Hypothalamus vs Thalamus
Thalamus and hypothalamus belong to the diencephalon in the cerebrum of brain. Diencephalon is located surrounding the third ventricle and adjacent to the midbrain. Since thalamus is the largest part of this region, much of the neural tissue of diencephalon is found in the thalamus. Both thalamus and hypothalamus are found close to the midline at the base of cerebrum.
Thalamus
Thalamus is a two lobed structure, which forms the superior portion of the lateral walls of the third ventricle of the brain. It contains paired oval masses of gray matter that consist of tracts of white matter and masses of gray matter organized into nuclei. The anterior nucleus is found in the floor of the lateral ventricle and is associated with emotions, memory, and limbic system. The medial nucleus is concerned with sensory information. Three ventral nuclei within the thalamus are ventral anterior nucleus and ventral lateral nucleus associated with somatic motar system, and ventral posterior nucleus concerned with sensory information such as tastes, touch, pressure, heat, cold and pain. Pulvinar nucleus is found at the posterior portion of the thalamus, and it integrates sensory information and project impulses to the other associated regions of the cerebrum. Lateral geniculate body and medial geniculate body are important visual and auditory relay centers on thalamus.
Hypothalamus
Hypothalamus is a fingernail sized structure, located on a hemisection of the brain and it surrounds the lower part of the third ventricle. Hypothalamus also contains some important nuclei. The supraoptic nucleus near optic chiasma secretes antidiuretic (Vasopressin) hormone. Paraventricular nucleus is found near the third ventricle, and it secretes oxytocin, which causes contraction of the smooth muscle of the uterus. Preoptic nucleus regulates some autonomic activities like body temperature. Other important regions with several nuclei in the hypothalamus are tubural region, sympathetic region, parasympathetic region, mammillary region, and emotional centre.
What is the difference between Thalamus and Hypothalamus?
• Thalamus is larger than hypothalamus.
• Hypothalamus is situated inferior to the thalamus in the diencephalon.
• Hypothalamus is connected to the pituitary gland by infundibulum, but thalamus is not.
• Unlike the thalamus, hypothalamus secretes hormones including Vasopressin and Oxytocin.
• All the sensory information (except olfactory impulses) passes to cerebrum through the thalamus, whereas hypothalamus acts as the interface between endocrine and nervous system.