Stefania Bruni | Università degli Studi di Parma (Italy) (original) (raw)

Papers by Stefania Bruni

NeuroSci

What is the significance of a touch encoded by slow-conducted unmyelinated C-tactile (CT) fibers?... more What is the significance of a touch encoded by slow-conducted unmyelinated C-tactile (CT) fibers? It is the so-called affiliative touch, which has a fundamental social impact. In humans, it has been demonstrated that the affiliative valence of this kind of touch is encoded by a dedicated central network, not involved in the encoding of discriminative touch, namely, the “social brain”. Moreover, CT-related touch has significant consequences on the human autonomic system, not present in the case of discriminative touch, which does not involve CT fibers as the modulation of vagal tone. In addition, CT-related touch provokes central effects as well. An interesting finding is that CT-related touch can elicit “mirror-like responses” since there is evidence that we would have the same perception of a caress regardless of whether it would be felt or seen and that the same brain areas would be activated. Information from CT afferents in the posterior insular cortex likely provides a basis fo...

Neurological Sciences

Background Thesevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents the most re... more Background Thesevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents the most recent severe pandemic resulting in coronavirus disease 2019 (COVID-19). COVID-19 can damage the central nervous system, requiring admission to intensive care units (ICU) and aggressive treatments (long-term ventilatory assistance and sedation) to stabilize vitals. Most post-COVID-19 patients experience cognitive impairments and mood or stress disorders. We aimed to study the frequency of cognitive deficits in COVID-19 survivors, the relationship between clinical factors in the acute phase and cognitive outcomes, affective states, and quality of life. We explored cognitive reserve (CR) role, as a post-COVID-19 resilience factor. Methods Twenty-nine COVID-19 inpatients were assessed using a neuropsychological battery, mood scales, quality of life, and social integration questionnaires. Twenty-five were retained through telephone follow-up to monitor cognitive sequelae, affective states, and reintegration levels roughly 8 months after hospital discharge. We administered the Cognitive Reserve Index questionnaire. Results We found most patients display no cognitive deficits. When they did, multi-domain impairment occurred most frequently, especially involving executive functions. Results revealed a significant correlation between depression levels and the interval between ICU admission and tracheal tube removal. We found increased levels of depression and anxiety at follow-up, a significant relationship between resuming daily life activities, high CR, and executive functions. Conclusions These findings suggest the importance of psychological support in the long term and the modulating role of cognitive reserve in quality of life after infection.

Nature Neuroscience, 2019

The prefrontal cortex (PFC) is implicated in processing of the affective state of others through ... more The prefrontal cortex (PFC) is implicated in processing of the affective state of others through non-verbal communication. This social cognitive function is thought to rely on an intact cortical neuronal excitatory and inhibitory balance. Here combining in vivo electrophysiology with a behavioral task for affective state discrimination in mice, we show a differential activation of medial PFC (mPFC) neurons during social exploration that depends on the affective state of the conspecific. Optogenetic manipulations revealed a double dissociation between the role of interneurons in social cognition. Specifically, inhibition of mPFC somatostatin (SOM + ), but not of parvalbumin (PV + ) interneurons, abolishes affective state discrimination. Accordingly, synchronized activation of mPFC SOM + interneurons selectively induces social discrimination. As visualized by in vivo single-cell microendoscopic Ca 2+ imaging, an increased synchronous activity of mPFC SOM + interneurons, guiding inhibition of pyramidal neurons, is associated with affective state discrimination. Our findings provide new insights into the neurobiological mechanisms of affective state discrimination. Scheggia et al. show that a specific subpopulation of cortical neurons expressing somatostatin in the prefrontal cortex has a primary role in orchestrating the ability of mice to discriminate positive and negative affective states in others.

We do not understand how neural nodes operate within the recurrent action-perception loops that c... more We do not understand how neural nodes operate within the recurrent action-perception loops that characterize naturalistic self-environment interactions, nor how brain networks reconfigure during changing computational demands. Here, we record local field potentials (LFPs) and spiking activity simultaneously from the dorsomedial superior temporal area (MSTd), parietal area 7a, and dorsolateral prefrontal cortex (dlPFC) as monkeys navigate in virtual reality to “catch fireflies”. This task requires animals to actively sample from a closed-loop visual environment while concurrently computing latent variables: the evolving distance and angle to a memorized firefly. We observed mixed selectivity in all areas, with even a traditionally sensory area (MSTd) tracking latent variables. Strikingly, global encoding profiles and unit-to-unit coupling suggested a functional subnetwork between MSTd and dlPFC, and not between these areas and 7a, as anatomy would suggest. When sensory evidence was r...

4 3. RESULTS 3.1. Movement-related neurons 3.2. Cue-related neurons 3.3. Movement-and-cue related... more 4 3. RESULTS 3.1. Movement-related neurons 3.2. Cue-related neurons 3.3. Movement-and-cue related neurons 3.4. Neurons discharging during OT 4. DISCUSSION 4.1 Movement-related prefrontal neurons 4.2 Cue-related prefrontal neurons 4.3 Sensory-and-motor related prefrontal neurons 4.4 Prefrontal neurons studied during the observation of others' action 4.5 Cortical mechanism for the organization of intentional actions 5. CONCLUSIONS 6. REFERENCES

Scientific Reports, 2019

Premotor neurons play a fundamental role in transforming physical properties of observed objects,... more Premotor neurons play a fundamental role in transforming physical properties of observed objects, such as size and shape, into motor plans for grasping them, hence contributing to "pragmatic" affordance processing. Premotor neurons can also contribute to "semantic" affordance processing, as they can discharge differently even to pragmatically identical objects depending on their behavioural relevance for the observer (i.e. edible or inedible objects). Here, we compared the response of monkey ventral premotor area F5 neurons tested during pragmatic (PT) or semantic (ST) visuomotor tasks. Object presentation responses in ST showed shorter latency and lower object selectivity than in PT. Furthermore, we found a difference between a transient representation of semantic affordances and a sustained representation of pragmatic affordances at both the single neuron and population level. Indeed, responses in ST returned to baseline within 0.5 s whereas in PT they showed the typical sustained visual-to-motor activity during Go trials. In contrast, during No-go trials, the time course of pragmatic and semantic information processing was similar. These findings suggest that premotor cortex generates different dynamics depending on pragmatic and semantic information provided by the context in which the to-be-grasped object is presented. Grasping an object requires to select the most appropriate hand posture (e.g. precision or power grip) to interact with it 1-4 but also to plan the whole sequence of movements that will lead to successfully accomplish the agent's behavioural goal (e.g. eating or placing the object, see 5-7). The neuronal circuits underlying visuomotor transformation of objects features into motor plans for grasping them have been extensively investigated. Existing data indicate that the intraparietal area AIP contains neurons responding to the visual presentation of specific objects as well as during the execution of the grip type required for grasping them 8. Neurons with similar properties have been also found in the parietal area V6A 9. Areas AIP and V6A are strongly and reciprocally connected with the premotor areas F5 and F2, respectively 10-12 , where visuomotor neurons with object-type specificity have been found 2,13-15. Most recently, the mesial premotor area F6 16,17 has been shown to constitute an additional node of the "cortical grasping network"-a set of richly interconnected parieto-frontal pathways underlying the sensorimotor transformation of object's physical properties in the most appropriate hand posture to interact with it 18. These circuits highlight the relevance of the "pragmatic" representation of observed objects 19. In the last decade, neurophysiological studies also highlighted a role of reciprocally interconnected parietal and frontal regions 20,21 in organizing and planning goal-directed manual actions 5-7. These studies showed that neurons responding during a grasping act performed with a given type of grip (e.g. precision grip) can exhibit markedly different activations depending on the final goal of the action (i.e. eating or placing). In fact, "what to do" with an object largely depends on its behavioural significance for the subject (e.g., palatability or repugnance), and both parietal and premotor neurons appear to be sensitive to this "semantic" information. A recent study 22

Biomedizinische Technik/Biomedical Engineering, 2014

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady re... more One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significan...

Brain structure & function, 2017

Mirror neurons (MNs) are a class of cells originally discovered in the monkey ventral premotor co... more Mirror neurons (MNs) are a class of cells originally discovered in the monkey ventral premotor cortex (PMv) and inferior parietal lobule (IPL). They discharge during both action execution and action observation and appear to play a crucial role in understanding others' actions. It has been proposed that the mirror mechanism is based on a match between the visual description of actions, encoded in temporal cortical regions, and their motor representation, provided by PMv and IPL. However, neurons responding to action observation have been recently found in other cortical regions, suggesting that the mirror mechanism relies on a wider network. Here we provide the first description of this network by injecting neural tracers into physiologically identified IPL and PMv sectors containing hand MNs. Our results show that these sectors are reciprocally connected, in line with the current view, but IPL MN sectors showed virtually no direct connection with temporal visual areas. In addit...

European Journal of Neuroscience, 2013

We do not understand how neural nodes operate within the recurrent action-perception loops that c... more We do not understand how neural nodes operate within the recurrent action-perception loops that characterize naturalistic self-environment interactions, nor how brain networks reconfigure during changing computational demands. Here, we record local field potentials (LFPs) and spiking activity simultaneously from the dorsomedial superior temporal area (MSTd), parietal area 7a, and dorsolateral prefrontal cortex (dlPFC) as monkeys navigate in virtual reality to catch fireflies. This task requires animals to actively sample from a closed-loop visual environment while concurrently computing latent variables: the evolving distance and angle to a memorized firefly. We observed mixed selectivity in all areas, with even a traditionally sensory area (MSTd) tracking latent variables. Strikingly, global encoding profiles and unit-to-unit coupling suggested a functional subnetwork between MSTd and dlPFC, and not between these are 7a, as anatomy would suggest. When sensory evidence was rendered ...

Scientific Reports

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Biomedizinische Technik/Biomedical Engineering, 2000

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady re... more One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significantly after several penetrations into the same restricted cortical sector, suggesting limited tissue damage due to probe insertion. These results indicate that these probes offer several advantages for acute neurophysiological experiments in awake monkeys, and suggest the possibility to employ them for semichronic or even chronic studies.

Journal of Neurophysiology, 2012

Grasping objects requires the selection of specific grip postures in relation to the objects&... more Grasping objects requires the selection of specific grip postures in relation to the objects' physical properties. Furthermore, grasping acts can be embedded in actions aimed at different goals, depending on the context in which the action is performed. Here we assessed whether information on grip and action type integrate at the single-neuron level within the parieto-frontal motor system. For this purpose, we trained three monkeys to perform simple grasp-to-eat and grasp-to-place actions, depending on contextual cues, in which different grip types were required in relation to target features. We recorded 173 grasping neurons: 86 from the inferior parietal area PFG and 87 from the ventral premotor area F5. Results showed that most neurons in both areas are selective for grip type, but the discharge of many of them, particularly in PFG, appears to differ in relation to action context. Kinematics data and control experiments indicated that neuronal selectivity appears more likely to depend on the action goal triggered by the context than on specific contextual elements. The temporal dynamics of grip and goal selectivity showed that grasping neurons reflect first "how" the object has to be grasped (grip), to guide and monitor the hand shaping phase, and then "why" the action is performed (goal), very likely to facilitate subsequent motor acts following grasping. These findings suggest that, in the parieto-frontal system, grip types and action goals are processed by both parallel and converging pathways, and area PFG appears to be particularly relevant for integrating this information for action organization.

Cerebral cortex (New York, N.Y. : 1991), Jan 22, 2015

Visuo-motor neurons of the ventral premotor area F5 encode "pragmatic" representations ... more Visuo-motor neurons of the ventral premotor area F5 encode "pragmatic" representations of object in terms of the potential motor acts (e.g., precision grip) afforded by it. Likewise, objects with identical pragmatic features (e.g., small spheres) but different behavioral value (e.g., edible or inedible) convey different "semantic" information and thus afford different goal-directed behaviors (e.g., grasp-to-eat or grasp-to-place). However, whether F5 neurons can extract distinct behavioral affordances from objects with similar pragmatic features is unknown. We recorded 134 F5 visuo-motor neurons in 2 macaques during a contextually cued go/no-go task in which the monkey grasped, or refrained from grasping, a previously presented edible or inedible target to eat it or placing it, respectively. Sixty-nine visuo-motor neurons showed motor selectivity for the target (35 food and 34 object), and about half of them (N = 35) exhibited congruent visual preference. Interes...

NeuroSci

What is the significance of a touch encoded by slow-conducted unmyelinated C-tactile (CT) fibers?... more What is the significance of a touch encoded by slow-conducted unmyelinated C-tactile (CT) fibers? It is the so-called affiliative touch, which has a fundamental social impact. In humans, it has been demonstrated that the affiliative valence of this kind of touch is encoded by a dedicated central network, not involved in the encoding of discriminative touch, namely, the “social brain”. Moreover, CT-related touch has significant consequences on the human autonomic system, not present in the case of discriminative touch, which does not involve CT fibers as the modulation of vagal tone. In addition, CT-related touch provokes central effects as well. An interesting finding is that CT-related touch can elicit “mirror-like responses” since there is evidence that we would have the same perception of a caress regardless of whether it would be felt or seen and that the same brain areas would be activated. Information from CT afferents in the posterior insular cortex likely provides a basis fo...

Neurological Sciences

Background Thesevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents the most re... more Background Thesevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents the most recent severe pandemic resulting in coronavirus disease 2019 (COVID-19). COVID-19 can damage the central nervous system, requiring admission to intensive care units (ICU) and aggressive treatments (long-term ventilatory assistance and sedation) to stabilize vitals. Most post-COVID-19 patients experience cognitive impairments and mood or stress disorders. We aimed to study the frequency of cognitive deficits in COVID-19 survivors, the relationship between clinical factors in the acute phase and cognitive outcomes, affective states, and quality of life. We explored cognitive reserve (CR) role, as a post-COVID-19 resilience factor. Methods Twenty-nine COVID-19 inpatients were assessed using a neuropsychological battery, mood scales, quality of life, and social integration questionnaires. Twenty-five were retained through telephone follow-up to monitor cognitive sequelae, affective states, and reintegration levels roughly 8 months after hospital discharge. We administered the Cognitive Reserve Index questionnaire. Results We found most patients display no cognitive deficits. When they did, multi-domain impairment occurred most frequently, especially involving executive functions. Results revealed a significant correlation between depression levels and the interval between ICU admission and tracheal tube removal. We found increased levels of depression and anxiety at follow-up, a significant relationship between resuming daily life activities, high CR, and executive functions. Conclusions These findings suggest the importance of psychological support in the long term and the modulating role of cognitive reserve in quality of life after infection.

Nature Neuroscience, 2019

The prefrontal cortex (PFC) is implicated in processing of the affective state of others through ... more The prefrontal cortex (PFC) is implicated in processing of the affective state of others through non-verbal communication. This social cognitive function is thought to rely on an intact cortical neuronal excitatory and inhibitory balance. Here combining in vivo electrophysiology with a behavioral task for affective state discrimination in mice, we show a differential activation of medial PFC (mPFC) neurons during social exploration that depends on the affective state of the conspecific. Optogenetic manipulations revealed a double dissociation between the role of interneurons in social cognition. Specifically, inhibition of mPFC somatostatin (SOM + ), but not of parvalbumin (PV + ) interneurons, abolishes affective state discrimination. Accordingly, synchronized activation of mPFC SOM + interneurons selectively induces social discrimination. As visualized by in vivo single-cell microendoscopic Ca 2+ imaging, an increased synchronous activity of mPFC SOM + interneurons, guiding inhibition of pyramidal neurons, is associated with affective state discrimination. Our findings provide new insights into the neurobiological mechanisms of affective state discrimination. Scheggia et al. show that a specific subpopulation of cortical neurons expressing somatostatin in the prefrontal cortex has a primary role in orchestrating the ability of mice to discriminate positive and negative affective states in others.

We do not understand how neural nodes operate within the recurrent action-perception loops that c... more We do not understand how neural nodes operate within the recurrent action-perception loops that characterize naturalistic self-environment interactions, nor how brain networks reconfigure during changing computational demands. Here, we record local field potentials (LFPs) and spiking activity simultaneously from the dorsomedial superior temporal area (MSTd), parietal area 7a, and dorsolateral prefrontal cortex (dlPFC) as monkeys navigate in virtual reality to “catch fireflies”. This task requires animals to actively sample from a closed-loop visual environment while concurrently computing latent variables: the evolving distance and angle to a memorized firefly. We observed mixed selectivity in all areas, with even a traditionally sensory area (MSTd) tracking latent variables. Strikingly, global encoding profiles and unit-to-unit coupling suggested a functional subnetwork between MSTd and dlPFC, and not between these areas and 7a, as anatomy would suggest. When sensory evidence was r...

4 3. RESULTS 3.1. Movement-related neurons 3.2. Cue-related neurons 3.3. Movement-and-cue related... more 4 3. RESULTS 3.1. Movement-related neurons 3.2. Cue-related neurons 3.3. Movement-and-cue related neurons 3.4. Neurons discharging during OT 4. DISCUSSION 4.1 Movement-related prefrontal neurons 4.2 Cue-related prefrontal neurons 4.3 Sensory-and-motor related prefrontal neurons 4.4 Prefrontal neurons studied during the observation of others' action 4.5 Cortical mechanism for the organization of intentional actions 5. CONCLUSIONS 6. REFERENCES

Scientific Reports, 2019

Premotor neurons play a fundamental role in transforming physical properties of observed objects,... more Premotor neurons play a fundamental role in transforming physical properties of observed objects, such as size and shape, into motor plans for grasping them, hence contributing to "pragmatic" affordance processing. Premotor neurons can also contribute to "semantic" affordance processing, as they can discharge differently even to pragmatically identical objects depending on their behavioural relevance for the observer (i.e. edible or inedible objects). Here, we compared the response of monkey ventral premotor area F5 neurons tested during pragmatic (PT) or semantic (ST) visuomotor tasks. Object presentation responses in ST showed shorter latency and lower object selectivity than in PT. Furthermore, we found a difference between a transient representation of semantic affordances and a sustained representation of pragmatic affordances at both the single neuron and population level. Indeed, responses in ST returned to baseline within 0.5 s whereas in PT they showed the typical sustained visual-to-motor activity during Go trials. In contrast, during No-go trials, the time course of pragmatic and semantic information processing was similar. These findings suggest that premotor cortex generates different dynamics depending on pragmatic and semantic information provided by the context in which the to-be-grasped object is presented. Grasping an object requires to select the most appropriate hand posture (e.g. precision or power grip) to interact with it 1-4 but also to plan the whole sequence of movements that will lead to successfully accomplish the agent's behavioural goal (e.g. eating or placing the object, see 5-7). The neuronal circuits underlying visuomotor transformation of objects features into motor plans for grasping them have been extensively investigated. Existing data indicate that the intraparietal area AIP contains neurons responding to the visual presentation of specific objects as well as during the execution of the grip type required for grasping them 8. Neurons with similar properties have been also found in the parietal area V6A 9. Areas AIP and V6A are strongly and reciprocally connected with the premotor areas F5 and F2, respectively 10-12 , where visuomotor neurons with object-type specificity have been found 2,13-15. Most recently, the mesial premotor area F6 16,17 has been shown to constitute an additional node of the "cortical grasping network"-a set of richly interconnected parieto-frontal pathways underlying the sensorimotor transformation of object's physical properties in the most appropriate hand posture to interact with it 18. These circuits highlight the relevance of the "pragmatic" representation of observed objects 19. In the last decade, neurophysiological studies also highlighted a role of reciprocally interconnected parietal and frontal regions 20,21 in organizing and planning goal-directed manual actions 5-7. These studies showed that neurons responding during a grasping act performed with a given type of grip (e.g. precision grip) can exhibit markedly different activations depending on the final goal of the action (i.e. eating or placing). In fact, "what to do" with an object largely depends on its behavioural significance for the subject (e.g., palatability or repugnance), and both parietal and premotor neurons appear to be sensitive to this "semantic" information. A recent study 22

Biomedizinische Technik/Biomedical Engineering, 2014

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady re... more One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significan...

Brain structure & function, 2017

Mirror neurons (MNs) are a class of cells originally discovered in the monkey ventral premotor co... more Mirror neurons (MNs) are a class of cells originally discovered in the monkey ventral premotor cortex (PMv) and inferior parietal lobule (IPL). They discharge during both action execution and action observation and appear to play a crucial role in understanding others' actions. It has been proposed that the mirror mechanism is based on a match between the visual description of actions, encoded in temporal cortical regions, and their motor representation, provided by PMv and IPL. However, neurons responding to action observation have been recently found in other cortical regions, suggesting that the mirror mechanism relies on a wider network. Here we provide the first description of this network by injecting neural tracers into physiologically identified IPL and PMv sectors containing hand MNs. Our results show that these sectors are reciprocally connected, in line with the current view, but IPL MN sectors showed virtually no direct connection with temporal visual areas. In addit...

European Journal of Neuroscience, 2013

We do not understand how neural nodes operate within the recurrent action-perception loops that c... more We do not understand how neural nodes operate within the recurrent action-perception loops that characterize naturalistic self-environment interactions, nor how brain networks reconfigure during changing computational demands. Here, we record local field potentials (LFPs) and spiking activity simultaneously from the dorsomedial superior temporal area (MSTd), parietal area 7a, and dorsolateral prefrontal cortex (dlPFC) as monkeys navigate in virtual reality to catch fireflies. This task requires animals to actively sample from a closed-loop visual environment while concurrently computing latent variables: the evolving distance and angle to a memorized firefly. We observed mixed selectivity in all areas, with even a traditionally sensory area (MSTd) tracking latent variables. Strikingly, global encoding profiles and unit-to-unit coupling suggested a functional subnetwork between MSTd and dlPFC, and not between these are 7a, as anatomy would suggest. When sensory evidence was rendered ...

Scientific Reports

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Biomedizinische Technik/Biomedical Engineering, 2000

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady re... more One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significantly after several penetrations into the same restricted cortical sector, suggesting limited tissue damage due to probe insertion. These results indicate that these probes offer several advantages for acute neurophysiological experiments in awake monkeys, and suggest the possibility to employ them for semichronic or even chronic studies.

Journal of Neurophysiology, 2012

Grasping objects requires the selection of specific grip postures in relation to the objects&... more Grasping objects requires the selection of specific grip postures in relation to the objects' physical properties. Furthermore, grasping acts can be embedded in actions aimed at different goals, depending on the context in which the action is performed. Here we assessed whether information on grip and action type integrate at the single-neuron level within the parieto-frontal motor system. For this purpose, we trained three monkeys to perform simple grasp-to-eat and grasp-to-place actions, depending on contextual cues, in which different grip types were required in relation to target features. We recorded 173 grasping neurons: 86 from the inferior parietal area PFG and 87 from the ventral premotor area F5. Results showed that most neurons in both areas are selective for grip type, but the discharge of many of them, particularly in PFG, appears to differ in relation to action context. Kinematics data and control experiments indicated that neuronal selectivity appears more likely to depend on the action goal triggered by the context than on specific contextual elements. The temporal dynamics of grip and goal selectivity showed that grasping neurons reflect first "how" the object has to be grasped (grip), to guide and monitor the hand shaping phase, and then "why" the action is performed (goal), very likely to facilitate subsequent motor acts following grasping. These findings suggest that, in the parieto-frontal system, grip types and action goals are processed by both parallel and converging pathways, and area PFG appears to be particularly relevant for integrating this information for action organization.

Cerebral cortex (New York, N.Y. : 1991), Jan 22, 2015

Visuo-motor neurons of the ventral premotor area F5 encode "pragmatic" representations ... more Visuo-motor neurons of the ventral premotor area F5 encode "pragmatic" representations of object in terms of the potential motor acts (e.g., precision grip) afforded by it. Likewise, objects with identical pragmatic features (e.g., small spheres) but different behavioral value (e.g., edible or inedible) convey different "semantic" information and thus afford different goal-directed behaviors (e.g., grasp-to-eat or grasp-to-place). However, whether F5 neurons can extract distinct behavioral affordances from objects with similar pragmatic features is unknown. We recorded 134 F5 visuo-motor neurons in 2 macaques during a contextually cued go/no-go task in which the monkey grasped, or refrained from grasping, a previously presented edible or inedible target to eat it or placing it, respectively. Sixty-nine visuo-motor neurons showed motor selectivity for the target (35 food and 34 object), and about half of them (N = 35) exhibited congruent visual preference. Interes...