Differential involvement of the shell and core subterritories of the nucleus accumbens in latent inhibition and amphetamine-induced activity

The Effects of Temporary Inactivation of the Core and the Shell Subregions of the Nucleus Accumbens on Prepulse Inhibition of the Acoustic Startle Reflex and Activity in Rats

“…Similar findings were reported by Johnson et al (1996) and Parkinson et al (1999). Furthermore, the core subregion appears to be the site of action for psychostimulant (such as amphetamine or nicotine)-induced locomotor activity (Boye et al, 2001;Parkinson et al, 1999;Sellings and Clarke, 2003; but see Weiner et al, 1996). Yet, our own recent findings as well as data of others indicate that the apparently less significant role of the shell subregion in locomotor activity remains ambiguous.…”

“…However, they are not in accordance with previous lesion findings, which suggest a preferential involvement of the shell subregion in locomotor activity (Jongen-Rêlo et al, 2002;Weiner et al, 1996). A satisfying explanation for this latter discrepancy is difficult to give, but might be found in the method of inactivation (pharmacological vs lesions), activity assessment (open field vs activity chambers), or recovery time allowed (see also Jongen-Rêlo et al, 2002, pp 104).…”

“…Yet, we believe that the remarkable resemblance between our present (using inactivation via muscimol) and our previous findings (employing selective permanent lesions) does indicate that the role of the shell in the regulation of PPI, if existent, is minor compared to that of the core. This later observation is in contrast to the regulation of latent inhibition in which both subregions appear to be involved (Jeanblanc et al, 2002;Weiner et al, 1996, for a review see Weiner and Feldon, 1997).…”

“…Several studies in the rodent brain employing permanent lesion techniques as well as intracerebral pharmacological manipulations have revealed a functional dissociation between the subregions of the nucleus accumbens: the 'core' and the 'shell' (as originally defined by Záborszky et al, 1985). Whereas the core subregion has been demonstrated to be preferentially involved in the mediation of motor behavior (Johnson et al, 1996;Maldonado-Irizarry and Kelley, 1994;Parkinson et al, 1999), the shell subregion tends to be more closely associated with motivational and attentional behavior (Jeanblanc et al, 2002;Weiner et al, 1996). We have recently confirmed and extended these findings by showing that selective N-methyl-D-aspartic acid (NMDA)-induced excitotoxic lesions of either the core or the shell result in differential effects on locomotor activity, latent inhibition assessed with two-way active avoidance, spatial working memory, and prepulse inhibition (PPI) of the acoustic startle reflex (Jongen-Rêlo et al, 2002.…”

“…Yet, our own recent findings as well as data of others indicate that the apparently less significant role of the shell subregion in locomotor activity remains ambiguous. Pharmacological blockade of NMDA neurotransmission in the shell using the NMDA receptor antagonist DL-2-amino-5-phosphonopentanoic acid (AP5, Pulvirenti et al, 1994), electrolytic lesions of the shell in combination with systemic saline injections (Weiner et al, 1996), as well as excitotoxic lesions restricted to the shell (Jongen-Rêlo et al, 2002), all resulted in changes in locomotor activity. In contrast, these manipulations were ineffective when applied to the core.…”