Antipsychotic drugs (typical and atypical) are used in the treatment of mental disorders such as schizophrenia. Typical antipsychotic drugs (such as haloperidol) specifically target dopamine D2 receptors and produce extrapyramidal side effects. Atypical antipsychotic drugs (such as risperidone and olanzapine) primarily target dopamine D2 and serotonin 5HT2A receptors and produce fewer extrapyramidal symptoms (EPS) than do the typical antipsychotic drugs at clinically effective doses (Meltzer and Nash, 1991). It has been proposed that the prefrontal cortex (a brain region implicated in the pathophysiology of schizophrenia) is the locus of antipsychotic drug action to improve cognitive dysfunction and negative symptoms of schizophrenia (Weinberger and Lipska, 1995; Jakab and Goldman-Rakic, 1998). Moreover, it is possible that the effects in the prefrontal cortex may contribute to the differences between typical and atypical antipsychotic drugs as well as differences among atypical antipsychotic drugs (Horacek et al., 2006). The core pathology associated with the dorsolateral prefrontal cortex includes reduced cerebral volume, increased ventricle size and deficits in neuronal morphology, including increased cell packing density, reduction in dendrites and its associated dendritic spines (Selemon and Goldman-Rakic, 1999). However, since most neuropathology data emerge from in vivo imaging and post-mortem studies of patients with schizophrenia, it is difficult to interpret and distinguish between findings that have an etiological or iatrogenic basis. Thus, the objective of the current study was to examine the effects of antipsychotic drugs, at therapeutically relevant concentrations, in a rat brain region that is homologous to that of the human dorsolateral prefrontal cortex. The hypothesis upon which this study was based is that haloperidol, risperidone and olanzapine (at 65 to 80% striatal dopamine D2 receptor occupancy) induce changes to pyramidal cell architecture in the rat anterior cingulate cortex (Vogt and Gabriel, 1993; Hoover and Vertes, 2007). This hypothesis was investigated by (a) determining doses that are within the therapeutic range (65 to 80% striatal dopamine D2 receptor occupancy) by measuring the occupancy of haloperidol, risperidone and olanzapine in the presence of 3H-raclopride ( a dopamine D2 receptor antagonist) at dopamine D2 receptors in the rat striatum; and (b) examining whether therapeutic doses of antipsychotic drugs in rats cause neuropathology comparable to that observed in human post-mortem brains of patients with schizophrenia. Antipsyhcotic drug doses were selected using an appropriate in vivo dopamine D2 receptor occupancy method. The findings from this study revealed that 0.25 mg/kg/day haloperidol, 5 mg/kg/day risperidone and 10 mg/kg/day olanzapine achieved therapeutically relevant rat striatal dopamine D2 receptor occupancy in the range of 65 to 80%. To determine whether antipsychotic drugs at therapeutic doses established above induce changes in neuronal cell density and morphology; immunohistochemistry, single cell injection of lucifer yellow dye and Golgi-Cox impregnation of layer II/III pyramidal cells was performed. The results from these experiments revealed that the density of cells expressing NeuN, parvalbumin, calretinin or calbindin is highly unlikely to be affected by chronic exposure to haloperidol, risperidone and olanzapine. The current study evaluated the effects of chronic antipsychotic drug exposure on spontaneous locomotor activity of a rat in a novel environment. The purpose of this study was to differentiate between a direct and an indirect drug effect. It was found that at the doses established above, risperidone and olanzapine did not overtly reduce spontaneous locomotor activity of a rat in a novel environment relative to controls. In contrast, haloperidol reduced spontaneous locomotor activity of rat in an open field, although this was not statistically significant. Nevertheless, the data reported here allowed us to conclude that the level of activity across groups is unlikely to affect the data obtained in subsequent studies investigating the effects of chronic antipsychotic drug treatment on pyramidal cell structure. Intracellular injection of lucifer yellow dye into pyramidal cells revealed that chronic haloperidol treatment (28 days) was associated with a relative increase in basal dendritic arborisation, but neither of these drug treatments induced changes in arborisation that were different from controls. No statistically significant change in the basal dendritic arbor was detected with animals treated with risperidone relative to controls. Similarly using the Golgi-impregnation method, changes in soma size, dendritic branching, total number of branches and the density of dendritic spines in antipsychotic drug treated groups were not significantly different to controls. Taken together, this finding indicates that only relatively subtle neuritic changes may be attributed to chronic treatment with typical or atypical antipsychotic drugs administered at doses that avhieved striatal dopamine D2 receptor occupancy in the range of 65 to 80%. In summary, this study confirms that antipsychotic drugs are unlikely to induce changes to neuronal cell density or morphology in the rat anterior cingulate cortex at therapeutically relevant doses. Hence, it can be concluded that the observed neuropathology, found in the brains of patients with schizophrenia that have undergone antipsychotic drug therapy, is more likely to be caused by the disease and not the effects of the concomitant drug therapy.

Alzheimer's Disease (AD) is more prevalent than any other disease under the umbrella of dementia (Alzheimer's Association, 2013). Certified Nursing Assistants (CNAs) are the typical front-line care staff who care for individuals in aging care (Sengupta, Harris-Kojetin, & Ejaz, 2010). The present study investigated the use of a pyramidal training model to teach aging facility staff to be able to conduct trainings and to teach direct care staff antecedent strategies shown to be effective when communicating with individuals with AD. Pyramidal training resulted in two tiers of staff successfully implementing training for subsequent tiers of staff and subsequent staff demonstrated mastery of the trained material. However, during maintenance observations, some decreases were observed both with regard to training integrity as well as implementation of the trained material.

Background: Altered brain morphology was one of the first pathobiological findings associated with autism spectrum disorder. These gross abnormalities, documented in both white and gray matter areas in autistic brains, are postulated to contribute to disrupted neuronal communication. For example, glutamatergic pyramidal neurons in the anterior cingulate cortex (ACC) have decreased size and increased cell density in autism. Objectives: We sought to determine whether autism-related gene expression abnormalities exist in the ACC that might underlie previously observed cell morphological alterations found in this brain region. Specifically, levels of expression of genes associated with glutamatergic neurotransmission were measured in pyramidal neurons and surrounding astrocytes in the ACC of postmortem brain tissues from autism donors and matched developmentally normal control donors. Methods: Postmortem brain tissues were obtained from 6-8 age-matched pairs of male subjects who had autism and developmentally normal control males (age range 6-37). Laser-guided microdissection was used to capture pure populations of pyramidal neurons and astrocytes from layer III of the ACC. The expression of glutamate-related genes was measured in RNA isolates by reverse transcription followed by end-point PCR using three stable reference genes to normalize expression levels. Results: ACC pyramidal neurons from autism subjects demonstrated significantly reduced gene expressions of the obligatory glutamatergic NMDA receptor subunit NR1, a glutamate transporter SLC1A1, and the glutamate receptor anchoring protein GRIP1. There was also a robust reduction in the gene expression of the brain-derived neurotrophic factor (BDNF) receptor NTRK2 in autism pyramidal neurons, with gene expression levels of BDNF itself unaffected. No gene expression abnormalities were observed in ACC astrocytes surrounding the pyramidal neurons from autistic subjects. Conclusions: Autism spectrum disorder is associated with a reduction in the expression of genes associated with glutamatergic neurotransmission and downstream BDNF signaling in pyramidal neurons of the ACC. These findings suggest that glutamatergic signaling is compromised in these excitatory neurons in autism and raise hope that drugs or other treatments may be developed to overcome these pathobiological deficits.

Background: The anterior cingulate cortex (ACC) is a brain area involved in modulating behavior associated with social interaction, disruption of which is a core feature of autism spectrum disorder (ASD). Functional brain imaging studies demonstrate abnormalities of the ACC in ASD as compared to typically developing control patients. However, little is known regarding the cellular basis of these functional deficits in ASD. Pyramidal neurons in the ACC are excitatory glutamatergic neurons and key cellular mediators of the neural output of the ACC. This study was designed to investigate the potential role of ACC pyramidal neurons in ASD brain pathology. Methods: Postmortem ACC tissue from carefully matched ASD and typically developing control donors was obtained from two national brain collections. Pyramidal neurons and surrounding astrocytes were separately collected from layer III of the ACC by laser capture microdissection. Isolated RNA was subjected to reverse transcription and endpoint PCR to determine gene expression levels for 16 synaptic genes relevant to glutamatergic neurotransmission. Cells were also collected from the prefrontal cortex (Brodmann area 10) to examine those genes demonstrating differences in expression in the ACC comparing typically developing and ASD donors. Results: The level of NTRK2 expression was robustly and significantly lower in pyramidal neurons from ASD donors as compared to typically developing donors. Levels of expression of GRIN1, GRM8, SLC1A1, and GRIP1 were modestly lower in pyramidal neurons from ASD donors, but statistical significance for these latter genes did not survive correction for multiple comparisons. No significant expression differences of any genes were found in astrocytes laser captured from the same neocortical area. In addition, expression levels of NTRK2 and other synaptic genes were normal in pyramidal neurons laser captured from the prefrontal cortex. Conclusions: These studies demonstrate a unique pathology of neocortical pyramidal neurons of the ACC in ASD. NTRK2 encodes the tropomyosin receptor kinase B (TrkB), transmission through which neurotrophic factors modify differentiation, plasticity, and synaptic transmission. Reduced pyramidal neuron NTRK2 expression in the ACC could thereby contribute to abnormal neuronal activity and disrupt social behavior mediated by this brain region.

Background: The anterior cingulate cortex (ACC) is a brain area involved in modulating behavior associated with social interaction, disruption of which is a core feature of autism spectrum disorder (ASD). Functional brain imaging studies demonstrate abnormalities of the ACC in ASD as compared to typically developing control patients. However, little is known regarding the cellular basis of these functional deficits in ASD. Pyramidal neurons in the ACC are excitatory glutamatergic neurons and key cellular mediators of the neural output of the ACC. This study was designed to investigate the potential role of ACC pyramidal neurons in ASD brain pathology. Methods: Postmortem ACC tissue from carefully matched ASD and typically developing control donors was obtained from two national brain collections. Pyramidal neurons and surrounding astrocytes were separately collected from layer III of the ACC by laser capture microdissection. Isolated RNA was subjected to reverse transcription and endpoint PCR to determine gene expression levels for 16 synaptic genes relevant to glutamatergic neurotransmission. Cells were also collected from the prefrontal cortex (Brodmann area 10) to examine those genes demonstrating differences in expression in the ACC comparing typically developing and ASD donors. Results: The level of NTRK2 expression was robustly and significantly lower in pyramidal neurons from ASD donors as compared to typically developing donors. Levels of expression of GRIN1, GRM8, SLC1A1, and GRIP1 were modestly lower in pyramidal neurons from ASD donors, but statistical significance for these latter genes did not survive correction for multiple comparisons. No significant expression differences of any genes were found in astrocytes laser captured from the same neocortical area. In addition, expression levels of NTRK2 and other synaptic genes were normal in pyramidal neurons laser captured from the prefrontal cortex. Conclusions: These studies demonstrate a unique pathology of neocortical pyramidal neurons of the ACC in ASD. NTRK2 encodes the tropomyosin receptor kinase B (TrkB), transmission through which neurotrophic factors modify differentiation, plasticity, and synaptic transmission. Reduced pyramidal neuron NTRK2 expression in the ACC could thereby contribute to abnormal neuronal activity and disrupt social behavior mediated by this brain region.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21453号 / 医博第4420号 / 新制||医||1032(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 渡邉 大, 教授 浅野 雅秀, 教授 林 康紀 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Parents of children with an autism spectrum disorder experience many stressors in their lives, including managing problem behaviors of their child. Parent training can effectively teach parents strategies to manage noncompliant behaviors; however, many parents spend months on wait lists before accessing this service. This study investigated the preliminary effects of both an expert-led and parent-led training for wait-listed parents. Thirteen parents of children currently on a waitlist to receive behavioral analytic services participated; most were highly educated, all were white and married. The study used a pyramidal training approach: a professional instructed one group of participants while a participant volunteer instructed the second group. Participants completed a training on several behavior management techniques. Training was conducted in a manner plausible for community clinics to implement. Checklists and direct observations of trainee behavior were taken to observe fidelity of training. Data were also collected using parent self-report measures using Likert-scales to report on their own behavior as well as their child’s behavior. Participants from both groups reported decreases in child noncompliant behavior and increases in parent self-efficacy, confidence and consistency in administering behavior management techniques, indicating that both expert-led and parent-led training are effective in decreasing reported noncompliant behavior and increasing parent-reported self-efficacy. Clinics and communities should seek to implement similar programs to address wait-list issues; using a pyramidal parent training module may allow more parents to access information in a more efficient fashion. Further research should be conducted on larger groups and additional levels of pyramidal training.

The central nervous system (CNS) is protected by a vascular blood-brain barrier that prevents many types of pathogens from entering the brain. Still, some pathogens have evolved mechanisms to traverse this barrier and establish a long-term infection. The apicomplexan parasite, Toxoplasma gondii, is one such pathogen with the ability to infect the CNS in virtually all warm-blooded animals, including humans. Across the globe, an estimated 30% of the human population is infected with Toxoplasma, an infection for which mounting evidence suggests increases the risk for developing neurological and neuropsychiatric disorders, like seizures and schizophrenia. In my dissertation, I investigate the telencephalic neural circuit changes induced by long-term Toxoplasma infection in the mouse brain and the neuroimmune signaling role of the complement system in mediating microglial remodeling of neural circuits following parasitic infection. While there has been keen interest in investigating neural circuit changes in the amygdala – a region of the brain involved in fear response and which Toxoplasma infection alters in many species of infected hosts – the hippocampus and cortex have been less explored. These are brain regions for which Toxoplasma also has tropism, and moreover, are rich with fast-spiking parvalbumin perisomatic synapses, a type of GABAergic synapse whose dysfunction has been implicated in epilepsy and schizophrenia. By employing a range of visualization techniques to assess cell-to-cell connectivity and neuron-glia interactions (including immunohistochemistry, ultrastructural microscopy, and microglia-specific reporter mouse lines), I discovered that longterm Toxoplasma infection causes microglia to target and ensheath neuronal somata in these regions and subsequently phagocytose their perisomatic inhibitory synapses. These findings provide a novel model by which Toxoplasma infection within the brain can lead to seizure susceptibility and a wider range of behavioral and cognitive changes unrelated to fear response. In the Toxoplasma infected brain, microglia, along with monocytes recruited to the brain from the periphery, coordinate a neuroinflammatory response against pathogenic invasion. This is characterized by a widespread activation of these cells and their increased interaction with neurons and their synaptic inputs. Yet, whether T. gondii infection triggers microglia and monocytes (i.e. phagocytes) to target, ensheath, and remove perisomatic inhibitory synapses on neuronal somata indiscriminately, or whether specificity exists in this type of circuit remodeling, remained unclear. Through a comprehensive assessment of phagocyte interactions with cortical neuron subtypes, I demonstrate that phagocytes selectively target and ensheath excitatory pyramidal cells in long-term infection. Moreover, coupling of in situ hybridization with transgenic reporter lines and immunolabeling revealed that in addition to phagocytes, excitatory neurons also express complement component C3 following infection (while inhibitory interneurons do not). Lastly, by employing targeted deletion of complement components, C1q and C3, I show that complement is required for phagocyte ensheathment of excitatory cells and the subsequent removal of perisomatic inhibitory synapses on these cells (albeit not through the classical pathway). Together, these studies highlight a novel role for complement in mediating synapse-type and cell-type specific circuit remodeling in the Toxoplasma infected brain. / Doctor of Philosophy / Parasites are microorganisms that rely on other living organisms (called hosts) for their survival. Although some parasites only live on their hosts, others have developed ways to establish infections and obtain the nutrients that keep them alive from host cells. My Ph.D. research has focused on studying one of these parasites, Toxoplasma gondii (commonly referred to as Toxo), that has evolved the unique ability to establish brain infections in almost all animals around the world, from rodents to humans. Recent discoveries show that brain infection with this parasite can cause seizures, an imbalance in the way that specialized cells of the brain (called neurons) communicate with each other, causing harmful hyperactivity within the brain. Toxo infection can also cause behavioral and cognitive changes in infected animals, making them more susceptible to predation. In humans, infection with Toxo increases their risk for developing different types of mental illness, such as schizophrenia. The focus of my Ph.D. research has been in trying to understand, at the cellular and molecular level, how infection with this parasite can lead to seizures and behavioral changes, by using mice as a model. Mice have a similar brain structure to humans, and over the years, scientists have developed many tools that allow us to visualize and study the connections between neurons (called synapses). I'm interested in understanding how changes in these connections affect how neurons communicate with each other, and ultimately, how we behave and think. I have been studying a type of connection that, if lost or damaged, can lead to seizures and some types of mental illness. These connections are called 'perisomatic inhibitory synapses', and they form on many distinct types of neurons, but specifically on the cell bodies of these neurons. They act as a traffic light, informing neurons when and for how long to 'slow down' their activity. I discovered that after the parasite enters the brain, it causes another type of cell in the brain, called microglia, to extensively interact with neurons in the cortex and hippocampus (areas of your brain important for thinking, executing behavior, and learning). Microglia are immune cells of the brain that inspect the brain for anything damaged or that doesn't belong (like parasites) and removes them from the brain. By performing experiments where I delete individual immune molecules from mice, I found that one immune molecule, called 'complement component C3' acts as cue for microglia to find these cells, wrap around them, and permanently remove these important connections. Surprisingly, however, microglia don't remove these connections from all neurons, indiscriminately, they do so only on one specific cell type called 'excitatory pyramidal neurons,' and as the name implies, they're the ones who drive activity in the brain. My half-a-decade's worth of research helps us understand parasitic infections in the brain in a couple of ways: First, I have discovered one of the mechanisms by which neuronal connections are lost in the Toxo-infected brain (which is a mechanism that leads to loss of neuronal connections in the injured and aging brain as well). This is significant because it might provide insight into why some people who are infected with Toxo develop seizures or mental illness, while others don't. More importantly, Toxo-infection causes changes in the brain that are very specific, in terms of both the type of neuronal connection that is affected and the type of cell that is affected. Why these changes are so specific remain to be uncovered, but it suggests that Toxo can either a) trigger a unique immune response in the brain that leads to very precise changes in neuron-toneuron connections and signaling or b) the parasite, while hiding inside of neurons, may hijack the machinery of certain cell types in a way that helps them survive longer.

The subiculum is a structure that forms a bridge between the hippocampus and the entorhinal cortex (EC) in the brain, and plays a major role in the memory consolidation process. It consists of different types of pyramidal neurons. Based on their firing behavior, these excitatory neurons are classified into strong burst firing (SBF), weak burst firing (WBF) and regular firing (RF) neurons. In the first part of the work, morphological differences in the different neuronal subtypes was explored by biocytin staining after classifying the neurons based on the differences in electrophysiological properties. Detailed morphological properties of these three neuronal subtypes were analyzed using Neurolucida neuron reconstruction method. Unlike the differences in their electrophysiological properties, no difference was found in the morphometric properties of these neuronal subtypes. In the second part of the thesis, experimental results on spike- timing- dependent plasticity (STDP) at the proximal excitatory inputs on the subicular pyramidal neurons of the juvenile (P15-P19) rat are described. The STDP was studied in the WBF and RF neurons. Causal pairing of a single EPSP with a single back propagating action potential (bAP) at a time interval of 10 ms failed to induce plasticity. However, increasing the number of bAPs in such EPSP-bAP pair to three at 50 Hz (bAP burst) induced LTD in both, the RF, as well as the WBF neurons. Increasing the frequency of action potentials to 150 Hz in the bAP burst during causal pairing also induced LTD in both the neuronal subtypes. However, all other STDP related experiments were performed only with the bAP bursts consisting of 3 bAPs evoked at 50 Hz. Amplitude of the causal pairing induced LTD decreased with increasing time interval between EPSP and the bAP burst. Reversing the order of the EPSP and the bAP burst in the pair induced LTP only with a short time interval of 10 ms. This finding is in contrast to most of the reports on excitatory synapses, wherein the pre-before post (causal) pairing induced LTP and vice-versa. The results of causal and anti-causal pairing were used to plot the STDP curve for the WBF neurons. In the STDP curve observed in these synapses, LTD was observed upto a causal time interval of 30 ms, while LTP was limited to 10 ms time interval. Hence, the STDP curve was biased towards LTD. These results reaffirm the earlier observations that the relative timing of the pre- and postsynaptic activities can lead to multiple types of STDP curves. Next, the mechanism of non-Hebbian LTD was studied in both, the RF and WBF neurons. The involvement of calcium in the postsynaptic neuron in plasticity induction was studied by chelating intracellular calcium with BAPTA. The results indicate that the LTD induction in WBF neurons required postsynaptic calcium, while LTD induction in the RF neurons was independent of postsynaptic calcium. Paired pulse ratio (PPR) experiments suggested the involvement of a presynaptic mechanism in the induction of LTD in the RF neurons, and not in the WBF neurons since the PPR was unaffected by the induction protocol only in the WBF neurons. LTD induction in the WBF neurons required activity of the NMDA receptors since LTD was not observed in the presence of the NMDA receptor blocker in the WBF neurons, while it was unaffected in the RF neurons. However, the RF neurons required the activity of L-type calcium channels for plasticity induction, since LTD was affected in the presence of the L-type calcium channel blockers, although the WBF neurons did not require the L-type calcium channel activity for plasticity induction. Hence, in addition to a non-Hebbian STDP curve, a novel mechanism of LTD induction has been reported, where L-type calcium channels are involved in a synaptic plasticity that is expressed via change in the release probability. The findings on the STDP in subicular pyramidal neurons may have strong implications in the memory consolidation process owing to the central role of the subiculum and LTD in it.

No description available.