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Clinical Neuroscience

JANUARY 30, 2021

Neuroscience highlights: The mirror inside our brain

KRABÓTH Zoltán, KÁLMÁN Bernadette

Over the second half of the 19th century, numerous theories arose concerning mechanisms involved in understanding of action, imitative learning, language development and theory of mind. These explorations gained new momentum with the discovery of the so called “mirror neurons”. Rizzolatti’s work inspired large groups of scientists seeking explanation in a new and hitherto unexplored area of how we perceive and understand the actions and intentions of others, how we learn through imitation to help our own survival, and what mechanisms have helped us to develop a unique human trait, language. Numerous studies have addressed these questions over the years, gathering information about mirror neurons themselves, their subtypes, the different brain areas involved in the mirror neuron system, their role in the above mentioned mechanisms, and the varying consequences of their dysfunction in human life. In this short review, we summarize the most important theories and discoveries that argue for the existence of the mirror neuron system, and its essential function in normal human life or some pathological conditions.

Clinical Neuroscience

JANUARY 30, 2016

Facial virus inoculations infect vestibular and auditory neurons in rats

HELFFERICH Frigyes, LOURMET Guillaume, SZABÓ Rebeka Éva, BOLDOGKŐI Zsolt, PALKOVITS Miklós

Background and purpose – There is growing evidence for the viral origin of the Bell’s facial palsy, vestibular neuritis and sudden sensorineural hearing loss, however their exact pathophysiology is still unknown. We investigated the possibility of brainstem infections following peripheral viral inoculations in rats. Methods – Pseudorabies virus, a commonly used neurotropic viral retrograde tracer was injected into the nasolabial region of rats. Five and 6 days after injections, infected brainstem nuclei were demonstrated by immunohistochemical techniques. Results – Infected neurons were found in the motor facial, the medial vestibular, and the sensory trigeminal nuclei, as well as in the medial nucleus of the trapezoid body. Conclusion – Pseudorabies virus infects auditory and vestibular sensory neurons in the brainstem through facial inoculation. The possible routes of infections: 1. trans-synaptic spread constituted by facio-vestibular anastomoses: primarily infected motor facial neuron infects neurons in the medial vestibular nucleus, 2. via trigeminal sensory nerves: the sensory trigeminal complex innervated by GABAergic medial vestibular neurons, and 3. one bisynaptical route: infected facial motoneurons may receive indirect input from the medial vestibular nucleus and the trapezoid body via connecting neurons in the sensory trigeminal complex. We may assume that latent infections of these areas may precede the infections of the peripheral organs and the reactivation of the virus exerts the symptoms.

Lege Artis Medicinae

SEPTEMBER 30, 2020

[The pain-trigger role of cytokines in the nervous system – the direct analgesic effect of anti-cytokine therapy ]

HODINKA László, VERECKEI Edit

[Nociceptive, neuropathic and central me­chanisms are involved in the perception, transmission and processing of chronic pain and shaping of cerebral pain image. Alar­mins – molecules alarming defence and signing the presence of pathogens and tissue damage - trigger a series of pathogenic events resulting in inflammatory pain stimuli. Proinflammatory cytokines play a determining role in the pain perception at the level of the nervous system. Continuous inflammatory stimuli while sensitizing the periferic and central neurons activate the pain-related cerebral areas and develop the complex pain image, the pain matrix. Ce­reb­ral functional connections are operating in networks and can be visualized by functional MRI. Cytokines activate the neurons directly or indirectly by other neuromediators. Cytokine receptors are expressed on no­ciceptors and even on higher-level neurons and on various non-neural cells, such as microglia and astrocytes. The most ubiquitous cytokines are the Tumour Necrosis Factor and Interleukin 6 in the nervous sys­tem. The signaling pathways are the Nuclear Factor κB and the Janus-kinase enzyme system. The proinflammatory cytokines and the Janus-kinase are therefore primary therapeutic targets. Anti-cytokine biologicals and small molecular kinase inhibitors decrease the pain and improve functional activity in rheumatoid arthritis. Decrease of pain was more pronounced than expected only from the decrease of the clinical biomarkers of inflammation. The early and ra­pid painkiller effect of targeted biological and chemical-biological response modifiers is attributed to their direct analgesic effect on the brain.]