Hypothalamus and Limbic System Flashcards
Where is the hypothalamus?
Inferior to the thalamus and forms the walls and floor of the 3rd ventricle
What part of the brain is the hypothalamus a part of anatomically?
Diencephalon
What are a few of the main functions of the hypothalamus?
- Regulates basic drives, emotional and affective behavior
- Regulates homeostasis, ANS and endocrine function
What is anterior to the hypothalamus?
Optic chiasm
Via the infundibular stalk, what is the hypothalamus continuous with?
Posterior pituitary
What are 3 anatomical parts of the hypothalamus?
Mammillary bodies, Tuber Cinereum and Median Eminence
What divides the hypothalamus into functional medial and lateral zones?
Fornix
Where are most of the hypothalamic nuclei located?
In the medial zone
What are the functional areas in the medial zone of the hypothalamus?
Anterior area
Middle/Tuberal area
Posterior area
What are the nuclei of the anterior area of the medial zone of the hypothalamus?
Preoptic and Anterior nuclei
Suprachiasmatic nucleus
Supraoptic nucleus
Paraventricular nucleus
Function of preoptic and anterior nuclei?
Heat loss; temp. regulation
Sleep and parasympathetic activity
Function of suprachiasmatic nucleus?
Circadian rhythms
Function of supraoptic nucleus?
Secretes hormones (oxytocin and anti-diuretic hormone)
Function of paraventricular nucleus?
Secretes hormones
What are the nuclei of the middle area of the medial zone of the hypothalamus?
Dorsomedial nucleus
Ventromedial nucleus
Arcuate nucleus
Function of dorsomedial nucleus?
Emotional behavior and role in circadian rhythms
Function of ventromedial nucleus?
Inhibits eating and drinking (satiety)
Function of arcuate nucleus?
Secretes releasing/inhibiting hormones
What are the nuclei of the posterior area of the medial zone of the hypothalamus?
Posterior nucleus and mammillary nucleus
Function of the posterior nucleus?
Heat gain; cold temp response
Wakefulness and sympathetic activity
Function of mammillary nucleus?
Memory
The lateral zone/nuclei of the hypothalamus is primarily involved in?
Initiating eating and drinking
What is the blood supply to the thalamus?
Perforating arteries of the Circle of Willis
What are some of the hypothalamic afferents?
Fornix
Stria terminals and ventral amygdalofugal fibers
Corticohypothalamic input
Retinohypothalamic fibers
Path of fornix?
Goes from hippocampal fibers to mammillary bodies
What do retinohypothalamic fibers target?
SCN (suprachiasmatic nucleus)
What are some 2-way hypothalamic efferent/afferent pathways?
Median Forebrain Bundle (MFB)
Dorsal Longitudinal Fasiculus (DLF)
Where do some hypothalamic efferents descend to?
PAG (periaquaductal gray)
RF (reticular formation)
What are the main descending efferents from hypothalamus?
Medial zone and mammillary bodies
What are some ascending hypothalamic efferents?
Hypothalamocortial fibers
Mammillothalamic tract - goes to thalamus
Lateral zone - goes to thalamus
Anterior area of the hypothalamus regulates ______
Parasympathetic activity
Posterior area of the hypothalamus regulates _______
Sympathetic activity
What is essential for timing of rest and activity and has cells that maintain 24 hours of transcriptional control over circadian genes?
Suprachiasmatic nucleus
Connections influence behavior, memory and pain perception
Limbic system
Anatomical basis for emotional, drive-related, and motivated aspects of behavior
Hypothalamus + limbic system
What is the hippocampal formation important for?
Learning and memory
What does the hippocampal formation consist of?
Subiculum, hippocampus proper (ammon horn), Dentate gyrus
Where is the parahippocampal gyrus?
Cortex overlying hippocampal formation
Afferent path of the hippocampal formation?
Dentate gryus - > CA3 -> CA1 - > Subiculum
Efferent path of the hippocampal formation?
Fibers from the subiculum and hippocampus proper bundle to form the fimbria -> FORNIX
What is an uncal herniation?
Movement of uncus and maybe parahippocampal gyrus down over edge of tentorium cerebelli that will compress midbrain/brainstem
Signs of an uncal herniation?
Dilated pupil, weakness of opposite extremity, respiration affected and abnormal reflexes
What is Korsakoff’s syndrome?
Degeneration of mammillary bodies, hippocampal complex and thalamic DM nucleus due to thiamine deficiency associated with chronic alcoholism
Signs of Korsakoff’s syndrome?
Patients have severe difficulty learning new tasks and forming long term memories
- pts will CONFABULATE
Confabulate?
Combine fragmented memories into a synthesized “event” that never happened
Seen in Korsakoff’s patients
What causes hippocampal amnesia?
Bilateral lesions of hippocampi
Signs of hippocampal amnesia?
Deficit in episodic memory (cannot learn new material) but spared procedural and working memory with a normal IQ
Loss of smell
Anosmia
Distortion of smell when no odor present
Phantosmia
Attaches emotional significance to a stimulus
Amygdala
What causes Kluver-bucy syndrome?
Bilateral lesions that abolish amygdala
What are some symptoms of Kluver-Bucy syndrome?
Visual agnosia Hyperorality Placidity Hyperphagia Hypersexuality
Important in reward and motivation
Ventral tegmental area
Important in reward/pleasure and controls rage behavior
Septal nuclei
Behaviors related to addiction and chronic pain
Nucleus Accumbens
What describes emotional experiences that involve reactions between diencephalon and cortex?
Papez circuit
Papez circuit
Loop including:
Hippocampus, mammillary bodies, thalamus anterior nuclei, cingulate cortex
