These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Changes in cortical activation during retrieval of clock time representations in patients with mild cognitive impairment and early Alzheimer's disease.
    Author: Leyhe T, Erb M, Milian M, Eschweiler GW, Ethofer T, Grodd W, Saur R.
    Journal: Dement Geriatr Cogn Disord; 2009; 27(2):117-32. PubMed ID: 19182479.
    Abstract:
    OBJECTIVE: We investigated healthy controls (HCs), and patients with mild cognitive impairment (MCI) and early Alzheimer's disease (AD) to identify neuronal correlates of clock time representation and changes resulting from neurodegenerative processes using functional magnetic resonance imaging. METHODS: Two clock-specific tasks demanding conceptual knowledge of clock hands, i.e. a minute hand and an hour hand task, were compared with a semantic control task. RESULTS: We observed that the minute hand task provoked a stronger activation of areas in the parietal lobes known to be involved in spatial mental imagery, while the semantic task primarily activated regions of the superior temporal lobes associated with verbal conceptual knowledge. The performance of the MCI group did not differ from that of the HC group, but additional activation was found in several brain regions. Decreased activation was detected during the minute hand task in the right middle temporal gyrus. Patients with early AD showed deteriorated performance in both clock tasks along with reduced activation in the occipital lobes and the left fusiform gyrus. Additional activation was detected in the precuneus. CONCLUSIONS: The fusiform gyrus might be crucial for the visual-semantic retrieval of clock time representation. In patients with early AD, access to this visual-semantic knowledge appears to be reduced.
    [Abstract] [Full Text] [Related] [New Search]