scholarly journals The horizontal brain slice preparation: a novel approach for visualizing and recording from all layers of the tadpole tectum

2015 ◽  
Vol 113 (1) ◽  
pp. 400-407 ◽  
Author(s):  
Ali S. Hamodi ◽  
Kara G. Pratt
Keyword(s):  
Optic Tectum ◽  
Brain Slice ◽  
Multisensory Processing ◽  
Deep Layer ◽  
Slice Preparation ◽  
Whole Cell ◽  
Xenopus Tadpole ◽  
Tectal Neurons ◽  
Brain Slice Preparation

The Xenopus tadpole optic tectum is a multisensory processing center that receives direct visual input as well as nonvisual mechanosensory input. The tectal neurons that comprise the optic tectum are organized into layers. These neurons project their dendrites laterally into the neuropil where visual inputs target the distal region of the dendrite and nonvisual inputs target the proximal region of the same dendrite. The Xenopus tadpole tectum is a popular model to study the development of sensory circuits. However, whole cell patch-clamp electrophysiological studies of the tadpole tectum (using the whole brain or in vivo preparations) have focused solely on the deep-layer tectal neurons because only neurons of the deep layer are visible and accessible for whole cell electrophysiological recordings. As a result, whereas the development and plasticity of these deep-layer neurons has been well-studied, essentially nothing has been reported about the electrophysiology of neurons residing beyond this layer. Hence, there exists a large gap in our understanding about the functional development of the amphibian tectum as a whole. To remedy this, we developed a novel isolated brain preparation that allows visualizing and recording from all layers of the tectum. We refer to this preparation as the “horizontal brain slice preparation.” Here, we describe the preparation method and illustrate how it can be used to characterize the electrophysiology of neurons across all of the layers of the tectum as well as the spatial pattern of synaptic input from the different sensory modalities.

23. A new adult rat brain slice preparation for ex vivo NMR spectroscopy studies of stroke

1994 ◽  
Vol 52 (1) ◽  
pp. A11
Author(s):  
M.T. Espanol ◽  
L. Litt ◽  
L.-H. Chang ◽  
T.L. James ◽  
P.R. Weinstein ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Rat Brain ◽  
Brain Slice ◽  
Ex Vivo ◽  
Slice Preparation ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Spectroscopy Studies ◽  
Rat Brain Slice ◽  
Brain Slice Preparation

Effect of anoxia on intracellular and extracellular potassium activity in hypoglossal neurons in vitro

1991 ◽  
Vol 66 (1) ◽  
pp. 103-111 ◽  
Author(s):  
C. Jiang ◽  
G. G. Haddad
Keyword(s):  
Brain Slice ◽  
Neuronal Response ◽  
Extracellular Potassium ◽  
Intracellular Recordings ◽  
High Concentration ◽  
Slice Preparation ◽  
Adult Rats ◽  
Short Period ◽  
Brain Slice Preparation

1. A brain slice preparation was used to study the hypoglossal (XII) neuronal response to anoxia. Both intra- and extracellular potassium activities (K+i,K+o) were measured by the use of ion-selective microelectrodes, and K+ flux was assessed by the use of pharmacologic blockers. 2. Extracellular recordings showed that a short period of anoxia (4 min) induced an increase in K+o of 26.4 +/- 7.5 mM (mean +/- SD, n = 20) in the XII nucleus of adult rats. 3. Intracellular recordings (n = 31) in XII neurons showed a substantial decrease in K+i during anoxia. Fourteen neurons were analyzed in detail and these showed that XII neurons depolarized to -25.3 +/- 7.7 mV, whereas K+i dropped from 93.6 +/- 14.9 to 32 +/- 9.0 mM. These results strongly suggested that K+ is lost from XII neurons during anoxia. 4. Although the extracellular space (ECS) shrank by approximately 50% during anoxia, the possibility that the increase in K+o and decrease in K+i were mainly caused by shrinkage of the ECS and swelling of intraneuronal space was excluded to a great degree because the changes in K+i and K+o during anoxia were relatively very large. 5. To study the mechanisms by which K+ is lost from XII neurons, we used several pharmacologic blockers. High concentration of ouabain (10 mM) and strophanthidin (80 microM) increased K+o from baseline (3-4 mM) to 40.9 +/- 2.5 mM (n = 6) but did not abolish an additional anoxia-induced increase in K+o, suggesting that mechanisms other than Na(+)-K(+)-adenosine triphosphatase inhibition were also responsible for the anoxia-induced K+ leakage.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Region-specific regulation of voltage-gated intrinsic currents in the developing optic tectum of the Xenopus tadpole

2014 ◽  
Vol 112 (7) ◽  
pp. 1644-1655 ◽  
Author(s):  
Ali S. Hamodi ◽  
Kara G. Pratt
Keyword(s):  
Optic Tectum ◽  
Action Potentials ◽  
Synaptic Activity ◽  
Intrinsic Excitability ◽  
Xenopus Tadpole ◽  
Caudal Portion ◽  
Developmental Gradient ◽  
Specific Regulation ◽  
Tectal Neurons ◽  
Whole Cell Recordings

Across the rostrocaudal (RC) axis of the Xenopus tadpole optic tectum exists a developmental gradient. This gradient has served as a useful model to study many aspects of synapse and dendrite maturation. To compliment these studies, we characterized how the intrinsic excitability, the ease in which a neuron can fire action potentials, might also be changing across the same axis. Whole-cell recordings from tectal neurons at different points along the RC axis revealed a graded increase in intrinsic excitability: compared with neurons at the caudal end of the tectum, neurons at the rostral end fired more action potentials in response to current injection and expressed greater peak Na+ and K+ currents, the major intrinsic currents in these neurons that underlie the action potential. We also observed, along the same axis and in the same direction, a previously described increase in the amount of synaptic drive received by individual neurons (Wu GY, Malinow R, Cline HT. Science 274: 972–976, 1996). Thus as synaptic activity ramps up across the RC axis, so does intrinsic excitability. The reduction of overall circuit activity induced a compensatory scaling up of peak Na+ and K+ currents only in the caudal portion of the tectum, suggesting a region-specific, compensatory form of plasticity.

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