Coronal section of brainstem, diencephalon, basal telencephalic nuclei, and emispheres.

Thalamus, lateral and third ventricles, nucleus caudatus, lentiform nuclei, epithalamus

Hypothalamic structures visible at the base of enchephalon

Medial view of diencephalon

Thalamus, basal encephalic ganglia and white internal capsule

Grey nuclei and white laminas in the thalamus

RELEVANT FUNCTIONS OF THALAMIC NUCLEI Midline nuclei: component of limbic system. Role in memory and awakening. Medial nuclei: back and forth connections with olphactory, frontal and motor cortex, basal ganglia. When damaged ansiety, aggressivity and tension are reduced; amnesia is also present (similar to frontal lobotomy). Anterior nuclei: back and forth connections with mammillary bodies, cingulum and parahippocampal area. Short term memory and attention.

Ventral nuclei: The anterior has connections with cerebellum, globus pallidum, and parietal cortex, and it partecipates to the “cortical recruitment response”. The lateral has afferences from spinal lemniscus, vestibolar nuclei and substantia nigra; it has efferences to motor cortex. Its isolation reduces Parkinson’s symptoms Ventral posteriore lateral and medial: it receives afferences from the lemnisci and vestibular nuclei; efferent fibers, grouped on the basis of type of sensation are directed to the sensory cortex. geniculate bodyes: the lateral has afferences from retina and occipital cortex. Efferences to visual cortex via optical radiations. Crossed by retino-tectal and cortico-tectal fibers. The medial has afferences from the inferior colliculum via the inferior connecting arm. Efferences to the acustic area of the temporal lobe. .

Subthalamus: below the thalamus and in contact with red nucleous and substantia nigra

SUBTHALAMUS White substance: is crossed by the cranial endings of the lemnisci directed to the thalamus; by dentatoto-thalamic and rubro-thalamic fasciculi; by the Forel field fibers (globus pallidus-subthalamus, subthalamus-thalamus). Subthalamic nucleus: it has connections with the striatum and is involved in the inhibitory control of the cortical motor activity. (emiballism)

SUBTHALAMIC REGION AND FOREL FIELDS

EPITHALAMUS: pineal gland, abenular nuclei and posterior commissure.

Pineal gland: contains pinealocytes Pineal gland: contains pinealocytes. It is reached by ortosimpathetic fibers and by optical fibers from the chiasma. Site of melatonin synthesis that is inhibited by light. In the hamster it inhibits gonadotropin secretion.

Exposed surface of the Hypothalamus: It spans from the optic chiasma to mammillary bodies

Transverse section of the Hypothalamus

HYPOTHALAMIC FUNCTIONS Food uptake and water content control Famine center: active at low glucose levels Satiety control: active at high glucose levels Thirst control: active at high osmolarity Osmolarity control via ADH secretion Temperature control Perypheral vasodilatation and swet control Peryphoeral vasoconstriction and tremor %

HYPOTHALAMIC FUNCTIONS Emotion and behaviour control Limbic and frontal afferences influence physical responses positive inothropism mouth drynes reddish and pale cheek skin perspiration peristalsis Vegetative nervous system control Parasympathetic actions (negative inothropism, increased peristalsis and secretion, pupillary contraction, increased salivation) Orthosympathetic actions (positive inothropism, reduced peristalsis and secretion, pupillary dilatation)

HYPOTHALAMIC AFFERENCES

HYPOTHALAMIC EFFERENCES

HYPOTHALAMIC FUNCTIONS Endocrine activity and endocrine system control Production of oxytocin and ADH; Production of releasing and inhibitory hypophyseal hormones; Neurohypophysis is reached by paraventricular and supraoptic neurones secreting oxytocine and ADH into capillaries. Regulatory hormones of hypophyseal secretions are secreated by hypothalamic neurons into the hypophyseal portal system (ACTH-RH, FSH-RH, LH-RH, TSH-RH, GH-RH; MSH-IH, PRL-IH)

HYPOTHALAMIC FUNCTIONS – Neurohypophisis HYPOPHYSEAL PORTAL CYRCULATION