Distribution of terminals from pedunculopontine tegmental nucleus and synaptic organization in lateralis medialis-suprageniculate nucleus of cat's thalamus: Anterograde tracing, immunohistochemical studies, and quantitative analysis

2000 ◽  
Vol 17 (6) ◽  
pp. 893-904 ◽  
Author(s):  
KAEKO HOSHINO ◽  
YOSHIMITSU Y. KATOH ◽  
WANZHU BAI ◽  
TADAYOSHI KAIYA ◽  
MASAO NORITA
Keyword(s):  
Brain Regions ◽  
Pedunculopontine Tegmental Nucleus ◽  
Association Cortex ◽  
Projection Neurons ◽  
Synaptic Organization ◽  
Electron Microscopic ◽  
Synaptic Contacts ◽  
Tegmental Nucleus ◽  
Visual Association Cortex ◽  
Immunohistochemical Studies

The cat's lateralis medialis-suprageniculate nuclear complex (LM-Sg) in the thalamus receives input from various brain regions such as the superior colliculus, brain stem, and spinal cord, as well as from visual association cortex. In a previous study, we demonstrated that LM-Sg receives cholinergic fibers from the pedunculopontine tegmental nucleus (PPT) and that cholinergic terminals make synaptic contacts with the dendrites of glutamatergic projection neurons and of GABAergic interneurons (Hoshino et al., 1997). In this study, we investigate the distribution and the organization of PPT terminals by means of a combined anterograde tracer (biotinylated dextran amine, BDA) and immunohistochemical methods. When stained by acetylcholinesterase (AChE), the LM-Sg is not uniformly immunoreactive, but rather is patchily labeled and shows a streaming type of reactivity. The tissue content appears high in enzyme activity in AChE-positive zones and is much lighter in activity in AChE-negative zones. We compared the synaptic organization between AChE-positive and AChE-negative portions of the LM-Sg in separate groups of electron-microscopic material: four types of vesicle containing profiles (RS, RL, F1, and PSD) as well as synaptic glomeruli were observed in this nucleus. Among these, the PSD profiles were observed more frequently in AChE-positive portions than in AChE-negative zones. Furthermore, the number of glomeruli was significantly higher in AChE-positive than in AChE-negative zones. Following the injection of BDA into PPT, labeled terminals within LM-Sg were rather more concentrated in the AChE-positive portion. Although the majority of PPT terminals made synaptic contacts with dendrites in the neuropil, a few terminals were involved in the synaptic glomeruli. The present results show that the synaptic organization is distinctly different between the AChE-positive and AChE-negative portions of LM-Sg. These results suggest that the AChE-positive portions of LM-Sg are relatively more involved in integrating information arising from a diverse set of inputs and processing that information within glomeruli in a complex manner than occurs in the AChE-negative portion of LM-Sg.

Synaptic organization of the pedunculopontine tegmental nucleus of the cat

1989 ◽  
Vol 478 (2) ◽  
pp. 315-325 ◽  
Author(s):  
Tetsuji Moriizumi ◽  
Yasuhisa Nakamura ◽  
Hironobu Tokuno ◽  
Motoi Kudo ◽  
Yasuko Kitao
Keyword(s):  
Pedunculopontine Tegmental Nucleus ◽  
Synaptic Organization ◽  
Tegmental Nucleus

scholarly journals Prefrontal somatostatin interneurons encode fear memory

2019 ◽  
Author(s):  
Kirstie A. Cummings ◽  
Roger L. Clem
Keyword(s):  
Specific Activity ◽  
Conditioned Fear ◽  
Gain Control ◽  
Brain Regions ◽  
Fear Learning ◽  
Causal Mechanism ◽  
Projection Neurons ◽  
Synaptic Organization ◽  
Cortical Projection ◽  
Output Neurons

AbstractTheories stipulate that memories are encoded within networks of cortical projection neurons (PNs). Conversely, GABAergic interneurons (INs) are thought to function primarily to inhibit PNs and thereby impose network gain control, an important but purely modulatory role. However, we found that associative fear learning potentiates synaptic transmission and cue-specific activity of medial prefrontal cortex (mPFC) somatostatin interneurons (SST-INs), and that activation of these cells controls both memory encoding and expression. Furthermore, the synaptic organization of SST- and parvalbumin (PV)-INs provides a potential circuit basis for SST-IN-evoked disinhibition of mPFC output neurons and recruitment of remote brain regions associated with defensive behavior. These data suggest that rather than constrain mnemonic processing, potentiation of SST-IN activity represents an important causal mechanism for conditioned fear.

scholarly journals Activity in mouse pedunculopontine tegmental nucleus reflects action and outcome in a decision-making task

2013 ◽  
Vol 110 (12) ◽  
pp. 2817-2829 ◽  
Author(s):  
John A. Thompson ◽  
Gidon Felsen
Keyword(s):  
Decision Making ◽  
Mammalian Species ◽  
Brain Regions ◽  
Pedunculopontine Tegmental Nucleus ◽  
Movement Direction ◽  
Neuron Activity ◽  
Distributed Network ◽  
Spatial Choice ◽  
Tegmental Nucleus ◽  
Subcortical Regions

Recent studies across several mammalian species have revealed a distributed network of cortical and subcortical brain regions responsible for sensorimotor decision making. Many of these regions have been shown to be interconnected with the pedunculopontine tegmental nucleus (PPTg), a brain stem structure characterized by neuronal heterogeneity and thought to be involved in several cognitive and behavioral functions. However, whether this structure plays a general functional role in sensorimotor decision making is unclear. We hypothesized that, in the context of a sensorimotor task, activity in the PPTg would reflect task-related variables in a similar manner as do the cortical and subcortical regions with which it is anatomically associated. To examine this hypothesis, we recorded PPTg activity in mice performing an odor-cued spatial choice task requiring a stereotyped leftward or rightward orienting movement to obtain a reward. We studied single-neuron activity during epochs of the task related to movement preparation, execution, and outcome (i.e., whether or not the movement was rewarded). We found that a substantial proportion of neurons in the PPTg exhibited direction-selective activity during one or more of these epochs. In addition, an overlapping population of neurons reflected movement direction and reward outcome. These results suggest that the PPTg should be considered within the network of brain areas responsible for sensorimotor decision making and lay the foundation for future experiments to examine how the PPTg interacts with other regions to control sensory-guided motor output.

Synaptic organization of the gustatory NST

1994 ◽  
Vol 52 ◽  
pp. 150-151
Author(s):  
M. C. Whitehead
Keyword(s):  
Central Nervous System ◽  
Dendritic Spines ◽  
Fundamental Problem ◽  
Cell Types ◽  
Brain Regions ◽  
Excitatory Synapses ◽  
Solitary Tract ◽  
Synaptic Organization ◽  
Synaptic Junctions ◽  
Afferent Terminals

A fundamental problem in taste research is to determine how gustatory signals are processed and disseminated in the mammalian central nervous system. An important first step toward understanding information processing is the identification of cell types in the nucleus of the solitary tract (NST) and their synaptic relationships with oral primary afferent terminals. Facial and glossopharyngeal (LIX) terminals in the hamster were labelled with HRP, examined with EM, and characterized as containing moderate concentrations of medium-sized round vesicles, and engaging in asymmetrical synaptic junctions. Ultrastructurally the endings resemble excitatory synapses in other brain regions.Labelled facial afferent endings in the RC subdivision synapse almost exclusively with distal dendrites and dendritic spines of NST cells. Most synaptic relationships between the facial synapses and the dendrites are simple. However, 40% of facial endings engage in complex synaptic relationships within glomeruli containing unlabelled axon endings particularly ones termed "SP" endings. SP endings are densely packed with small, pleomorphic vesicles and synapse with both the facial endings and their postsynaptic dendrites by means of nearly symmetrical junctions.

CONTEXTUAL LEARNING IN THE MORRIS WATER MAZE

2018 ◽  
pp. 13-20
Author(s):  
Е.И. Захарова ◽  
З.И. Сторожева ◽  
А.Т. Прошин ◽  
М.Ю. Монаков ◽  
А.М. Дудченко
Keyword(s):  
Morris Water Maze ◽  
Choline Acetyltransferase ◽  
Water Maze ◽  
Synaptic Membranes ◽  
Projection Neurons ◽  
Synaptic Organization ◽  
Acetyltransferase Activity ◽  
Cholinergic Interneurons ◽  
Late Stages ◽  
Choline Acetyltransferase Activity

Цель - исследование холинергической синаптической организации функций обучения и памяти у крыс с разными когнитивными способностями. Методы. Крыс обучали на пространственной обстановочной модели в водном лабиринте Морриса. Через 2-3 сут. после окончания тренировок животных декапитировали, из неокортекса и гиппокампа с помощью центрифугирования выделяли субфракции синаптических мембран и синаптоплазмы легких и тяжелых синаптосом. В синаптических субфракциях определяли активность ключевого фермента холинергических нейронов холинацетилтрансферазы (ХАТ). Сравнивали результаты тестирования (время достижения скрытой платформы) и активность фермента у способных и неспособных к обучению крыс. Результаты. Были выявлены: 1) различия в холинергической организации исследованных функций в процессе обучения у способных и неспособных к обучению крыс, в том числе: положительные корреляции активности ХАТ в синапсах проекционных нейронов неокортекса у способных крыс со временем достижения платформы на промежуточных этапах обучения и в синапсах проекционных нейронов гиппокампа у неспособных крыс на позднем этапе обучения; разнонаправленные корреляции активности ХАТ в синапсах, предположительно, интернейронов гиппокампа (фракция тяжелых синаптосом) у способных и неспособных крыс на начальном и позднем этапах обучения; 2) индивидуальность холинергической организации функций на всех этапах обучения. Выводы. Полученные данные свидетельствуют в пользу представлений о специфике холинергической организации функций пространственного обстановочного обучения у крыс с выраженными и слабыми способностями к обучению, а также избирательной роли холинергических интернейронов гиппокампа на исходном этапе обучения и в консолидации памяти. In order to expand the knowledge about neuronal organization of the cognitive functions required for understanding plastic processes in the brain, we investigated the cholinergic synaptic organization of learning and memory functions in rats with different cognitive abilities. Methods. Rats were trained on a contextual situation model in the Morris water maze. At 2-3 days after the end of training, animals were decapitated, and subfractions of synaptic membranes and synaptoplasm of light and heavy synaptosomes were isolated from the cortex and the hippocampus by centrifugation. In synaptic subfractions, activity of the key enzyme of cholinergic neurons, choline acetyltransferase, was measured. We compared the test results (latent period to reach the hidden platform) and the enzyme activity in capable (lower quartile) and incapable of learning rats (upper quartile). Results. The following was found: 1) differences in the cholinergic organization of studied functions in capable and uncapable of learning rats during training, including: positive correlations of choline acetyltransferase activity in synapses of projection neurons in the cortex of capable rats with latency to reach the platform at intermediate stages of training and in the hippocampus ofincapable rats at late stages of training; multidirectional correlations of choline acetyltransferase activity in synapses of hippocampal, presumably, interneurons (heavy synaptosomes) in capable and incapable rats at early and late stages of training; 2) distinctness of the cholinergic organization of functions at all stages of training. Conclusions. The study demonstrated for the first time a specificity of the cholinergic organization of functions in spatial situational learning of rats with strong and poor learning abilities and a selective role of hippocampal cholinergic interneurons at the initial stage of learning and in memory consolidation.

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