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| #acl 2944E,2963E,2949E:read,write Default Amphetamine Related Drugs and the Limbic System "bold" |
#acl 2944E,2963E,2949E:read,write Default . . <<TableOfContents(3)>> == Intoduction == The term limbic system is applied to a collection of brain structures found in all mammals which is involved with a variety of functions including epinephrine flow, emotion, behavior, motivation, long-term memory, and olfaction. Emotional life is largely housed in the limbic system, and it has a great deal to do with the formation of memories. The limbic system has great input on thirst, hunger, sexual behavior, and reward. Many drugs of abuse such as cocaine and amphetamines directly affect the structures of the limbic system. Perhaps the simplest way to understand the functions of the limbic system is to use the mnemonic “M-O-V-E.” * '''M''' – Motivation and Memory formation * '''O''' – Olfaction or sense of smell * '''V''' – Visceral of autonomic nervous system functions * '''E''' – Emotional components of behavior All mammals have a limbic system, however many specie variants developed related to the magnitude olfaction plays in the animal’s evolution. In species where olfaction development and function is high (canines, rodents, etc.), the limbic system constitutes more of the brain mass and less devotion to outer cortex development (Finlay et al., 2001). Primates, insectivores, and ungulates collectively demonstrate an inverse relationship between cerebral cortex and limbic volumes, but terrestrial carnivores have high relative volumes of both; meanwhile bats have low relative volumes of both (Reep et al., 2007). Marine mammals with reduced olfactory bulbs also have a reduced limbic system overall (Clark et al., 2001). == Structures of the Limbic System == The Limbic System consists of cortical and subcortical components that have developed from the telencephalon, diencephalon and mesencephalon. The cortical part comprises interconnected telencephalic structures on the medial and basal aspect of the hemispheres, namely the cingulated gyrus, hippocampus and the piriform lobe. The subcortical part includes components of the diencephalon (habenula, hypothalamus, thalamus), midbrain (tegmental nuclei) and the amygdala. The limbic system receives olfactory input from the amygdala and piriform lobe that can trigger emotional behavior such as fear, aggression, and apparent pleasure. Sheep Brain: Image of sheep brain was taken in 2008 at St. Mary’s College of Maryland under the guidance of Dr. Anne Marie Brady in a Biological Psychology course. == Dog Brain Extraction == The extraction, fixation, and dissection of the dog brain was completed at Szent Istvan University under the guidance of Dr. Kalman Czeibert. Skin surround skull was incised, then using scalpel, the temporal and masseter muscles were transected and scrapes off skull. Using a surgical saw, a rostral cut was made into the frontal sinus. Superficial cuts were made laterally on the temporal bone starting at the occipital condyles, through the nuchal crest and along the temporal bones connecting to the rostral cut at the frontal sinus. Using a surgical chisel and hammer, the superficial cuts were widened allowing the skull to easily be removed dorsally. Carefully, the cranial nerves were removed and the brain was extracted from the cranial cavity. === Fixation === The structure and consistency of the dog brain upon removal was not ideal for dissecting in order to expose the limbic system. Upon removal of the canine brain, it was placed in a 7% formaldehyde solution for 24 hours than transferred into a 3% formaldehyde solution for another 24 hours. === Dissection === . The two hemispheres were gently widened, exposing the white matter of the corpus callosum. A light incision was made on the corpus callosum (Figure 1), removing the dense axon fibers connecting the two hemispheres, and making visible the third ventricle and choroid plexus (Figure 2). Using the borders of the lateral ventricles, gently a transverse incision was made through the parietal lobe as well as a lateral cut that would continue all the way through the occipital lobe (Figure 3). The horn of the hippocampus was made visible. Using finite and precise cuts, the remainder of the cortex was removed around the hippocampus (Figure 4). Through a similar process, the remaining part of the left hemisphere was removed, making the thalamus and other components of the limbic system visible (Figure 5&6). . . A second brain was similarly fixed and used for cross sectional dissections. Approximately 5-9 mm thick cuts were made transecting through the canine brain from a dorsal to ventral position. Brain slices allowed the exposure of the internal components of the limbic system (Figure 7). . The various components of the limbic system are each associated with different functions. The Amygdala is involved with several emotional responses (Sato et al., 2016); the Hippocampus is involved with learning and memory formation (Mao et al., 2015); the Thalamus relays sensory and motor signals plus regulates sleep and alertness (Li et al., 2014); the Nucleus Accumbens with reward, pleasure and addiction (West et al., 2016); Hypothalamus is involved with regulation of the pituitary gland and hormonal function (Perez et al., 2016); Olfactory bulbs involved in the perception of smell and connect to piriform lobe & amygdala (De La Rosa et al., 2015); the Habenula receives input from the limbic system and basal ganglia, influencing the brains response to pain, stress, anxiety, sleep and reward (Velasquez et al., 2014). . . == Molecular and Cellular Neuroscience == Neuroscience is an expansive field of science which integrates multiple fields of research and investigation in order to understand the functioning of this complex system. The anatomy and physiology of the mammalian brain neural systems have been thoroughly investigated and documented; yet, new discoveries are still being unveiled every day. Through immunohistological studies of many animal species, the location and functioning of neurons and glia (the cells that compose the central and peripheral nervous system) have been identified. Generally speaking, the neuron is the implementation system of the nervous system and the variation of their composition generates the many capabilities possible. The structure of a neuron consists of three components: 1. '''Soma''' – cell body - location of typical cell functions and genetic information storage 1. '''Axon''' - a very slender nerve fiber - projects from the neuron's cell body and transmits electrical impulses to the neuron's axon terminals. This electrical signal stimulates release of a neurotransmitter, which is produced inside the nerve cell. It is neurotransmitters that light up the brain with life. 1. '''Dendrites''' – multiple short branched extensions of a neuron, along which impulses and neurochemical communication is received from other cells at synapses are transmitted to soma. <<BR>> == Neurotransmission == As an action potential travels down the axon, the depolarized cell membrane opens voltage gated calcium channels at the terminal button and stimulates vesicular release. These synaptic vesicles are filled with a particular neurotransmitter (neuro-chemical). There are over 100 different neurotransmitters that have identified in the mammalian nervous system. The location, post-synaptic effect, metabolism, and removal of these neurotransmitters significantly differ from one another. Neurotransmitter transport systems are integral to the release, re-uptake and recycling of neurotransmitters at synapses. High affinity transport proteins found in the plasma membrane of presynaptic nerve terminals and glial cells are responsible for the removal from the extracellular space of released-transmitters, thereby terminating their action. In addition to these removal systems, several neurotransmitter-specific enzymes are present to inactivate or regulate these chemicals released into the synapse. Upon bonding to a post-synaptic receptor, these neurochemicals will typically have an excitatory or inhibitory response on the sequential neuron through ionotropic or metabotropic functions. Through electrophysiological studies, immunohistochemistry, and genetic knock-out models, the understanding of these brain chemicals has vastly improved in the past couple decades. In regards to the topic of this essay and its relation to the Limbic System, we are only going to focus on the neurotransmitters specifically relevant. == Neurotransmitters And Corresponding Receptors == === Catecholamines === ==== Dopamine ==== ===== Dopamine Synthesis Dopamine Receptors ===== ===== Class D1 ===== ===== Class D2 ===== ==== Dopamine Metabolism ==== ===== Dopmanine Transporter Monoamine Oxidase Catachol-O-Methyl-Transferase Trace Amine Associated Receptor Veiscular Monoamine Transporter ===== ==== Neural Pathways ==== ===== Mesolimbic Pathway Mesocortical Pathway Nigrostriatal Pathway Tuberoinfundibular Pathway ===== ==== Norepinephrine ==== ===== Norepinephrine Synthesis Receptors ===== ===== Alpha 1A Alpha 1B Alpha 1D Alpha 2A Alpha 2B Alpha 2C 1, 2 & 3 ===== ===== Norepinephrine Metabolism ===== ===== Plasma Membrane Monoamine TransporterMonoamine OxidaseCatechol-O-Methyl-TransferaseTrace Amine Associated ReceptorVeiscular Monoamine Transporter ===== === Neural Pathways === === Monoamines === ==== Serotonin (5-HT)SynthesisReceptors ==== ===== 5-HT1A 5-HT2A 5-HT2C 5-HT6 ===== ==== Monoamines Metabolism ==== ===== Serotonin TransporterMonoamine OxidaseVesicular Monoamine TransporterNeural PathwaysOther Relevent Neurotransmiters ===== === Glutamate === == Behavioural Effects of Amphetamines == == Amphetamine Effect on Neurotransmitters == ==== Dopmanine Transporter Monoamine Oxidase Inhibitor VMAT Malfunction Catechol-O-Methyl-Transferase ==== ===== Glutamate Effect ===== == Dependance and Withdrawl == == References == . . . . ||<tablebgcolor="#eeeeee" tablestyle="float:center;font-size:0.85em;margin:0 0 0 0; "style="padding:0.5em; ;text-align:center"><<BR>>'''Fig 1.'''<<BR>>''Cat Fig.'' || |
Intoduction
The term limbic system is applied to a collection of brain structures found in all mammals which is involved with a variety of functions including epinephrine flow, emotion, behavior, motivation, long-term memory, and olfaction. Emotional life is largely housed in the limbic system, and it has a great deal to do with the formation of memories. The limbic system has great input on thirst, hunger, sexual behavior, and reward. Many drugs of abuse such as cocaine and amphetamines directly affect the structures of the limbic system. Perhaps the simplest way to understand the functions of the limbic system is to use the mnemonic “M-O-V-E.”
M – Motivation and Memory formation
O – Olfaction or sense of smell
V – Visceral of autonomic nervous system functions
E – Emotional components of behavior
All mammals have a limbic system, however many specie variants developed related to the magnitude olfaction plays in the animal’s evolution. In species where olfaction development and function is high (canines, rodents, etc.), the limbic system constitutes more of the brain mass and less devotion to outer cortex development (Finlay et al., 2001). Primates, insectivores, and ungulates collectively demonstrate an inverse relationship between cerebral cortex and limbic volumes, but terrestrial carnivores have high relative volumes of both; meanwhile bats have low relative volumes of both (Reep et al., 2007). Marine mammals with reduced olfactory bulbs also have a reduced limbic system overall (Clark et al., 2001).
Structures of the Limbic System
The Limbic System consists of cortical and subcortical components that have developed from the telencephalon, diencephalon and mesencephalon. The cortical part comprises interconnected telencephalic structures on the medial and basal aspect of the hemispheres, namely the cingulated gyrus, hippocampus and the piriform lobe. The subcortical part includes components of the diencephalon (habenula, hypothalamus, thalamus), midbrain (tegmental nuclei) and the amygdala. The limbic system receives olfactory input from the amygdala and piriform lobe that can trigger emotional behavior such as fear, aggression, and apparent pleasure.
Sheep Brain: Image of sheep brain was taken in 2008 at St. Mary’s College of Maryland under the guidance of Dr. Anne Marie Brady in a Biological Psychology course.
Dog Brain Extraction
The extraction, fixation, and dissection of the dog brain was completed at Szent Istvan University under the guidance of Dr. Kalman Czeibert. Skin surround skull was incised, then using scalpel, the temporal and masseter muscles were transected and scrapes off skull. Using a surgical saw, a rostral cut was made into the frontal sinus. Superficial cuts were made laterally on the temporal bone starting at the occipital condyles, through the nuchal crest and along the temporal bones connecting to the rostral cut at the frontal sinus. Using a surgical chisel and hammer, the superficial cuts were widened allowing the skull to easily be removed dorsally. Carefully, the cranial nerves were removed and the brain was extracted from the cranial cavity.
Fixation
The structure and consistency of the dog brain upon removal was not ideal for dissecting in order to expose the limbic system. Upon removal of the canine brain, it was placed in a 7% formaldehyde solution for 24 hours than transferred into a 3% formaldehyde solution for another 24 hours.
Dissection
The two hemispheres were gently widened, exposing the white matter of the corpus callosum. A light incision was made on the corpus callosum (Figure 1), removing the dense axon fibers connecting the two hemispheres, and making visible the third ventricle and choroid plexus (Figure 2). Using the borders of the lateral ventricles, gently a transverse incision was made through the parietal lobe as well as a lateral cut that would continue all the way through the occipital lobe (Figure 3). The horn of the hippocampus was made visible. Using finite and precise cuts, the remainder of the cortex was removed around the hippocampus (Figure 4). Through a similar process, the remaining part of the left hemisphere was removed, making the thalamus and other components of the limbic system visible (Figure 5&6).
- A second brain was similarly fixed and used for cross sectional dissections. Approximately 5-9 mm thick cuts were made transecting through the canine brain from a dorsal to ventral position. Brain slices allowed the exposure of the internal components of the limbic system (Figure 7).
The various components of the limbic system are each associated with different functions. The Amygdala is involved with several emotional responses (Sato et al., 2016); the Hippocampus is involved with learning and memory formation (Mao et al., 2015); the Thalamus relays sensory and motor signals plus regulates sleep and alertness (Li et al., 2014); the Nucleus Accumbens with reward, pleasure and addiction (West et al., 2016); Hypothalamus is involved with regulation of the pituitary gland and hormonal function (Perez et al., 2016); Olfactory bulbs involved in the perception of smell and connect to piriform lobe & amygdala (De La Rosa et al., 2015); the Habenula receives input from the limbic system and basal ganglia, influencing the brains response to pain, stress, anxiety, sleep and reward (Velasquez et al., 2014).
Molecular and Cellular Neuroscience
- Neuroscience is an expansive field of science which integrates multiple fields of research and investigation in order to understand the functioning of this complex system. The anatomy and physiology of the mammalian brain neural systems have been thoroughly investigated and documented; yet, new discoveries are still being unveiled every day. Through immunohistological studies of many animal species, the location and functioning of neurons and glia (the cells that compose the central and peripheral nervous system) have been identified. Generally speaking, the neuron is the implementation system of the nervous system and the variation of their composition generates the many capabilities possible. The structure of a neuron consists of three components:
Soma – cell body - location of typical cell functions and genetic information storage
Axon - a very slender nerve fiber - projects from the neuron's cell body and transmits electrical impulses to the neuron's axon terminals. This electrical signal stimulates release of a neurotransmitter, which is produced inside the nerve cell. It is neurotransmitters that light up the brain with life.
Dendrites – multiple short branched extensions of a neuron, along which impulses and neurochemical communication is received from other cells at synapses are transmitted to soma.
Neurotransmission
As an action potential travels down the axon, the depolarized cell membrane opens voltage gated calcium channels at the terminal button and stimulates vesicular release. These synaptic vesicles are filled with a particular neurotransmitter (neuro-chemical). There are over 100 different neurotransmitters that have identified in the mammalian nervous system. The location, post-synaptic effect, metabolism, and removal of these neurotransmitters significantly differ from one another. Neurotransmitter transport systems are integral to the release, re-uptake and recycling of neurotransmitters at synapses. High affinity transport proteins found in the plasma membrane of presynaptic nerve terminals and glial cells are responsible for the removal from the extracellular space of released-transmitters, thereby terminating their action. In addition to these removal systems, several neurotransmitter-specific enzymes are present to inactivate or regulate these chemicals released into the synapse. Upon bonding to a post-synaptic receptor, these neurochemicals will typically have an excitatory or inhibitory response on the sequential neuron through ionotropic or metabotropic functions. Through electrophysiological studies, immunohistochemistry, and genetic knock-out models, the understanding of these brain chemicals has vastly improved in the past couple decades. In regards to the topic of this essay and its relation to the Limbic System, we are only going to focus on the neurotransmitters specifically relevant.
Neurotransmitters And Corresponding Receptors
Catecholamines
Dopamine
Dopamine Synthesis Dopamine Receptors
Class D1
Class D2
Dopamine Metabolism
Dopmanine Transporter Monoamine Oxidase Catachol-O-Methyl-Transferase Trace Amine Associated Receptor Veiscular Monoamine Transporter
Neural Pathways
Mesolimbic Pathway Mesocortical Pathway Nigrostriatal Pathway Tuberoinfundibular Pathway
Norepinephrine
Norepinephrine Synthesis Receptors
Alpha 1A Alpha 1B Alpha 1D Alpha 2A Alpha 2B Alpha 2C 1, 2 & 3
Norepinephrine Metabolism
Plasma Membrane Monoamine TransporterMonoamine OxidaseCatechol-O-Methyl-TransferaseTrace Amine Associated ReceptorVeiscular Monoamine Transporter
Neural Pathways
Monoamines
Serotonin (5-HT)SynthesisReceptors
5-HT1A 5-HT2A 5-HT2C 5-HT6
Monoamines Metabolism
Serotonin TransporterMonoamine OxidaseVesicular Monoamine TransporterNeural PathwaysOther Relevent Neurotransmiters
Glutamate
Behavioural Effects of Amphetamines
Amphetamine Effect on Neurotransmitters
Dopmanine Transporter Monoamine Oxidase Inhibitor VMAT Malfunction Catechol-O-Methyl-Transferase
Glutamate Effect
Dependance and Withdrawl
References
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