Mechanisms Explaining Transitions between Tonic and Phasic Firing in Neuronal Populations as Predicted by a Low Dimensional Firing Rate Model

Rǎdulescu, Anca

doi:10.1371/journal.pone.0012695

Cited by 12 publications

(11 citation statements)

References 87 publications

(161 reference statements)

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“…This is different from the activity of other types of neurons (e.g. dopaminergic neurons in the ventral tegmental area of the midbrain 47 , which exhibit ongoing (tonic) firing activity interleaved by brief periods of bursting (phasic) activity 48 . In this context, the Wilson-Cowan type model used here allows us to accurately capture the temporal evolution of the mean level of activity of distinct neuronal populations without adding further information on the specific firing activity of individual cells.…”

Section: Discussionmentioning

confidence: 72%

Global and local excitation and inhibition shape the dynamics of the cortico-striatal-thalamo-cortical pathway

Rǎdulescu

Herron

Kennedy

et al. 2017

Sci Rep

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The cortico-striatal-thalamo-cortical (CSTC) pathway is a brain circuit that controls movement execution, habit formation and reward. Hyperactivity in the CSTC pathway is involved in obsessive compulsive disorder (OCD), a neuropsychiatric disorder characterized by the execution of repetitive involuntary movements. The striatum shapes the activity of the CSTC pathway through the coordinated activation of two classes of medium spiny neurons (MSNs) expressing D1 or D2 dopamine receptors. The exact mechanisms by which balanced excitation/inhibition (E/I) of these cells controls the network dynamics of the CSTC pathway remain unclear. Here we use non-linear modeling of neuronal activity and bifurcation theory to investigate how global and local changes in E/I of MSNs regulate the activity of the CSTC pathway. Our findings indicate that a global and proportionate increase in E/I pushes the system to states of generalized hyper-activity throughout the entire CSTC pathway. Certain disproportionate changes in global E/I trigger network oscillations. Local changes in the E/I of MSNs generate specific oscillatory behaviors in MSNs and in the CSTC pathway. These findings indicate that subtle changes in the relative strength of E/I of MSNs can powerfully control the network dynamics of the CSTC pathway in ways that are not easily predicted by its synaptic connections.

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Section: Discussionmentioning

confidence: 72%

Global and local excitation and inhibition shape the dynamics of the cortico-striatal-thalamo-cortical pathway

Rǎdulescu

Herron

Kennedy

et al. 2017

Sci Rep

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“…Given that the stretch reflex loop is sensitive to both the muscle length and velocity, we analyzed the responses for both the phasic and tonic intervals of stretch [21]. We segmented the responses per [22, 23]: ( i ) the phasic interval was 1400 (ms) starting at the onset of the perturbation; ( ii ) the tonic interval was 450 (ms) following the phasic interval.…”

Section: Methodsmentioning

confidence: 99%

Neuromorphic meets neuromechanics, part II: the role of fusimotor drive

et al. 2017

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Objective We studied the fundamentals of muscle afferentation by building a neuro-mechano-morphic system actuating a cadaveric finger. This system is a faithful implementation of the stretch reflex circuitry. It allowed the systematic exploration of the effects of different fusimotor drives to the muscle spindle on the closed-loop stretch reflex response. Approach As in Part I of this work, sensory neurons conveyed proprioceptive information from muscle spindles (with static and dynamic fusimotor drive) to populations of α-motor neurons (with recruitment and rate coding properties). The motor commands were transformed into tendon forces by a Hill-type muscle model (with activation-contraction dynamics) via brushless DC motors. Two independent afferented muscles emulated the forces of flexor digitorum profundus and the extensor indicis proprius muscles, forming an antagonist pair at the metacarpophalangeal joint of a cadaveric index finger. We measured the physical response to repetitions of bidirectional ramp-and-hold rotational perturbations for 81 combinations of static and dynamic fusimotor drives, across four ramp velocities, and three levels of constant cortical drive to the α-motor neuron pool. Results We found that this system produced responses compatible with the physiological literature. Fusimotor and cortical drives had nonlinear effects on the reflex forces. In particular, only cortical drive affected the sensitivity of reflex forces to static fusimotor drive. In contrast, both static fusimotor and cortical drives reduced the sensitivity to dynamic fusimotor drive. Interestingly, realistic signal-dependent motor noise emerged naturally in our system without having been explicitly modeled. Significance We demonstrate that these fundamental features of spinal afferentation sufficed to produce muscle function. As such, our neuro-mechano-morphic system is a viable platform to study the spinal mechanisms for healthy muscle function — and its pathologies such as dystonia and spasticity. In addition, it is a working prototype of a robust biomorphic controller for compliant robotic limbs and exoskeletons.

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“…Indeed, in vivo rodent and monkey VTA and SN DA neurons display basal tonic firing rates of up to 20 Hz (Radulescu, 2010). This view predicts that these neurons should show decreased rates of firing during the sexual refractory period.…”

Section: The Relation Between the Freudian Theory Of Drives And The Nmentioning

confidence: 99%

Reading the Freudian theory of sexual drives from a functional neuroimaging perspective

Stoléru

2014

Front. Hum. Neurosci.

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One of the essential tasks of neuropsychoanalysis is to investigate the neural correlates of sexual drives. Here, we consider the four defining characteristics of sexual drives as delineated by Freud: their pressure, aim, object, and source. We systematically examine the relations between these characteristics and the four-component neurophenomenological model that we have proposed based on functional neuroimaging studies, which comprises a cognitive, a motivational, an emotional and an autonomic/neuroendocrine component. Functional neuroimaging studies of sexual arousal (SA) have thrown a new light on the four fundamental characteristics of sexual drives by identifying their potential neural correlates. While these studies are essentially consistent with the Freudian model of drives, the main difference emerging between the functional neuroimaging perspective on sexual drives and the Freudian theory relates to the source of drives. From a functional neuroimaging perspective, sources of sexual drives, conceived by psychoanalysis as processes of excitation occurring in a peripheral organ, do not seem, at least in adult subjects, to be an essential part of the determinants of SA. It is rather the central processing of visual or genital stimuli that gives to these stimuli their sexually arousing and sexually pleasurable character. Finally, based on functional neuroimaging results, some possible improvements to the psychoanalytic theory of sexual drives are suggested.

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Mechanisms Explaining Transitions between Tonic and Phasic Firing in Neuronal Populations as Predicted by a Low Dimensional Firing Rate Model

Cited by 12 publications

References 87 publications

Global and local excitation and inhibition shape the dynamics of the cortico-striatal-thalamo-cortical pathway

Global and local excitation and inhibition shape the dynamics of the cortico-striatal-thalamo-cortical pathway

Neuromorphic meets neuromechanics, part II: the role of fusimotor drive

Reading the Freudian theory of sexual drives from a functional neuroimaging perspective

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