scholarly journals Thalamus gates active dendritic computations in cortex during sensory processing

2021 ◽  
Author(s):  
Jason M Guest ◽  
Arco Bast ◽  
Rajeevan T Narayanan ◽  
Marcel Oberlaender
Keyword(s):  
Sensory Processing ◽  
Action Potentials ◽  
Pyramidal Tract ◽  
Sensory Stimulation ◽  
Sensory Signals ◽  
Calcium Dependent ◽  
Thalamocortical Axons ◽  
Pyramidal Tract Neurons ◽  
Layer 4 ◽  
Information Streams

Perception is causally linked to a calcium-dependent spiking mechanism that is built into the distal dendrites of layer 5 pyramidal tract neurons – the major output cell type of the cerebral cortex. It is yet unclear which circuits activate this cellular mechanism upon sensory stimulation. Here we found that the same thalamocortical axons that relay sensory signals to layer 4 also densely target the dendritic domain by which pyramidal tract neurons initiate calcium spikes. Distal dendritic inputs, which normally appear greatly attenuated at the cell body, thereby generate bursts of action potentials in cortical output during sensory processing. Our findings indicate that thalamus gates an active dendritic mechanism to facilitate the combination of sensory signals with top-down information streams into cortical output. Thus, in addition to being the central hub for sensory signals, thalamus is also likely to ensure that the signals it relays to cortex are perceived by the animal.

Dendritic action potentials of pyramidal tract neurons in the cat sensorimotor cortex

1986 ◽  
Vol 18 (4) ◽  
pp. 307-314 ◽  
Author(s):  
T. Sh. Labakhua ◽  
M. G. Kokaya ◽  
V. M. Okudzhava
Keyword(s):  
Sensorimotor Cortex ◽  
Action Potentials ◽  
Pyramidal Tract ◽  
Pyramidal Tract Neurons

Calcium-dependent potassium conductance in rat supraoptic nucleus neurosecretory neurons

1985 ◽  
Vol 54 (6) ◽  
pp. 1375-1382 ◽  
Author(s):  
C. W. Bourque ◽  
J. C. Randle ◽  
L. P. Renaud
Keyword(s):  
Time Constant ◽  
Action Potentials ◽  
Supraoptic Nucleus ◽  
Potassium Conductance ◽  
Reversal Potential ◽  
Input Resistance ◽  
Mean Amplitude ◽  
Progressive Increase ◽  
Calcium Dependent ◽  
Neurosecretory Neurons

Intracellular recordings of rat supraoptic nucleus neurons were obtained from perfused hypothalamic explants. Individual action potentials were followed by hyperpolarizing afterpotentials (HAPs) having a mean amplitude of -7.4 +/- 0.8 mV (SD). The decay of the HAP was approximated by a single exponential function having a mean time constant of 17.5 +/- 6.1 ms. This considerably exceeded the cell time constant of the same neurons (9.5 +/- 0.8 ms), thus indicating that the ionic conductance underlying the HAP persisted briefly after each spike. The HAP had a reversal potential of -85 mV and was unaffected by intracellular Cl- ionophoresis of during exposure to elevated extracellular concentrations of Mg2+. In contrast, the peak amplitude of the HAP was proportional to the extracellular Ca2+ concentration and could be reversibly eliminated by replacing Ca2+ with Co2+, Mn2+, or EGTA in the perfusion fluid. During depolarizing current pulses, evoked action potential trains demonstrated a progressive increase in interspike intervals associated with a potentiation of successive HAPs. This spike frequency adaptation was reversibly abolished by replacing Ca2+ with Co2+, Mn2+, or EGTA. Bursts of action potentials were followed by a more prolonged afterhyperpolarization (AHP) whose magnitude was proportional to the number of impulses elicited (greater than 20 Hz) during a burst. Current injection revealed that the AHP was associated with a 20-60% decrease in input resistance and showed little voltage dependence in the range of -70 to -120 mV. The reversal potential of the AHP shifted with the extracellular concentration of K+ [( K+]o) with a mean slope of -50 mV/log[K+]o.(ABSTRACT TRUNCATED AT 250 WORDS)

Membrane Properties Related to the Firing Behavior of Zebrafish Motoneurons

2003 ◽  
Vol 89 (2) ◽  
pp. 657-664 ◽  
Author(s):  
Robert R. Buss ◽  
Charles W. Bourque ◽  
Pierre Drapeau
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Membrane Properties ◽  
High Threshold ◽  
Calcium Dependent ◽  
Larval Zebrafish ◽  
Plateau Potential ◽  
Potassium Conductances ◽  
Action Potential Burst

The physiological and pharmacological properties of the motoneuron membrane and action potential were investigated in larval zebrafish using whole cell patch current-clamp recording techniques. Action potentials were eliminated in tetrodotoxin, repolarized by tetraethylammonium (TEA) and 3,4-diaminopyridine (3,4-AP)-sensitive potassium conductances, and had a cobalt-sensitive, high-threshold calcium component. Depolarizing current injection evoked a brief (approximately 10–30 ms) burst of action potentials that was terminated by strong, outwardly rectifying voltage-activated potassium and calcium-dependent conductances. In the presence of intracellular cesium ions, a prolonged plateau potential often followed brief depolarizations. During larval development (hatching to free-swimming), the resting membrane conductance increased in a population of motoneurons, which tended to reduce the apparent outward rectification of the membrane. The conductances contributing to action potential burst termination are hypothesized to play a role in patterning the synaptically driven motoneuron output in these rapidly swimming fish.

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