Carlos Acuña - Academia.edu (original) (raw)
Papers by Carlos Acuña
Revista clínica española, Jan 31, 1970
Neuropharmacology, 1994
We have shown that application of an inhibitor of the enzyme nitric oxide synthase (NOS) effectiv... more We have shown that application of an inhibitor of the enzyme nitric oxide synthase (NOS) effectively suppresses the visual responses of relay cells in the dorsal lateral geniculate nucleus (dLGN) of the anaesthetized paralysed cat. Such suppression seems to result from a specific reduction in transmission via N-methyl-D-aspartic acid (NMDA) receptors, since iontophoretic application of the inhibitor of NOS selectively and in a dose-dependent manner decreased the responses to exogenously applied NMDA. Responses to other exogenously applied amino acid agonists, such as quisqualate (Quis), kainate (Kain) and cc-amino-3-hydroxy-5-5-methyl-4-isoxazole-propionic acid (AMPA) were largely unaffected. Furthermore, the excitatory action of acetylcholine (ACh), normally co-localized with NOS in axonal terminals within the dLGN arising from the brainstem, was also unaffected. Unlike some other actions of nitric oxide (NO), this role seems not to involve an increase in production of cyclic guanosine-3',5'-mono-phosphate (cGMP), since application of the membrane permeable cGMP analogue &bromo-cGMP did not alter the suppressive effect of NOS inhibitors on either visual or NMDA evoked responses. We conclude that the normal function of NO at this level of the visual system is permissive, allowing full expression of NMDA mediated visually elicited information.
Experimental Brain Research, 1993
We examined the orientation tuning curves of 86 cells located in layer V of area 17, before, duri... more We examined the orientation tuning curves of 86 cells located in layer V of area 17, before, during, and after focal blockade of a small (300-microns diameter) region of near-retinotopic register in layer V of area 18 of quantitatively established orientation preference. Such focal blockade revealed three distinct populations of area 17 layer V cells-cells with decreased responses to stimuli of some orientations (21%), cells with increased responses to stimuli of some orientations (43%), and cells unaffected by the focal blockade (36%). These effects were clearcut, reproducible, and generally directly related to the known receptive field properties of the cell recorded in area 18 at the center of the zone of blockade. These effects were also analyzed in terms of alterations in orientation bandwidth in the cells in area 17 as a result of the blockade-bandwidth increases (22%) and decreases (24%) were found; however, these changes were essentially unrelated to the measured receptive field properties. Inhibitory and excitatory effects were most pronounced when the regions in areas 17 and 18 were of like ocular dominance and were of similar orientation preference. Inhibitory effects (suggesting a normally excitatory input) were most dependent upon the similarity of receptive fields; excitatory effects (suggesting a normally inhibitory input) were less heavily dependent.
Brain Research, 1973
Development of rat-killer behaviour by environmental factors was observed in two cats. Food depri... more Development of rat-killer behaviour by environmental factors was observed in two cats. Food deprivation, however, never converted a non-killer into a killer cat. Stimulation of certain points in the basolateral region of the amygdala arrests the spontaneous rat-killer behaviour, but does not prevent the attack which is induced by electrical stimulation of hypothalamus or central gray matter. On the other hand, the stimulation of hypothalamus and/or central gray matter may overcome the inhibitory effects of the electrical stimulation of the amygdala.
Acta Neurobiologiae Experimentalis, 2003
Neuroscience, 2016
In the last decades it has been shown that two components of the event-related potentials (ERPs),... more In the last decades it has been shown that two components of the event-related potentials (ERPs), the feedback-related negativity (FRN) and the P300, reflect the evaluation of the outcomes of a given course of action. Within the reinforcement learning theory, the prevailing interpretation of the relationship between FRN and P300 is the classical "independent coding model". This model proposes that the FRN is only sensitive to feedback valence whereas the P300 is only sensitive to feedback magnitude. However, these predictions have recently been challenged and the question remains unsolved. The goal of the present study is to shed light on the effects of outcome valence and magnitude on the FRN and the feedback-P300. The electroencephalographic (EEG) activity was recorded while participants performed a perceptual discrimination task with two levels of difficulty, in which they could receive large or small rewards and penalties. We used receiver operating characteristics (ROC) analyses, which allowed us to analyze the relationship between the outcomes and EEG on a trial-by-trial basis. The results reveal that both components, which are contingent on feedback presentation, are sensitive to outcome valence. Regarding magnitude, this only affects the feedback P300, and only in conjunction with difficulty. Finally, we found that task difficulty has the opposite effect on these components, both in their latencies and discriminability. Our results suggest that the FRN and the feedback-P300 in fact reflect different performance monitoring processes in a flexible way that depends on the behavioral context.
Revue neurologique, 1986
We have showed in a previous paper that the pulvinar extracellular unit activity in behaving monk... more We have showed in a previous paper that the pulvinar extracellular unit activity in behaving monkeys was dependent on the attention the animal paid to the stimulus, or on its behavioral significance or on the intentional movements the animal performed. Several groups of pulvinar cells quantitatively studied in the behavioral tasks the monkeys performed were described. "Projection and hand manipulation" neurons belong to a group of pulvinar cells that increased their activity when the animal made an intentional movement of the limb towards an object that attracted his attention. Some of these cells showed temporal patterns of discharge as well as peak rates of activity that frequently differed for reaching movements to spatially separated targets. This suggested that the overall pattern of discharge of these population of cells differ for different directions of arm movements. We give here a description of the observations made in three behaving Macaca Nemestrina monkeys tr...
Proceedings of the National Academy of Sciences, 2009
Depending on the circumstances, decision making requires either comparing current sensory informa... more Depending on the circumstances, decision making requires either comparing current sensory information with that showed recently or with that recovered from long-term memory (LTM). In both cases, to learn from past decisions and adapt future ones, memories and outcomes have to be available after the report of a decision. The ventral premotor cortex (PMv) is a good candidate for integrating memory traces and outcomes because it is involved in working-memory, decision-making, and encoding the outcomes. To test this hypothesis we recorded the extracellular unit activity while monkeys performed 2 variants of a visual discrimination task. In one task, the decision was based on the comparison of the orientation of a current stimulus with that of another stimulus recently shown. In the other task, the monkeys had to compare the current orientation of the stimulus with the correct one retrieved from LTM. Here, we report that when the task required retrieval of the stimulus and its use in the...
Experimental Brain Research, 1990
Brain Research, 1978
We measured the capacity of monkeys to project the arm to visually located targets under conditio... more We measured the capacity of monkeys to project the arm to visually located targets under conditions differing in the nature of visual control allowed during reaching. This capacity was impaired by a unilateral posterior parietal lesion which increased the magnitude and variability of errors in projecting the contralateral arm to targets located on either side of the midline. Furthermore, accurate projections of the arm were often accompanied by misorientations of the fingers of the hand. These errors occurred whether reaching with or without visual guidance of the limb. The presence or absence of vision influenced the direction of errors in arm projection. Under conditions permitting a view of the limb and sight of the target, errors occurred in a direction toward the side of the lesion. When all visual cues were eliminated during reaching, errors were directed away from on-target toward the midline as they are in normal monkeys, but were greater in magnitude following the lesion.
Journal of Neuroscience, 2008
Biometrical Journal, 2009
Revista de Neurología
A pesar de que inicialmente se considero la corteza premotora como el sustrato de funciones puram... more A pesar de que inicialmente se considero la corteza premotora como el sustrato de funciones puramente motoras, pronto se vio que esta implicada en procesos cognitivos de alto nivel. El uso combinado de tareas conductuales y registros electrofisiologicos ha permitido importantes avances en la comprension y descripcion funcional de esta area. El patron de conexiones de la corteza premotora ventral la situa en una posicion privilegiada para participar en las decisiones perceptivas, en las que la informacion sensorial se combina con las expectativas y el conocimiento previo para alcanzar la eleccion conductual. Los correlatos neuronales del proceso de decision se han descrito en varias areas corticales de los primates. En este trabajo describimos resultados experimentales que demuestran que las diferentes etapas de las decisiones perceptivas se codifican en la tasa de descarga de las neuronas de la corteza premotora ventral. Esto sugiere que esta area esta implicada en el uso de informacion sensorial, almacenada en la memoria de trabajo o recuperada de la memoria a largo plazo, para alcanzar una decision. Ademas, una vez que los sujetos han comunicado la eleccion, las neuronas codifican toda la informacion necesaria para evaluar el resultado del proceso de decision, lo que sugiere que la corteza premotora ventral podria participar en la modificacion del comportamiento futuro como resultado de dicha evaluacion.
PeerJ, 2018
Previous works have shown that neurons from the ventral premotor cortex (PMv) represent several e... more Previous works have shown that neurons from the ventral premotor cortex (PMv) represent several elements of perceptual decisions. One of the most striking findings was that, after the outcome of the choice is known, neurons from PMv encode all the information necessary for evaluating the decision process. These results prompted us to suggest that this cortical area could be involved in shaping future behavior. In this work, we have characterized neuronal activity and behavioral performance as a function of the outcome of the previous trial. We found that the outcome of the immediately previous trial (-1) significantly changes, in the current trial (), the activity of single cells and behavioral performance. The outcome of trial -2, however, does not affect either behavior or neuronal activity. Moreover, the outcome of difficult trials had a greater impact on performance and recruited more PMv neurons than the outcome of easy trials. These results give strong support to our suggestio...
Revista clínica española, Jan 31, 1970
Neuropharmacology, 1994
We have shown that application of an inhibitor of the enzyme nitric oxide synthase (NOS) effectiv... more We have shown that application of an inhibitor of the enzyme nitric oxide synthase (NOS) effectively suppresses the visual responses of relay cells in the dorsal lateral geniculate nucleus (dLGN) of the anaesthetized paralysed cat. Such suppression seems to result from a specific reduction in transmission via N-methyl-D-aspartic acid (NMDA) receptors, since iontophoretic application of the inhibitor of NOS selectively and in a dose-dependent manner decreased the responses to exogenously applied NMDA. Responses to other exogenously applied amino acid agonists, such as quisqualate (Quis), kainate (Kain) and cc-amino-3-hydroxy-5-5-methyl-4-isoxazole-propionic acid (AMPA) were largely unaffected. Furthermore, the excitatory action of acetylcholine (ACh), normally co-localized with NOS in axonal terminals within the dLGN arising from the brainstem, was also unaffected. Unlike some other actions of nitric oxide (NO), this role seems not to involve an increase in production of cyclic guanosine-3',5'-mono-phosphate (cGMP), since application of the membrane permeable cGMP analogue &bromo-cGMP did not alter the suppressive effect of NOS inhibitors on either visual or NMDA evoked responses. We conclude that the normal function of NO at this level of the visual system is permissive, allowing full expression of NMDA mediated visually elicited information.
Experimental Brain Research, 1993
We examined the orientation tuning curves of 86 cells located in layer V of area 17, before, duri... more We examined the orientation tuning curves of 86 cells located in layer V of area 17, before, during, and after focal blockade of a small (300-microns diameter) region of near-retinotopic register in layer V of area 18 of quantitatively established orientation preference. Such focal blockade revealed three distinct populations of area 17 layer V cells-cells with decreased responses to stimuli of some orientations (21%), cells with increased responses to stimuli of some orientations (43%), and cells unaffected by the focal blockade (36%). These effects were clearcut, reproducible, and generally directly related to the known receptive field properties of the cell recorded in area 18 at the center of the zone of blockade. These effects were also analyzed in terms of alterations in orientation bandwidth in the cells in area 17 as a result of the blockade-bandwidth increases (22%) and decreases (24%) were found; however, these changes were essentially unrelated to the measured receptive field properties. Inhibitory and excitatory effects were most pronounced when the regions in areas 17 and 18 were of like ocular dominance and were of similar orientation preference. Inhibitory effects (suggesting a normally excitatory input) were most dependent upon the similarity of receptive fields; excitatory effects (suggesting a normally inhibitory input) were less heavily dependent.
Brain Research, 1973
Development of rat-killer behaviour by environmental factors was observed in two cats. Food depri... more Development of rat-killer behaviour by environmental factors was observed in two cats. Food deprivation, however, never converted a non-killer into a killer cat. Stimulation of certain points in the basolateral region of the amygdala arrests the spontaneous rat-killer behaviour, but does not prevent the attack which is induced by electrical stimulation of hypothalamus or central gray matter. On the other hand, the stimulation of hypothalamus and/or central gray matter may overcome the inhibitory effects of the electrical stimulation of the amygdala.
Acta Neurobiologiae Experimentalis, 2003
Neuroscience, 2016
In the last decades it has been shown that two components of the event-related potentials (ERPs),... more In the last decades it has been shown that two components of the event-related potentials (ERPs), the feedback-related negativity (FRN) and the P300, reflect the evaluation of the outcomes of a given course of action. Within the reinforcement learning theory, the prevailing interpretation of the relationship between FRN and P300 is the classical "independent coding model". This model proposes that the FRN is only sensitive to feedback valence whereas the P300 is only sensitive to feedback magnitude. However, these predictions have recently been challenged and the question remains unsolved. The goal of the present study is to shed light on the effects of outcome valence and magnitude on the FRN and the feedback-P300. The electroencephalographic (EEG) activity was recorded while participants performed a perceptual discrimination task with two levels of difficulty, in which they could receive large or small rewards and penalties. We used receiver operating characteristics (ROC) analyses, which allowed us to analyze the relationship between the outcomes and EEG on a trial-by-trial basis. The results reveal that both components, which are contingent on feedback presentation, are sensitive to outcome valence. Regarding magnitude, this only affects the feedback P300, and only in conjunction with difficulty. Finally, we found that task difficulty has the opposite effect on these components, both in their latencies and discriminability. Our results suggest that the FRN and the feedback-P300 in fact reflect different performance monitoring processes in a flexible way that depends on the behavioral context.
Revue neurologique, 1986
We have showed in a previous paper that the pulvinar extracellular unit activity in behaving monk... more We have showed in a previous paper that the pulvinar extracellular unit activity in behaving monkeys was dependent on the attention the animal paid to the stimulus, or on its behavioral significance or on the intentional movements the animal performed. Several groups of pulvinar cells quantitatively studied in the behavioral tasks the monkeys performed were described. "Projection and hand manipulation" neurons belong to a group of pulvinar cells that increased their activity when the animal made an intentional movement of the limb towards an object that attracted his attention. Some of these cells showed temporal patterns of discharge as well as peak rates of activity that frequently differed for reaching movements to spatially separated targets. This suggested that the overall pattern of discharge of these population of cells differ for different directions of arm movements. We give here a description of the observations made in three behaving Macaca Nemestrina monkeys tr...
Proceedings of the National Academy of Sciences, 2009
Depending on the circumstances, decision making requires either comparing current sensory informa... more Depending on the circumstances, decision making requires either comparing current sensory information with that showed recently or with that recovered from long-term memory (LTM). In both cases, to learn from past decisions and adapt future ones, memories and outcomes have to be available after the report of a decision. The ventral premotor cortex (PMv) is a good candidate for integrating memory traces and outcomes because it is involved in working-memory, decision-making, and encoding the outcomes. To test this hypothesis we recorded the extracellular unit activity while monkeys performed 2 variants of a visual discrimination task. In one task, the decision was based on the comparison of the orientation of a current stimulus with that of another stimulus recently shown. In the other task, the monkeys had to compare the current orientation of the stimulus with the correct one retrieved from LTM. Here, we report that when the task required retrieval of the stimulus and its use in the...
Experimental Brain Research, 1990
Brain Research, 1978
We measured the capacity of monkeys to project the arm to visually located targets under conditio... more We measured the capacity of monkeys to project the arm to visually located targets under conditions differing in the nature of visual control allowed during reaching. This capacity was impaired by a unilateral posterior parietal lesion which increased the magnitude and variability of errors in projecting the contralateral arm to targets located on either side of the midline. Furthermore, accurate projections of the arm were often accompanied by misorientations of the fingers of the hand. These errors occurred whether reaching with or without visual guidance of the limb. The presence or absence of vision influenced the direction of errors in arm projection. Under conditions permitting a view of the limb and sight of the target, errors occurred in a direction toward the side of the lesion. When all visual cues were eliminated during reaching, errors were directed away from on-target toward the midline as they are in normal monkeys, but were greater in magnitude following the lesion.
Journal of Neuroscience, 2008
Biometrical Journal, 2009
Revista de Neurología
A pesar de que inicialmente se considero la corteza premotora como el sustrato de funciones puram... more A pesar de que inicialmente se considero la corteza premotora como el sustrato de funciones puramente motoras, pronto se vio que esta implicada en procesos cognitivos de alto nivel. El uso combinado de tareas conductuales y registros electrofisiologicos ha permitido importantes avances en la comprension y descripcion funcional de esta area. El patron de conexiones de la corteza premotora ventral la situa en una posicion privilegiada para participar en las decisiones perceptivas, en las que la informacion sensorial se combina con las expectativas y el conocimiento previo para alcanzar la eleccion conductual. Los correlatos neuronales del proceso de decision se han descrito en varias areas corticales de los primates. En este trabajo describimos resultados experimentales que demuestran que las diferentes etapas de las decisiones perceptivas se codifican en la tasa de descarga de las neuronas de la corteza premotora ventral. Esto sugiere que esta area esta implicada en el uso de informacion sensorial, almacenada en la memoria de trabajo o recuperada de la memoria a largo plazo, para alcanzar una decision. Ademas, una vez que los sujetos han comunicado la eleccion, las neuronas codifican toda la informacion necesaria para evaluar el resultado del proceso de decision, lo que sugiere que la corteza premotora ventral podria participar en la modificacion del comportamiento futuro como resultado de dicha evaluacion.
PeerJ, 2018
Previous works have shown that neurons from the ventral premotor cortex (PMv) represent several e... more Previous works have shown that neurons from the ventral premotor cortex (PMv) represent several elements of perceptual decisions. One of the most striking findings was that, after the outcome of the choice is known, neurons from PMv encode all the information necessary for evaluating the decision process. These results prompted us to suggest that this cortical area could be involved in shaping future behavior. In this work, we have characterized neuronal activity and behavioral performance as a function of the outcome of the previous trial. We found that the outcome of the immediately previous trial (-1) significantly changes, in the current trial (), the activity of single cells and behavioral performance. The outcome of trial -2, however, does not affect either behavior or neuronal activity. Moreover, the outcome of difficult trials had a greater impact on performance and recruited more PMv neurons than the outcome of easy trials. These results give strong support to our suggestio...