Movement representation in the dorsal and ventral premotor areas of owl monkeys: A microstimulation study

Abstract

We used intracortical microstimulation to investigate the lateral premotor cortex and neighboring areas in 14 hemispheres of owl monkeys, focusing on the somatotopic distribution of evoked movements, thresholds for forelimb movements, and the relative representation of proximal and distal forelimb movements. We elicited movements from the dorsal and ventral premotor areas (PMD, PMV), the caudal and rostral divisions of primary motor cortex (M1c, M1r), the frontal eye field (FEF), the dorsal oculomotor area (OMD; area 8b), the supplementary motor area (SMA), and somatosensory cortex (areas 3a and 3b). Area PMD was composed of architectonically distinguishable caudal and rostral subdivisions (PMDc, PMDr). Stimulation of PMD elicited movements of the hindlimb, forelimb, neck and upper trunk, face, and eyes. Hindlimb and forelimb movements were represented in the caudalmost part of PMDc. Face, neck, and eye movements were represented in the lateral and rostral parts of PMDc and in PMDr. Stimulation of PMV elicited forelimb and orofacial movements, but not hindlimb movements. Both proximal and distal forelimb movements were elicited from PMDc and PMV, although PMD stimulation elicited mainly shoulder and elbow movements, while PMV stimulation evoked primarily wrist and digit movements. Distal movements were evoked more frequently from PMV than from M1r or M1c. Across cases, the median forelimb thresholds for PMDc and PMV were 60 and 36 microA, respectively, values that differ significantly from each other and from the value of 11 microA obtained for M1r. Our observations indicate that premotor cortex is much more responsive to electrical stimulation than commonly thought, and contains a large territory from which eye movements can be elicited. These results suggest that in humans, much of the electrically excitable cortex located on the precentral gyrus, including cortex sometimes considered part of the frontal eye field, is probably homologous to the premotor cortex of nonhuman primates.

“What” Becoming “Where”: Functional Magnetic Resonance Imaging Evidence for Pragmatic Relevance Driving Premotor Cortex

“…For ventral PM, a series of recent studies in monkeys point to extrinsic-like rather than intrinsic-like coding (Kakei et al, 1999(Kakei et al, , 2001(Kakei et al, , 2003. Moreover, the representation of the fingers has been located within ventral PM rather than in dorsal PM (Godschalk et al, 1995;Preuss et al, 1996). Together, these findings support the notion that in the present study, dorsal PM activation reflects coding of the spatial arrangement of the response buttons rather than the motor effector.…”

Cerebral cortical dysfunction in patients with temporomandibular disorders in association with jaw movement observation

“…Especially, the ventral precentral gyrus contains area 6 representing the face in the motor homunculus as the face motor area involved in jaw movements (see Preuss et al, 1996), suggesting that activation of the PrCG in our study would correspond to activation of the primary motor cortex along with area 6 aa. The lateral part of the precentral gyrus includes Brodmann's area 6aa representing the orofacial motor function, which was reported to be involved in a visuomotor transformations (Matsumoto et al, 2003).…”

“…As well known, most of the human precentral gyrus is occupied by Brodmann's area 6, while area 4 is largely confined to the central sulcus (Brodmann, 1903, and see also Preuss et al, 1996). Especially, the ventral precentral gyrus contains area 6 representing the face in the motor homunculus as the face motor area involved in jaw movements (see Preuss et al, 1996), suggesting that activation of the PrCG in our study would correspond to activation of the primary motor cortex along with area 6 aa.…”

Epileptic baboons have lower numbers of neurons in specific areas of cortex

“…In contrast, M1 is defined by large pyramidal neurons in layers 2/3 and layer 5 (e.g., refs. [44][45][46][47], and a nearly absent layer 4. There is regional variation in the structural complexity of cortical pyramidal neurons that have implications for plasticity.…”