Potentiation of synaptic responses in slices from the chick forebrain

Abstract

Coronal slices, containing part of the medial hyperstriatum ventrale (MHV), were cut from the left forebrains of domestic chicks and maintained in vitro. Records were made of the field responses evoked in the MHV by local electrical stimuli provided at 0.1 Hz. Two 1 min periods of stimulation at 5 Hz, separated by 10 min, were used in attempts to induce a persistent increase in the size of the postsynaptic response to test stimulation at 0.1 Hz. This procedure produced a potentiation which usually lasted longer than 2 h. The probability of inducing this persistent potentiation of the response (PPR) is not distributed evenly over the whole anteroposterior length of the MHV but is higher in slices that also contain the septo-mesencephalic tract ventrally. These are the slices that contain the intermediate part of the medial hyperstriatum ventrale (IMHV); an area that is essential for early behavioural learning. At this level PPR is not confined to the IMHV. It can also be produced in the lateral neostriatum in response to similar local stimulation at 5 Hz. No PPR was observed in either the caudal ectostriatum, or the paleostriatum.

Visual Imprinting in Birds: Behavior, Models, and Neural Mechanisms

“…Associative long-term potentiation and depression are well-established forms of synaptic plasticity based on Hebbian mechanisms, which depends on activation of NMDA receptors (see e.g., Morris, 2003). Investigation of the IMM in vitro has revealed plasticity resembling glutamate receptor-mediated long-term potentiation (Bradley et al., 1991, 1993, reviewed in Matsushima and Aoki, 1995; Bradley et al, 1999) and susceptibility of imprinting to local pharmacological blockade of NMDA receptors in the IMM (Mccabe et al., 1992).…”

Suppressive Modulation of the Chick Forebrain Network for Imprinting by Thyroid Hormone: An in Vitro Study

“…In addition to detailed Golgi cytoarchitecture ( Tömböl et al, 1988 ), ample histochemical and connectivity data are available for the IMM ( Bradley et al, 1985 ; Csillag, 1999 ). A neuro-physiological study reported activity-dependent synaptic potentiation in the IMM ( Bradley et al, 1991 ), although the synaptic transmission responsible was not specified. We ( Yanagihara et al, 1998 ) then showed that a DNQX-sensitive excitatory component (namely AMPA receptor mediated) is potentiated by locally applied tetanic electrical stimulation, but the plastic change was not linked to immediate early gene ( c-fos ) expression, which was clearly associated with the imprinting score at the individual level ( McCabe and Horn, 1994 ).…”