Neural Evidence of Mirror Self-Recognition in the Secondary Somatosensory Cortex of Macaque: Observations from a Single-Cell Recording Experiment and Implications for Consciousness.

Despite mirror self-recognition being regarded as a classical indication of self-awareness, little is known about its neural underpinnings. An increasing body of evidence pointing to a role of multimodal somatosensory neurons in self-recognition guided our investigation toward the secondary somatosensory cortex (SII), as we observed single-neuron activity from a macaque monkey sitting in front of a mirror. The monkey was previously habituated to the mirror, successfully acquiring the ability of mirror self-recognition.

Secondary somatosensory cortex of primates: beyond body maps, toward conscious self-in-the-world maps.

Recent human imaging studies have revealed the involvement of the secondary somatosensory cortex (SII) in processes that require high-level information integration, such as self-consciousness, social relations, whole body representation, and metaphorical extrapolations. These functions are far beyond its known role in the formation of body maps (even in their most complex forms), requiring the integration of different information modalities in addition to somatosensory information. However, no evidence of such complex processing seems to have been detected at the neuronal level in animal experiments, which would constitute a major discrepancy between human and non-human animals.

Fast Electrophysiological Mapping of Rat Cortical Motor Representation on a Time Scale of Minutes during Skin Stimulation.

The topographic map of motor cortical representation, called the motor map, is not invariant, but can be altered by motor learning, neurological injury, and functional recovery from injury. Although much attention has been paid to short-term changes of the motor map, robust measures have not been established. The existing mapping methods are time-consuming, and the obtained maps are confounded by time preference.

Rapid Identification of Cortical Motor Areas in Rodents by High-Frequency Automatic Cortical Stimulation and Novel Motor Threshold Algorithm.

Cortical stimulation mapping is a valuable tool to test the functional organization of the motor cortex in both basic neurophysiology (e.g., elucidating the process of motor plasticity) and clinical practice (e.

Identification of tool use acquisition-associated genes in the primate neocortex.

Japanese macaques are able to learn how to use rakes to take food after only a few weeks of training. Since tool-use training induced rapid morphological changes in some restricted brain areas, this system will be a good model for studying the neural basis of plasticity in human brains. To examine the mechanisms of tool-use associated brain expansion on the molecular and cellular level, here, we performed comprehensive analysis of gene expressions with microarray.

Visual Responsiveness of Neurons in the Secondary Somatosensory Area and its Surrounding Parietal Operculum Regions in Awake Macaque Monkeys.

Previous neurophysiological studies performed in macaque monkeys have shown that the secondary somatosensory cortex (SII) is essentially engaged in the processing of somatosensory information and no other sensory input has been reported. In contrast, recent human brain-imaging studies have revealed the effects of visual and auditory stimuli on SII activity, which suggest multisensory integration in the human SII. To determine whether multisensory responses of the SII also exist in nonhuman primates, we recorded single-unit activity in response to visual and auditory stimuli from the SII and surrounding regions in 8 hemispheres from 6 awake monkeys.

Modulation of cortical vestibular processing by somatosensory inputs in the posterior insula.

Primary Objective: To study the mechanism of somatosensory-vestibular interactions, this study examined the effects of somatosensory inputs on body sway induced by galvanic vestibular stimulation (GVS) in healthy participants and persons with brain injury in the posterior insula, a region constituting a part of the parietoinsular vestibular cortex.

Research Design: This study adopted an experimental, controlled, repeated measures design.

Methods And Procedures: Participants were 11 healthy individuals, two persons with unilateral posterior insular injury and two age-matched controls.

Hand before foot? Cortical somatotopy suggests manual dexterity is primitive and evolved independently of bipedalism.

People have long speculated whether the evolution of bipedalism in early hominins triggered tool use (by freeing their hands) or whether the necessity of making and using tools encouraged the shift to upright gait. Either way, it is commonly thought that one led to the other. In this study, we sought to shed new light on the origins of manual dexterity and bipedalism by mapping the neural representations in the brain of the fingers and toes of living people and monkeys.

Neural response to movement of the hand and mouth in the secondary somatosensory cortex of Japanese monkeys during a simple feeding task.

Neural activity was recorded in the secondary somatosensory cortex (SII) of macaque monkeys during a simple feeding task. Around the border between the representations of the hand and face in SII, we found neurons that became active during both retrieving with the hand and eating; 59% had receptive fields (RFs) in the hand/face and the remaining 41% had no RFs. Neurons that responded to touching objects were rarely found.

Triadic (ecological, neural, cognitive) niche construction: a scenario of human brain evolution extrapolating tool use and language from the control of reaching actions.

Hominin evolution has involved a continuous process of addition of new kinds of cognitive capacity, including those relating to manufacture and use of tools and to the establishment of linguistic faculties. The dramatic expansion of the brain that accompanied additions of new functional areas would have supported such continuous evolution. Extended brain functions would have driven rapid and drastic changes in the hominin ecological niche, which in turn demanded further brain resources to adapt to it.

Adaptive changes in firing of primary auditory cortical neurons following illumination shift from light to dark in freely moving guinea pigs.

Some animals are forced to rely more on non-visual signals, such as audition or olfaction, than on vision when a bright environment becomes dark. By recording from a primary-like auditory cortex (field A) in freely moving guinea pigs, possible changes in the responsiveness of single units were explored in association with illumination changes. For a subset of units, we found that robust decreases (off-decrease) or increases (off-increase) in baseline discharge (BsD) were initiated soon after room light was silently extinguished.

Postcentral neurons with covert receptive fields in conscious macaque monkeys: their selective responsiveness to simultaneous two-point stimuli applied to discrete oral portions.

The representation of the oral structures in the postcentral somatosensory cortex was studied in conscious macaque monkeys by recording the activity of single neurons. A total of 2,807 neurons were isolated in the oral regions of three hemispheres in two animals. Of these, 375 neurons (area 3a, 3; area 3b, 123; area 1, 99; area 2, 150) lacked an apparent receptive field (RF), and their relative frequency was significantly higher in area 2 (19%) than in more rostral areas (area 3a, 8%; area 3b, 10%; area 1, 12%).

Converging patterns of inputs from oral structures in the postcentral somatosensory cortex of conscious macaque monkeys.

Single neuronal activities were recorded in the oral region of the postcentral gyrus in conscious Japanese monkeys. Among 5,756 neurons isolated, receptive fields (RFs) and submodalities were identified in 1,502 neurons in area 3b, 970 in area 1, and 1,461 in area 2. The relative incidence of neurons that had bilateral RFs increased gradually upon moving caudally from area 3b to area 2 (bilateral integration).

Hierarchical somesthetic processing of tongue inputs in the postcentral somatosensory cortex of conscious macaque monkeys.

The representation of the oral structures in the lateralmost part of the postcentral somatosensory cortex in conscious macaque monkeys was studied by recording the activities of single neurons. A total of 104 penetrations were made in the oral regions of six hemispheres in four animals and 2,292 neurons were isolated. The characteristics of the receptive fields (RF) of 1,598 neurons were identified.

Integration of the upper and lower lips in the postcentral area 2 of conscious macaque monkeys (Macaca fuscata).

The representation of the lip in area 2 of the postcentral somatosensory cortex was studied in conscious macaque monkeys by recording single-neurone activities. Seventy penetrations were made in the oral region of six hemispheres of four animals and 1157 neurones were isolated. The receptive field characteristics of 839 neurones were identified.