This 2014 German rodent study showed how the thalamus actively controlled and gated information to and from the cerebrum.
In the study’s news coverage, the researchers elaborated on how thalamic control and gating represented a form of memory:
“When asked if, given that
- sensory signals en route to the cortex undergo profound signal transformations in the thalamus,
- a key thalamic transformation is sensory adaptation in which neural output adjusts to the statistics and dynamics of past stimuli, and
- the thalamus, hypothalamus and hippocampus being part of the limbic system,
might memory reconsolidation play a role in the cortico-thalamic pathway?
“It’s conceivable that the cortico-thalamic pathway is subject to long term plasticity,” Groh conjectures. “In fact, on a synaptic level, these inputs can change their strength and retain the adjusted strength for long periods. This process represents another albeit much slower form of adaptation which some interpret as memory.“
Conversely, might the thalamic-cortical pathway affect memory?
“If particular sensory-evoked activity patterns would cause long-term changes in the cortico-thalamic pathway, and thereby change the way incoming signals are processed before reaching the cortex,” he opines, “then this would indeed reflect a form of information storage.“
In other words, there are ways in addition to our usual ideas about memory that the limbic system remembers.
Other items in the news coverage included:
“Rodents, cats, primates and humans show a common architecture of two feedback pathways from cortex to thalamus in the auditory, visual and somatosensory (but not olfactory) systems. “In this study we looked at the processing of touch information, and we’d like to know how the homologous pathways affect visual or auditory processing. It’s fascinating that despite the fundamental differences between visual, auditory and somatosensory signals, the basic layouts of the thalamocortical systems for each modality are quite similar.”
Other areas of research that might benefit from their study include “any medical research involving the thalamocortical system..that might involve inappropriate gating of sensory signals.”
For a given stimulus, the output neural response will not be static, but will depend on recent stimulus and response history.”
http://www.pnas.org/content/111/18/6798.full “Cortical control of adaptation and sensory relay mode in the thalamus”