Browsing by Author "Coutinho, Ester"
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- CA2/3-dependent stability of frontal mnemonic representations predict episodic deficits in human amnesiaPublication . Miller, Thomas D.; Hickling, Alice L.; Wu, Yan I.; Zhou, Joseph H.; Handel, Adam E.; Coutinho, Ester; Pollak, Thomas A.; Zandi, Michael S.; Maguire, Eleanor A.; Rosenthal, Clive R.The hippocampus reconstructs past experiences by integrating sensory, perceptual, and conceptual information across a cortico-hippocampal autobiographical memory network. Here, in 18 human participants with amnesia, we decode the effects of bilateral focal hippocampal damage on distinct autobiographical representations using representational dissimilarity matrices (RDMs). Hippocampal pathology results in impaired generalized episodic memory retrieval RDM model fit in the left angular gyrus and in reduced distinct episodic memory RDM model fit in the right inferior frontal gyrus (rIFG), while right angular gyrus (rANG) and right orbitofrontal cortex (rOFC) fall below multiple correction thresholds. Trial-by-trial voxelrepresentational stability is reduced in the rANG, rIFG, and rOFC. The RDM model fits and mnemonic stability are predicted by total CA2/3 volumes. Trial-by-trial retrieval stability within the rOFC and rIFG predicts episodic memory performance, providing a direct neural correlation between hippocampal dysfunction, altered mnemonic representations, and amnesia.
- Neuromyotonia and CASPR2 antibodies: electrophysiological clues to disease pathophysiologyPublication . Moura, João; Antenucci, Pietro; Coutinho, Ester; Bhatia, Kailash P.; Rocchi, Lorenzo; Latorre, AnnaContactin-associated protein-like 2 (CASPR2) is a transmembrane protein of the neurexin superfamily, essential for clustering voltage-gated potassium channels, particularly Kv1, at the juxtaparanodal regions of myelinated axons. This precise localisation is essential for maintaining normal axonal excitability and preventing aberrant signal propagation. Autoantibodies targeting CASPR2 have been associated with various neurological syndromes, notably peripheral nerve hyperexcitability (PNH), which presents clinically with neuromyotonia and myokymia. PNH is characterised by distinctive electrophysiological findings, including neuromyotonic discharges, myokymic discharges, and afterdischarges, which provide diagnostic value and insight into underlying pathophysiology. This review explores the mechanisms of anti-CASPR2-associated PNH, focusing on how antibody-mediated disruption of Kv1 channel clustering leads to altered axonal excitability. Current evidence suggests that both the distal and proximal segments of the axon are sites of pathological activity, where impairments in action potential termination and re-entry prevention result in spontaneous, repetitive discharges. While afterdischarges likely originate within the axon, the precise location—whether in the alpha-motoneuron soma or axon—is uncertain. The involvement of spinal inhibitory circuits has also been proposed, though it remains speculative. Understanding the neurophysiological features of anti-CASPR2-associated PNH is essential for improving diagnostic accuracy and guiding treatment strategies. Further research is needed to clarify the mechanisms of CASPR2-related hyperexcitability.