This study investigates how semantic information is encoded in the brain during language comprehension at the single-cell level. Using single-neuron recordings from the left language-dominant prefrontal cortex of humans, the researchers found that individual neurons selectively respond to specific word meanings and reliably distinguish words from nonwords. These neurons' activities are highly dynamic, reflecting the words' meanings based on their specific sentence contexts and independent of their phonetic form. The study shows that these cell ensembles accurately predict the semantic categories of words as they are heard in real time during speech and track the sentences in which they appear. The findings reveal a finely detailed cortical organization of semantic representations at the neuron scale in humans and begin to illuminate the cellular-level processing of meaning during language comprehension. The study also shows that the semantic representations are robust and generalizable, and that the neurons' responses are context-dependent, reflecting the words' meanings based on the specific sentences in which they are heard. The results suggest that the brain uses a hierarchical structure to represent semantic information, and that these representations are encoded in the population's response patterns. The study highlights the potential of single-neuronal recordings to begin unraveling the real-time dynamics of word and sentence comprehension at a combined spatial and temporal resolution that has been inaccessible through traditional human neuroscience approaches. The findings provide an initial framework for studying linguistic and semantic processing during comprehension at the level of individual neurons and highlight the potential benefit of using different recording techniques, linguistic materials, and analytic techniques to evaluate the generalizability and robustness of neuronal responses. The study also suggests that these semantic representations may be modality independent, generalizing to reading comprehension or even to non-linguistic stimuli.This study investigates how semantic information is encoded in the brain during language comprehension at the single-cell level. Using single-neuron recordings from the left language-dominant prefrontal cortex of humans, the researchers found that individual neurons selectively respond to specific word meanings and reliably distinguish words from nonwords. These neurons' activities are highly dynamic, reflecting the words' meanings based on their specific sentence contexts and independent of their phonetic form. The study shows that these cell ensembles accurately predict the semantic categories of words as they are heard in real time during speech and track the sentences in which they appear. The findings reveal a finely detailed cortical organization of semantic representations at the neuron scale in humans and begin to illuminate the cellular-level processing of meaning during language comprehension. The study also shows that the semantic representations are robust and generalizable, and that the neurons' responses are context-dependent, reflecting the words' meanings based on the specific sentences in which they are heard. The results suggest that the brain uses a hierarchical structure to represent semantic information, and that these representations are encoded in the population's response patterns. The study highlights the potential of single-neuronal recordings to begin unraveling the real-time dynamics of word and sentence comprehension at a combined spatial and temporal resolution that has been inaccessible through traditional human neuroscience approaches. The findings provide an initial framework for studying linguistic and semantic processing during comprehension at the level of individual neurons and highlight the potential benefit of using different recording techniques, linguistic materials, and analytic techniques to evaluate the generalizability and robustness of neuronal responses. The study also suggests that these semantic representations may be modality independent, generalizing to reading comprehension or even to non-linguistic stimuli.