Compensatory Mechanism for Face Perception Suggested by a SPECT Activation Study

Abstract

Background The bilateral temporo-occipital lobes are the usual site of pathology in patients with prosopagnosia. However, the mechanisms leading to this disorder are not fully understood. We investigated the neural mechanism of compensation for prosopagnosia in a patient with focal right posterior temporal lobe encephalitis without prosopagnosia.

Methods A single-photon emission computed tomography (SPECT) scan was performed using a brain-dedicated 32-phototube SPECT scanner and technetium-99m hexamethyl-propylene amine oxime to measure regional cerebral blood flow (rCBF). A SPECT activation study was performed in each of two conditions: the familial faces retrieval task and a control task.

Results The SPECT activation study revealed a significant increase in rCBF in the contralateral temporal lobe (from 72 during control conditions to 99 mL/100 g/min during the activation paradigm).

Conclusions This finding suggests that the region contralateral to the brain lesion compensates for the function of face perception. Our result may explain the reason why prosopagnosia rarely occurs with single, well-circumscribed lesions. The activation pattern seen in this study may be helpful for understanding the neural mechanism of compensation for prosopagnosia.

Keywords

prosopagnosia - face perception - compensation - single-photon emission computed tomography - regional cerebral blood flow

• References

• 1 Sorger B, Goebel R, Schiltz C, Rossion B. Understanding the functional neuroanatomy of acquired prosopagnosia. Neuroimage 2007; 35 (2) 836-852
• 2 Unrath A, Müller HP, Ludolph AC, Kassubek J. Reversible cortical diffusion restriction, hyperperfusion and T2-hyperintensity caused by two different types of epileptic seizure. Clin Neuroradiol 2012; 22 (3) 239-243
• 3 Kanemura H, Sano F, Sugita K, Aihara M. Ictal SPECT of thalamocortical coupling in a patient with frontal absence. Neuropediatrics 2011; 42 (5) 200-203
• 4 Chapman LJ, Chapman JP. The measurement of handedness. Brain Cogn 1987; 6 (2) 175-183
• 5 Podgorny P, Shepard RN. Functional representations common to visual perception and imagination. J Exp Psychol Hum Percept Perform 1978; 4 (1) 21-35
• 6 Patlak CS, Blasberg RG. Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. Generalizations. J Cereb Blood Flow Metab 1985; 5 (4) 584-590
• 7 McCarthy G, Puce A, Gore JC, Allison T. Face-specific processing in the human fusiform gyrus. J Cogn Neurosci 1997; 9 (5) 605-610
• 8 Behrmann M, Plaut DC. Bilateral hemispheric processing of words and faces: evidence from word impairments in prosopagnosia and face impairments in pure alexia. Cereb Cortex 2014; 24 (4) 1102-1118
• 9 Fuster JM, Bodner M, Kroger JK. Cross-modal and cross-temporal association in neurons of frontal cortex. Nature 2000; 405 (6784) 347-351