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Biomedical subjects

M Matelli

Publications and source records attributed to M Matelli.

At least 55 records · Page 3Linked to original sources
PubMed1986

Afferent and efferent projections of the inferior area 6 in the macaque monkey.

The rostral part of the agranular frontal cortex (area 6) can be subdivided on the basis of its cytoarchitecture, enzymatic properties, and connections into two large sectors: a superior region, lying medial to the spur of the arcuate sulcus, and an inferior region, lying lateral to it. In this study we traced the afferent and efferent connections of the inferior region of area 6 by injecting small amounts of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) and fluorescent tracers (fast blue and diamidino yellow) into restricted parts of inferior area 6 and in physiologically determined fields of area 4. There is an ordered topographic pattern of connections between inferior area 6 and area 4. The region near the spur of the arcuate sulcus (hand field) projects to the area 4 hand field while the lateral part of inferior area 6 (mouth field) is connected with the corresponding field in area 4. The organization of the connections between the two fields is, however, different. The hand fields in area 6 and 4 have direct reciprocal projections, whereas the mouth field in the postarcuate cortex relays information to area 4 via a zone intermediate between the arcuate and the central sulcus. This zone corresponds to the cytochrome oxidase area F4 (Matelli, Luppino, and Rizzolatti: Behav. Brain Res. 18: 125-137, '85). The inferior area 6 also has topographically organized connections with the supplementary motor area. The inferior area 6 receives and sends fibers to a series of discrete cortical areas located in the lower cortical moiety (Sanides: The Structure and Function of the Nervous Tissue, Vol. 5. New York: Academic Press, pp 329-453, '72). These areas that form a broad ring around the central sulcus are the ventral bank of the principal sulcus and the adjacent area 46, the precentral operculum (PrOC), area SII (Jones and Burton: J. Comp. Neurol. 168:197-248, '76), the parietal operculum, and the rostral part of the inferior parietal lobule including the lower bank of the intraparietal sulcus. Finally, the inferior area 6 has sparse but consistent connections with insular and cingulate cortices. The functional significance of this complex pattern of connections is discussed.

Afferent Pathways↗
PubMed1984

Interconnections within the postarcuate cortex (area 6) of the macaque monkey.

Small amounts of horseradish peroxidase conjugated with wheat germ were injected in restricted parts of the postarcuate premotor area of the macaque monkey. It was found that regions of this area having different somatotopic representations are richly interconnected among them. This pattern of intra-areal connectivity was not observed in the precentral motor area. It appears therefore that the postarcuate area is organized according to anatomical principles which are different from those of the primary motor cortex.

Animals↗
PubMed1984

[Intrinsic and extrinsic connections of the postarcuate premotor area of the monkey].

Horseradish peroxidase conjugated with wheat germ agglutinine was injected in restricted parts of the postarcuate cortex in the macaque monkey. Anterograde and retrograde transport was found in the parietal and frontal lobes. In the parietal lobe two areas were marked: the antero-lateral part of area 7 and the superior bank of the sylvian fissure. In the frontal lobe the marked areas were the precentral motor cortex, the supplementary motor area and the gyrus cinguli. The intrinsic connections within the postarcuate cortex were rich and widespread. The hand representation was connected anterogradely and retrogradely with the mouth representation and anterogradely with the leg representation; the mouth representation was connected both ways with the hand representation but not with the leg area. The richness of intrinsic connections in the postarcuate cortex supports the suggestion that this area is involved in the organization of sequential motor acts.

Animals↗
PubMed1984

[Functional organization of the intermediate and deep layers of the superior colliculus of the monkey].

Single neurons and polispike activity were recorded from the superior colliculus of anesthetized, behaving monkeys. In agreement with previous findings neurons of the superficial layers responded exclusively to visual stimuli. In the intermediate layers most neurons were oculomotor, although some of them showed also a visual receptive field. No neurons responding to tactile or auditory stimuli were found. Occasionally the discharge of an oculomotor neuron increased if the ocular movement was triggered by a visual or an acoustical stimulus. Rare tacticle and auditory neurons were recorded in deep layers. However their receptive fields were difficult to map and their responses lacked the precision of the responses of the specific acoustic and tactile areas. Electrical stimulation of the SC produced contralateral eye and head movements, the threshold being high in the superficial layers and low in the intermediate and deep ones. In the deep layers complex limb and trunk movements could be also elicited. In conclusion, in contrast with carnivores and other mammals, the primate superior colliculus appears to be dominated by the visual modality.

Animals↗
PubMed1984

[Neurological deficit following a lesion in the parietal area 7b in the monkey].

The effect of unilateral surgical ablations of lateral part of inferior parietal lobule (area 7b) has been studied in the macaque monkey. The following neurological deficits were found: 1) A hemi-inattention for tactile stimuli applied to the hemiface and hand contralateral to the lesion; 2) A hemi-inattention for visual stimuli in the contralateral peripersonal space; 3) A reluctance to use the contralateral arm; 4) A mild and transient deficit in mouth grasping movements towards stimuli contralaterally presented; 5) Postural abnormalities of the hand contralateral to the lesion. It is proposed that area 7b is involved in the perception of the peripersonal space and in the organization of movements towards stimuli presented in that space.

Animals↗
PubMed1983

Upper visual space neglect and motor deficits after section of the midbrain commissures in the cat.

The neurological deficits following section of the midbrain commissures were studied in the cat. After a lesion of the commissures between the superior and inferior colliculi, with or without involvement of the posterior commissure, the animals showed a long lasting inattention for stimuli in the upper visual space, lack of exploratory head movements towards the neglected space, head ventroflexion and vertical paralysis of gaze. After a lesion of the commissure between the superior colliculi or of its rostral part only, the same symptomatology appeared, but it was short lasting. After a lesion of the posterior commissure, the head was kept dorsiflexed, the exploratory head movements towards the lower visual space were reduced and the stimuli presented in this space were often neglected. There was a paralysis of vertical eye movements. The findings are discussed in the frame of a premotor theory of neglect.

Animals↗
PubMed1983

Deficits in attention and movement following the removal of postarcuate (area 6) and prearcuate (area 8) cortex in macaque monkeys.

The effect of unilateral surgical ablations of the postarcuate cortex (area 6) has been studied in the macaque monkey (Macaca irus). Two series of neurological deficits were found: (1) a failure to grasp food with the mouth when presented contralaterally to the lesion and a reluctance to use the contralateral hand; (2) a severe hemi-inattention. This was present in both the somatosensory and visual modalities but, in the latter, was limited to the peripersonal space. Both motor and attentional deficits improved with time. However, when the symptomatology was stabilized, the animals tended to use the ipsilateral hand and, when presented with two stimuli, preferred that ipsilateral to the lesion. Control experiments in which area 8 (frontal eye fields) was ablated unilaterally showed a decrease of eye movements contralateral to the lesion and a neglect of the contralateral hemispace. No somatosensory deficits were found. The visual neglect was more prominent for 'far' space than for that near the animal. The role of area 6 in organizing motor acts and the strict relation between the type of motor deficit and the type of neglect are discussed.

Animals↗
PubMed1982

[Unilateral lesions of the periarcuate cortex in the monkey].

Subpial unilateral ablations of the postarcuate cortex (area 6) were performed in four macaque monkeys. After the operation the animals showed a tactile contralateral neglect and a visual neglect for stimuli presented in the space immediately around the contralateral hemiface, they tended to use the hand ipsilateral to the lesion and their mouth and face movements in response to contralateral stimuli were disorganized. No primary motor deficits were described. With time there was a marked recovery of the symptomatology, but the preference for using the ipsilateral hand and extinction of the contralateral stimuli were present until the animals' death. The deficits after the postarcuate cortex are discussed with reference to previous electrophysiological data.

Animals↗
PubMed1981

[Neurological deficits after section of the intertectal commissure in the cat].

The effects of cutting the intertectal commissure have been studied in three cats. After the operation all animals tended to look downwards, as if attracted by the ground. There was no paralysis of the head movements. However spontaneous vertical head movements necessary for exploring the space in front and especially above the animal were very rare. Visual field examination showed a clear neglect for stimuli presented in the upper hemifields. The intertectal commissure syndrome is interpreted as a consequence of a disruption of intertectal nervous circuits responsible for the exploration of the portion of the space above the animal's head.

Animals↗
PubMed1981

Afferent properties of periarcuate neurons in macaque monkeys. I. Somatosensory responses.

The afferent properties of single neurons of the periarcuate cortex have been studied in the macaque monkey. Most of the recorded neurons responded to stimuli in one or two sensory modalities and, accordingly, they were classified as somatosensory, visual or bimodal (visual and somatosensory) neurons. Visual neurons were located rostral to the arcuate sulcus, whereas the somatosensory and the bimodal neurons were found predominantly caudal to this sulcus. Somatosensory neurons (n = 102) and bimodal neurons (n = 69) had identical somatic afferent properties. They were subdivided into 'tactile' neurons, 'joint' neurons and 'tactile and joint' neurons. 'Tactile' neurons (70%) had their receptive fields formed either by one or by two or more spatially separated responding areas. The parts of the body most represented were the hands and the mouth. 'Joint' neurons (10%) were activated by the rotation of one or, more often, of two or more articulations. The movement of the hand towards the mouth was the most frequently represented movement. 'Tactile and joint' neurons (20%) responded to both tactile and joint stimulation having receptive field locations and properties like those of the other two classes of neurons. Some 'joint' and 'tactile and joint' neurons had summing properties, i.e. their response to tactile or joint stimulation was conditional upon a simultaneous stimulation of another articulation. The data are interpreted as evidence in favor of the existence of an area in the agranular cortex that organizes the mouth and the hand to mouth movements.

Afferent Pathways↗
PubMed1981

Afferent properties of periarcuate neurons in macaque monkeys. II. Visual responses.

The visual response of single neurons of the periarcuate cortex have been studied in the macaque monkey. Two sets of neurons responding to visual stimuli have been found. The first set, located rostral to the arcuate sulcus, was formed by units that could be activated by stimuli presented far from the animal. These neurons had large receptive fields and were neither orientation nor direction selective. The second set, found predominantly caudal to the arcuate sulcus, was formed by units that were maximally or even exclusively activated by stimuli presented in the space immediately around the animal. These neurons were bimodal, responding also to somatosensory stimuli. According to the location of their visual responding regions the bimodal neurons were subdivided into pericutaneous (54%) and distant peripersonal neurons (46%). The former responded best to stimuli presented a few centimeters from the skin, the latter to stimuli within the animal's reaching distance. The visual responding regions were spatially related to the tactile fields. It is argued that neurons with a receptive field consisting of several responding areas, some in one sensory modality, some in another, have a praxic function and that they are involved in organizing sequences of movements.

Animals↗