Monosynaptic excitatory inputs to spinal lamina I anterolateral-tract-projecting neurons from neighbouring lamina I neurons.
J Physiol
; 588(Pt 22): 4489-505, 2010 Nov 15.
Article
em En
| MEDLINE
| ID: mdl-20876196
ABSTRACT
Spinal lamina I receives nociceptive primary afferent input to project through diverse ascending pathways, including the anterolateral tract (ALT). Large projection neurons (PNs) form only a few per cent of the cell population in this layer, and little is known about their local input from other lamina I neurons. We combined single-cell imaging in the isolated spinal cord, paired recordings, 3-D reconstructions of biocytin-labelled neurons and computer simulations to study the monosynaptic input to large ALT-PNs from neighbouring (somata separated by less than 80 µm) large lamina I neurons. All 11 connections identified were excitatory. We have found that an axon of a presynaptic neuron forms multiple synapses on an ALT-PN, and both Ca(2+)-permeable and Ca(2+)-impermeable AMPA receptors are involved in transmission. The monosynaptic EPSC latencies (1-12 ms) are determined by both post- and presynaptic factors. The postsynaptic delay, resulting from the electrotonic EPSC propagation in the dendrites of an ALT-PN, could be 4 ms at most. The presynaptic delay, caused by the spike propagation in a narrow highly branched axon of a local-circuit neuron, can be about 10 ms for neighbouring ALT-PNs and longer for more distant neurons. In many cases, the EPSPs evoked by release from a lamina I neuron were sufficient to elicit a spike in an ALT-PN. Our data show that ALT-PNs can receive input from both lamina I local-circuit neurons and other ALT-PNs. We suggest that lamina I is a functionally interconnected layer. The intralaminar network described here can amplify the overall output from the principal spinal nociceptive projection area.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sinapses
/
Potenciais Pós-Sinápticos Excitadores
/
Células do Corno Anterior
/
Neurônios
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Physiol
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Portugal