. Output neurons in layer V of Ml have several features of the descending neurons in the evolutionary schema described above. Many single Ml neurons have outputs that diverge to innervate multiple spinal motoneuron pools.3136 Spike-triggered averaging has shown that the discharges of single M1 neurons may produce effects in the motoneuron pools of several forearm and intrinsic hand muscles.3233 Some Ml neurons that project to wrist and finger muscles also produce effects in elbow or shoulder muscles.37 These divergent connections from many Ml neurons to multiple muscles may be the remnants of connections to common primordial muscles that subsequently divided. The fact that divergent connections remain today suggests, however, that they are important to the present function of the motor cortex. Their importance may lie in the fact, described above, that the most frequently performed behavioral tasks, such as grasping, require the simultaneous contraction of multiple muscles acting on multiple fingers. These movements may be controlled most efficiently through Ml neurons with divergent connections to multiple muscles.
Effect of selective attention on auditory brainstem response
Published in Hearing, Balance and Communication, 2023
Sathish Kumar, Srikanth Nayak, Arivudai Nambi Pitchai Muthu
The auditory system of mammals consists of afferent and efferent auditory pathways, indicating a bidirectional flow of information. The efferent system consists of descending neural chains and loops that innervate at various auditory system levels, including the medial geniculate body, inferior colliculus, superior olivary complex, cochlear nucleus, and the cochlea [8,9]. The activation of these descending neurons seems to influence the various cortical and subcortical processes, including the response plasticity [10], frequency selectivity, and tuning [11]. Thus, the efferent pathways may provide a mechanism for an influence of attention on the neural activity of various structures along the auditory pathway. The attentional mechanism can be studied behaviourally using speech perception in noise, sound localisation in noise, and dichotic hearing tests [12]. In addition, neuroimaging techniques like functional Magnetic Resonance Imaging [13–15] and electrophysiological techniques like auditory evoked potentials can provide information about the attentional modulation at various structures.
An up-to-date overview of the pharmacotherapeutic options for premature ejaculation
Published in Expert Opinion on Pharmacotherapy, 2022
Iraklis Mitsogiannis, Athanasios Dellis, Athanasios Papatsoris, Mohamad Moussa
Normal ejaculation consists of two consecutive phases, emission and expulsion, which are under the control of the autonomic and somatic nervous systems, respectively. Emission is characterized by the passage of semen fluid from the accessory genital glands into the posterior urethra and is controlled by autonomic stimuli originating from the pelvic plexus. Expulsion is the second phase of antegrade ejaculation, during which passage of semen from the posterior urethra to external urethral meatus occurs as a result of rhythmic pelvic striated muscle contractions [20]. Ejaculation is a highly coordinate process controlled by spinal and cerebral centers, with serotonin being the primary neurotransmitter involved in the central control of ejaculation. Serotonin can be found in the brain and the descending neurons to the spinal cord and serotonergic neurons are deemed to act on post-synaptic receptors exerting an inhibitory effect on ejaculation [20]. Animal studies have shown serotonin receptor subtypes 5-H1T1B and 5-H1T2C to mediate inhibition of ejaculation, whereas 5-H1T1A subtype, which can be found in abundance in the nuclei raphe and in spinal centers, primarily exert a pre-ejaculatory effect [21]. The inhibitory role of serotonin in the process of ejaculation formed a basis for the pharmacological treatment of PE.
Patients with chronic musculoskeletal pain present low level of the knowledge about the neurophysiology of pain
Published in European Journal of Physiotherapy, 2021
Paula S. Ferreira, Leticia A. Corrêa, Juliana V. Bittencourt, Felipe J. J. Reis, Ney Meziat-Filho, Leandro A. C. Nogueira
The three groups varied in the percentages of correct answers despite the nonsignificant result. All patients classified with the predominance of peripheral neuropathic pain inaccurate responded the items 7, 8, 9 and 10 in the current study. Although the individual analysis of the items demonstrated a trend to identify specific items with lack of neurophysiological knowledge, there were no statistically significant differences between the groups. The low number of participants recruited here may influence the outcome. The items ‘descending neurons are always inhibitory’, ‘when you are injured, special receptors convey the danger message to your spinal cord’ and ‘chronic pain means that an injury hasn’t healed properly’ were the most difficult items for our participants, respectively. Likewise, Alodaibi et al. [36] described the item ‘when you are injured, special receptors convey the danger message to your spinal cord’ and ‘chronic pain means that an injury hasn’t healed properly’ as the second and third items with lower values of correct answers for physiotherapist students, respectively. Accordingly, an educational programme of pain should encompass these items to enhance the neurophysiology knowledge of pain.