Neurosciences Commons^™

Long Days Enhance Recognition Memory And Increase Insulin-Like Growth Factor 2 In The Hippocampus, Adriano Dellapolla, Ian Kloehn, Harshida Pancholi, Ben L. Callif, David Wertz, Kayla Rohr, Matthew M. Hurley, Kimberly Baker, Samer Hattar, Marieke R. Gilmartin, Jennifer A. Evans

Biomedical Sciences Faculty Research and Publications

Light improves cognitive function in humans; however, the neurobiological mechanisms underlying positive effects of light remain unclear. One obstacle is that most rodent models have employed lighting conditions that cause cognitive deficits rather than improvements. Here we have developed a mouse model where light improves cognitive function, which provides insight into mechanisms underlying positive effects of light. To increase light exposure without eliminating daily rhythms, we exposed mice to either a standard photoperiod or a long day photoperiod. Long days enhanced long-term recognition memory, and this effect was abolished by loss of the photopigment melanopsin. Further, long days markedly altered …

Are There Place Cells In The Avian Hippocampus?, David F Sherry, Stephanie L Grella, Mélanie F Guigueno, David J White, Diano F Marrone

Brain and Mind Institute Researchers' Publications

Birds possess a hippocampus that serves many of the same spatial and mnemonic functions as the mammalian hippocampus but achieves these outcomes with a dramatically different neuroanatomical organization. The properties of spatially responsive neurons in birds and mammals are also different. Much of the contemporary interest in the role of the mammalian hippocampus in spatial representation dates to the discovery of place cells in the rat hippocampus. Since that time, cells that respond to head direction and cells that encode a grid-like representation of space have been described in the rat brain. Research with homing pigeons has discovered hippocampal cells, …

Genomics And Csf Analyses Implicate Thyroid Hormone In Hippocampal Sclerosis Of Aging, Peter T. Nelson, Yuriko Katsumata, Kwangsik Nho, Sergey C. Artiushin, Gregory A. Jicha, Wang-Xia Wang, Erin L. Abner, Andrew J. Saykin, Walter A. Kukull, Alzheimer’S Disease Neuroimaging Initiative (Adni), David W. Fardo

Sanders-Brown Center on Aging Faculty Publications

We report evidence of a novel pathogenetic mechanism in which thyroid hormone dysregulation contributes to dementia in elderly persons. Two single nucleotide polymorphisms (SNPs) on chromosome 12p12 were the initial foci of our study: rs704180 and rs73069071. These SNPs were identified by separate research groups as risk alleles for non-Alzheimer’s neurodegeneration. We found that the rs73069071 risk genotype was associated with hippocampal sclerosis (HS) pathology among people with the rs704180 risk genotype (National Alzheimer’s Coordinating Center/Alzheimer’s Disease Genetic Consortium data; n = 2113, including 241 autopsy-confirmed HS cases). Furthermore, both rs704180 and rs73069071 risk genotypes were associated with widespread brain …

Positive Allosteric Modulator Of Gabab Receptor Alters Behavioral Effects But Not Afterdischarge Progression Induced By Partial Hippocampal Kindling., L Stan Leung, Miao Jin, Liangwei Chu, Jingyi Ma

Physiology and Pharmacology Publications

Hippocampal seizures decreased the function of GABAB receptors, which may further increase seizure susceptibility and contribute to development of schizophrenia-like behaviors. Recent literature indicates that GABAB receptor agonist may normalize schizophrenia-like behaviors and prevent drug-induced behavioral sensitization. We hypothesized that positive modulation of GABAB receptor function during seizure induction will reduce seizure-induced schizophrenia-like behaviors. Using a partial hippocampal kindling model, afterdischarges were induced after injection of saline or dimethyl sulfoxide (vehicle-kindled rats), or a GABAB receptor positive allosteric modulator CGP7930, at 1 mg/kg i.p. (CGP1-kindled) or 5 mg/kg i.p. (CGP5-kindled). The increase in the primary afterdischarge duration during kindling was …

Differential Involvement Of Hippocampal Angiotensin 1 Receptors In Learning And Memory Processes In Bulbectomized Rats, Roman Tashev, Margarita Ivanova, Stiliana Belcheva, Iren Belcheva

Journal of Mind and Medical Sciences

There is conflicting evidence regarding the effect of AT1 receptor antagonists on learning and memory processes. The effects of angiotensin II and losartan administration into CA1 hippocampal area on the avoidance performance in olfactory bulbectomized (OBX) rats using active avoidance (shuttle box) test and passive avoidance (step through) test were investigated. Rats were microinjected unilaterally through implanted guide cannulas into the CA1 area of the dorsal hippocampus and the drugs were administered separately, 5 minutes before each training session. The microinjections of losartan into the left, but not the right CA1 hippocampal area improved the acquisition and retention of active …

The Representational-Hierarchical View Of Pattern Separation: Not Just Hippocampus, Not Just Space, Not Just Memory?, B. A. Kent, M. Hvoslef-Eide, L. M. Saksida, T. J. Bussey

Brain and Mind Institute Researchers' Publications

Pattern separation (PS) has been defined as a process of reducing overlap between similar input patterns to minimize interference amongst stored representations. The present article describes this putative PS process from the "representational-hierarchical" perspective (R-H), which uses a hierarchical continuum instead of a cognitive modular processing framework to describe the organization of the ventral visual perirhinal-hippocampal processing stream. Instead of trying to map psychological constructs onto anatomical modules in the brain, the R-H model suggests that the function of brain regions depends upon what representations they contain. We begin by discussing a main principle of the R-H framework, the resolution …

In Vivo Mri Signatures Of Hippocampal Subfield Pathology In Intractable Epilepsy., Maged Goubran, Boris C Bernhardt, Diego Cantor-Rivera, Jonathan C Lau, Charlotte Blinston, Robert R Hammond, Sandrine De Ribaupierre, Jorge G Burneo, Seyed M Mirsattari, David A Steven, Andrew G Parrent, Andrea Bernasconi, Neda Bernasconi, Terry M Peters, Ali R Khan

Brain and Mind Institute Researchers' Publications

OBJECTIVES: Our aim is to assess the subfield-specific histopathological correlates of hippocampal volume and intensity changes (T1, T2) as well as diff!usion MRI markers in TLE, and investigate the efficacy of quantitative MRI measures in predicting histopathology in vivo.

EXPERIMENTAL DESIGN: We correlated in vivo volumetry, T2 signal, quantitative T1 mapping, as well as diffusion MRI parameters with histological features of hippocampal sclerosis in a subfield-specific manner. We made use of on an advanced co-registration pipeline that provided a seamless integration of preoperative 3 T MRI with postoperative histopathological data, on which metrics of cell loss and gliosis were quantitatively …

Context-Dependent Egr1 Expression In The Avian Hippocampus., Stephanie L Grella, Mélanie F Guigueno, David J White, David F Sherry, Diano F Marrone

Brain and Mind Institute Researchers' Publications

In mammals, episodic memory and spatial cognition involve context-specific recruitment of unique ensembles in the hippocampal formation (HF). Despite their capacity for sophisticated spatial (e.g., for migration) and episodic-like (e.g., for food-caching) memory, the mechanisms underlying contextual representation in birds is not well understood. Here we demonstrate environment-specific Egr1 expression as male brown-headed cowbirds (Molothrus ater) navigate environments for food reward, showing that the avian HF, like its mammalian counterpart, recruits distinct neuronal ensembles to represent different contexts.

Microglia And Neurons In The Hippocampus Of Migratory Sandpipers., C G Diniz, N G M Magalhães, A A Sousa, C Santos Filho, D G Diniz, C M Lima, M A Oliveira, D C Paulo, P D C Pereira, D F Sherry, C W Picanço-Diniz

Brain and Mind Institute Researchers' Publications

The semipalmated sandpiper Calidris pusilla and the spotted sandpiper Actitis macularia are long- and short-distance migrants, respectively. C. pusilla breeds in the sub-arctic and mid-arctic tundra of Canada and Alaska and winters on the north and east coasts of South America. A. macularia breeds in a broad distribution across most of North America from the treeline to the southern United States. It winters in the southern United States, and Central and South America. The autumn migration route of C. pusilla includes a non-stop flight over the Atlantic Ocean, whereas autumn route of A. macularia is largely over land. Because of …

An Analysis Of Virtual Place Learning/Navigation In Children And Young Adults Prenatally Exposed To Alcohol, Neil Christopher Dodge

Wayne State University Dissertations

Fetal alcohol spectrum disorder refers to the spectrum of disorders resulting from prenatal alcohol exposure and is the leading cause of preventable mental retardation. Rodent studies have found that prenatal alcohol exposure impairs performance on the Morris water maze. This task requires the rodent to use distal room cues to locate a hidden platform in a pool of opaque water. Successful performance on this task is dependent upon hippocampal function. Rodents prenatally exposed to alcohol are impaired on the Morris water maze and show damage to hippocampal neurons. A human analogue of the Morris water maze, the virtual water maze …

Abcc9/Sur2 In The Brain: Implications For Hippocampal Sclerosis Of Aging And A Potential Therapeutic Target, Peter T. Nelson, Gregory A. Jicha, Wang-Xia Wang, Eseosa T. Ighodaro, Sergey C. Artiushin, Colin G. Nichols, David W. Fardo

Sanders-Brown Center on Aging Faculty Publications

The ABCC9 gene and its polypeptide product, SUR2, are increasingly implicated in human neurologic disease, including prevalent diseases of the aged brain. SUR2 proteins are a component of the ATP-sensitive potassium (“K _ATP ”) channel, a metabolic sensor for stress and/or hypoxia that has been shown to change in aging. The K _ATP channel also helps regulate the neurovascular unit. Most brain cell types express SUR2, including neurons, astrocytes, oligodendrocytes, microglia, vascular smooth muscle, pericytes, and endothelial cells. Thus it is not surprising that ABCC9 gene variants are associated with risk for human brain diseases. For example, Cantu syndrome is …

Novel Human Abcc9/Sur2 Brain-Expressed Transcripts And An Eqtl Relevant To Hippocampal Sclerosis Of Aging, Peter T. Nelson, Wang-Xia Wang, Bernard R. Wilfred, Angela Wei, James Dimayuga, Qingwei Huang, Eseosa T. Ighodaro, Sergey C. Artiushin, David W. Fardo

Sanders-Brown Center on Aging Faculty Publications

ABCC9 genetic polymorphisms are associated with increased risk for various human diseases including hippocampal sclerosis of aging. The main goals of this study were 1 > to detect the ABCC9 variants and define the specific 3′ untranslated region (3′UTR) for each variant in human brain, and 2 > to determine whether a polymorphism (rs704180) associated with risk for hippocampal sclerosis of aging pathology is also associated with variation in ABCC9 transcript expression and/or splicing. Rapid amplification of ABCC9 cDNA ends (3′RACE) provided evidence of novel 3′ UTR portions of ABCC9 in human brain. In silico and experimental studies were performed focusing on …

Finding The Engram., Sheena A Josselyn, Stefan Köhler, Paul W Frankland

Brain and Mind Institute Researchers' Publications

Many attempts have been made to localize the physical trace of a memory, or engram, in the brain. However, until recently, engrams have remained largely elusive. In this Review, we develop four defining criteria that enable us to critically assess the recent progress that has been made towards finding the engram. Recent 'capture' studies use novel approaches to tag populations of neurons that are active during memory encoding, thereby allowing these engram-associated neurons to be manipulated at later times. We propose that findings from these capture studies represent considerable progress in allowing us to observe, erase and express the engram.

Seasonal Change In The Avian Hippocampus., David F Sherry, Scott A Macdougall-Shackleton

Brain and Mind Institute Researchers' Publications

The hippocampus plays an important role in cognitive processes, including memory and spatial orientation, in birds. The hippocampus undergoes seasonal change in food-storing birds and brood parasites, there are changes in the hippocampus during breeding, and further changes occur in some species in association with migration. In food-storing birds, seasonal change in the hippocampus occurs in fall and winter when the cognitively demanding behaviour of caching and retrieving food occurs. The timing of annual change in the hippocampus of food-storing birds is quite variable, however, and appears not to be under photoperiod control. A variety of factors, including cognitive performance, …

Mitochondria-Associated Micrornas In Rat Hippocampus Following Traumatic Brain Injury, Wang-Xia Wang, Nishant P. Visavadiya, Jignesh D. Pandya, Peter T. Nelson, Patrick G. Sullivan, Joe E. Springer

Sanders-Brown Center on Aging Faculty Publications

Traumatic brain injury (TBI) is a major cause of death and disability. However, the molecular events contributing to the pathogenesis are not well understood. Mitochondria serve as the powerhouse of cells, respond to cellular demands and stressors, and play an essential role in cell signaling, differentiation, and survival. There is clear evidence of compromised mitochondrial function following TBI; however, the underlying mechanisms and consequences are not clear. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression post-transcriptionally, and function as important mediators of neuronal development, synaptic plasticity, and neurodegeneration. Several miRNAs show altered expression following TBI; however, the …

Effects Of (R)-(-)-5-Methyl-1-Nicotinoyl-2-Pyrazoline On Glutamate Transporter 1 And Cysteine/Glutamate Exchanger As Well As Ethanol Drinking Behavior In Male, Alcohol-Preferring Rats, Munaf Aal-Aaboda, Hasan Alhaddad, Francis Osowik, Surya M. Nauli, Youssef Sari

Pharmacy Faculty Articles and Research

Alcohol consumption is largely associated with alterations in the extracellular glutamate concentrations in several brain reward regions. We recently showed that glutamate transporter 1 (GLT-1) is downregulated following chronic exposure to ethanol for 5 weeks in alcohol-preferring (P) rats and that upregulation of the GLT-1 levels in nucleus accumbens and prefrontal cortex results, in part, in attenuating ethanol consumption. Cystine glutamate antiporter (xCT) is also downregulated after chronic ethanol exposure in P rats, and its upregulation could be valuable in attenuating ethanol drinking. This study examines the effect of a synthetic compound, (R)-(−)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), on ethanol drinking and expressions of …

Automatic Segmentation Of The Hippocampus For Preterm Neonates From Early-In-Life To Term-Equivalent Age., Ting Guo, Julie L Winterburn, Jon Pipitone, Emma G Duerden, Min Tae M Park, Vann Chau, Kenneth J Poskitt, Ruth E Grunau, Anne Synnes, Steven P Miller, M Mallar Chakravarty

Brain and Mind Institute Researchers' Publications

INTRODUCTION: The hippocampus, a medial temporal lobe structure central to learning and memory, is particularly vulnerable in preterm-born neonates. To date, segmentation of the hippocampus for preterm-born neonates has not yet been performed early-in-life (shortly after birth when clinically stable). The present study focuses on the development and validation of an automatic segmentation protocol that is based on the MAGeT-Brain (Multiple Automatically Generated Templates) algorithm to delineate the hippocampi of preterm neonates on their brain MRIs acquired at not only term-equivalent age but also early-in-life.

METHODS: First, we present a three-step manual segmentation protocol to delineate the hippocampus for preterm …

Quantitative Mri Correlates Of Hippocampal And Neocortical Pathology In Intractable Temporal Lobe Epilepsy, Maged Goubran

Electronic Thesis and Dissertation Repository

Intractable or drug-resistant epilepsy occurs in over 30% of epilepsy patients, with many of these patients undergoing surgical excision of the affected brain region to achieve seizure control. Advances in MRI have the potential to improve surgical treatment of epilepsy through improved identification and delineation of lesions. However, validation is currently needed to investigate histopathological correlates of these new imaging techniques. The purpose of this work is to investigate histopathological correlates of quantitative relaxometry and DTI from hippocampal and neocortical specimens of intractable TLE patients. To achieve this goal I developed and evaluated a pipeline for histology to in-vivo MRI …

A Study Of Small Rnas From Cerebral Neocortex Of Pathology-Verified Alzheimer's Disease, Dementia With Lewy Bodies, Hippocampal Sclerosis, Frontotemporal Lobar Dementia, And Non-Demented Human Controls, Sébastien S. Hébert, Wang-Xia Wang, Qi Zhu, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are small (20-22 nucleotides) regulatory non-coding RNAs that strongly influence gene expression. Most prior studies addressing the role of miRNAs in neurodegenerative diseases (NDs) have focused on individual diseases such as Alzheimer's disease (AD), making disease-to-disease comparisons impossible. Using RNA deep sequencing, we sought to analyze in detail the small RNAs (including miRNAs) in the temporal neocortex gray matter from non-demented controls (n = 2), AD (n = 5), dementia with Lewy bodies (n = 4), hippocampal sclerosis of aging (n = 4), and frontotemporal lobar dementia (FTLD) (n = 5) cases, together accounting for the most prevalent …

Predator-Based Fear Conditioning: A Novel Approach To The Study Of The Neurobiology Of Memory, Joshua D. Halonen

USF Tampa Graduate Theses and Dissertations

This series of experiments developed novel paradigms involving the integration of conventional and ethologically relevant forms of reinforcement in the study of fear conditioning in rats. Experiment 1 compared the effects of foot shock, immobilization and predator exposure, alone and in combination, on the expression of conditioned fear memory and extinction. The combination of all 3 reinforcers produced a significantly stronger fear memory and greater resistance to extinction, compared to when each reinforcer was administered alone. Furthermore, whereas conditioning with foot shock, alone, resulted in rapid extinction of the fear memory, the combination of immobilization and cat exposure, or all …

Signals From Intraventricular Depth Electrodes Can Control A Brain-Computer Interface, Jerry J. Shih, Dean J. Krusienski

Electrical & Computer Engineering Faculty Publications

A Brain-Computer Interface (BCI) is a device that enables severely disabled people to communicate and interact with their environments using their brain waves. Most research investigating BCI in humans have used scalp-recorded electroencephalography (EEG). We have recently demonstrated that signals from intracranial electrocorticography (ECoG) and stereotactic depth electrodes (SDE) in the hippocampus can be used to control a BCI P300 Speller paradigm. We report a case in which stereotactic depth electrodes positioned in the ventricle were able to obtain viable signals for a BCI. Our results demonstrate that event-related potentials from intraventricular electrodes can be used to reliably control the …

Efficacy Of Increased Ube3a Protein Levels In The Brain In Rescuing The Phenotype Of An Angelman Syndrome Mouse, Jennifer L. Daily

USF Tampa Graduate Theses and Dissertations

Angelman syndrome (AS), a genetic disorder occurring in approximately one in every 15,000 births, is characterized by severe mental retardation, seizures, difficulty speaking and ataxia. The gene responsible for AS was discovered to be UBE3A and encodes an E6-AP ubiquitin ligase. A unique feature of this gene is that it undergoes maternal imprinting in a neuron-specific manner. In the majority of AS cases, there is a mutation or deletion in the maternally inherited UBE3A gene, although other cases are the result of uniparental disomy or mismethylation of the maternal gene. While most human disorders characterized by severe mental retardation involve …

The Effects Of Pten Deletion On Cell Size And Plasticity In The Hippocampus, Margaret Sperow

Theses and Dissertations (ETD)

The tumor suppressor phosphatase and tensin homolog (PTEN) is the central negative regulator of the phosphatidylinositol 3-kinase (PI3K) -signaling pathway, which mediates diverse processes in various tissues. In the nervous system, the PI3K pathway modulates proliferation, migration, cellular size and synaptic transmission and plasticity. Neurologic abnormalities such as autism, seizures, and ataxia are associated with inherited PTEN mutations. Yet, how PTEN loss contributes to neurologic dysfunction remains unknown. PTEN loss during early development is associated with extensive deficits in neuronal migration and substantial hypotrophy of neurons and synaptic densities. However, whether its effect on synaptic transmission and plasticity is direct …

Mitochondrial Fragmentation Is Involved In Methamphetamine-Induced Cell Death In Rat Hippocampal Neural Progenitor Cells., Changhai Tian, L. Charles Murrin, Jialin C. Zheng

Journal Articles: Pharmacology & Experimental Neuroscience

Methamphetamine (METH) induces neurodegeneration through damage and apoptosis of dopaminergic nerve terminals and striatal cells, presumably via cross-talk between the endoplasmic reticulum and mitochondria-dependent death cascades. However, the effects of METH on neural progenitor cells (NPC), an important reservoir for replacing neurons and glia during development and injury, remain elusive. Using a rat hippocampal NPC (rhNPC) culture, we characterized the METH-induced mitochondrial fragmentation, apoptosis, and its related signaling mechanism through immunocytochemistry, flow cytometry, and Western blotting. We observed that METH induced rhNPC mitochondrial fragmentation, apoptosis, and inhibited cell proliferation. The mitochondrial fission protein dynamin-related protein 1 (Drp1) and reactive oxygen …

Torsina And The Pathophysiology Of Dyt1 Dystonia, Yu Zhao

Theses and Dissertations (ETD)

The goal of my dissertation work was to examine the systems biology of torsinA, a DYT1 dystonia-associated protein, by using rodent model systems. TorsinA is a putative ATPase associated with a variety of cellular activities (AAA+). Deletion of glutamic acid residue 302/303 in TOR1A is causally associated with many cases of early-onset primary dystonia.

In our work, transient forebrain ischemia and sciatic nerve transection were used as central and peripheral neural perturbations, respectively, to gain insight into the in vivo role(s) of torsinA. Moreover, transgenic mouse models that overexpress either human mutant torsinA (hMT) or wild-type torsinA (hWT) were used …

Dominance Of The Proximal Coordinate Frame In Determining The Locations Of Hippocampal Place Cell Activity During Navigation, Jennifer J Siegel, Joshua P Neunuebel, James J Knierim

Journal Articles

The place-specific activity of hippocampal cells provides downstream structures with information regarding an animal's position within an environment and, perhaps, the location of goals within that environment. In rodents, recent research has suggested that distal cues primarily set the orientation of the spatial representation, whereas the boundaries of the behavioral apparatus determine the locations of place activity. The current study was designed to address possible biases in some previous research that may have minimized the likelihood of observing place activity bound to distal cues. Hippocampal single-unit activity was recorded from six freely moving rats as they were trained to perform …

Activation Of Brain Regions Vulnerable To Alzheimer's Disease: The Effect Of Mild Cognitive Impairment, S. C. Johnson, T. W. Schmitz, C. H. Moritz, M. E. Meyerand, H. A. Rowley, A. L. Alexander, K. W. Hansen, C. E. Gleason, C. M. Carlsson, M. L. Ries, S. Asthana, K. Chen, E. M. Reiman, G. E. Alexander

Brain and Mind Institute Researchers' Publications

This study examined the functionality of the medial temporal lobe (MTL) and posterior cingulate (PC) in mild cognitive impairment amnestic type (MCI), a syndrome that puts patients at greater risk for developing Alzheimer disease (AD). Functional MRI (fMRI) was used to identify regions normally active during encoding of novel items and recognition of previously learned items in a reference group of 77 healthy young and middle-aged adults. The pattern of activation in this group guided further comparisons between 14 MCI subjects and 14 age-matched controls. The MCI patients exhibited less activity in the PC during recognition of previously learned items, …

Structural Mri Discriminates Individuals With Mild Cognitive Impairment From Age-Matched Controls: A Combined Neuropsychological And Voxel Based Morphometry Study, Mehul A. Trivedi, Allison K. Wichmann, Britta M. Torgerson, Michael A. Ward, Taylor W. Schmitz, Michele L. Ries, Rebecca L. Koscik, Sanjay Asthana, Sterling C. Johnson

Brain and Mind Institute Researchers' Publications

Background: Several previous studies have reported that amnestic mild cognitive impairment (aMCI), a significant risk factor for Alzheimer's disease (AD), is associated with greater atrophy in the medial temporal lobe (MTL) and posterior cingulate gyrus (PCG). Method: In the present study, we examined the cross-sectional accuracy (i.e., the sensitivity and specificity) of voxel-based morphometry (VBM) in discriminating individuals with MCI (n = 15) from healthy age-matched controls (n = 15). In addition, we also sought to determine whether baseline GM volume predicted aMCI patients that converted to AD from those that did not approximately 2 years after the baseline visit. …

Double Dissociation Between The Effects Of Peri-Postrhinal Cortex And Hippocampal Lesions On Tests Of Object Recognition And Spatial Memory: Heterogeneity Of Function Within The Temporal Lobe., Boyer D Winters, Suzanna E Forwood, Rosemary A Cowell, Lisa M Saksida, Timothy J Bussey

Brain and Mind Institute Researchers' Publications

It is widely believed that declarative memory is mediated by a medial temporal lobe memory system consisting of several distinct structures, including the hippocampus and perirhinal cortex. The strong version of this view assumes a high degree of functional homogeneity and serial organization within the medial temporal lobe, such that double dissociations between individual structures should not be possible. In the present study, we tested for a functional double dissociation between the hippocampus and peri-postrhinal cortex in a single experiment. Rats with bilateral excitotoxic lesions of either the hippocampus or peri-postrhinal cortex were assessed in tests of spatial memory (radial …

Fornix Lesions Can Facilitate Acquisition Of The Transverse Patterning Task: A Challenge For "Configural" Theories Of Hippocampal Function., T J Bussey, E Clea Warburton, J P Aggleton, J L Muir

Brain and Mind Institute Researchers' Publications

Configural theories of hippocampal function predict that hippocampal dysfunction should impair acquisition of the transverse patterning task, which involves the concurrent solution of three discrimination problems: A+ versus B-; B+ versus C-; and C+ versus A-. The present study tested this prediction in rats using computer-graphic stimuli presented on a touchscreen. Experiment 1 assessed the effects of fornix lesions when the three problems were introduced sequentially (phase 1: A+ vs B-; phase 2: A+ vs B-, B+ vs C-; phase 3: A+ vs B-, B+ vs C-, C+ vs A-). Fornix lesions significantly facilitated acquisition of the complete transverse patterning …