Basal Ganglia and Limbic System Flashcards
Discuss the history of limbic lobe and how it was developed. What did limbic lobe consist of?
Limbic Lobe: described by Broca in 1874, as word ‘“limbic’” described the border or edge that formed between Diencepaholon and the more lateral Neocortex of the telencephalic hemispheres
-limbic lobe consists of a ring of cortex outside corpus callous, largely made up of subcallosal and cingulate gyro as well as parhippocampul gyrus
What structures of the brain are seen in saggital view?
Forebrain (Telencephalon and Diencephalon), Midbrain (mesencephalon), Hindbrain (Metencephalon and myencephalon)
Describe how James Papez, and his discovery of Papez circuit
James Papez- American physician who describes his anatomical model of emotion called Papez Circuit
-He hypothesized that hippocampus, cingulate gyrus, the hypothalamus, anterior thalamic nuclei and interconnections among these structures created a mechanism that would describe the functions of emotions
Papez believed that experience of emotion was determined by activity cingulate cortex, and less directly and other cortical areas.
(emotional expression thought to be governed by hypothalamus)
Describe who Paul MacLean was and his Triune brain theory
Paul MacLean proposed that human brain was in reality 3 brains in one:
1) Reptilian complex
2) The limbic system
3) The Neocortex
Describe the components of Triune theory and how it influenced behavior
Triune theory:
1) Reptilian Level
-Pavlovian/Adams
-Risk Thermostat
made of up brain stem and cerebellum, responsible for fight or flight response, Autopilot (each response for a stimulus)
2) Mammalian Brain:(CHIMP level) limbic system was responsible for emotions, memories and habits formed by humans ; corresponded to Decisions or “gut feel” that people have. It described one’s perception of things
3) The Human Brain: made up Neocortex portion of brain that contributed to language, abstract thought, imagination, consciousness. It also correlated to how one reasons or rationalizes, or one’s persona
These different brains described how one anyalzed physiological behavior and how there is a balacne between taking risks, being rewarded, having accidents and how one perceives risks
What were cellular structures that were considered a part of limbic cortex for All vs Most or Some authors?
There is no universal on total list of structures that are included in limbic system.
-All authors include limbic cortex (cingulate and parahippocampal gyri), the Hippocampal Formation, the Amygdala, and the Septal area.
-most include the hypothalamus, part of midbrain reticular formation and olfactory areas
-Some authors include thalamic and neocortical regions
What part of brain is responsible for control of movement?
Basal Nuclei
Describe the different roles in Cingulate gyrus, Hippocampus and Amygdala that are apart of limbic system
Limbic System:
-Cingulate gyrus: role in EMOTION
-Hippocampus: Learning and Memory
-Amygdala: Emotion and Memory
What are the three anatomical planes of the body?
Anatomical planes;
-Coronal (frontal) will separate Anterior(front) and Posterior (back) parts of the body
-Saggital (longitudinal; vertical) : separates the left and right sides of the body
-Transverse plane (axial; horizontal) separates upper(superior; dorsal) and lower (inferior; ventral) halves of the body
Describe the structure of Amygdala and its role in Limbic system
Amydala: two almond shaped neural clusters that are components of limbic system, linked to emotion and fear.
(play important role in behavior: fear, agreeableness, rage)
What occurs in the Basolateral amygdala and where is it located in brain?
Basolateral amygdala:
-basaloateral nuclear group receives higher-order sensory information from association areas in the frontal, temporal and insular cortex
-axons run back from amygdala to association regions of the cortex, suggesting that activity in amygdala may **modulate sensory information processing in association cortex **
-basolateral amygdala is also connected via stria terminals and amydalofugal pathway, to ventral striatum and thalamus
Where is Corticomedial amygdala and what is its role?
Corticomedial amydala
-the corticomedial nuclear group of the amygdala is located close to the Olfactory Cortex, and is interconnected with it and also the Olfactory Bulb
-Connections also run via the stria terminals and amygdalofugal pathway, to and from the brain stem and hypothalamus
Describe the major functions of the Amydala
Functions:
-because of the interconnections with sensory association cortex and hypothalamus, its suggested that Amydala plays an important role in establishing associations between sensory inputs and various affective states*
-The amygdala appears to participate in regulating endocrine activity, sexual behavior, food and water intake possibly by modulating hypothalamic activity
Describe the two broad functional divisions of Limbic system
The Broad functional Divisions of Limbic system:
Rostral limbic system: amygdala, septum, orbitofrontal cortex, anterior insula and anterior cingulate
-Important for EMOTION
Caudal system: Hippocampus, posterior parahippocampal cortex and posterior cingulate
-Important for MEMORY and Visual-spatial functions
What happens to people who have gotten lobotomies?
People with lobotomies, have experienced issue with rostral limbic system, that leads to many psychotic disorder (bipolar disorder)
Differentiate between the Limbic Lobe vs Limbic System and include the cellular structures that are a part of each
Limbic Lobe (cortical areas of limbic system)
-Parahippocampal gyrus, hippocampus, orbitalforntal, cingulate gyrus and insula
Limbic System (Limbic Lobe + Nuclei and connection);
-include all structures from limbic lobe, AND Nuclei (amygdala, septal nuclei, mammillary body, anterial thalamus connection) and Fornix (median forebrain bundle, stria terminals, and Mamillothalamic tract)
What are all of the different structures of limbic system and what are their functions?
Limbic system:
-Hypothalamus, pituitary, amygdala, and hippocampus all deal with BASIC drives, emotions, and memory
-Hippocampus–> Memory processing
-Amydala–> Agression (fight) and Fear (flight)
-hypothalamus–>Hunger, thirst, body temperature, pleasure; regulates pituitary gland (hormones)
Describe how structures of limbic system are connected and how sensory information is transferred.
The major structures of limbic system are interconnected with each other and with other components of nervous system. Sensory information from cingulate, orbital and temporal cortices, and amygdala is transmitted to entorhinal cortex of parahippocampal gyrus and then to hippocampal formation
What are the comments of the limbic system?
Components of Limbic system:
-Olfactory pathways,
Anterior perforated substance
pyriform lobe
Septal area
Amygdaloid body
Limbic cortex
Hippocampal formation
-Elements of diencephalon
Bundles of ions connecting above region
Describe how information is transferred in the Function circuit between hippocampal formation , thalamus, cerebral cortex and hypothalamus
After traversing the intrinsic circuitry of Hippocampal formation, information is projected through the fornix, either to the Anterior Thalamus, which in turn projects to limbic cortex, or to Septal Area and Hypothalamus
-The Septal area and Hypothalamus also provide feedback to hippocampal formation through fornix
The mammillary bodies of hypothalamus project to anterior thalamus
Finally, the hypothalamus and septal area project to the brainstem and spinal cord
(other function circuits are between amygdala, hypothalamus and prefrontal and temporal cortices)
What are the three major Amygdala pathways?
1) Ventral Amdydalofugal pathway
-Nucleus Accumbens septi
(ventral striatum), global pallidus (ventral pallidum), anterior olfactory nucleus, orbital cingulate cortex, prefrontal cortex, septal area and hypothalamus )
2) Stria Terminalis (septal area, hypothalamus (lateral/ventral nucleus) , habenula, and contralateral amygdala)
3) Direct connections from Amygdala
-Hippocampus, Entorhinal cortex, dorsomedial thalamus and brain stem
What is the major role of basal Ganglia and why is important?
Basal Ganglia: controls voluntary movement and is involved in all motor disorders (like Parkinson’s disease)
How is the Limbic system associated with Olfaction?
Olfaction
-The limbic structures are closely related to olfactory cortex
-Amygdala is involved in emotional response to smell Entorhinal cortex, is concerned with olfactory memories.
(sense of smell is crucial to survival)
you are able to form direct connections that don’t require memory processing when it comes to olfaction
(Olfactory receptors–> Axons of Olfactory neurons–> Olfactory bulb (mitral and Tufted) –> Perform Cortex (Primary olfactory cortex) –> Amydala
What structures in brain contribute to appetite and eating behaviors?
Appetite and Eating Behaviors:
Amygdala plays a role in food choice and emotional modulation of food intake
-The lateral nucleus of the hypothalamus is the center for control of feeding
Whereas, the ventromedial nucleus functions as SATIETY center
What causes emotional responses like fear? Which structures in the brain are involved? How can fear be diminished or activated?
Fear responses are produced by the stimulation of Hypothalamus and Amygdala
-Amygdala Destruction abolishes fear and its autonomic and endocrine responses
-Amydala is also involved in fear learning
-imaging studies have shown that viewing fearful faces activates the left amygdala.
What can induce rage and placidity? How can placidity turn into rage?
-The Destruction of the Ventromedial Hypothalamic Nuclei and septal nuclei in animals may induce Rage.
-Bilateral destruction of the amygdala results in Placidity (calm or peacefulness)
-However, when the Ventromedian nucleus is destroyed after the destruction of the amygdala, the placidity generated is converted to rage.
Describe the different autonomic and endocrine responses to emotion. What happens when limbic system or hypothalamus is stimulated?
limbic stimulation causes changes in respiration and blood pressure
-The stimulation of the cingulate gyrus and hypothalamus can elicit autonomic responses
Hypothalamic autonomic responses are mediated by cortical and limbic structures processing drives and emotions
Which structures of the brain will be stimulated when fear and rage responses occur? What is the Fight or Flight Response?
The fear and rage responses mediated by the limbic system cause stimulation of the hypothalamus, especially lateral areas and produce diffuse sympathetic discharge.
-The massive sympathetic discharge, during stress is called the “Fight or Flight” response
How does CRH (corticotropin releasing hormone) become released and what is its role?
Stress via cortical and limbic connections causes the release of corticotropin-releasing hormone (CRH) from the paraventricular nuclei of hypothalamus.
CRH release mediates endocrine and immune responses
Explain how sensory information is transferred through different areas of the brain and causes autonomic and endocrine responses
Sensory stimuli–> Cortex–> Limbic system (attaches emotion) –> hypothalamus –> activate autonomic, somatic, immune and endocrine responses.
Explain how emotions influences memory and which brain structures are involved. Which structure is crucial for long-term memory storage? How does Anxiety affect memories?
Emotion has a powerful influence on learning and memory
-Amygdala, prefrontal cortex, and medial temporal lobe is involved in consolidation, and retrieval of emotional memories
-Amygdala, prefrontal cortex and hippocampus are also involved in the acquisition, extinction and recovery of fears to cues and contexts
-Hippocampus is critical for long-term, declarative memory storage
(with anxiety, reduce ability to learn or consolidate memories)
What is the Medial Temporal Lobe Memory System? What role does it play?
Medial Temporal Lobe Memory System:
includes the hippocampus and adjacent cortex, the parahippocampal regions (PHG) and the entorhinal and perirhinal regions
involved in storage of NEW Memories
What is the role of Diencephalic Memory System? What occurs if there is a disfunction in this system?
Diencephalic Memory System:
Consists of the hypothalamus, mammillary body, and the dorsomedial nucleus of thalamus
-Important for the storage of RECENT memory
- A dysfunction of this circuit results in KORSAKOFF’S Syndrome (caused by a deficiency of thiamine, vitamin B1; not made in our bodies)
(This deficiency in thiamine can cause anterograde or retrograde amnesia (associated with alcoholics, since Vitamin B1 is required for metabolism of alcohol) )
What is social cognition?
Social Cognition: thought processes involved in understanding and dealing with other people
-limbic structures involved are the cingulate gyrus and amygdala
Describe the brain’s shortcut to emotions, including an example
The brain’s shortcut for emotions:
short cut enables instant fear response
Ex: seeing a snake and running away from it. The speed of response. we do not need to process visual input of snake and go through all processes. We go straight from visually seeing snake to fight or flight response (running or “freezing”) Sympathetic activation occurs.
Also, how people respond to dogs, if they have been attacked before, due to association of fear formed with dogs, (PTSD) which is hard to overcome it. It is hard to rewire, needs therapy, retraining and relearning .
Explain the different ways that amygdala stimulation produces emotional behaviors through subcortical pathways.
The Lateral hypothalamus–> Sympathetic Activation (due to amygdala stimulation) –> may cause tachycardia, galvanic skin response, paleness, pupil dilation, blood pressure elevation
-Dorsal motor n of vagus and Nucleus ambiguous can affect parasympathetic activation (due to amygdala stimulation) which may lead to ulcers, urination, defecation and bradycardia
-The Parabrachial nucleus can lead to increased respiration and causes panting, and respiratory distress.
-The ventral tegmental area, locus ceruleus, Doral lateral segmental neuron can affect activation of dopamine, norepinephrine and acetlycholine causing behavioral and EEG arousal, increased vigilance.
-The N. Reticularis pontis and caudalis can cause increased reflexes (due to amygdala) and lead to increased startle
-The Central grey can cause cessation of behavior (due to amygdala stimulation) leading to freezing, conflict test, CER, or social interaction
-Trigeminal, facial motor nerves can cause mouth open, jaw movements (amygdala stimulation) and lead to facial expressions of fear
-paraventricular nerves (hypothalamus) can cause ACTH release (amygdala stimulation) and lead to corticosteroid release (“stress response”)
What are functions of the Amygdala?
Functions of the Amygdala:
-Behavioral awareness areas
-Project into the limbic system (one’s current status in relation to both surroundings and thoughts)
-Make the person behavioral response appropriate for each occasion
-relate environmental stimulus to coordinated behavioral autonomic and endocrine responses seen in species-preservation
-Responses include:
feeding and drinking
-Fighting behavior
-mating and maternal care
-responses to physical or emotional stresses
Who was Charles Whitman and why was he significant
Charles Witman (August 1st, 1966) was married and had a dog. During last few months, he wrote a note on August 1st, about him hearing voices for him to do certain things. He talked to a psychiatrist and no psychiatric conditions were detected. That same day, Charles killed his wife (with a knife) and went to his mother and killed her as well. He also went to public place and started shooting people.
-his pathology showed that something was haunting Charles and he was being forced to do this.
He had a pathological condition (astrocytoma; brain tumor on his amygdala) that led him to do this. He had this tumor going on for a year.
-This brought the attention to the amygdala, the function and importance of it
Who was Phineas Gage? How did his behavior change before vs after incident
Phones Gage (September 13, 1948)
-he was working on railroad and had an accident, where rod went through his frontal cortex. After reconstruction of brain he had a lot of damage, lost Vision in one eye, and entire prefrontal cortex was lesioned, and had major sprouting due to inflammation and trauma he went through.
He changed his behavior after accident, from being very nice, and hardworking to rage, violence
Hence our prefrontal cortex can change our behavior or our personality.
Before accident: capable, efficient, best freeman and well balanced mind
After accident: extravagant, anti-social, liar, grossly profane
He died 12 years later
What is the Kluver Bucy syndrome? How does this affect behavior in animals? What can help those with this syndrome?
Kluver -Bucy Syndrome: odd behavior that appears in cats, and also occurs in humans that are addicted to pornography
- Cats become sexually very active, hyper sexual, orally fixated and compulsive behavior when you REMOVE the amygdala in animals.
-Preoperation (before removal of amygdala)
-cat will be aggressive and raging
-Postoperation (after removal): Docile, orally fixated, increased sexual and compulsive behaviors)
What are the features that occur with Kluver Bucy syndrome in Humans?
Kluver Bucy Syndrome in Humans:
- caused by Severe temporal lobe damage (also seen in humans addicted to pornography)
may occur with people who had tumors, surgery, trauma
Symptoms:
-Visual Agnosia- the inability to identify the face of a familiar person or object
-Apathy/placidity
-Hyperorality
-Disturbance in sexual function (hyper sexuality)
-Dementia, aphasia, amnesia
-
What are the roles of Anterior Cingulate Gyri and Subcallosal gyri? What happens if the gyri are destroyed?
The Anterior Cingulate gyri and Subcallosal Gyri: are portions of the limbic cortex that communicate between the prefrontal cortex and cerebral cortex and the subcortical limbic structures.
-Destruction of these gyri bilaterally releases the rage centers of the septum and hypothalamus from prefrontal inhibitory influence
-Animals can become viscous and Violent and much more subject to fits of rage than normally.
What are the different Roles of prefrontal cortex?
Roles of the Prefrontal Cortex:
-Higher levels of the cortex are also crucial for CONSCIOUS AWARENESS of emotional feelings
-Higher levels of the cortex, particularly the prefrontal and limbic association areas, are important in conscious learned control of innate behavioral patterns
-Prefrontal cortex formulates plans and guides behavior, SUPPRESSING amygdala-induced responses that may be inappropriate for the situation at hand.
(prefrontal cortex has inhibitory repose on amygdala response to rage)
Which brain structures modulate emotion?
Hypothalamus, Limbic system, limbic cortex, amygdala and brainstem
What are the functions of the Hypothalamus ?
Hypothalamus:
-Nueral structure lying below (hypo) the thalamus; directs several maintenance activities:
-eating
-drinking
-body temperature
-helps govern the endocrine system via the pituitary gland
-linked to emotion
what other brain structures is the hypothalamus connected?
Hypothalamus is also connected to Lamina terminals, ventral thalamus, internal capsule and third ventricle
Discuss the afferent connections present in brain
Afferent connections :
-The hypothalamus receives visceral (including taste) through spinal cord and brain stem
-Afferents from nucleus of tractors solitarus to hypothalamus carry taste sensation
-somatic afferents reach through collaterals of major ascending tract
-Afferents from olfactory pathway and limbic system (anterior perforated substance, septal nuclei, amygdaloid complex, hippocampus, pyriform cortex)
How are animal models used to describe how behavior is generated?
Animal model: rats are very smart, and used for conditioning experiment
triune brain: reptilian, limbic and human brain; you need to decide how much risk you are willing to to take to get reward
rat must balance how much fear it must go through (on electrified grid) to press lever and receive stimulation that induces well being or pleasure or perhaps psychotic drugs.
Which brain structures are apart of reward circuit?
Reward circuit involve the hippocampus, amygdala, nucleus accumbent, prefrontal cortex, ventral pallidum, ventral segmental area
Ventral segmental area- reward system
when fear and rage occurs, you need a reward system (way of recovering and a prize to help overcome emotion)
-Glutamate (excitatory amino acid) , GABA and Dopamine are always involved.
GABA-aminobutryic acid always need to stop excitation in the brain
