 Prof. MUDr. Josef Syka, DrSc.email: syka@biomed.cas.cz tel: +420241062787 Laboratory of Auditory Physiology and PathologyHead: Prof. MUDr. Josef Syka, DrSc. Laboratory of Synaptic PhysiologyHead: RNDr. Rostislav Tureček, Ph.D. Scientists:MUDr. Daniela Buckiová, CSc. Ph.D. Students:Mgr. Jana Burianová Technical Assistants:Jana Janoušková Laboratory of Auditory Physiology and PathologyStructure and function of the auditory system The main research aim of the Laboratory of Auditory Physiology and Pathology is to investigate the structure and function of the auditory system in animal models under normal conditions, during development and aging, and under different pathological situations such as noise exposure. Using immunohistochemical techniques the expression of calcium binding proteins (calbindin, parvalbumin, calretinin) and GABA precursors GAD 65 and GAD 67 is evaluated in the auditory system in normal and noise-exposed guinea pigs and rats. Recordings of single-unit or multiple-unit extracellular activity with multielectrode probes have revealed basic principles of the processing of complex sounds such as animal vocalizations in the higher auditory centers (auditory cortex, thalamus and tectum). Multielectrode recording combined with immunohistochemical techniques is used for investigation of a detailed parcellation of the auditory cortex. Study of the age-related changes of the hearing function in a fast ageing rat strain Fischer 344 serves as model for understanding mechanisms and progression of the presbycusis in man. The effects of noise exposure on hearing acuity is under evaluation in Long Evans rats with the aid of behavioral operant conditioning procedures, recording of auditory evoked responses and recording of different types of otoacoustic emissions. Behavioral tests are also used to study the lateralization of auditory functions in the rat auditory cortex. Close collaboration with the ENT clinics is oriented to investigation of hearing function in children and adolescents and to characterization of problems of presbycusis. Current research at the Laboratory of Auditory Physiology and Pathology focuses on the following topics:
Laboratory of Synaptic PhysiologyModulation of excitatory synaptic transmission by GABA and glycine in brainstem auditory nuclei Rostislav Tureček and his coworkers are interested in the mechanisms of excitatory and inhibitory synaptic transmission. They use electrophysiological and immunohistochemical approaches to study neurons of the medial nucleus of the trapezoid body (MNTB) in rat or mouse brainstem slices. Principal cells of the MNTB play a key role in the acoustic information processing by the brain stem auditory circuitry. These cells accurately convert excitatory signals provided by the ventral cochlear nucleus (AVCN) to inhibitory signals directed to the lateral/medial superior olive (LSO/MSO). Each MNTB principal cell receives the excitatory input forming a giant nerve terminal, the calyx of Held (Fig. 5). This can be directly examined by the patch-clamp recording technique (Fig. 6). Using presynaptic recording we have provided an evidence for the presence of chloride-permeable glycine receptors in the calyx of Held (Fig 7A). These receptors, when activated, potentiate the release of glutamate from the calyx. In addition to the excitatory input, principal cells are innervated by glycinergic inhibitory fibers. Glycine released from the nerve endings of these fibers activates pre- and postsynaptic glycine receptors and generates extremely fast inhibitory postsynaptic currents. The laboratory’s results have shown that the subunit compositions of pre- and postsynaptic glycine receptors differ (Fig. 7B, 8). The presynaptic receptors are homomers composed from α1 subunits, while the postsynaptic receptors are heteromers composed from α1 and β subunits. The results suggest that the postsynaptic phenotype provides receptors with fast kinetics, able to follow repetitive synaptic stimuli at high frequencies, while the presynaptic phenotype is tuned to sense low concentrations of glycine delivered by spillover. Current research at the Laboratory of Synaptic Physiology focuses on the following topics:
Fig. 1 The function of the cortico-thalamic pathway
Fig. 2 Avoidance conditioning behavioral procedures on rats
Fig. 3 The effects of noise exposure on the central auditory nuclei
Fig. 4 Age-related changes in hearing in Fischer 344 rats
Fig. 5 The calyx of Held
Fig. 6 Cells and patch-clamp recordings from the calyx of Held in MNTB supravital slices
Fig. 7 Current responses of chloride-permeable glycine receptors
Fig. 8 An imaging of MNTB cells labelled with antibodies directed against the glycine receptor α1-subunit.
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Name of the grant |
Grant agency |
Number of the grant |
Principal investigator |
Duration of the grant |
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Plasticity of hearing and sensorineural hearing impairment - from early development to presbycusis |
IGA MZ |
NR/8113 - 4 |
Prof. Syka |
2004-07 |
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Center of neuroscience |
MŠMT ČR |
LC554 |
Prof. Syka |
2005-09 |
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Nanotechnology-based targeted drug delivery (NANOEAR) |
FP6 framework |
NMP-2004-3.4.1.5-1 -1 |
Prof. Syka |
2006-10 |
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Acoustical signal processing in the neuronal circuits of the auditory system |
GAČR |
309/07/1336 |
Dr. Popelář |
2007-11 |
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The role of GABA-B receptors in the mammalian MNTB |
GAČR |
309/06/1304 |
Dr. Tureček |
2006-08 |
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From molecules to networks: understanding synaptic physiology and pathology in the brain through mouse models |
Integrated FP6 Project |
LSHM-CT- |
Dr. Tureček |
2005-09 |
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The role of inhibition in mammalian MNTB |
Wellcome Trust |
073966 |
Dr. Tureček |
2004-09 |
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