Deciphering the Century-Old Mystery: Revealing the Temporal Pole’s Function in the Brain

Summary: Researchers uncovered the critical role of the temporal pole, a previously mysterious area of the brain. A disease called TDP-C that specifically damages the temporal pole allowed the team to discern its function in word comprehension, face recognition, and behavior regulation.

The research offers new insights into brain networks, which may provide valuable help for patients with this condition.

Key Facts:

  1. The temporal pole, a previously mysterious region at the tip of the temporal lobe, plays a crucial role in word comprehension, face recognition, and behavior regulation.
  2. The functions were identified by studying patients suffering from a unique disease, TDP-C, which specifically affects the temporal pole.
  3. The research can help in understanding how the brain decodes the meaning of words, the feelings of others, and the identity of faces, opening new avenues for treatment of related conditions.

Source: Northwestern University

Every part of the brain surface (the cerebral cortex) has a specific job description. Some areas move the arms, others the legs, still others make it possible to see or speak.

But one part of the brain surface, a region called the temporal pole because it is at the very tip of the temporal lobe, could not be linked to a specific function for at least the first 100 years of research on the cortex.

Northwestern Medicine scientists have just discovered that this mysterious and seemingly silent surface is actually one of the most colorful regions of the brain. It has critical functions in word comprehension, face recognition and the regulation of behavior.

The paper was recently published in Annals of Neurology.

This shows a head.
Now Northwestern researchers are studying the relationship between the temporal pole and these complex functions, and the nature of the relationships between TDP-C and the temporal pole. Credit: Neuroscience News

The scientists were able to identify this region’s previously unknown function through the investigation of 28 patients with a unique disease, known as TDP-C, that ultimately destroys the temporal pole. The cases reviewed post-mortem offer the most precise delineation of the brain areas that are first hit in a disease that progresses over 10 to 15 years.

“Research on this disease helps us understand how the brain decodes the meaning of words, the feelings of others and the identity of faces,” said study corresponding author Dr. Marsel Mesulam, chief of behavioral neurology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine neurologist.

“This knowledge will help to determine the nature of the disease and the nature of brain networks that are responsible for word comprehension, person identification and the monitoring of interpersonal conduct.”

Now Northwestern researchers are studying the relationship between the temporal pole and these complex functions, and the nature of the relationships between TDP-C and the temporal pole.

“Answering these questions is key for helping patients with this condition,” said Mesulam, also the Ruth Dunbar Davee Professor of Neuroscience and founder of the Mesulam Center for Cognitive Neurology and Alzheimer’s Disease.

“The next steps in the research are to identify the unique properties of the areas targeted by TDP-C, determine how the disease progresses and find out if there are patient-specific risk factors.”

The patients with TDP-C had been followed longitudinally at the Mesulam Center. The longitudinal data on brain function was linked to the tissue damage seen by examination with the microscope after autopsy.

About this neuroscience research news

Author: Marla Paul
Source: Northwestern University
Contact: Marla Paul – Northwestern University
Image: The image is credited to Neuroscience News

Original Research: Open access.
Frontotemporal Degeneration with Transactive Response DNA‐Binding Protein Type C at the Anterior Temporal Lobe” by Marek‐Marsel Mesulam et al. Annals of Neurology


Abstract

Frontotemporal Degeneration with Transactive Response DNA‐Binding Protein Type C at the Anterior Temporal Lobe

The anatomical distribution of most neurodegenerative diseases shows considerable interindividual variations.

In contrast, frontotemporal lobar degeneration with transactive response DNA-binding protein type C (TDP-C) shows a consistent predilection for the anterior temporal lobe (ATL). The relatively selective atrophy of ATL in TDP-C patients has highlighted the importance of this region for complex cognitive and behavioral functions.

This review includes observations on 28 TDP-C patients, 18 with semantic primary progressive aphasia and 10 with other syndromes.

Longitudinal imaging allowed the delineation of progression trajectories. At post-mortem examination, the pathognomonic feature of TDP-C consisted of long, thick neurites found predominantly in superficial cortical layers.

These neurites may represent dystrophic apical dendrites of layer III and V pyramidal neurons that are known to play pivotal roles in complex cortical computations. Other types of frontotemporal lobar degeneration TDP, such as TDP-A and TDP-B, are not associated with long dystrophic neurites in the cerebral cortex, and do not show similar predilection patterns for ATL.

Research is beginning to identify molecular, structural, and immunological differences between pathological TDP-43 in TDP-C versus TDP-A and B. Parallel investigations based on proteomics, somatic mutations, and genome-wide association studies are detecting molecular features that could conceivably mediate the selective vulnerability of ATL to TDP-C.

Future work will focus on characterizing the distinctive features of the abnormal TDP-C neurites, the mechanisms of neurotoxicity, initial cellular targets within the ATL, trajectory of spread, and the nature of ATL-specific markers that modulate vulnerability to TDP-C. 

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