summary: A new study provides unprecedented insights into the human brain’s response to the loss of a major language center.
During epilepsy surgery, the team recorded brain activity before and after removing the anterior temporal lobe, the center of linguistic meaning. These recordings revealed rapid disruption of brain signals and attempted partial compensation by distant brain regions, challenging previous theories about the possibility of replacing brain centers.
This pioneering study provides new perspectives on the brain’s plasticity and adaptability, and supports neurobiological theories about the brain’s tendency to maintain order.
Key facts:
- The study was conducted during epilepsy surgery, allowing unique pre- and post-operative brain recordings.
- Loss of the anterior temporal lobe causes immediate disruption in speech and language processing, followed by partial compensation by other brain regions.
- This research supports the theory that brain centers are essential for maintaining normal brain processing and that the brain actively works to restore order after a center is lost.
source: University of Iowa
A team of international neuroscientists led by the University of Iowa has obtained the first direct recordings of the human brain in the minutes before and after a brain center important for the meaning of language is surgically severed.
The findings reveal the importance of brain centers in neural networks and the remarkable way in which the human brain attempts to compensate when an axon is lost, with a speed never before observed.
Hubs are essential for communication
Hubs are everywhere. The bicycle wheel hub, which runs from the center, prevents the wheel from collapsing when riding. Airport hubs connect cities all over the world. Social hubs such as coffee shops or online social networks are places where people come together to interact.
The human brain also contains axons – the intersection of many neural pathways that help coordinate brain activity required for complex functions such as understanding and responding to speech. However, whether these highly interconnected brain centers are irreplaceable for some brain functions has been controversial.
By some accounts, the brain, as an already highly interconnected neural network, could in principle instantly compensate for a loss of center, in the same way that traffic can be redirected around a blocked city center.
With a rare experimental opportunity, neurosurgery and research teams at IU led by Matthew Howard III, MD, professor and DEO of neurosurgery, and Christopher Petkoff, MD, professor and vice chair for research in neurosurgery, have made significant progress in understanding the necessity of a single axis.
By obtaining evidence of what happens when the axis required for language meaning is lost, the researchers have demonstrated the essential importance of the axis as well as the brain’s remarkable and rapid ability to adapt and attempt to immediately compensate for its loss, at least partially. .
The results were recently published in the journal Nature Communications.
Evaluate the impact of loss of the brain center
The study was conducted during surgical treatment of two patients with epilepsy. Both patients were undergoing procedures that required surgical removal of the anterior temporal lobes — the brain’s center for language meaning — to allow neurosurgeons to access a deeper area of the brain that causes the patients’ debilitating epileptic seizures.
Before this type of surgery, neurosurgery teams often ask patients to perform speech and language tasks in the operating room where the team uses implanted electrodes to record activity from parts of the brain near and far from the area of the planned surgery.
These recordings help the clinical team treat seizures effectively while limiting the impact of surgery on the patient’s speech and language abilities.
Usually, recording electrodes are not needed after surgical excision and are removed. The innovation of this study was that the neurosurgical team was able to safely complete the procedure with the recording electrodes left in place or replaced at the same site after the procedure.
This made it possible to obtain rare pre- and post-operative recordings, allowing the researchers to evaluate signals from off-axon brain areas, including speech and language areas far from the surgical site.
Analysis of the change in responses to speech sounds before and after axon loss revealed a rapid interruption of signals and subsequent partial compensation of the broader brain network.
“The rapid effect on speech and language processing areas that were well removed from the surgical treatment site was surprising, but even more surprising was how the brain worked to compensate, albeit imperfectly over such a short time frame,” says Petkoff, who is also responsible for This matter. Appointment at Newcastle University School of Medicine in the UK.
The findings rebut theories that challenge the necessity of specific brain centers by showing that the center is important for maintaining the brain’s normal processing of language.
“Neurosurgical treatment and new technologies continue to improve treatment options for patients,” says Howard, who is also a member of the Iowa Neuroscience Institute.
“Such research underscores the importance of safely obtaining and comparing electrical recordings before and after surgery, especially when the center of the brain is affected.”
According to the researchers, observing the nature of the direct effect on the neural network and its rapid attempt to compensate provides evidence that supports the brain theory proposed by Professor Karl Friston at University College London, which posits that any self-regulating system in a state of equilibrium works to regulate itself by reducing its free energy, which is resistance. The global tendency towards chaos.
These neurobiological findings following human brain axon disconnection were consistent with many predictions about this and related neurobiological theories, showing how the brain works to try to restore order after the loss of one of its axons.
In addition to Petkoff and Howard, the research team included researchers in the UI Departments of Neurosurgery, Radiology, Psychological Sciences and Brain Sciences, as well as colleagues from the University of Newcastle, UCL, and the University of Cambridge in the UK, and from Carnegie Mellon University. The University of Wisconsin-Madison and Gonzaga University in the United States.
Financing: The research was funded in part by grants from the National Institutes of Health and the Wellcome Fund. And the European Research Council.
About neuroplasticity research news
author: Jennifer Brown
source: University of Iowa
communication: Jennifer Brown – University of Iowa
picture: Image credited to Neuroscience News
Original search: Open access.
“Immediate neural impact and incomplete compensation after semantic axis interruption” by Matthew Howard III et al. Nature Communications
a summary
Immediate neural impact and incomplete compensation after semantic axis interruption
The human brain extracts meaning using a large-scale neural system of semantic knowledge. Whether large-scale distributed systems rely on the loss of a highly interconnected core or can compensate afterwards is controversial.
We report intracranial recordings from two patients during a speech prediction task, obtained minutes before and after neurosurgical treatment requiring separation of the left anterior temporal lobe (ATL), a candidate center for semantic cognition. Based on recent disjunction and predictive coding frameworks, we tested hypotheses ranging from disruption of the neural network only to complete compensation through language-related sites and speech processing that are indirectly affected.
Immediately after ATL interruption, we observed neurophysiological changes in recorded frontal and auditory sites, providing direct evidence of the importance of the ATL as a semantic center.
We have also obtained evidence of rapid, if imperfect, attempts at neural network compensation, with largely neural influence in the forms provided by the predictive coding framework, in particular, and the neodisjunction framework, in general.
The overall results confirm the validity of these frameworks and reveal the immediate impact and adaptability of the human brain after loss of the brain center.