Diencephalon Thalamus and Hypothalamus January 13 2009 Diencephalon

Diencephalon: Thalamus and Hypothalamus January 13, 2009

Diencephalon • Relay between the brainstem & cerebral cortex • Dorsal-posterior structures – Epithalamus • Habenular nuclei – integrate smell & emotions • Pineal gland – monitors diurnal / nocturnal rhythm – Thalamus – Metathalamus • Medial geniculate body – auditory relay • Lateral geniculate body – visual relay • Ventral-anterior structure – Hypothalamus

Function of the Thalamus • Sensory relay – ALL sensory information (except smell) • Motor integration – Input from cortex, cerebellum and basal ganglia • Arousal – Part of reticular activating system • Pain modulation – All nociceptive information • Memory & behavior – Lesions are disruptive

Input to the Thalamus

Input to the Thalamus Metathalamus Vision and Hearing

Input to the Thalamus Sensory relay - Ventral posterior group all sensation from body and head, including pain

Input to the Thalamus Motor control and integration

Input to the Thalamus Behavior and emotion connection with hypothalamus

Projections from the Thalamus Metathalamus Vision and Hearing

Projections from the Thalamus Sensory relay Ventral posterior group all sensation from body and head, including pain

Projections from the Thalamus Motor control and integration

Projections from the Thalamus Behavior and emotion connection with hypothalamus

Thalamus: axial view Descending upper motor neurons Cerebral peduncles Internal capsule

Thalamus: axial view

Thalamus: Pons sagittal view

Thalamus: sagittal view

Thalamus: coronal view

Thalamus: coronal view 3 rd ventricle

Thalamus: coronal view Internal capsule

Thalamus: coronal view Cerebral peduncles Internal capsule

Thalamus: coronal view Dorsomedial nucleus has reciprocal connections to prefrontal cortex. Concerned with judgment, decision making, memory and behavior. Mediodorsal nucleus Internal capsule

Thalamus Ventral lateral nucleus Mediodorsal nucleus VL nucleus has reciprocal connections with primary motor cortex. It receives input from cerebellar nuclei. With VA nucleus (which receives input from basal ganglia) contributes to planning and control of movement. Internal capsule

Thalamus: blood supply

Hypothalamus Located ventral-anterior to thalamus. (Subthalamus, located ventral to thalamus, will be discussed with basal ganglia. )

Hypothalamus Coronal view

Hypothalamus Sagittal view

Hypothalamus

Hypothalamus Thalamus

Hypothalamus Optic chiasm

Hypothalamus Pituitary Gland

Hypothalamus Mammillary body: termination of fornix

Hypothalamus Fornix: part of the limbic system

Hypothalamus Coronal view Lateral view Fornix to mammillary bodies

Hypothalamus: sagittal view

Hypothalamus: sagittal view

Hypothalamus: sagittal view

Hypothalamus: sagittal view Connects temporal lobes, sharing olfactory and audiovisual information

Hypothalamus: coronal view (rostral to caudal) MAMMILLARY TUBERAL SUPRACHIASMATIC PRE-OPTIC

Hypothalamus: coronal view Pre-Optic Region Gonadotropic releasing hormone Sexual arousal, appetite, reproduction

Hypothalamus: coronal view

Hypothalamus: coronal view

Hypothalamus: coronal view Suprachiasmic Region Secrete ADH, oxytocin Transported via axons to posterior pituitary (hypophysis)

Hypothalamus: coronal view Regulates thirst

Hypothalamus: coronal view Body temperature Circadian rhythms

Hypothalamus: coronal view

Hypothalamus: coronal view Tuberal Region Satiety

Hypothalamus: coronal view Regulates prolactin and growth hormone β endorphin for pain

Hypothalamus: coronal view

Hypothalamus: coronal view Mammillary region Limbic system

Hypothalamus: coronal view Hypocretin (orexin) Narcolepsy, reward

Hypothalamus Relationship to Pituitary Gland

Hypothalamic Connections Anterior pituitary From Pre-optic nucleus Tubero-infundibular tract to Median eminence, then via Portal veins Gonadotropic releasing hormone

Hypothalamic Connections Posterior pituitary Supraoptic-hypophyseal tract ADH / Vasopressin (supraoptic nuclei) Oxytocin (paraventricular nuclei)

Function of the Pituitary

Weds Basal ganglia