Firing patterns of maternal rat prelimbic neurons during spontaneous contact with pups

Abstract

Extracellular single unit activity was recorded from medial prefrontal cortex (mPFC) of postpartum dams over the course of 3 days while they engaged in spontaneous pup-directed behaviors and non-specific exploratory behavior. Out of 109 units identified over the course of the experiment, 15 units were observed to be pup-responsive and 15 increased their discharge rates non-specifically while not attending to pups. An association between neuronal activity and typical maternal behaviors (e.g., retrieval, pup-grooming, nursing) was not observed. Instead, brief bouts of snout contact with pups were accompanied by phasic increases and decreases in spike rates. The observed pup contact responsive cells might play a role in processing of sensory feedback from pups or the transmission of modulatory output to other subcortical maternal brain areas.

Oxytocin in the medial prefrontal cortex regulates maternal care, maternal aggression and anxiety during the postpartum period

“…The mPFC of the rodent brain consists of three subregions—the infralimbic (IL) cortex, PL cortex, and anterior cingulate cortex (Cg1; Heidbreder and Groenewegen, 2003 ). Here we targeted only the PL mPFC because it has been most consistently linked to maternal care and aggression (Nephew et al, 2009 ; Febo et al, 2010 ; Pereira and Morrell, 2011 ; Febo, 2012 ) as well as OT regulation of social (Young et al, 2014 ) and anxiety behaviors (Sabihi et al, 2014 ). However, the various subregions of the mPFC show different patterns of connectivity with subcortical and cortical structures which could lead to different behavioral outcomes following OTR blockade.…”

“…Bilateral cannula guides (pedestal mounted 22-gauge stainless steel tubes with 1.5 mm separation and cut 3.5 mm below the pedestal; Plastics One, Roanoke, VA) were secured in a stereotaxic holder and lowered into the PL mPFC (AP: + 3.2 mm, ML: ± 0.75 mm, DV: −3.2 mm; Paxinos and Watson, 1998 ). The PL mPFC was targeted because it has been most consistently linked to maternal care, maternal aggression, and anxiety (Nephew et al, 2009 ; Febo et al, 2010 ; Pereira and Morrell, 2011 ; Febo, 2012 ; Sabihi et al, 2014 ). The cannula were secured by stainless steel screws and dental cement.…”

“…First, in addition to expressing OTR (Insel and Shapiro, 1992 ; Gould and Zingg, 2003 ; Liu et al, 2005 ; Smeltzer et al, 2006 ), the mPFC contains OT-sensitive neurons (Ninan, 2011 ) and receives long-range axonal projections from OT producing neurons in the hypothalamus (Sofroniew, 1983 ; Knobloch et al, 2012 ). Second, the mPFC of postpartum rats becomes activated by suckling or OT administration (Febo et al, 2005 ; Febo, 2012 ) as well as during the display of maternal aggression (Gammie et al, 2004 ; Nephew et al, 2009 ). Third, lesion and inactivation studies have implicated the mPFC in the regulation of anxiety (Shah and Treit, 2003 ; Stern et al, 2010 ) and some aspects of maternal care (Afonso et al, 2007 ; Febo et al, 2010 ).…”

Common and divergent psychobiological mechanisms underlying maternal behaviors in non-human and human mammals

“…Neurons of the postpartum rat mPFC respond electrophysiologically to nest odors (Hernández-González, Navarro-Meza, Prieto-Beracoechea, & Guevara, 2005) and snout contact with pups (Febo, 2012), and in sheep and rats have increased immediate-early gene activity after an interaction with offspring or cues associated with them (Broad, Hinton, Keverne, & Kendrick, 2002; Da Costa, Kampa, Windle, Ingram, & Lightman, 1997b; Fleming & Korsmit, 1996; Mattson & Morrell, 2005). The female rat mPFC also shows elevated fMRI activity in response to natural or artificial suckling (Febo, Numan, & Ferris, 2005; Febo et al, 2008; Ferris et al, 2005).…”

Brain Reward Pathway Dysfunction in Maternal Depression and Addiction: A Present and Future Transgenerational Risk

“…Using a modified neuroimaging paradigm to present in vivo natural stimuli in an fMRI environment, Nephew et al reported that several PFC subregions, including anterior cingulate (ACg), orbital cortex and insula, show increased neural activity in response to the presentation of a male intruder in the presence of pups [ 145 , 146 ]. Inhibiting the medial PFC just ventral the ACg in maternal rats significantly impairs retrieval of pups to a nest region of their home cages [ 147 ] and neurons within this area are responsive during maternal-offspring interactions [ 148 ]. A role for PFC in maternal care and its potential role in deficits in maternal reward is not unexpected given its widespread corticocortical connectivity and its extensive outputs to striatal and other limbic targets involved in maternal behavior [ 149 – 155 ].…”