Neuronal Firing Patterns and Models
Nassir H. Sabah in Neuromuscular Fundamentals, 2020
Another type of synchrony may be forced on target cells of inhibitory interneurons. In Figure 8.5a, a single GABAergic interneuron is shown innervating several pyramidal cells. If the inhibition is strong enough and if generated at the somata, it would inhibit the three pyramidal cells, but, at the end of the ipsps, the pyramidal cells will fire in near synchrony (Figure 8.5b). The firing of the target cells following an ipsp can be due to release of inhibition or to rebound depolarization, as mentioned earlier in connection with T-type Ca2+ currents and the Ih current (Section 7.3). The synchronizing action of a single inhibitory interneuron, illustrated in Figure 8.5, is potentiated by the aforementioned synchronized firing of networks of GABAergic interneurons because several interneurons of the same network may converge on a given pyramidal cell, and the synchrony of a network of interneurons will, in turn, synchronize the firing of a larger population of pyramidal cells. The pyramidal cells are thus entrained to fire synchronously at a rate determined by that of the GABAergic network. In general, entrainment is a phenomenon by which some external stimulation synchronizes the firing of a group of neurons at a frequency that is different from any native rhythm that the group of neurons may have.
Endocrine Functions of Brain Dopamine
Nira Ben-Jonathan in Dopamine, 2020
Living organisms have an internal clock that helps the body adapt to the external environment. Throughout the 24-h day, the clock regulates many physiological, endocrine, and mental processes, including sleep, body temperature, metabolism, blood pressure, hormone release and alertness. Circadian rhythms are endogenously generated ~24-h biological rhythms that are organized in two levels: a molecular level represented by the clock genes, and a systemic regulatory level represented by the neuroendocrine networks. The circadian oscillation is synchronized by external environmental cycles, primarily the light/dark cycle of the geophysical day and night. External rhythmic events that can synchronize biological rhythms are called zeitgebers or synchronizers. “Entrainment” is defined as a synchronization between oscillators with different but similar periods that occurs when one of the oscillators imposes its period on the other.
The Internal Milieu Brain and Body
Rolland S. Parker in Concussive Brain Trauma, 2016
Entrainment: This is the process by which an endogenous rhythm is regulated by a zeitgeber (an external cue, e.g., the light-dark cycle) to synchronize endogenous rhythms. Rhythms are normally entrained to a light-dark cycle with a period of 24 h and a stable phase relationship to the timing of the solar cycle. It is mediated by the photopigment melanopsin, which is located in retinal ganglion cells that project through the RHT to the SCN and the intrageniculate leaflet (IGL) independently of the familiar retinal circuits to the geniculate colliculus and accessory optic systems. The body’s natural rhythm is now estimated at 24.2 h (Czeisler et al., 2005), which is periodically reset by light stimuli. For the body clock to be useful, it should be adjusted to the actual solar day. Rhythmic cues in the environment are known as zeitgebers (time-givers) whose effect on the body clock depends on its time of presentation (a phase advance, delay, or no phase shift). The primary zeitgebers are the light-dark cycle and rhythmic secretion of the pineal hormone melatonin, during nocturnal sleep in healthy people. Circadian rhythms persist in the absence of a light-dark cycle, with a free-running period that is slightly more than 24 h. The mammalian eye appears to have a circadian pacemaker maintaining the rhythm of visual sensitivity.
Evidence of Implicit and Explicit Motor Learning during Gait Training with Distorted Rhythmic Auditory Cues
Published in Journal of Motor Behavior, 2023
Chelsea Parker Duppen, Hailey Wrona, Eran Dayan, Michael D. Lewek
The human neuromuscular system is remarkably sensitive to rhythm, such that movement tends to entrain to rhythmic auditory cues, like music or metronomes (Thaut et al., 2014; Thaut & Kenyon, 2003). As we drive, we tap our fingers on the steering wheel while listening to music, we run faster when a quicker tempo song plays through our headphones, and we bounce with the crowd at a concert. These processes are illustrative of the entrainment process that occurs when movement is synchronized with a rhythmic auditory cue. The subconscious nature of entrainment suggests that a portion occurs implicitly (Heideman et al., 2015; Praamstra et al., 2006), and likely involves the cerebellum and a distributed network extending from the inferior colliculus to the motor areas (sensorimotor cortex and supplementary motor area) (Del Olmo et al., 2007; Fujioka et al., 2012; Grahn et al., 2011; Thaut et al., 2014; Tierney & Kraus, 2013).
The Effect of Rhythm Abilities on Metronome-Cued Walking with an Induced Temporal Gait Asymmetry in Neurotypical Adults
Published in Journal of Motor Behavior, 2022
Lucas D. Crosby, Joyce L. Chen, Jessica A. Grahn, Kara K. Patterson
Human movement and rhythm are intrinsically linked. There is widespread neural connectivity between auditory and motor systems of the brain (Chen et al., 2008), thus auditory perception of a regular rhythm primes the motor system leading to rhythmical movement (Comstock et al., 2018). Through this process, known as entrainment, we can synchronize our movements to the frequency of an externally perceived rhythm. An example of entrainment occurs when one taps their foot to the music’s beat. When the rhythm of the auditory stimulus is regular, we can cognitively infer a beat from the regular sound pattern, synchronize to it by predicting the regular pattern – a uniquely human feat (Levitin et al., 2018). While animals such as cockatiels and macaque monkeys can synchronize to a beat, humans are superior at this task (Zarco et al., 2009) and can even continue the rhythmical movement when the auditory stimulus is removed (Levitin et al., 2018). This inherent auditory-motor entrainment underlies the rationale for prescribing rhythm- and music-based therapeutic approaches for the rehabilitation of motor deficits observed in neurological conditions such as brain injury and stroke.
Do patients with PD benefit from music assisted therapy plus treadmill-based gait training? An exploratory study focused on behavioral outcomes
Published in International Journal of Neuroscience, 2020
Rosaria De Luca, Desiree Latella, Maria Grazia Maggio, Simona Leonardi, Chiara Sorbera, Giuseppe Di Lorenzo, Tina Balletta, Antonio Cannavò, Antonino Naro, Federica Impellizzeri, Rocco Salvatore Calabrò
We may argue that MT applied to the Biodex treadmill may be related to the creation of an external timekeeper that supports the weakened role of the basal ganglia [42], perhaps through the involvement of compensatory networks involving the cerebellum [43]. Regarding the motor outcomes of our exploratory study, we found better improvement in the EG (as per FIM scores and 10mWT). Rochester [44] demonstrated that a 3-week-training with RAS implied a learning effect that improved gait, freezing and movements fluidity. This was probably due to the “boosting” of brain plasticity within the internal time-keeping and rhythm formation process, known as entrainment mechanism. The latter can be enhanced by both a selected music [43] and the use of technologies that utilize interactive computer-generated systems for improving brain-body interaction and sensory-motor integration.
Related Knowledge Centers
- Advanced Sleep Phase Disorder
- Chronobiology
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- Sleep Hygiene
- Suprachiasmatic Nucleus
- Zeitgeber
- Phase Response Curve
- Hypothalamus