IFIBYNE   05513
INSTITUTO DE FISIOLOGIA, BIOLOGIA MOLECULAR Y NEUROCIENCIAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Integration of auditory and visual inputs depends on differential properties of the Mauthner cell
Autor/es:
MEDAN, VIOLETA; PREUSS, THOMAS; MÄKI-MARTTUNEN, TUOMO; SZTARKER, JULIETA
Lugar:
San Diego, CA
Reunión:
Congreso; Society for Neuroscience Meeting 2016; 2016
Institución organizadora:
Society for Neuroscience
Resumen:
Most animals take advantage of multiple informationsources to form a coherent percept of the world for adaptive behavioral decisions;however, the underlying mechanisms of such interactions are still far from clear.Here we address two essential questions (i) how do neurons process multimodalsensory inputs with different temporal characteristics, and (ii) what role dointrinsic properties of dendrites play in selective sensory filtering?  For that we took advantage of the startleescape network in goldfish, which is centered on a pair of indefinabledecision-making neurons, the Mauthner-cells (M-cells). These cells receive auditory and visual inputsvia separate dendrites, both accessible for morphological characterization, in vivo recordings, and computationalmodeling.Reconstructionsof labeled cells (N=3) revealed that the visual dendrite (VD) is on average 30%longer and 25%, thinner than the auditory dendrite (LD), resulting in a 28 ± 8% higher surface/volume ratio of the VD when compared to the LD (t-test; p =0.036). Accordingly, our electrophysiological results showed differences in cableproperties in the two dendrites. Namely, a lower transfer resistance in the VD(29.1 ± 20.2 kΩ) than in the LD (77.9 ± 33.4 kΩ; t=3.55, df=13, p=0.004), and alonger time constant in the VD (0.57 ± 0.23 ms) compared to the LD (0.25 ± 0.07ms; t=2.66, df=5, p=0.04). Similarly, the dendritic space constant of visuallyevoked PSPs in the VD (λ ortho,VD=145 µm) is about half of that for auditoryPSP in the LD (λ ortho,LD=361µm).Modelingexperiments showed that these passive cable properties fully account for theobserved differences in PSP decay in the two dendrites.  Interestingly,our electrophysiological experiments showed that auditory evoked PSPs originating in the LD also invade the VD, as well asthe opposite, visual PSPs invading the LD. The effects of the antidromically propagatingPSPs are asymmetrical between the dendrites however, with auditory PSPs beingmore prominent in the VD than visual PSPs in the LD. Modeling experiments implythat this asymmetry might be due to active conductances expressed in theproximal segments of the VD.Takentogether, our results suggest modality-dependentmembrane specialization in the two M-cell dendrites that are suited forprocessing stimuli of different time domains (e.g. visual looms and auditoryclicks), which might be critical for vital startle-escape decisions.