Limbic System Flashcards by Cipryana Mack

what are the major functions of the limbic system?

Homeostasis
Olfactory
Memory
Emotions and drive

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Where can the hypothalamus be found

posterior to the optic chiasm and ventral to the thalamus (separated via the hypothalamic sulcus)

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what are the major components of the hypothalamus?

many nuclei
tuber cereneum
mammillary bodies
infundibulum

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what are the major functions of the hypothalamus? (HEAL)

endocrine and autonomic control, limbic mechanisms

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what are the major inputs to the hypothalamus and their functions?

solitary nucleus: BP/HR
reticular formation and spinal cord: thermal regulation (ant-dissipates heat, post conserves it)
retinal pathways : day/night> circadian rhythm
limbic system (consumption: medial-inhib, lat-stim)
circumventricular organs: osmolality and toxins

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Explain the anatomy and physiology behind circadian rhythms.

NIGHT: suprachiasmatic nucleus projects to hypothalamic nuclei +pineal gland> body temp reg and sleep hormones

day:posterior hypothalamic nucleic/ glutamatergic,hist, and orexin neurons>arousal

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List the major outputs to the hypothalamus and what their specific functions are.

autonomic system: projects to PNS and SNS
endocrine system :pituitary gland
limbic system: reciprocal connex w/ hippocampus and amygdala

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where is the pituitary gland

inferior to the infundibulum; separated into 2 parts

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what does the anterior pituitary gland do?

Ant: produces 6 hormones (LH, FSH, HGH, Adrenaline, Prolactin, TSH)

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what does the posterior pituitary gland do?

Post: relays ant’s hormones and modulates oxytocin and vasopressin synthesized in the hypothalamus

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adrenocorticotropic hormone (ACTH)

stimulate adrenal cortex> maintains BP, electrolyte balance, promote glucose metabolization

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growth hormone (HGH)

organs produce insulin-like growth factors, long bone growth +other tissues

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prolactin

stim mammary glands for lactation

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thyroid-stimulating hormone (TSH)

stimulate thyroid for T3 and T4; promote cellular metabolism

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luteinizing hormone

regulate ovarian hormones for ovulation and oocyte production

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follicle-stimulating hormone (FSH)

regulate testosterone and spermatogenesis in males

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Post: oxytocin

smooth contractions in the breast for milk letdown and uterus for labor; compassion and social bonding…?

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Post: vasopressin

water retention> controls urine output to regulate BP

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Where are the primary cortical regions involved in olfaction, and what are each of their roles in the processing and integration of smell?

Primary olfactory cortex

-piriform and periamygdaloid cortices: intricately bound to memory and emotion

What are our 3 types of memory?

less than a second (attention)
seconds to minutes (working memory)
minutes to years (consolidation)

where do we store info for attention/registration?

brainstem-diencephalic junction
frontoparietal association cortices
unimodal and heteromodal assn cortices

where do we store info for our working memory?

frontal assn cortices

unimodal ad heteromodal cortices

where do we store info for our consolidation?

medial temporal and diencephalic structures***

unimodal and heteromodal assn cortices

What type of memory is our limbic system involved with in?

declarative (facts and events)

Where are the major limbic memory centers located?

medial temporal lobe and the medial diencephalic memory areas

where is the hippocampal formation and what does it do?

composed of the dentate gyrus, hippocampus, and the subiculum; long term memory

what is the parahippocampal gyrus and what does it do?

entorhinal (rostrally) and parahippocampal (caudally); memory encoding and retrieval

where is the perirhinal cortex and what does it do?

recognition and identification of environmental stimuli

List the major inputs to the medial temporal lobe memory structures .

ENTORHINAL cortex: heteromodal assn area contralateral hippocampus Basal forebrain and septal nuclei

what is the function of input arising from the entorhinal cortex?

higher order info for memory storage

what is the function of input arising from the basal forebrain and septal nuclei?

ACh projections for neuromodulation (excitability and synaptic plasticity) hippocampal theta rhythm: possible short-term storage and additional support?

List the major outputs of the medial temporal lobe memory structures.

entorhinal cortex>heteromodal assn | medial diencephalic structures (via inf thalamic peduncle and fornix)

what is the function of output arising from the entorhinal cortex?

heteromodal assn

what is the function of output arising from the medial diencephalic structures via the inf thalamic peduncle?

working memory/executive fn and long term? memory;

where is the fornix and what is it's function

medial aspect of cerebral hemisphere underneath the corpus callosum; connects hippocampus w/ subcortical areas

What are the major targets of fibers traveling through the fornix?

mamillary bodies of the hypothalamus anterior nucleus of the thalamus septal nuclei (modulation)

How are temporal poles involved in memory?

-social and emotional processing Left: meanings, names, general impersonal facts Right: personal and episodic memory ~socially and emotionally relevant memories

What is the major structure associated with emotion and drive? How does it function in this regard?

the amygdala; tons of bidirectional connections

what is the function of the connection between the amygdala and the olfactory system/hypothalamus?

appetitive states, emotional and motivational aspects of smell

what is the function of the connection between the amygdala and the brainstem/hypothalamus?

``` autonomic control (initiation of fight/flight), note the connection to the brainstem is mainly efferent ```

what is the function of the connection between the amygdala and the mediodorsal nucleus of the thalamus?

fear reflex and emotional learning

what is the function of the connection between the amygdala and the limbic cortex/hypothalamus?

neuroendocrinological modulation; changes in emotional states (commonly seen in breastfeeding

what is the function of the connection between the amygdala and the uncus?

olfaction, emotions, new memories

what is the function of the connection between the amygdala and the hippocampal formation?

emotional aspects of memory, esp fear-inducing events

what is the function of the connection between the amygdala and the septal nuclei/basal forebrain?

processing rewarding or pleasurable experiences

what is the function of the connection between the amygdala and the medial orbitofrontal cortex?

decision making and emotion, bodily changes w/ emotion (ex. stomach drop in anxiety)

Where are the secondary cortical regions involved in olfaction, and what are each of their roles in the processing and integration of smell?

Secondary Olf Structures: entorhinal: smell and memory; orbitofrontal olf area: smell discrimination amygdala: smell and emotion ad motivation