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Adding tactile sensors to a robotic system is becoming a common practice to achieve more complex manipulation skills than those robotics systems that only use external cameras to manipulate objects. The key of tactile sensors is that they provide extra information about the physical properties of the grasping. In this paper, we implemented a system to predict and quantify the rotational slippage of objects in hand using the vision-based tactile sensor known as Digit. Our system comprises a neural network that obtains the segmented contact region (object-sensor), to later calculate the slippage rotation angle from this region using a thinning algorithm. Besides, we created our own tactile segmentation dataset, which is the first one in the literature as far as we are concerned, to train and evaluate our neural network, obtaining results of 95% and 91% in Dice and IoU metrics. In real-scenario experiments, our system is able to predict rotational slippage with a maximum mean rotational error of 3 degrees with previously unseen objects. Thus, our system can be used to prevent an object from falling due to its slippage.

En aquesta tesi s'aborda el repte de detectar i reconèixer múltiples matrícules de cotxe en una sola imatge. Primer de tot es fa una recerca d'articles previs i es miren opcions factibles per crear un model propi. A partir d'aquí es crea, s'entrena i es testeja el model en un escenari real. A partir dels resultats es conclourà o no la viabilitat del model., En esta tesis se aborda el reto de detectar y reconocer múltiples matrículas de coche en una sola imagen. Primero de todo se hace una búsqueda de artículos previos y se miran opciones factibles para crear un modelo propio. A partir de ahí se crea, entrena y testea el modelo en un escenario real. Con los resultados obtenidos se concluirá o no la viabilidad del modelo., This thesis addresses the challenge of detecting and recognizing multiple car license plates in a single image. First of all, a search of previous articles is made and feasible options are looked at to create a unique model. From here the model is created, trained and tested on a real scenario. Based on the results, it will be concluded whether or not the model is viable.

Acquired digital fibrokeratoma is a benign fibrous tumor usually located on the toes and fingers. A 63-year-old man with an acquired giant plantar fibrokeratoma is described. He presented with an asymptomatic exophytic nodule of ten years duration; there is no history of trauma to the site. It measured 15x10x5mm and was located on the plantar foot proximal to the third toe. Excisional biopsy established the diagnosis of fibrokeratoma. Giant acquired fibrokeratoma,has been described in 16 patients including ours: three women and 13 men. They are located on either the upper extremity (one man) or the lower extremity (15 individuals). Acquired plantar fibrokeratoma is rare. Including our patient, it has been reported in 11 patients: one woman and ten men. The woman was 13 years of age and the men ranged from 15 to 77-years-old. Plantar acquired fibrokeratomas are located on either the plantar aspect of the toes, the sole of the foot, or the heel. An excisional biopsy provided adequate treatment without subsequent recurrence of both giant and plantar fibrokeratomas.

En este proyecto se pretende implementar un sistema de percepción táctil para un control en lazo cerrado que permita llevar a cabo tareas de agarre robótico con una pinza robótica. El controlador deberá tomar como entrada datos procedentes de sensores táctiles-visuales. Los sensores registran información de contacto de la pinza con la superficie del objeto que está manipulando. En función de la información de contacto, el robot deberá ejecutar movimientos articulares de los dedos de la pinza.

Acquired digital fibrokeratoma is a benign fibrous tumor usually located on the toes and fingers. A 63-year-old man with an acquired giant plantar fibrokeratoma is described. He presented with an asymptomatic exophytic nodule of ten years duration; there is no history of trauma to the site. It measured 15x10x5mm and was located on the plantar foot proximal to the third toe. Excisional biopsy established the diagnosis of fibrokeratoma. Giant acquired fibrokeratoma,has been described in 16 patients including ours: three women and 13 men. They are located on either the upper extremity (one man) or the lower extremity (15 individuals). Acquired plantar fibrokeratoma is rare. Including our patient, it has been reported in 11 patients: one woman and ten men. The woman was 13 years of age and the men ranged from 15 to 77-years-old. Plantar acquired fibrokeratomas are located on either the plantar aspect of the toes, the sole of the foot, or the heel. An excisional biopsy provided adequate treatment without subsequent recurrence of both giant and plantar fibrokeratomas.

En este proyecto se pretende implementar un sistema de percepción táctil para un control en lazo cerrado que permita llevar a cabo tareas de agarre robótico con una pinza robótica. El controlador deberá tomar como entrada datos procedentes de sensores táctiles-visuales. Los sensores registran información de contacto de la pinza con la superficie del objeto que está manipulando. En función de la información de contacto, el robot deberá ejecutar movimientos articulares de los dedos de la pinza.

Introduction Hand and digit replantations can be complicated by vascular insufficiency necessitating revision of the original replantation. To date, few studies have evaluated outcomes in secondary revascularizations following replantation. Therefore, the objective of this study was to evaluate the incidence, etiology, and survival rates following secondary revascularization after hand and digit replantations. Materials and Methods A literature search was performed on NCBI for studies documenting secondary revascularization procedures following hand and digit replant. Studies were evaluated for the etiology of vascular failure, frequency of secondary revascularization, and survival rates following intervention. Statistical analysis was conducted across the pooled dataset. Results A total of 16 studies including 1,192 amputations were analyzed. We found that 16.9% (201/1,192) of replants were complicated by vascular compromise. The frequency of vascular compromise was not statistically different between arterial and venous etiologies. The survival rate following secondary revascularization was 55.6%, with no significant difference between the arterial and venous groups. Secondary arterial revascularization was often treated with arterial revision (nine of nine studies) and/or with vein grafting (two of nine studies). Secondary revascularization for venous insufficiency resulted in different survival rates for nonsurgical modalities (58%) versus vein revision (37.5%) versus vein grafting (100%). Conclusion Survival rates following secondary revascularization are lower; however, they may be improved using vein grafts following venous insufficiency. These data can be used to better understand the etiology of replant failure and guide decision-making.

The epidermis, the outermost layer of the skin, continuously develops to form a tight epidermal barrier that is required for animal hydration and survival. Epidermal development occurs during embryogenesis via the mechanism of epidermal differentiation. We have previously described the role of the epidermal transcription factor Grainyhead like-3 (GRHL3) in epidermal differentiation and barrier formation. Additionally, we observed that mice lacking Grhl3 in the epidermis exhibit soft-tissue syndactyly between their digits, this phenomenon was also detected in Grhl3 germline knockouts (Grhl3KO). Through our work, we identified epithelial mechanisms required for normal digit separation during development. We discovered the formation of a multi-layered epithelial structure between the digits. In Grhl3KO embryos, the interdigital epithelia is fused, resulting in syndactyly. The separation of the epithelial structure depends on the anti-adhesive properties of the periderm, a transient layer located at the uppermost surface of the embryonic epidermis. We found that periderm cells in Grhl3 KO are hyper-adhesive with abnormal expression of adhesion molecules on their surfaces. Our findings reveal novel epithelial mechanisms required for digit separation; they also uncover a crucial role of Grhl3 in normal periderm development. Adult skin is normally maintained in the absence of Grhl3. Our previous work indicated that Grhl3 is required for epidermal recovery after injury. Adult mice lacking Grhl3 in the epidermis exhibit impaired full-thickness wound healing and delayed keratinocyte migration. We observed an increase in cell-cell adhesion between follower cells at the wound-edge in Grhl3 cKO, concomitant with an increase expression of the adherens junction’s protein, E-cadherin. Gene expression analysis of Grhl3 cKO wounded-keratinocytes 3 days post wounding shows a significant downregulation of F-actin protein Fscn1, a protein known to negatively regulate the expression of E

The epidermis, the outermost layer of the skin, continuously develops to form a tight epidermal barrier that is required for animal hydration and survival. Epidermal development occurs during embryogenesis via the mechanism of epidermal differentiation. We have previously described the role of the epidermal transcription factor Grainyhead like-3 (GRHL3) in epidermal differentiation and barrier formation. Additionally, we observed that mice lacking Grhl3 in the epidermis exhibit soft-tissue syndactyly between their digits, this phenomenon was also detected in Grhl3 germline knockouts (Grhl3KO). Through our work, we identified epithelial mechanisms required for normal digit separation during development. We discovered the formation of a multi-layered epithelial structure between the digits. In Grhl3KO embryos, the interdigital epithelia is fused, resulting in syndactyly. The separation of the epithelial structure depends on the anti-adhesive properties of the periderm, a transient layer located at the uppermost surface of the embryonic epidermis. We found that periderm cells in Grhl3 KO are hyper-adhesive with abnormal expression of adhesion molecules on their surfaces. Our findings reveal novel epithelial mechanisms required for digit separation; they also uncover a crucial role of Grhl3 in normal periderm development. Adult skin is normally maintained in the absence of Grhl3. Our previous work indicated that Grhl3 is required for epidermal recovery after injury. Adult mice lacking Grhl3 in the epidermis exhibit impaired full-thickness wound healing and delayed keratinocyte migration. We observed an increase in cell-cell adhesion between follower cells at the wound-edge in Grhl3 cKO, concomitant with an increase expression of the adherens junction’s protein, E-cadherin. Gene expression analysis of Grhl3 cKO wounded-keratinocytes 3 days post wounding shows a significant downregulation of F-actin protein Fscn1, a protein known to negatively regulate the expression of E

The combinatorial expression of Hox genes along the body axes is a major determinant of cell fate and plays a pivotal role in generating the animal body plan. Loss of HOXA13 and HOXD13 transcription factors (HOX13) leads to digit agenesis in mice, but how HOX13 proteins regulate transcriptional outcomes and confer identity to the distal-most limb cells has remained elusive. Here, we report on the genome-wide profiling of HOXA13 and HOXD13 in vivo binding and changes of the transcriptome and chromatin state in the transition from the early to the late-distal limb developmental program, as well as in Hoxa13-/-; Hoxd13-/- limbs. Our results show that proper termination of the early limb transcriptional program and activation of the late-distal limb program are coordinated by the dual action of HOX13 on cis-regulatory modules.

The combinatorial expression of Hox genes along the body axes is a major determinant of cell fate and plays a pivotal role in generating the animal body plan. Loss of HOXA13 and HOXD13 transcription factors (HOX13) leads to digit agenesis in mice, but how HOX13 proteins regulate transcriptional outcomes and confer identity to the distal-most limb cells has remained elusive. Here, we report on the genome-wide profiling of HOXA13 and HOXD13 in vivo binding and changes of the transcriptome and chromatin state in the transition from the early to the late-distal limb developmental program, as well as in Hoxa13-/-; Hoxd13-/- limbs. Our results show that proper termination of the early limb transcriptional program and activation of the late-distal limb program are coordinated by the dual action of HOX13 on cis-regulatory modules.

It was investigated whether task-related body movements yield beneficial effects on children's learning of two-digit numbers and whether these learning effects are affected by mirror-based self-observation of those movements. Participants were 118 first-graders, who were randomly assigned to two movement conditions and two non-movement control conditions. In the movement conditions, children were instructed to build two-digit numbers by making and simultaneously verbalizing out loud different sized steps representing the smaller units the numbers consisted of (e.g., the number "36" was construed by saying out loud "10," "20," "30," "35," "36," while making three big steps, one medium, and one small step) on a ruler across the floor. In one of the movement conditions, the children were additionally asked to observe their steps in a mirror. In the first conventionally taught control condition, the children were asked to verbally build and mark the two-digit numbers on a ruler depicted on a sheet of paper. In the second control condition, children were seated before the ruler across the floor, and after verbally constructing the two-digit number, they had to walk to the appropriate position of the number on the ruler across the floor. In the subsequent test phase, children's knowledge of two-digit numbers was assessed by a final math test. The results confirmed the hypothesis that the movement conditions lead to higher test performance than the non-movement condition and revealed that test performance was not differentially affected by mirror-based self-observation.

Variation in sex hormone exposure during early embryonic development contributes to individual differences in behaviour and cognitive abilities later in life. Digit ratio has gained considerable interest as a putative marker for early androgen/oestrogen exposure in behavioural ecology research. Studying digit ratio in nonhuman laboratory as well as wild vertebrate species may be useful to assess whether different traits may be influenced by a common (e.g. endocrine-related) mechanism and whether digit ratio might be used as a phenotypic indicator for behavioural or fitness-related traits. We examined whether digit ratio (third-to-fourth toe ratio; 3D:4D) may indicate a common mechanism underlying endurance and antipredator behaviour in male painted dragon lizards, Ctenophorus pictus. We have previously shown that 3D:4D is associated with the presence/absence of a yellow throat patch (bib), with males with bibs having higher 3D:4D than those without bibs. In this study we found that 3D:4D predicted antipredator behaviour with individuals with higher 3D:4D having shorter escape response times; however, 3D:4D was not associated with endurance. Endurance and antipredator behaviour were also associated with male coloration. Males expressing a bib had shorter escape response times and lower endurance than those without a bib. Moreover, males with orange head colour had lower endurance compared to yellow-headed and uncoloured males. On the basis of these results, we speculate that the associations between antipredator behaviour, endurance, 3D:4D and male sexual coloration are caused, at least partly, by different underlying mechanisms.

Variation in sex hormone exposure during early embryonic development contributes to individual differences in behaviour and cognitive abilities later in life. Digit ratio has gained considerable interest as a putative marker for early androgen/oestrogen exposure in behavioural ecology research. Studying digit ratio in nonhuman laboratory as well as wild vertebrate species may be useful to assess whether different traits may be influenced by a common (e.g. endocrine-related) mechanism and whether digit ratio might be used as a phenotypic indicator for behavioural or fitness-related traits. We examined whether digit ratio (third-to-fourth toe ratio; 3D:4D) may indicate a common mechanism underlying endurance and antipredator behaviour in male painted dragon lizards, Ctenophorus pictus. We have previously shown that 3D:4D is associated with the presence/absence of a yellow throat patch (bib), with males with bibs having higher 3D:4D than those without bibs. In this study we found that 3D:4D predicted antipredator behaviour with individuals with higher 3D:4D having shorter escape response times; however, 3D:4D was not associated with endurance. Endurance and antipredator behaviour were also associated with male coloration. Males expressing a bib had shorter escape response times and lower endurance than those without a bib. Moreover, males with orange head colour had lower endurance compared to yellow-headed and uncoloured males. On the basis of these results, we speculate that the associations between antipredator behaviour, endurance, 3D:4D and male sexual coloration are caused, at least partly, by different underlying mechanisms.

Variation in sex hormone exposure during early embryonic development contributes to individual differences in behaviour and cognitive abilities later in life. Digit ratio has gained considerable interest as a putative marker for early androgen/oestrogen exposure in behavioural ecology research. Studying digit ratio in nonhuman laboratory as well as wild vertebrate species may be useful to assess whether different traits may be influenced by a common (e.g. endocrine-related) mechanism and whether digit ratio might be used as a phenotypic indicator for behavioural or fitness-related traits. We examined whether digit ratio (third-to-fourth toe ratio; 3D:4D) may indicate a common mechanism underlying endurance and antipredator behaviour in male painted dragon lizards, Ctenophorus pictus. We have previously shown that 3D:4D is associated with the presence/absence of a yellow throat patch (bib), with males with bibs having higher 3D:4D than those without bibs. In this study we found that 3D:4D predicted antipredator behaviour with individuals with higher 3D:4D having shorter escape response times; however, 3D:4D was not associated with endurance. Endurance and antipredator behaviour were also associated with male coloration. Males expressing a bib had shorter escape response times and lower endurance than those without a bib. Moreover, males with orange head colour had lower endurance compared to yellow-headed and uncoloured males. On the basis of these results, we speculate that the associations between antipredator behaviour, endurance, 3D:4D and male sexual coloration are caused, at least partly, by different underlying mechanisms.

omputer-assisted telephone interviewing and random digit dialling are increasingly being used to conduct household surveys in Australia. However, there is little published information concerning Australian experience with such surveys. In 1995 the Government Statistician's Office in Queensland conducted a household survey to study population migration using these techniques. The survey involved a sample of 110 000 telephone numbers resulting in 38 000 responding households. This article describes a computerized survey management system that was developed and which provided information concerning important operational and quality aspects of the survey.

omputer-assisted telephone interviewing and random digit dialling are increasingly being used to conduct household surveys in Australia. However, there is little published information concerning Australian experience with such surveys. In 1995 the Government Statistician's Office in Queensland conducted a household survey to study population migration using these techniques. The survey involved a sample of 110 000 telephone numbers resulting in 38 000 responding households. This article describes a computerized survey management system that was developed and which provided information concerning important operational and quality aspects of the survey.

Hox genes play a critical role in the development of the vertebrate axis and limbs, and previous studies have implicated them in the specification of positional identity, the control of growth, and the timing of differentiation. Axolotl limbs offer an opportunity to distinguish these alternatives because the sequence of skeletal differentiation is reversed along the anterior-posterior axis relative to that of other tetrapods. We report that during early limb development, expression patterns of HoxD genes in axolotls resemble those in amniotes and anuran amphibians. At later stages, the anterior boundary of Hoxd-11 expression is conserved with respect to morphological landmarks, but there is no anterior-distal expansion of the posterior domain of Hoxd-11 expression similar to that observed in mice and chicks. Since axolotls do not form an expanded paddle-like handplate prior to digit differentiation, we suggest that anterior expansion of expression in higher vertebrates is linked to the formation of the handplate, but is clearly not necessary for digit differentiation. We also show that the 5' HoxD genes are reexpressed during limb regeneration. The change in the expression pattern of Hoxd-11 during the course of regeneration is consistent with the hypothesis that the distal tip of the regenerate is specified first, followed by intercalation of intermediate levels of the pattern. Both Hoxd-8 and Hoxd-10 are expressed in non-regenerating wounds, but Hoxd-11 is specific for regeneration. It is also expressed in the posterior half of nerve-induced supernumerary outgrowths.

Hox genes play a critical role in the development of the vertebrate axis and limbs, and previous studies have implicated them in the specification of positional identity, the control of growth, and the timing of differentiation. Axolotl limbs offer an opportunity to distinguish these alternatives because the sequence of skeletal differentiation is reversed along the anterior-posterior axis relative to that of other tetrapods. We report that during early limb development, expression patterns of HoxD genes in axolotls resemble those in amniotes and anuran amphibians. At later stages, the anterior boundary of Hoxd-11 expression is conserved with respect to morphological landmarks, but there is no anterior-distal expansion of the posterior domain of Hoxd-11 expression similar to that observed in mice and chicks. Since axolotls do not form an expanded paddle-like handplate prior to digit differentiation, we suggest that anterior expansion of expression in higher vertebrates is linked to the formation of the handplate, but is clearly not necessary for digit differentiation. We also show that the 5' HoxD genes are reexpressed during limb regeneration. The change in the expression pattern of Hoxd-11 during the course of regeneration is consistent with the hypothesis that the distal tip of the regenerate is specified first, followed by intercalation of intermediate levels of the pattern. Both Hoxd-8 and Hoxd-10 are expressed in non-regenerating wounds, but Hoxd-11 is specific for regeneration. It is also expressed in the posterior half of nerve-induced supernumerary outgrowths.

1. Acute effects of permanent and temporary denervation of the flying fox thumb were examined to test the hypothesis that a large area of skin around the cutaneous receptive field of multiunits (MRF) at a locus in primary somatosensory cortex (SI) supplies viable inputs which can be rapidly unmasked by interruption of the dominant input from the area of the MRF. 2. The immediate effect of amputation of the thumb at loci where the original receptive field was entirely removed was to produce large MRFs on adjacent body areas (wrist, forearm, prowing, and finger membranes). Greatly expanded MRFs were also produced when amputation removed only part of the original MRF at a cortical locus. 3. The probable source of input to account for the new receptive fields is the extensive arborization of ascending projections within the somatosensory pathway, which supply a cortical locus with a potential input from a far larger area than is represented in its normal receptive field. The rapidity with which new or expanded fields are seen following denervation indicates that the normally unexpressed inputs around a receptive field are not only potential inputs but are inherently viable. Hence the most likely explanation for the results of this study is that the effect of the denervation is to disrupt an inhibitory influence that normally has the role of shaping the receptive field. 4. Temporary anesthesia of all or part of a MRF produced similar initial effects to amputation. When responsiveness returned to the locally anesthetized area (after 10-30 min), an expanded MRF persisted for a short time after which the boundaries of the MRF shrank. This rapid reversal suggests that a mechanistic rather than a plastic change is the basis for the acute effect of a small denervation on SI.

The short-term effect of total or partial single-digit denervation on receptive fields (Rds) of neurons in somatosensory cortex (area 3b) was examined in five macaque monkeys. In two animals, after denervation by amputation, it was found that electrode positions that initially recorded neurons with Rds on the amputated digit had new Rds extending from the wound. Often the new fields were on adjacent digits. Neurons with initial Rds that were partially amputated, or in some cases close to but not on the amputated digit, showed considerable expansion of the remaining RF. In three monkeys local anesthesia was used to provide a temporary denervation. In these experiments electrodes were placed in equivalent positions in both cortices. The effect on cortex contralateral to the denervation was similar to that seen with amputation. However, after esthesia returned to the digit, the expanded Rds contracted. In cortex ipsilateral to the denervation, Rds were on the opposite unaffected hand. These also rapidly expanded and then contracted, with the same time course as their counterparts in cortex contralateral to the denervation. Because of the rapidity of the expansion and its temporary nature with short-term denervation, the basis of the effect is probably an unmasking of existing but normally unexpressed connections, which are normally inhibited by the intact output from the denervated area. The wide arborization fields of thalamocortical afferents provide a potential source for the unmasked sensitivity. A mechanism for the inhibition that normally suppresses the expression of large Rds is not readily apparent. However, work in other species suggests that peripheral C fibers provide the primary source of input to central inhibitory circuits.

The immediate effect of changing the driving cutaneous input to locations within primary somatosensory cortex (SI) was examined by denervating one or more digits of the rat hindpaw by amputation or local anesthesia. When all or part of a receptive field of a cluster of neurons was denervated, it was found that the cortical location recorded from gained responsiveness to cutaneous stimulation of hindpaw areas bordering the denervated region. In 22 of the 29 animals studied this expansion took place within 5 min of the denervation.

1. Acute effects of permanent and temporary denervation of the flying fox thumb were examined to test the hypothesis that a large area of skin around the cutaneous receptive field of multiunits (MRF) at a locus in primary somatosensory cortex (SI) supplies viable inputs which can be rapidly unmasked by interruption of the dominant input from the area of the MRF. 2. The immediate effect of amputation of the thumb at loci where the original receptive field was entirely removed was to produce large MRFs on adjacent body areas (wrist, forearm, prowing, and finger membranes). Greatly expanded MRFs were also produced when amputation removed only part of the original MRF at a cortical locus. 3. The probable source of input to account for the new receptive fields is the extensive arborization of ascending projections within the somatosensory pathway, which supply a cortical locus with a potential input from a far larger area than is represented in its normal receptive field. The rapidity with which new or expanded fields are seen following denervation indicates that the normally unexpressed inputs around a receptive field are not only potential inputs but are inherently viable. Hence the most likely explanation for the results of this study is that the effect of the denervation is to disrupt an inhibitory influence that normally has the role of shaping the receptive field. 4. Temporary anesthesia of all or part of a MRF produced similar initial effects to amputation. When responsiveness returned to the locally anesthetized area (after 10-30 min), an expanded MRF persisted for a short time after which the boundaries of the MRF shrank. This rapid reversal suggests that a mechanistic rather than a plastic change is the basis for the acute effect of a small denervation on SI.

The short-term effect of total or partial single-digit denervation on receptive fields (Rds) of neurons in somatosensory cortex (area 3b) was examined in five macaque monkeys. In two animals, after denervation by amputation, it was found that electrode positions that initially recorded neurons with Rds on the amputated digit had new Rds extending from the wound. Often the new fields were on adjacent digits. Neurons with initial Rds that were partially amputated, or in some cases close to but not on the amputated digit, showed considerable expansion of the remaining RF. In three monkeys local anesthesia was used to provide a temporary denervation. In these experiments electrodes were placed in equivalent positions in both cortices. The effect on cortex contralateral to the denervation was similar to that seen with amputation. However, after esthesia returned to the digit, the expanded Rds contracted. In cortex ipsilateral to the denervation, Rds were on the opposite unaffected hand. These also rapidly expanded and then contracted, with the same time course as their counterparts in cortex contralateral to the denervation. Because of the rapidity of the expansion and its temporary nature with short-term denervation, the basis of the effect is probably an unmasking of existing but normally unexpressed connections, which are normally inhibited by the intact output from the denervated area. The wide arborization fields of thalamocortical afferents provide a potential source for the unmasked sensitivity. A mechanism for the inhibition that normally suppresses the expression of large Rds is not readily apparent. However, work in other species suggests that peripheral C fibers provide the primary source of input to central inhibitory circuits.

The immediate effect of changing the driving cutaneous input to locations within primary somatosensory cortex (SI) was examined by denervating one or more digits of the rat hindpaw by amputation or local anesthesia. When all or part of a receptive field of a cluster of neurons was denervated, it was found that the cortical location recorded from gained responsiveness to cutaneous stimulation of hindpaw areas bordering the denervated region. In 22 of the 29 animals studied this expansion took place within 5 min of the denervation.

1. Acute effects of permanent and temporary denervation of the flying fox thumb were examined to test the hypothesis that a large area of skin around the cutaneous receptive field of multiunits (MRF) at a locus in primary somatosensory cortex (SI) supplies viable inputs which can be rapidly unmasked by interruption of the dominant input from the area of the MRF. 2. The immediate effect of amputation of the thumb at loci where the original receptive field was entirely removed was to produce large MRFs on adjacent body areas (wrist, forearm, prowing, and finger membranes). Greatly expanded MRFs were also produced when amputation removed only part of the original MRF at a cortical locus. 3. The probable source of input to account for the new receptive fields is the extensive arborization of ascending projections within the somatosensory pathway, which supply a cortical locus with a potential input from a far larger area than is represented in its normal receptive field. The rapidity with which new or expanded fields are seen following denervation indicates that the normally unexpressed inputs around a receptive field are not only potential inputs but are inherently viable. Hence the most likely explanation for the results of this study is that the effect of the denervation is to disrupt an inhibitory influence that normally has the role of shaping the receptive field. 4. Temporary anesthesia of all or part of a MRF produced similar initial effects to amputation. When responsiveness returned to the locally anesthetized area (after 10-30 min), an expanded MRF persisted for a short time after which the boundaries of the MRF shrank. This rapid reversal suggests that a mechanistic rather than a plastic change is the basis for the acute effect of a small denervation on SI.

1. Acute effects of permanent and temporary denervation of the flying fox thumb were examined to test the hypothesis that a large area of skin around the cutaneous receptive field of multiunits (MRF) at a locus in primary somatosensory cortex (SI) supplies viable inputs which can be rapidly unmasked by interruption of the dominant input from the area of the MRF. 2. The immediate effect of amputation of the thumb at loci where the original receptive field was entirely removed was to produce large MRFs on adjacent body areas (wrist, forearm, prowing, and finger membranes). Greatly expanded MRFs were also produced when amputation removed only part of the original MRF at a cortical locus. 3. The probable source of input to account for the new receptive fields is the extensive arborization of ascending projections within the somatosensory pathway, which supply a cortical locus with a potential input from a far larger area than is represented in its normal receptive field. The rapidity with which new or expanded fields are seen following denervation indicates that the normally unexpressed inputs around a receptive field are not only potential inputs but are inherently viable. Hence the most likely explanation for the results of this study is that the effect of the denervation is to disrupt an inhibitory influence that normally has the role of shaping the receptive field. 4. Temporary anesthesia of all or part of a MRF produced similar initial effects to amputation. When responsiveness returned to the locally anesthetized area (after 10-30 min), an expanded MRF persisted for a short time after which the boundaries of the MRF shrank. This rapid reversal suggests that a mechanistic rather than a plastic change is the basis for the acute effect of a small denervation on SI.

The short-term effect of total or partial single-digit denervation on receptive fields (Rds) of neurons in somatosensory cortex (area 3b) was examined in five macaque monkeys. In two animals, after denervation by amputation, it was found that electrode positions that initially recorded neurons with Rds on the amputated digit had new Rds extending from the wound. Often the new fields were on adjacent digits. Neurons with initial Rds that were partially amputated, or in some cases close to but not on the amputated digit, showed considerable expansion of the remaining RF. In three monkeys local anesthesia was used to provide a temporary denervation. In these experiments electrodes were placed in equivalent positions in both cortices. The effect on cortex contralateral to the denervation was similar to that seen with amputation. However, after esthesia returned to the digit, the expanded Rds contracted. In cortex ipsilateral to the denervation, Rds were on the opposite unaffected hand. These also rapidly expanded and then contracted, with the same time course as their counterparts in cortex contralateral to the denervation. Because of the rapidity of the expansion and its temporary nature with short-term denervation, the basis of the effect is probably an unmasking of existing but normally unexpressed connections, which are normally inhibited by the intact output from the denervated area. The wide arborization fields of thalamocortical afferents provide a potential source for the unmasked sensitivity. A mechanism for the inhibition that normally suppresses the expression of large Rds is not readily apparent. However, work in other species suggests that peripheral C fibers provide the primary source of input to central inhibitory circuits.

1. Acute effects of permanent and temporary denervation of the flying fox thumb were examined to test the hypothesis that a large area of skin around the cutaneous receptive field of multiunits (MRF) at a locus in primary somatosensory cortex (SI) supplies viable inputs which can be rapidly unmasked by interruption of the dominant input from the area of the MRF. 2. The immediate effect of amputation of the thumb at loci where the original receptive field was entirely removed was to produce large MRFs on adjacent body areas (wrist, forearm, prowing, and finger membranes). Greatly expanded MRFs were also produced when amputation removed only part of the original MRF at a cortical locus. 3. The probable source of input to account for the new receptive fields is the extensive arborization of ascending projections within the somatosensory pathway, which supply a cortical locus with a potential input from a far larger area than is represented in its normal receptive field. The rapidity with which new or expanded fields are seen following denervation indicates that the normally unexpressed inputs around a receptive field are not only potential inputs but are inherently viable. Hence the most likely explanation for the results of this study is that the effect of the denervation is to disrupt an inhibitory influence that normally has the role of shaping the receptive field. 4. Temporary anesthesia of all or part of a MRF produced similar initial effects to amputation. When responsiveness returned to the locally anesthetized area (after 10-30 min), an expanded MRF persisted for a short time after which the boundaries of the MRF shrank. This rapid reversal suggests that a mechanistic rather than a plastic change is the basis for the acute effect of a small denervation on SI.

The immediate effect of changing the driving cutaneous input to locations within primary somatosensory cortex (SI) was examined by denervating one or more digits of the rat hindpaw by amputation or local anesthesia. When all or part of a receptive field of a cluster of neurons was denervated, it was found that the cortical location recorded from gained responsiveness to cutaneous stimulation of hindpaw areas bordering the denervated region. In 22 of the 29 animals studied this expansion took place within 5 min of the denervation.

The immediate effect of changing the driving cutaneous input to locations within primary somatosensory cortex (SI) was examined by denervating one or more digits of the rat hindpaw by amputation or local anesthesia. When all or part of a receptive field of a cluster of neurons was denervated, it was found that the cortical location recorded from gained responsiveness to cutaneous stimulation of hindpaw areas bordering the denervated region. In 22 of the 29 animals studied this expansion took place within 5 min of the denervation.

The short-term effect of total or partial single-digit denervation on receptive fields (Rds) of neurons in somatosensory cortex (area 3b) was examined in five macaque monkeys. In two animals, after denervation by amputation, it was found that electrode positions that initially recorded neurons with Rds on the amputated digit had new Rds extending from the wound. Often the new fields were on adjacent digits. Neurons with initial Rds that were partially amputated, or in some cases close to but not on the amputated digit, showed considerable expansion of the remaining RF. In three monkeys local anesthesia was used to provide a temporary denervation. In these experiments electrodes were placed in equivalent positions in both cortices. The effect on cortex contralateral to the denervation was similar to that seen with amputation. However, after esthesia returned to the digit, the expanded Rds contracted. In cortex ipsilateral to the denervation, Rds were on the opposite unaffected hand. These also rapidly expanded and then contracted, with the same time course as their counterparts in cortex contralateral to the denervation. Because of the rapidity of the expansion and its temporary nature with short-term denervation, the basis of the effect is probably an unmasking of existing but normally unexpressed connections, which are normally inhibited by the intact output from the denervated area. The wide arborization fields of thalamocortical afferents provide a potential source for the unmasked sensitivity. A mechanism for the inhibition that normally suppresses the expression of large Rds is not readily apparent. However, work in other species suggests that peripheral C fibers provide the primary source of input to central inhibitory circuits.

The somatosensory cortex of adult mammals has been shown to have a capacity to reorganize when inputs are removed by cutting afferent nerves or amputating a part of the body. The area of cortex that would normally respond to stimulation of the missing input can become responsive to inputs from other parts of the body surface. Although a few animals have been studied with repeat recording, no attempt has been made to follow the time-course of changes at cortical loci and the immediate effects of a small amputation have not been reported. We have followed the changes in response in the primary somatosensory cortex in the flying-fox following amputation of the single exposed digit on the forelimb. Immediately after amputation, neurons in the area of cortex receiving inputs from the missing digit were not silent but responded to stimulation of adjoining regions of the digit, hand, arm and wing. In the week following amputation, the enlarged receptive fields shrank until they covered only the skin around the amputation wound. The immediate response is interpreted as a removal of inhibition and the subsequent shrinking of the field may be due to re-establishment of the inhibitory balance in the affected cortex and its inputs.

The somatosensory cortex of adult mammals has been shown to have a capacity to reorganize when inputs are removed by cutting afferent nerves or amputating a part of the body. The area of cortex that would normally respond to stimulation of the missing input can become responsive to inputs from other parts of the body surface. Although a few animals have been studied with repeat recording, no attempt has been made to follow the time-course of changes at cortical loci and the immediate effects of a small amputation have not been reported. We have followed the changes in response in the primary somatosensory cortex in the flying-fox following amputation of the single exposed digit on the forelimb. Immediately after amputation, neurons in the area of cortex receiving inputs from the missing digit were not silent but responded to stimulation of adjoining regions of the digit, hand, arm and wing. In the week following amputation, the enlarged receptive fields shrank until they covered only the skin around the amputation wound. The immediate response is interpreted as a removal of inhibition and the subsequent shrinking of the field may be due to re-establishment of the inhibitory balance in the affected cortex and its inputs.

The somatosensory cortex of adult mammals has been shown to have a capacity to reorganize when inputs are removed by cutting afferent nerves or amputating a part of the body. The area of cortex that would normally respond to stimulation of the missing input can become responsive to inputs from other parts of the body surface. Although a few animals have been studied with repeat recording, no attempt has been made to follow the time-course of changes at cortical loci and the immediate effects of a small amputation have not been reported. We have followed the changes in response in the primary somatosensory cortex in the flying-fox following amputation of the single exposed digit on the forelimb. Immediately after amputation, neurons in the area of cortex receiving inputs from the missing digit were not silent but responded to stimulation of adjoining regions of the digit, hand, arm and wing. In the week following amputation, the enlarged receptive fields shrank until they covered only the skin around the amputation wound. The immediate response is interpreted as a removal of inhibition and the subsequent shrinking of the field may be due to re-establishment of the inhibitory balance in the affected cortex and its inputs.

The somatosensory cortex of adult mammals has been shown to have a capacity to reorganize when inputs are removed by cutting afferent nerves or amputating a part of the body. The area of cortex that would normally respond to stimulation of the missing input can become responsive to inputs from other parts of the body surface. Although a few animals have been studied with repeat recording, no attempt has been made to follow the time-course of changes at cortical loci and the immediate effects of a small amputation have not been reported. We have followed the changes in response in the primary somatosensory cortex in the flying-fox following amputation of the single exposed digit on the forelimb. Immediately after amputation, neurons in the area of cortex receiving inputs from the missing digit were not silent but responded to stimulation of adjoining regions of the digit, hand, arm and wing. In the week following amputation, the enlarged receptive fields shrank until they covered only the skin around the amputation wound. The immediate response is interpreted as a removal of inhibition and the subsequent shrinking of the field may be due to re-establishment of the inhibitory balance in the affected cortex and its inputs.