thalamus

Examples of thalamus in the following topics:

• Thalamus

  • The thalamus is part of a nuclear complex of composed of four parts: the hypothalamus, epithalamus, the ventral thalamus, and the dorsal thalamus.
  • The thalamus is connected to the hippocampus via the mammillothalamic tract.
  • The thalamus has multiple functions, serving as a sort of switchboard of information.
  • The thalamus is believed to both process and relay sensory information.
  • Damage to the thalamus can lead to permanent coma.

• Functions of the Diencephalon

  • It is made up of four distinct components: the thalamus, the subthalamus, the hypothalamus, and the epithalamus.
  • The thalamus is a kind of switchboard of information, believed to act as a relay between a variety of subcortical areas and the cerebral cortex.
  • The thalamus also plays an important role in regulating states of sleep and wakefulness.
  • The thalamus plays a major role in regulating arousal, awareness level, and activity.
  • Damage to the thalamus can lead to permanent coma.

• Sensory Areas

  • The cerebral cortex is connected to various subcortical structures such as the thalamus and the basal ganglia.
  • Most sensory information is routed to the cerebral cortex via the thalamus.
  • Olfactory information, however, passes through the olfactory bulb to the olfactory cortex, bypassing the thalamus.
  • Parts of the cortex that receive sensory inputs from the thalamus are called primary sensory areas.
  • Olfaction is the only sensory system that is not routed through the thalamus.

• Somatic Sensory Pathways

  • The somatosensory pathway is composed of three neurons located in the dorsal root ganglion, the spinal cord, and the thalamus.
  • The axons of many of these neurons terminate in the thalamus, and others terminate in the reticular activating system or the cerebellum.
  • In the case of touch and certain types of pain, the third neuron has its cell body in the ventral posterior nucleus of the thalamus and ends in the postcentral gyrus of the parietal lobe.
  • Note that many ascending somatosensory pathways include synapses in either the thalamus or the reticular formation before they reach the cortex.
  • The thalamus is a midline symmetrical structure within the brain of vertebrates including humans; it is situated between the cerebral cortex and midbrain, and surrounds the third ventricle.

• Pons

  • The pons is a relay station between the forebrain and cerebellum that passes sensory information from the periphery to the thalamus.
  • The white matter of the pons includes tracts that conduct signals from the cerebrum down to the cerebellum and medulla, and tracts that carry the sensory signals up into the thalamus.

• Clusters of Neuronal Cell Bodies

  • For example, the reticular nucleus of the thalamus is a thin layer of inhibitory neurons that surround the thalamus.

• Basal Ganglia

  • They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus, and other brain areas.
  • The pallidum receives its most important input from the striatum (either directly or indirectly), and sends inhibitory output to a number of motor-related areas, including the part of the thalamus that projects to the motor-related areas of the cortex.

• Midbrain

  • ., thalamus, hypothalamus).
  • The tegmentum is involved in many unconscious homeostatic and reflexive pathways, and is the motor center that relays inhibitory signals to the thalamus and basal nuclei to prevent unwanted body movement.

• General Organization of the Somatosensory System

  • This neuron's ascending axons will cross, or decussate, to the opposite side of the spinal cord or brainstem and travel up the spinal cord to the brain, where most will terminate in either the thalamus or the cerebellum.
  • Tertiary neurons have cell bodies in the thalamus and project to the postcentral gyrus of the parietal lobe, forming a sensory homunculus in the case of touch.

• The Brain

  • The thalamus is perched on top of the brainstem near the center of the brain, with nerve fibers projecting out to the cerebral cortex in all directions.
  • The hypothalamus is a small part of the brain located just below the thalamus on both sides of the third ventricle.