Key points• The dorsal (DHC) and ventral (VHC) regions of the rodent hippocampus are anatomically, behaviourally, and biochemically distinct.• The intrinsic electrophysiological properties of CA1 pyramidal neurones from these regions however, have not been fully characterized.• In this study, we found that VHC neurones were intrinsically more excitable than DHC neurones.• The difference in intrinsic excitability stems from a higher input resistance (R in ) and more depolarized resting membrane potential observed in the soma and apical dendrite of VHC neurones.• Morphological analysis of reconstructed neurones revealed significantly more dendritic surface area for DHC than VHC neurones.• Simulations using morphologically realistic passive models indicate that morphological differences could, in principle, underlie somatic but not dendritic differences in R in .Abstract The hippocampus has a central role in learning and memory. Although once considered a relatively homogenous structure along the longitudinal axis, it has become clear that the rodent hippocampus can be anatomically and functionally divided into a dorsal component generally associated with spatial navigation, and a ventral component primarily associated with non-spatial functions that involve an emotional component. The ventral hippocampus (VHC) is also more sensitive to epileptogenic stimuli than the dorsal hippocampus (DHC), and seizures tend to originate in the VHC before spreading to other brain regions. Although synaptic and biochemical differences in DHC and VHC have been investigated, the intrinsic excitability of individual neurones from the DHC and VHC has received surprisingly little attention. In this study, we have characterized the intrinsic electrophysiological properties of CA1 pyramidal neurones from the DHC and the VHC using the whole-cell current-clamp method. Our results demonstrate that somatic current injections of equal magnitude elicit significantly more action potentials in VHC neurones than DHC neurones, and that this difference stems from the more depolarized resting membrane potential (RMP; 7 mV) and higher input resistance (R in ; 46 M measured from RMP) observed in VHC neurones. These differences in RMP and R in were also observed in dendritic whole-cell current-clamp recordings. Furthermore, morphological reconstructions of individual neurones revealed significant differences in the dendritic branching pattern between DHC and VHC neurones that could, in principle, contribute to the lower somatic R in of DHC neurones. Together, our results highlight significant differences in the intrinsic electrophysiological properties of CA1 pyramidal neurones across the longitudinal hippocampal axis, and suggest that VHC neurones are intrinsically more excitable than DHC neurones. This difference is likely to predispose the VHC to hyperexcitability.

Differences in behavioral roles, anatomical connectivity and gene expression patterns in the dorsal, intermediate and ventral regions of the hippocampus are well characterized. Relatively fewer studies have, however, focused on comparing the physiological properties of neurons located at different dorsoventral extents of the hippocampus. Recently we reported that dorsal CA1 neurons are less excitable than ventral neurons. There is little or no information for how neurons in the intermediate hippocampus compare to those from the dorsal and ventral ends. Also, it is not known whether the transition of properties along the dorsoventral axis is gradual or segmented. In this study, we developed a statistical model to predict the dorsoventral position of transverse hippocampal slices. Using current clamp recordings combined with this model, we found that CA1 neurons in dorsal, intermediate and ventral hippocampus have distinct electrophysiological and morphological properties and that the transition in most (but not all) of these properties from the ventral to dorsal end is gradual. Using linear and segmented regression analyses, we found that input resistance and resting membrane potential changed linearly along the V–D axis. Interestingly, the transition in resonance frequency, rebound slope, dendritic branching in stratum radiatum and action potential properties was segmented along the V–D axis. Together, the findings from this study highlight the heterogeneity in CA1 neuronal properties along the entire longitudinal axis of hippocampus.

Since the 1970s, federal and state policy-makers have become increasingly concerned with improving higher education performance. In this quest, state performance funding for higher education has become widely used. As of June 2014, twenty-six states were operating performance funding programs and four more have programs awaiting implementation. This article reviews the forms, extent, origins, implementation, impacts (intended and unintended), and policy prospects of performance funding. Performance funding has become quite widespread with formidable political support, yet it has also experienced considerable implementation vicissitudes, with many programs being discontinued and even those that have survived encountering substantial obstacles and unintended impacts. Although evidence suggests that performance funding does stimulate colleges and universities to substantially change their policies and practices, it is yet unclear whether performance funding improves student outcomes. The article concludes by advancing policy recommendations for addressing the implementation obstacles and unintended side effects associated with performance funding.

The growing policy interest in community colleges as gateways to the baccalaureate degree naturally raises the question of how equitably transfer opportunities are distributed by student background and what factors may explain background differences that might be found. We analyze two nationally representative data sets to examine how the likelihood of transfer is affected by social background, precollege academic characteristics, external demands at college entrance, and experiences during college. We find that high-SES students have significantly higher transfer rates, in part because of advantages in precollege academic preparation and educational aspirations. Older college entrants are much less likely to transfer than students entering college right out of high school, and a significant portion of this age gap is more often due to having children, lower educational aspirations, and a vocational major, and being enrolled part time. Though women and nonwhites differ from men and whites in transfer rates, these differences are not statistically significant. But there is an important caveat: blacks tend to have higher educational aspirations than whites of the same socioeconomic background. When we control for educational aspirations, thus removing this black aspirational advantage, the black-white gap in transfer rates widens considerably, becoming statistically significant in one of our samples but not the other.