Overlapping representations of the neck and whiskers in the rat motor cortex revealed by mapping at different anaesthetic depths

Abstract

The primary motor cortex of mammals has an orderly representation of different body parts. Within the representation of each body part the organization is more complex, with groups of neurons representing movements of a muscle or a group of muscles. In rats, uncertainties continue to exist regarding organization of the primary motor cortex in the whisker and the neck region. Using intracortical microstimulation (ICMS) we show that movements evoked in the whisker and the neck region of the rat motor cortex are highly sensitive to the depth of anaesthesia. At light anaesthetic depth, whisker movements are readily evoked from a large medial region of the motor cortex. Lateral to this is a small region where movements of the neck are evoked. However, in animals under deep anaesthesia whisker movements cannot be evoked. Instead, neck movements are evoked from this region. The neck movement region thus becomes greatly expanded. An analysis of the threshold currents required to evoke movements at different anaesthetic depths reveals that the caudal portion of the whisker region has dual representation, of both the whisker and the neck movements. The results also underline the importance of carefully controlling the depth of anaesthesia during ICMS experiments.

All Rodents Are Not the Same: A Modern Synthesis of Cortical Organization

“…f Mouse: Tennant et al [2010] e Rat: Brecht et al [2004] d Rat: Tandon et al [2008] c Rat: Neafsey et al [1986] b Rat: Donoghue and Wise [1982] a Rat: Hall and Lindholm [1974] g Eastern grey squirrel: Cooke et al [2011] The Line drawings of the topographic organization of M1 (AGl) as described in different studies in rats ( a-e ), mice ( f ), and squirrels ( g ). Despite the differences in stimulation parameters and anesthetic, the maps in rats generated in different laboratories are remarkably similar.…”

“…Conventions are as in previous figures. than Tandon et al, 2008]. The functional organization of motor cortex in the mouse [Li and Waters, 1991;Pronichev and Lenkov, 1998;Tennant et al, 2010], and squirrel [Cooke et al, 2008[Cooke et al, , 2011 are limited and only within the last year have full functional maps for mice been generated [Tennant et al, 2010].…”

“…Second, the type and level of anesthetic used can generate different motor maps that are more or less inclusive in terms of body part representations [see fig. 4 of Tandon et al, 2008]. Third, when movements generated at suprathreshold currents are considered, the locations and sizes of body part representations shift [see fig.…”

Synergistic combination of near-infrared irradiation and targeted gold nanoheaters for enhanced photothermal neural stimulation

“…3). The stimulation parameters are 50 ms train of fifteen 1.5 ms pulses at 300 Hz with a pulse intensity of 128 mJ/cm 2 which are determined based on the stimulation parameter of intracortical microstimulation (ICMS) [37,38]. The pulse duration of the optical stimulus is selected as 1.5 ms at which whisker movement is maximized when it is varied in the range from 0.5 ms to 2.0 ms. A train of stimulus set is given every two seconds.…”

“…The pulse duration of the optical stimulus is selected as 1.5 ms at which whisker movement is maximized when it is varied in the range from 0.5 ms to 2.0 ms. A train of stimulus set is given every two seconds. After optical stimulation, electrical stimulation (66.7 ms train of twenty monophasic, negative, 0.2 ms pulses at 300 Hz with amplitude of 2.4 mA) is delivered through tungsten microelectrode where light is delivered to check the functionality after optical stimulation [37,38]. We videotape whisker movement using CCD camera (C920, Logitech, Lausanne, Switzerland) before and after optical stimulation.…”