A Revised Clinical Assessment of Motor and Memory Disturbances

Abstract

For clinical assessment of motor disturbances, the motor system is better classified into the voluntary versus automatic motor systems than into the pyramidal versus extrapyramidal motor systems. The voluntary motor system is related to externally guided movements initiated by the premotor area while the automatic motor system is related to memory guided automatic movements initiated by the supplementary motor area and supported by an appropriate posture and associated movements. Among the pyramidal tract signs, muscle weakness alone is related to involvement of the corticospinal fibers of Betz cell origin while hyperreflexia and spasticity is related to involvement of the reticulospinal fibers running medial to the corticospinal fibers in the spinal cord. The earliest clinical manifestation of cervical myelopathy due to cervical spondylosis is always hyperreflexia and spasticity without any muscle weakness. The memory depends upon the 3 processes of encoding, retention, and recall, and must be classified into the immediate memory or recall lasting for only several seconds tested by the digit span test, the intermediate memory lasting for up to 2 years at maximum at the hippocampus whose disturbance can best be tested by the digit learning test, and the long-term memory which can last as long as one lives which can be tested by asking one's experience before more than 2 years. The classical dichotic concept of recent (short-term) versus remote (long-term) memories must be abandoned.

Visuomotor Coordination and Motor Representation by Human Temporal Lobe Neurons

“…Little evidence exists regarding the role of the medial-temporal lobe in visual guidance of movements and in visuomotor or motor tasks. The hippocampus has recently been described in the context of memoryguided automatic movements (Uemura, 2010) and is believed to participate in the control of the ventral-striatal loop (or limbic loop), which plays a role in the control of motor behavior (e.g., motor reactions to emotions; Fernández-Seara, Aznárez-Sanado, Mengual, Loayza, & Pastor, 2009;van Rooyen, Young, Larson, & Teskey, 2006;Duvernoy, Vannson, Cattin, & Naidich, 2005;Tesche & Karhu, 1999;Halgren, 1991;Miyashita, Rolls, Cahusac, Niki, & Feigenbaum, 1989). The entorhinal cortex represents self-position in the environment in the form of place cells (Howard & Natu, 2005) and grid cells (McNaughton, Battaglia, Jensen, Moser, & Moser, 2006) and velocity for path integration (i.e., inference of position by integration of velocity; Burak & Fiete, 2009;Blair, Gupta, & Zhang, 2008;Howard, Fotedar, Datey, & Hasselmo, 2005;Lengyel & Erdi, 2004).…”