Hypothalamus and Limbic System Flashcards
What is the primary role of the hypothalamus?
Homeostasis
What is the rostral/anterior boundary of the hypothalamus?
Optic chaism
What is the caudal/posterior boundary of the hypothalamus?
Tegmentum and PAG
The hypothalamus forms the floor and ventral walls of?
3rd ventricle
The hypothalamus continues inferiorly through?
Infundibular stalk with posterior pituitary
What forms the posterior part of the hypothalamus and are adjacent to the cerebral peduncles?
Mammillary bodies
What is the floor of the hypothalamus and are small swellings between the mammillary bodies and the optic chiasm and tract?
Tuber cinereum
What arises from the tuber cinereum and narrows into the infundibulum and attaches to pituitary gland?
Median eminence
What is the area immediately adjacent to the 3rd ventricle and blends with PAG?
Periventricular zone
What divides the remainder of hypothalamus into medial and lateral zones?
Fornix
What is the characteristic of neurons within the lateral zone?
They are diffusely arranged and do not have solid boundaries
If you lesion the lateral zone what occurs?
Decrease in feeding behavior resulting in weight loss
Where is the median forebrain bundle located?
Lateral zone
What nuclei release oxytocin?
ADH?
1) Paraventricular nucleus
2) Supraoptic
What nuclei are critical for posterior pituitary regulatory function?
Supraoptic and paraventricular nucleus
What happens if you lesion the supraoptic and paraventricular nucleus?
1) Diabetes insipidus
2) Increase in H2O intake
3) Increase urination
What nucleus is in the supraoptic region and receives retinal input and is involved in circadian rhythms?
Suprachiasmatic nucleus
What happens if you lesion the Suprachiasmatic nucleus?
May modify or abolish circadian rhythms
What nucleus is in the supraoptic region and does a range of visceral/somatic functions such as temperature regulation?
Anterior nucleus
What nucleus is in the posterior region and receives afferents from the hippocampus via the fornix and sends efferents to the thalamus and brainstem?
Medial mammillary nucleus
Lesion to the medial mammillary nucleus results in what?
Inability to process short term events into long term memory
What nucleus is in the tuberal region and is considered to be a satiety center?
Ventromedial nucleus
What happens if you lesion the ventromedial nucleus?
Excessive eating and abnormal weight gain
What nucleus is in the tuberal region and subserves functions of emotional behavior?
Dorsomedial nucleus
Stimulation of the dorsomedial nucleus in animal models can cause?
Sham rage
What happens if you lesion the dorsomedial nucleus?
Decrease in aggression and feeding
What arteries serve the preoptic area and supraoptic region, septal nuclei, and rostral portion of lateral hypothalamic area?
Branches from anterior communication and A1 of ACA
What artery serves the tuberal region?
Rostral portion of posterior communicating artery
What artery serves the mammillary region?
Caudal parts of posterior communicating artery
What afferent arises from the subiculum and hippocampus and is the largest single input to the hypothalamus?
Fornix
What afferent interconnects septal nuclei, hypothalamus, and midbrain tegmentum while also coursing through lateral hypothalamic zone?
Medial forebrain bundle
The mammillary fasciculus bifurcates into what tracts?
Mammillothalamic and mammillotegmental tracts
What projects to the anterior nucleus of thalamus and is an important part of circuit of Papez?
Mammillothalamic tract
What targets brainstem nuclei in the tegmental areas?
Mammillotegmental tract
What efferents come from the lateral preoptic area and project to dorsomedial nucleus of thalamus and amygdaloid nucleus?
Hypothalamothalamic fibers
What fibers are direct links to the ANS and go to the solitary nucleus, dorsal vagal motor nucleus, and nucleus ambiguus?
Hypothalamomedullary fibers
What fibers are direct links to the ANS and go to the intermediolateral cell column (GVE preganglinoics)?
Hypothalamospinal fibers
A lesion where will disrupt the Hypothalamomedullary and Hypothalamospinal fibers?
Anterolateral medulla
A lesion in the anterolateral medulla results in?
Sympathetic outflow to face and head (Horner’s) or to the body
What fibers are indirect links to the ANS and target the PAG?
Posterior longitudinal fasciculus and mammillotegmental tract
What do posterior longitudinal fasciculus and mammillotegmental tract influence?
Autonomic nuclei in the brainstem
What tract is made up of axons of neurons in supraoptic nucleus and paraventricular nucleus and travels to the posterior pituitary?
Supraopticohypophyseal tract
Supraopticohypophyseal tract is involved in the release of what?
Oxytocin and ADH
Where is oxytocin and ADH stored?
Released?
1) Herring bodies
2) Capillary plexus of posterior pituitary
What tract has inputs from neurons located in periventricular zone and paraventricular neuron and travels to the anterior pituitary?
Tuberoinfundibular tract
The Tuberoinfundibular tract conveys releasing hormones to?
Median eminence and infundibulum
The activity of what nucleus opposes drive for sleep and is essential for timing of rest vs activity?
Suprachiasmatic nucleus
Circadian gene products indirectly control?
Melatonin secretion from pineal gland
When does melatonin secretion increase?
Decrease?
1) Prior to sleep
2) Waking up
What does the hippocampal formation include?
1) Hippocampus
2) Subiculum
3) Entorhinal cortex
4) Dentate gyrus
What is the translational area between hippocampus and entorhinal cortex?
Subiculum
What is the afferent pathway of the hippocampal formation?
Dentate gyrus –> CA3 –> CA1 –> Subiculum
What is the efferent pathway of hippocampal formation?
Subiculum to fornix
In the efferent pathway of hippocampal formation what does the fornix target?
1) Medial mammillary nucleus
2) Ventromedial nucleus
3) Anterior nucleus
The cingulate gyrus receives afferents from?
It projects to?
1) Thalamus and cortex
2) Entorhinal cortex via cingulum
What efferent projections of the amygdala has outputs to the hypothalamus and basal ganglia to permit motor behavioral responses?
Stria terminalis
What efferent projections of the amygdala has major efferent fiber bundle with two general trajectories to the hypothalamus and septal nuclei and then to the brainstem?
Ventral amygdalofugal pathway
What is the Papez circuit pathway?
Cingulate gyrus –> Hippocampal formation–> Fornix –> Medial mammillary nuclei –> Anterior nucleus of thalamus –> Cingulate gyrus
What structure is the small area just rostral to the anterior commissure thought to control of rage behavior?
Septal region
What structure consist of dopaminergic fibers that runs rostrocaudally through the lateral hypothalamic area?
Medial forebrain bundle
What is the major conduit for septal nuclei and hypothalamus to communicate with the brainstem?
Medial forebrain bundle
What structure is located in the rostral and ventral forebrain, receives input from amygdala and hippocampus, and plays an important role in behaviors related to addiction and chronic pain?
Nucleus Accumbens
What does the ventral tegmental area contain?
Large amounts of dopaminergic neurons
What structure has efferents to nucleus accumbens that play an important role in reward and motivation and may contribute to addiction?
Ventral tegmental area
What leads to hippocampal amnesia?
Bilateral lesions of hippocampi
What is the deficit in hippocampal amnesia?
Anterograde episodic memory (cannot learn new material)
What is spared in hippocampal amnesia?
Procedural and working memory along with IQ and formal reasoning
Progressive degeneration of the mammillary bodies, hippocampal complex, and dorsomedial thalamic nucleus leads to what?
Korsakoff’s syndrome
What is seen in a patient with Korsakoff’s syndrome?
Unable to convert short-term memory to long-term memory
In terms of language, patients with Korsakoff’s syndrome have a difficulty with?
Understanding written material and conducting meaningful conversations
What do Korsakoff patients commonly do in terms of recalling memory?
Confabulate: combine fragmented memories into a synthesized memory that never happened
What is Korsakoff’s syndrome typically caused by?
Thiamine deficiency typically associated with chronic alcoholism
What is the term for distortion in a smell experience or the perception of a smell when no odor is present?
Phantosmia
What can cause phantosmia?
Lesion of anterior/medial temporal lobe
What causes Kluver-Bucy syndrome?
Bilateral temporal lobe lesions that abolish amygdaloid complex
What are some common behavior changes seen in patients with Kluver-Bucy Syndrome?
1) Hyperorality: Randomly examine objects by mouth
2) Hypermetamorphosis: Compulsion to intensively explore the immediate environment
3) Hypersexuality: Inappropriate sexual behavior
What is uncal herniations?
Movement of the uncus downward over the edge of tentorium cerebelli
What causes uncal herniations?
Hemorrhagic lesion or tumor in the hemisphere
What are some signs of uncal herniation?
1) Dilated pupil, abnormal eye movements (CN III involved), and double vision ipsilateral to herniation
2) Weakness of extremities (CST involved) opposite to dilated pupil
3) Abnormal reflexes and respiration is affected as it progresses
