Testing Predictions from the Hunter-Gatherer Hypothesis — 1: Sex Differences in the Motor Control of Hand and Arm

Here, in the first of two reports that test predictions from the hunter-gatherer hypothesis, we focus on sex differences in motor control. Published evidence confounds the cognitive demands, the muscles used and the spatial location in which tasks are performed. To address these issues our participants used hand or arm movements to track a moving target within near space. Study 1 identified an optimal level of task difficulty for the differentiation of male and female performance and showed that women tracked better using their hands and men using their arms. Employing the optimal level of task difficulty, Study 2 replicated the findings of Study 1 and, for men, demonstrated a significant correlation between arm tracking and performance on the nonmotor sex-dimorphic Mental Rotations task. This correlation suggests that the same or related events are responsible for the development of sex differences in motor and cognitive systems. The distal (hand) muscles are controlled by the primary motor cortex via two dorsolateral corticospinal tracts whereas the proximal (arm) muscles are controlled via two ventromedial corticospinal tracts. Our findings point to possible sex differences in these two neural pathways and they are compatible with an evolutionary origin as predicted by the hunter-gatherer hypothesis.

Download Full-text

Sex Differences in Performance with the Hand and Arm in near and Far Space: A Possible Effect of Tool Use

Evolutionary Psychology ◽

10.1177/147470490700500408 ◽

2007 ◽

Vol 5 (4) ◽

pp. 147470490700500 ◽

Cited By ~ 3

Author(s):

Geoff Sanders ◽

Marta Perez

Keyword(s):

Sex Differences ◽

Motor Control ◽

Tool Use ◽

Visual Processing ◽

Visual Information ◽

Relative Performance ◽

Visual Neglect ◽

Near Space ◽

Visual Systems

Using novel tasks, we tested two predictions from the hunter-gatherer hypothesis concerning sex differences in the motor control of hand and arm and in the visual processing of near and far space. In Study 1 we replicated earlier findings by demonstrating that women scored higher with the hand while men scored higher with the arm. Study 2 tested the motor and visual predictions concurrently and showed that the Muscle*Sex interaction, seen in Study 1, occurs in far as well as near space. However, we failed to confirm that women perform better with visual information from near and men from far space. Instead the relative performance of women and men was the same in far as it was in near space. Drawing on evidence from studies of selective visual neglect we suggest that this outcome arose because tool use causes far space to be re-mapped as near space. Finally, the selective visual neglect literature indicates that the processing of far and near space is located in the ventral and dorsal cortical streams, previously described as two “what”/“where” visual systems. We draw attention to their additional “there”/“here” functions that are sex dimorphic and, as we have shown, modulated by tool use.

Download Full-text

Testing Predictions from the Hunter-Gatherer Hypothesis — 2: Sex Differences in the Visual Processing of near and Far Space

Evolutionary Psychology ◽

10.1177/147470490700500314 ◽

2007 ◽

Vol 5 (3) ◽

pp. 147470490700500

Author(s):

Geoff Sanders ◽

Kamila Sinclair ◽

Tom Walsh

Keyword(s):

Sex Differences ◽

Visual Processing ◽

Time Estimation ◽

Spatial Location ◽

Virtual Space ◽

Near Space ◽

Visual Systems ◽

Completion Task ◽

Cortical Regions ◽

The Impact

Here, in the second of two linked reports, we focus on sex differences in visual processing. Study 1 presented a time estimation task in virtual space and generated the predicted Space*Sex interaction with men performing significantly better in far than in near space. Study 2 used a laboratory-based puzzle completion task in which participants saw their hands and the puzzle in far or near space. This time women performed significantly better in near than far space. Study 3 simplified the puzzle completion task. Once again the predicted Space*Sex interaction was significant but with both sexes showing significantly different performances: women better in near, men in far space. These findings are compatible with an evolutionary origin as predicted by the hunter-gatherer hypothesis. Far and near space are processed in the ventral and dorsal streams, two cortical regions more widely known as the “what” and “where” visual systems. To those traditional descriptions we suggest adding that the two streams are sex-dimorphic, with the ventral “there” system interacting with far space and favored in men and the dorsal “here” system interacting with near space and favored in women. Future studies of visual systems should consider the impact of sex differences and the spatial location of stimulus presentations.

Download Full-text

Sex Differences in the Weighting of Metric and Categorical Information in Spatial Location Memory

PsycEXTRA Dataset ◽

10.1037/e633262013-550 ◽

2013 ◽

Author(s):

Mark P. Holden ◽

Elizabeth Hampson

Keyword(s):

Sex Differences ◽

Spatial Location ◽

Location Memory ◽

Categorical Information

Download Full-text

Strengthened Corticosubcortical Functional Connectivity during Muscle Fatigue

Neural Plasticity ◽

10.1155/2016/1726848 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 5

Author(s):

Zhiguo Jiang ◽

Xiao-Feng Wang ◽

Guang H. Yue

Keyword(s):

Motor Control ◽

Functional Connectivity ◽

Quantile Regression ◽

Muscle Fatigue ◽

Motor Performance ◽

Primary Motor Cortex ◽

Motor Task ◽

Voluntary Contraction ◽

Control Network ◽

Subcortical Structures

The present study examined functional connectivity (FC) between functional MRI (fMRI) signals of the primary motor cortex (M1) and each of the three subcortical neural structures, cerebellum (CB), basal ganglia (BG), and thalamus (TL), during muscle fatigue using the quantile regression technique. Understanding activation relation between the subcortical structures and the M1 during prolonged motor performance should help delineate how central motor control network modulates acute perturbations at peripheral sensorimotor system such as muscle fatigue. Ten healthy subjects participated in the study and completed a 20-minute intermittent handgrip motor task at 50% of their maximal voluntary contraction (MVC) level. Quantile regression analyses were carried out to compare the FC between the contralateral (left) M1 and CB, BG, and TL in the minimal (beginning 100 s) versus significant (ending 100 s) fatigue stages. Widespread, statistically significant increases in FC were found in bilateral BG, CB, and TL with the left M1 during significant versus minimal fatigue stages. Our results imply that these subcortical nuclei are critical components in the motor control network and actively involved in modulating voluntary muscle fatigue, possibly, by working together with the M1 to strengthen the descending central command to prolong the motor performance.

Download Full-text

Long range high-gamma (60-90 Hz) coupling between primary motor cortex and SMA during motor control revealed by MEG source imaging

NeuroImage ◽

10.1016/s1053-8119(09)71874-9 ◽

2009 ◽

Vol 47 ◽

pp. S173

Author(s):

K Jerbi ◽

H Hui ◽

D Pantazis ◽

J-P Lachaux ◽

O Bertrand ◽

...

Keyword(s):

Motor Control ◽

Motor Cortex ◽

Long Range ◽

Primary Motor Cortex ◽

Source Imaging ◽

High Gamma

Download Full-text

Herophilus, Erasistratus, Aretaeus, and Galen: ancient roots of the Bell–Magendie Law

Neurosurgical FOCUS ◽

10.3171/foc-07/07/e12 ◽

2007 ◽

Vol 23 (1) ◽

pp. 1-3 ◽

Cited By ~ 7

Author(s):

Matthew I. Tomey ◽

Ricardo J. Komotar ◽

J Mocco

Keyword(s):

Motor Control ◽

19Th Century ◽

Neural Pathways ◽

Early 19Th Century ◽

Spinal Roots ◽

Dorsal Spinal

✓Since the early 19th century, significant controversy has persisted over the competing claims of two men, Charles Bell and François Magendie, to a pivotal discovery: that the dorsal spinal roots subserve sensation, whereas the ventral spinal roots subserve motion. However, the foundations of neuroanatomy on which Bell and Magendie built their research was formed two millennia in advance. Exploration of the work of four ancient scholars—Herophilus, Erasistratus, Aretaeus, and Galen–reveals a remarkable early appreciation of the separate neural pathways (if not the correct physiology) responsible for sensory and motor control.

Download Full-text

Motor control: spinal and cortical mechanisms

10.1093/med/9780199688395.003.0003 ◽

2016 ◽

Author(s):

David Burke

Keyword(s):

Motor Control ◽

Motor Cortex ◽

Voluntary Movement ◽

Primary Motor Cortex ◽

Lower Limbs ◽

Spinal Reflex ◽

Extensive Literature ◽

Spinal Level ◽

Corticospinal System ◽

The Brain

There is extensive machinery at cerebral and spinal levels to support voluntary movement, but spinal mechanisms are often ignored by clinicians and researchers. For movements of the upper and lower limbs, what the brain commands can be modified or even suppressed completely at spinal level. The corticospinal system is the executive pathway for movement arising largely from primary motor cortex, but movement is not initiated there, and other pathways normally contribute to movement. Greater use of these pathways can allow movement to be restored when the corticospinal system is damaged by, e.g. stroke, but there can be unwanted consequences of this ‘plasticity’. There is an extensive literature on cerebral mechanisms in the control of movement, and an equally large literature on spinal reflex function and the changes that occur during movement, and when pathology results in weakness and/or spasticity.

Download Full-text