Hypothalamic and Limbic Systems Dr. Dennis Flashcards
(49 cards)
1
Q
Where is the hypothalamus and what is its relationship to the third ventricle?
A
Inferior to thte thalamus forms walls and floors of third ventricle
2
Q
Where are the mammillary bodies located?
A
posterior part of hypothalamus and are adjacent to cerebral peduncles
3
Q
Where is the Tuber Cinereum?
A
Small swelling between mammillary bodies and optic chiasm and tract
4
Q
Where is the median eminence?
A
arisses from tuber cinereum and narrows into infundibulum attaches to pituitary gland
5
Q
What is the lateral zone of the hypothalamus?
A
- Carries two way traffic through hypothalamus rostrally towards forebrain and caudally to brainstem
6
Q
What is found in the medial zone of hypothalamus
A
- Conrtains majority of hypothalamic nuclei
- Has three fxnl areas:
- Anterior area
- Middle area
- Posterior area
7
Q
What is the anterior area?
A
- Within medial zone
- Superior to optic chiasm
- contains pre optic suprachiasmatic supraoptic paraventricular and anterior nuclei
8
Q
Middle area?
A
- Within Medial zone
- Superior to and including tuber cinereum
- contains dorsomedial ventromedial and arcuate nuclei
9
Q
Posterior area
A
- Within medial zone
- Superior to and including mammillary bodies
- contains posterior nucleus and mammillary bodies
10
Q
Describe the lateral nucleus
A
- Contains median forebrain bundle that carries info to and from hypothalamus
- Within the lateral zone
- Damage to this area results in decrease in feeding behavior with weight loss
11
Q
Supraoptic & Paraventricular nuclei?
A
- Contain oxytocin (PVN) and ADH (SON)
- Lesionis can result in diabetes insipidus
- Within the anterior area of the medial zone of hypothalamus
12
Q
Suprachiasmatic nucleus?
A
- Receives retinal input and involved in circadian trhythms
13
Q
Anterior nucleus
A
- Range of visceral somatic functions, temp regulation
- Within the anterior area of medial zone
14
Q
Ventromedial nucleus
A
- Satiety center
- Lesions causae excessive eating and weight gain
- Middle tuberal area of hypothalamus
15
Q
Dorsomedial nucleus
A
- Emotional behavior, stimulation causes rage
- Destruction results in decreased aggression and feeding
- Middle tuberal area of hypothalamus
16
Q
Arcuate nucleus
A
- Secretes releasing and inhibiting hormones
- Middle tuberal area of hypothalamus
17
Q
Medial mammillary nucleus
A
- Part of posterior area
- Afferents from hippocampus via fornix
- Efferents to the thalamus and brainstem
- Lesions result in inability to process short term events into long term memories
18
Q
What is the blood supply to hypothalamus?
A
- Anteromedial group from A1 and anterior communicating to preoptic area supraoptic nuclei and rostral part of lateral hypothalamus
- Posteromedial group perforating arteries from PoCoA and PCA P1
- Rostral portion of PoCoA tuberal region
- Caudal parts of PoCoA mammillary region
19
Q
What does the fornix do?
A
Hippocampal fibers relaying afferents to the mammillary bodies
20
Q
What does the stria terminalis and ventral amygdalofugal fibers do?
A
Afferent fibers from amygdala to hypothalamus
21
Q
What is corticohypothalamic input?
A
- Afferents from orbitofrontal and cingulate areas, multiple assoc. areas and frontal lobe to lateral zone
22
Q
Where do Retinohypothalamic fibers go?
A
Afferents that Target SCN
23
Q
What is median forebrain bundle and Dorsal longitudinal fasciculus?
A
- Relay two way information to and from the hypothalamus
- Efferent
24
Q
What are the efferents descending to PAG and RF?
A
- Hypothalamomedullary fibers
- Hypothalamospinal fibers
- Medial zone and mammillary bodies
- Enables hypothalamus to influence emotion aspects of behavior
25
What are the ascending routes of the efferents in hypothalamus? (4)
* Hypothalamocortical fibers ascend to forebrain target frontal lobe
* Mammillothalamic tract projects to anterior nucleus of thalamus
* Lateral zone projects to DM nucleus of thalamus
* Thalamic nuclei send projections to frontal lobe
26
What is the supraopticohypophysial tract?
* Made of axons of neurons in supraoptic nucleus and Paraventricular nucleus
* Produces oxytocin and ADH to be released by Post Pit.
* Stored in herring bodies and released into the capillary plexus of posterior pituitary
27
What is the tuberoinfundibular tract?
* Input from neurons located in periventricular zone, PVN
* Conveys releasing hormones to median eminence and infundibulum
28
How is the anterior area of the hypothalamus relate to ANS?
* Activates Parasympathetic activity
* Efferents to the brainstem parasympathetic neurons from CN III VII IX X and spinal S2-4
29
How does the posterior area of the hypothalamus relate to ANS?
* Activates sympathetic activity
* Efferents to sympathetic neurons in lateral horn of T1-L2
* **Lesions in anterolateral medulla disrupt hypothalamomedullary fibers so the sympathetic output to the face and head or body resulting in hroners syndrome**
30
What is the significance of the suprachiasmatic nucleus?
* Receives direct input from the retina to mediate circadian rhythms
* This coveys circadian info to other hypothalamic regions for sleep and wake cycles
* SCN activity opposes drive for sleep
31
In general what does the limbic system include and what does it do?
* Includes subcallosal area, cingulate gyrus, parahippocampal gyrus, uncus, hippocampal formation and subcortical nuclei
* between hypothalamus and neocortex
* Connections influence behavior, memory and pain perception
32
What is the hippocampal formation?
* Curved sheet of cortex for learning and memory folded into the medial part of temp lobe
* Made of Subiculum, Hippocampus propper, and Dentate nucleus
33
What is the parahippocampal gyrus?
* Cortex overlying the hippocampal formationi anterior part of parahippocampal gyrus is called the entorhinal cortex
34
What is the afferent pathway of the hippocampal formation?
* Dentate gyrus to CA3 to CA1 to the Subculum
35
What is the hippocampal formation efferent pathway?
* Fibers from cell bodies in the subiculum (CA2) and hippocampus proper (CA1) bundle into fibria making the fornix
* This terminates in the medial mammillary nucleus ventromedial nucleus and anterior nucleus
36
What is an Uncal Herniation and signs?
* Movement of the unus and potential the parahippocampal gyrus down over the tentorium cerebelli
* can compress midbrain and can damage lower brainstem if not caught
* Dialated pupil, abnormal eye movements, diplopia, weakness due to CST involvement, respiration eventually can be affected as well as abnormal reflexes
* eventual decline if not caught
37
What is Korsakoff's syndrome?
* Progressive degeneration of mammillary bodies hippocampal complex and dorsomedial thalamic nucleus
* This impedes retention of new memories to create long term memories
* Difficulty constructing meaningful statements and confabulation occurs
* caused by thiamine deficiency caused by chronic alcoholism
38
What is hippocampal amnesia?
* Bilateral lesions of hippocampus
* Profound deficit in anterograde episodic memory cant learn new material combined with spared procedural and working memory
* IQ and formal reasoning are normal
39
What is Anosmia?
* Loss sof smell due to viral infection of olfactory mucosa obstruction of nasal passage or possibly congenital
* If lesion shearing CN1 or tumors in floor of anterior cranial fossa patients do not recover smell
40
Phantosomia?
* Olfactory hallucination
* distortion in smell or perception of it when none is present
* abnormal sequence of neuronal activity due to lesion of anterior medial temporal lobe hippocampus amygdala or medial dorsal thalamic nuclei
41
What is the amygdala?
* Attaches emotional significance to a stimulus
* Regulates visceral responses to emotional stimuli and pain
* emotional responses to food pleasant smells stimulate appetite and unpleasant smells suppreses appetite
42
What are the afferents of the amygdala?
* Sensory info from raphe nuclei, PAG, dorsal motor nucleus of X, nucleus ssolitarius and locus ceruleus
* Input from dorsomedial nucleus of thalamus and info from widespread cortical areas
43
What are the efferents of the amygdala?
* Stria terminalis and ventral amygdalofugal paths
* These target the hypothalamus ventral striatum and septal nuclei
* cerebral cortex including frontal prefrontal cingulate and inferior temproal cortical areas
44
What happens if tehre is a lesion in the amygdala?
* Lesion results in imparied recognition of fear, anger, and disgust in facial expressions and vocal affect
45
What is Kluver-Bucy syndrome?
* Bilateral temporal lobe lesions that abolish amygladoid complex
* results in behavioral changes such as:
* visual agnosia
* Hyperorality
* Hypermetamorphosis-compulsion to intensively expore environment
* Placidity
* Hyperphagia
* Hypersexuality
46
What is the ventral tegmental area?
* Medial to substantia nigra and houses dopaminergic neurons
* connects with ventral striatum amygdala and other limbic structures
* **important for reward and motivation, may contribute to addiction**
47
What is the septal nuclei?
* Small area rostral to anterior commissure
* Reciprocal connections with oolfactory bulub hippocampus throughthe fornix and amygdala
* Reole in reward/pleasure and control of rage
48
What is the nucleus accumbens?
* Located in forebrain near continuation of caudate and putamen
* Important in behaviors related to addiction and chronic pain
49
Papez circuit?
* emotional experience involves reciprocal interactions btw diencephalon and cerebal cortex
* fornix projects to mammillary bodies
* Amygdala is key in expression emotions emotional memory
* Inerconnectiosn btw limbic system and hypothalamus
* Assoc. areas of cortex prefrontal are important
## Footnote
**Cingulate cortex--\>cingulum--\> hippocampus---\>fornix--\>mammiillary bodies--\> mammilothalamic tracti--\> thalamus anterior nuclei--\>cingulate cortex**
