Visual Cortical Area MT Is Required for Development of the Dorsal Stream and Associated Visuomotor Behaviors

Abstract

The middle temporal (MT) area of the extrastriate visual cortex has long been studied in adulthood for its distinctive physiological properties and function as a part of the dorsal stream, yet interestingly it possesses a similar maturation profile as the primary visual cortex (V1). Here, we examined whether an early-life lesion in MT of marmoset monkeys (six female, two male) altered the dorsal stream development and the behavioral precision of reaching-to-grasp sequences. We observed permanent changes in the anatomy of cortices associated with both reaching (parietal and medial intraparietal areas) and grasping (anterior intraparietal area), as well as in reaching-and-grasping behaviors. In addition, we observed a significant impact on the anatomy of V1 and the direction sensitivity of V1 neurons in the lesion projection zone. These findings indicate that area MT is a crucial node in the development of primate vision, affecting both V1 and areas in the dorsal visual pathway known to mediate visually guided manual behaviors.

Time course of recovery of different motor functions following a reproducible cortical infarction in non-human primates

“…An initial movement direction error that represents the initial motor response was defined as the angular deviation between a straight line from the MP joint position at the “reaching start” to the target position and a vector from the MP joint position at the “reaching start” to the “initial movement.” The number of speed maxima that represents the feedback corrections was defined as the number of Y-axis movement speed maxima between the “reaching start” and the “endpoint.” We also evaluated the grasping performance in detail to measure the grasping time and the maximum grip aperture. Grasping time was defined as the total time from “grasping start” to “grasping end.” Maximum grip aperture is a clinically relevant outcome measure of functional impairment in human patients ( 46 ), and has been demonstrated to be altered in marmosets after lesion of the cortical visual pathway ( 13 , 19 ). Following the methods of previous studies, we defined the maximum grip aperture as the maximum value of the grip aperture between the thumb and index finger before “grasping start” ( 13 , 19 ).…”

“…Grasping time was defined as the total time from “grasping start” to “grasping end.” Maximum grip aperture is a clinically relevant outcome measure of functional impairment in human patients ( 46 ), and has been demonstrated to be altered in marmosets after lesion of the cortical visual pathway ( 13 , 19 ). Following the methods of previous studies, we defined the maximum grip aperture as the maximum value of the grip aperture between the thumb and index finger before “grasping start” ( 13 , 19 ).…”

“…Area 6DR is part of the parietofrontal network (52), which plays a role in visually guided reaching and grasping (21,68). Previous marmoset studies have shown that impairment of the parietofrontal network without damage to M1 disrupts the feed-forward aspect of visually guided reaching and grasping (13,19).…”

“…Second, the cortical visual pathway for visually guided behaviors is developed in primates (13). For example, neurons in the parietofrontal cortex are activated during visually guided reaching (14)(15)(16), and lesions in this pathway cause deficits in reaching performance (17)(18)(19). In contrast, rodents primarily use olfaction to identify the location of a target, and thus, reaching toward a target is guided more by olfaction than by vision (20)(21)(22).…”

Functional Deficits and Structural Changes Associated With the Visual Attention Network During Resting State in Adult Strabismic and Anisometropic Amblyopes

“…Visual attention is primarily driven by the dorsal cortical visual stream, which includes the primary visual cortex (V1), middle temporal area (MT), intraparietal sulcus (IPS), and frontal eye field (FEF) ( Gilbert and Li, 2013 ; Liu et al, 2014 ; Patel et al, 2015 ) and frontal cortical areas with the three longitudinal fasciculi filling a significantly larger volume in the right hemisphere ( Corbetta and Shulman, 2002 ). V1 is the initial area in the cortical visual processing system, and feeds to MT, although MT in developing primate also receives other subcortical fast visual-related signals via Pulvinar with projection of signals to IPS and FEF ( Mundinano et al, 2019 ; Kwan et al, 2021 ). IPS is known to be critically involved in contralateral spatial selective attention ( Gillebert et al, 2011 ) and FEF contribute to fixation, saccade, pursuit, and vergence movements and cognitive processes such as attentional orienting, visual awareness, and perceptual modulation ( Vernet et al, 2014 ; Matsubayashi et al, 2018 ).…”