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The Thalamus

The thalamus sits above the hypothalamus and is often referred to as the "switching center" of the brain. It is sort of the central terminal where inputs from the lower centers of the brain including the spinal cord, brainstem, autonomic nervous system, hypothalamus and cerebellum are brought together and routed to the surface of the brain, the cortex. The thalamus also receives input from the limbic system, which is essential to memory and learning...

Your thalamus is kind of like the United Parcel Service. It will gather information from various centers of the brain and spinal cord and will direct them to the correct address in the cortex. However, it does more than just deliver…

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New role discovered for the thalamus

The thalamus has long been thought of as a relay station for sensory information. This belief was based on its connections with parts of the brain that process inputs from the senses. But the thalamus has many connections with other parts of the brain as well. One such connection is with the prefrontal cortex, an area involved in high level thinking, decision-making, and attention. Brain imaging studies in people with schizophrenia have found decreased connectivity between the mid/upper thalamus and the prefrontal cortex.

The cognitive thalamus

The thalamus, once viewed as passively relaying sensory information to the cerebral cortex, is becoming increasingly acknowledged as actively regulating the information transmitted to cortical areas. There are a number of reasons for this change. First, evidence suggests that first-order thalamic areas, like the lateral geniculate nucleus, ventral division of the medial geniculate nucleus, and the ventral posterior nuclei, can modulate neural processing along the sensory pathways to the cortex according to behavioral context.

The Human Thalamus Is an Integrative Hub for Functional Brain Networks

The thalamus is traditionally viewed as a passive relay station of information from sensory organs or subcortical structures to the cortex. However, the thalamus has extensive connections with the entire cerebral cortex, which can also serve to integrate information processing between cortical regions.

The impact of the human thalamus on brain-wide information processing

The thalamus is a small, bilateral structure in the diencephalon that integrates signals from many areas of the CNS. This critical anatomical position allows the thalamus to influence whole-brain activity and adaptive behaviour. However, traditional research paradigms have struggled to attribute specific functions to the thalamus, and it has remained understudied in the human neuroimaging literature.

The thalamus: gateway to the mind

The thalamus of the brain is far more than the simple sensory relay it was long thought to be. From its location at the top of the brain stem it interacts directly with nearly every part of the brain. Its dense loops into and out of cortex render it functionally a seventh cortical layer. Moreover, it receives and sends connections to most subcortical areas as well.

The Thalamus: More than just Central Station

The role of the thalamus has directly inspired some recent AI architectures such as ThalNet (Hafner et al. 2017), in which a central network learns to route information through a set of recurrent modules - in principle like the corticothalamic system does.

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KenHub

Every major city has a central hub through which its citizens can access public transportation to get to their desired destination. In the case of the human body, the nervous system can be divided into the major road ways (nerves) that carry individuals (impulses) to and from the big city (the brain). The thalamus is ideally situated at the core of the diencephalon, deep to the cerebral cortices and conveniently acts as the central hub. The thalamus relays and integrates a myriad of motor and sensory impulses between the higher centres of the brain and the peripheries.

Know your brain: Thalamus

However, to consider the thalamus as just a gatekeeper or relay station is selling this structure a bit short. A significant portion of the incoming fibers to the thalamus come not from sensory systems, but from the cortex itself. There are many connections to the thalamus that are involved in taking information from the cortex, modulating it, and then sending it back to the cortex. This means that the thalamus is an important part of cortical processing in general, and more than just a brief stop for signals on their way to the cortex.

Physiopedia

The thalamus is engaged in an intimate relationship with the cerebral cortex, with numerous mutual connections. These connections make up the thalamacortical loop. The thalamus also modulates arousal mechanisms, maintains alertness, and directs attention to sensory events.

Radiopaedia

Structurally, the thalamus is composed of two symmetrical egg-shaped masses (thalami) which are usually connected at the midline by a band of grey matter, the interthalamic adhesion. The anterior pole narrows to form the posterior boundary of the interventricular foramen. Posteriorly the thalamus expands to form the pulvinar. On the posteroventral surface of the thalamus lie two rounded protrusions called the medial and lateral geniculate nuclei.

StatPearls

Generally, the thalamus acts as a relay station filtering information between the brain and body. Except for olfaction, every sensory system has a thalamic nucleus that receives, processes, and sends information to an associated cortical area.