THALAMUS & HYPOTHALAMUS TOPIC PRESENTATION

anatomy of thalamus & hypothalamus

1. THALAMUS & HYPOTHALAMUS DR HARI RAM SEDAI 1 ST YEAR RESIDENT PSYCHIATRY, NMCTH

2. CONTENTS

3. THALAMUS

4. DIVISION OF THALAMUS

5. BLOOD SUPPLY

6. CONNCETION OF THALAMIC NUCLEI

7. FUNCTIONS OF THALAMUS Thalamus forms the relay center for the sensations Forms the major centre for processing the sensory information Centre for determining the quality of sensations ( Discriminative/Affective) P lays a crucial role in regulating states of sleep and wakefulness P lays a serious role in regulating arousal, extent of awareness and activity Thalamus is a part of the limbic system, which is the area of the brain that is mostly responsible for emotions and memory

8. EFFECT OF LESION AT THALAMUS

9. PSYCHIATRIC IMPLICATIONS Schizophrenia: Reduced thalamic volumes and blood flow along with prefrontal dysfunction. Decreased functional connectivity between the medio -dorsal thalamic nucleus and regions like the middle frontal cortex, anterior cingulate cortex, insula and cerebellum has been found Bipolar disorder and major depressive disorder (MDD): Dysfunctions of the limbic system, which includes the thalamus are implicated in these conditions. Autism spectrum disorder (ASD): Abnormalities in the thalamic connectivity system have been reported R educed thalamo -prefrontal connectivity in schizophrenia and bipolar disorder I ncreased thalamo -temporal connectivity in MDD and ASD

10. DIVISION OF HYPOTHALAMUS

11. HYPOTHALAMIC NUCLEI

12. AFFERENT PATHWAY Somatic and visceral afferents : through collateral branch of lemniscal afferent fibers and tractus solitarius and through reticular formation Visual afferents : leave the optic chiasma and pass to the suprachiasmatic nucleus Olfaction : travels through medial forebrain bundle Corticohypothalamic Fibers : arise from frontal lobe of cerebral cortex and pass directly to hypothalamus

13. 5) Hippocampo -hypothalamic Fibers : pass from hippocampus through fornix to mammillary bodies 6) Tegmental fibers : arise from midbrain 7) Thalamo -hypothalamic fibers : arise from dorsomedial and midline thalamic nuclei 8) Amygdalo -hypothalamic fibers : pass from amygdaloid complex to hypothalamus through stria terminalis

14. EFFERENT PATHWAY 1) Descending fibers to the brainstem and spinal cord 2) Mammillothalamic tract : arises in the mammillary body and terminates in the anterior nucleus of thalamus 3 ) Mammillotegmental tract : arises from mammillary body and terminates in the cells of reticular formation in tegmentum of the midbrain 4) Multiple pathways to limbic system

15. HYPOTHALAMO-HYPOPHYSEAL TRACT

16. FUNCTIONS OF HYPOTHALAMUS 1) Autonomic control 2) Endocrine control Antidiuretic hormone , actively monitors the volume of water in the body and controls water retention in body Corticotropin -releasing hormone , which helps regulate metabolism and immune response by working with the pituitary gland and adrenal gland to release certain steroids Gonadotropin-releasing hormone , which instructs the pituitary gland to release more hormones that keep the sexual organs working

17. Oxytocin involved in several processes, including the release of a mother’s breast milk, moderating body temperature, and regulating sleep cycles Prolactin-controlling hormones tells the pituitary gland to either start or stop breast milk production in lactating mothers Thyrotropin -releasing hormone activates the thyroid, which releases the hormones that regulate metabolism, energy levels, and developmental growth

18. 3) Temperature regulation : Anterior portion of hypothalamus controls mechanisms that dissipate heat loss Posterior portion of hypothalamus results in vasoconstriction of skin blood vessels and inhibits sweating 4) Regulation of food and water intake : Lateral region of hypothalamus is known as hunger center Medial region is known as satiety center

19. 5) Emotion and behavior : Function of limbic system, hypothalamus and prefrontal cortex 6) Control of circadian rhythm : Body temperature, adrenocortical activity, eosinophil count and renal secretion Sleeping and wakefulness also controlled Lesion of anterior part of hypothalamus interferes with the rhythm of sleeping and waking

20. PSYCHIATRIC IMPLICATIONS OF HYPOTHAMUS DYSFUNCTION 1) Eating Disorders Hypothalamic dysfunction can contribute to the development of eating disorders such as anorexia nervosa and bulimia nervosa Hypothalamus regulates appetite, satiety, and energy balance, and its dysfunction can lead to distorted perceptions of hunger and body image 2) Sleep Disorders H ypothalamus is involved in the regulation of sleep-wake cycles. Damage to the hypothalamus can result in sleep disorders

21. 3) Mood Disorders H ypothalamus is linked to the regulation of mood and emotions Dysfunction of the hypothalamus has been associated with mood disorders such as depression and anxiety 4) Cognitive Impairment Hypothalamic dysfunction can lead to cognitive impairment, including memory deficits and difficulties with attention and concentration O ften seen in cases of acquired hypothalamic damage, such as from tumors or head trauma

22. 5) Behavioural Changes Damage to the hypothalamus can result in changes in behavior , such as increased aggression, impulsivity, and apathy B ehavioral alterations are thought to be related to the hypothalamus's role in regulating emotional responses and social behavior

23. SUMMARY Thalamus acts as the relay center Thalamus is the part of the limbic system which is responsible for emotions and memory Hypothalamus is important for autonomic control and secretion of various endocrine hormones Hypothalamus plays a major role in controlling circadian rhythm of the body

24. REFERENCES Kaplan & Sadock’s Comprehensive Textbook Of Psychiatry, 10 th edition. Snell’s Clinical Neuroanatomy , 8 TH Edition Guyton and Hall Textbook of Medical Physiology 14 th edition Thalamic Connectivity System Across Psychiatric Disorders: Current Status and Clinical Implications Wu Jeong Hwang,a Yoo Bin Kwak,a Kang Ik K. Cho,g Tae Young Lee,e,f Harin Oh,a Minji Ha,a Minah Kim,b and Jun Soo Kwona,b,c,d ,∗