Cerebral blood flow correlates of word list learning

• Published in: Journal of neurolinguistics 1991, Vol.6 (3), p.253-272
• Main Authors: Celsis, Pierre, Agniel, Alain, Démonet, Jean-François, Marc-Vergnes, Jean-Pierre
• Format: Article
• Language: English
• ISSN: 0911-6044; 1873-8052
• DOI: 10.1016/0911-6044(91)90021-A

Techniques of brain functional assessment have contributed to information about the localization and organization of cerebral areas involved in higher brain functions. Nevertheless, few studies have concentrated on the organization of neural networks supporting verbal memory. In the present study, regional cerebral blood flow (rCBF) was measured by single photon emission computerized tomography and IV Xenon 133 in 20 normal volunteers. Measurements were made within 20 regions of interest (ROI) during three experimental conditions: rest, word passive binaural listening and word list learning. A list of 12 words, all differing from the 36 words used for the passive listening, was presented three times to the subjects, in the sarne order. Word characteristics and mode of presentation were as for the passive listening. Compared with the rest, passive listening significantly increased rCBF in the cerebellar hemispheres (+8 m/100 g/min). Learning condition increased rCBF in predominantly three left-sided conical [the anterior-middle frontal ( +6 ml/100 g/min), the posterior—inferior frontal ( +7 ml/100 g/min) and the superior-middle temporal ( +7 ml/100 g/min) and two leftsided subcortical (the subcortical thalamic ( +6 ml/100 g/min) and lenticular regions (+7 ml/100 g/min)] areas. Two regions (the superior—middle temporal and the posterior—inferior frontal regions) showed significant changes in lateral asymmetry (left > right) between listening and learning. Eleven subjects performed at the maximum level (12 words over 12 with no false positive). Whereas CBF tended to be slightly higher on the average in these subjects who performed at maximal level compared to the remaining subjects (67 vs 64 ml/100 g/min, NS), none of the regional differences reached significance. The 11 subjects who tried or perfectly succeeded in learning in the order of presentation all the words of the list showed marked left lateral asymmetry in thalamus (p < 0.01) and posterior-inferior frontal lobe (p < 0.02) regions. The present results confirm the predominant involvement of certain left cortical and subcortical regions in regulation and control of verbal memory and suggest that these same regions would participate in the processing of learning and memorizing of verbal material by short or long-term memory systems.