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Jason R. Potas - One of the best experts on this subject based on the ideXlab platform.

  • functional organization and connectivity of the Dorsal Column Nuclei complex reveals a sensorimotor integration and distribution hub
    The Journal of Comparative Neurology, 2021
    Co-Authors: Alastair J Loutit, Jason R. Potas, Richard M. Vickery
    Abstract:

    The Dorsal Column Nuclei complex (DCN-complex) includes the Dorsal Column Nuclei (DCN, referring to the gracile and cuneate Nuclei collectively), external cuneate, X, and Z Nuclei, and the median accessory nucleus. The DCN are organized by both somatotopy and modality, and have a diverse range of afferent inputs and projection targets. The functional organization and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. To consolidate insights into their sensorimotor functions, this review examines the morphology, organization, and connectivity of the DCN and their associated Nuclei. First, we briefly discuss the receptors, afferent fibers, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the remaining constituents of the DCN-complex. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the diencephalon, midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organization and connectivity of the DCN-complex suggest that these Nuclei should be considered a complex integration and distribution hub for sensorimotor information.

  • Dorsal Column Nuclei neural signal features permit robust machine learning of natural tactile and proprioception dominated stimuli
    Frontiers in Systems Neuroscience, 2020
    Co-Authors: Alastair J Loutit, Jason R. Potas
    Abstract:

    Neural prostheses enable users to effect movement through a variety of actuators by translating brain signals into movement control signals. However, to achieve more natural limb movements from these devices, the restoration of somatosensory feedback is required. We used feature-learnability, a machine-learning approach, to assess signal features for their capacity to enhance decoding performance of neural signals evoked by natural tactile and proprioceptive somatosensory stimuli, recorded from the surface of the Dorsal Column Nuclei (DCN) in urethane-anesthetized rats. The highest performing individual feature, spike amplitude, classified somatosensory DCN signals with 70% accuracy. The highest accuracy achieved was 87% using 13 features that were extracted from both high and low-frequency (LF) bands of DCN signals. In general, high-frequency (HF) features contained the most information about peripheral somatosensory events, but when features were acquired from short time-windows, classification accuracy was significantly improved by adding LF features to the feature set. We found that proprioception-dominated stimuli generalize across animals better than tactile-dominated stimuli, and we demonstrate how information that signal features contribute to neural decoding changes over the time-course of dynamic somatosensory events. These findings may inform the biomimetic design of artificial stimuli that can activate the DCN to substitute somatosensory feedback. Although, we investigated somatosensory structures, the feature set we investigated may also prove useful for decoding other (e.g., motor) neural signals.

  • The Dorsal Column Nuclei Complex Neuroanatomy Reveals a Complex Sensorimotor Integration and Distribution Hub
    2020
    Co-Authors: Alastair J Loutit, Richard M. Vickery, Jason R. Potas
    Abstract:

    The Dorsal Column Nuclei complex (DCN-complex) includes the Dorsal Column Nuclei (DCN, referring to the gracile and cuneate Nuclei collectively), external cuneate, X, and Z Nuclei, and the median accessory nucleus. The DCN are organised by both somatotopy and modality, and have a diverse range of afferent inputs and projection targets. The functional organisation and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. To consolidate insights into their sensorimotor functions, this review examines the morphology, organisation, and connectivity of the DCN and their associated Nuclei. First, we briefly discuss the receptors, afferent fibres, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the remaining constituents of the DCN-complex. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the diencephalon, midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organisation and connectivity of the DCN-complex suggest that these Nuclei should be considered a complex integration and distribution hub for sensorimotor information.

  • The Dorsal Column Nuclei Complex Neuroanatomy Reveals a Complex Sensorimotor Integration and Distribution Hub
    2019
    Co-Authors: Alastair J Loutit, Richard M. Vickery, Jason R. Potas
    Abstract:

    The Dorsal Column Nuclei (DCN) are organised by both somatotopy and modality, and have a diverse range of afferent inputs and projection targets. The functional organisation and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. In this review, we examine the morphology, organisation, and connectivity of the DCN and their associated Nuclei, to improve understanding of their sensorimotor functions. First, we briefly discuss the receptors, afferent fibres, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the constituents of the Dorsal Column Nuclei complex (DCN-complex), which includes the gracile, cuneate, external cuneate, X, and Z Nuclei, and Bischoff’s nucleus. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organisation and connectivity of the DCN-complex suggest that these Nuclei should be considered a complex integration and distribution hub for sensorimotor information.

  • novel neural signal features permit robust machine learning of natural tactile and proprioception dominated Dorsal Column Nuclei signals
    bioRxiv, 2019
    Co-Authors: Alastair J Loutit, Jason R. Potas
    Abstract:

    Neural prostheses enable users to effect movement through a variety of actuators by translating brain signals into movement control signals. However, to achieve more natural limb movements from these devices, restoration of somatosensory feedback and advances in neural decoding of motor control-related brain signals are required. We used a machine-learning approach to assess signal features for their capacity to enhance decoding performance of neural signals evoked by natural tactile and proprioceptive somatosensory stimuli, recorded from the surface of the Dorsal Column Nuclei in urethane-anaesthetised rats. We determined signal features that are highly informative for decoding somatosensory stimuli, yet these appear underutilised in neuroprosthetic applications. We found that proprioception-dominated stimuli generalise across animals better than tactile-dominated stimuli, and we demonstrate how information that signal features contribute to neural decoding changes over a time-course of dynamic somatosensory events. These findings may improve neural decoding for various applications including novel neuroprosthetic design.

Alastair J Loutit - One of the best experts on this subject based on the ideXlab platform.

  • functional organization and connectivity of the Dorsal Column Nuclei complex reveals a sensorimotor integration and distribution hub
    The Journal of Comparative Neurology, 2021
    Co-Authors: Alastair J Loutit, Jason R. Potas, Richard M. Vickery
    Abstract:

    The Dorsal Column Nuclei complex (DCN-complex) includes the Dorsal Column Nuclei (DCN, referring to the gracile and cuneate Nuclei collectively), external cuneate, X, and Z Nuclei, and the median accessory nucleus. The DCN are organized by both somatotopy and modality, and have a diverse range of afferent inputs and projection targets. The functional organization and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. To consolidate insights into their sensorimotor functions, this review examines the morphology, organization, and connectivity of the DCN and their associated Nuclei. First, we briefly discuss the receptors, afferent fibers, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the remaining constituents of the DCN-complex. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the diencephalon, midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organization and connectivity of the DCN-complex suggest that these Nuclei should be considered a complex integration and distribution hub for sensorimotor information.

  • Dorsal Column Nuclei neural signal features permit robust machine learning of natural tactile and proprioception dominated stimuli
    Frontiers in Systems Neuroscience, 2020
    Co-Authors: Alastair J Loutit, Jason R. Potas
    Abstract:

    Neural prostheses enable users to effect movement through a variety of actuators by translating brain signals into movement control signals. However, to achieve more natural limb movements from these devices, the restoration of somatosensory feedback is required. We used feature-learnability, a machine-learning approach, to assess signal features for their capacity to enhance decoding performance of neural signals evoked by natural tactile and proprioceptive somatosensory stimuli, recorded from the surface of the Dorsal Column Nuclei (DCN) in urethane-anesthetized rats. The highest performing individual feature, spike amplitude, classified somatosensory DCN signals with 70% accuracy. The highest accuracy achieved was 87% using 13 features that were extracted from both high and low-frequency (LF) bands of DCN signals. In general, high-frequency (HF) features contained the most information about peripheral somatosensory events, but when features were acquired from short time-windows, classification accuracy was significantly improved by adding LF features to the feature set. We found that proprioception-dominated stimuli generalize across animals better than tactile-dominated stimuli, and we demonstrate how information that signal features contribute to neural decoding changes over the time-course of dynamic somatosensory events. These findings may inform the biomimetic design of artificial stimuli that can activate the DCN to substitute somatosensory feedback. Although, we investigated somatosensory structures, the feature set we investigated may also prove useful for decoding other (e.g., motor) neural signals.

  • The Dorsal Column Nuclei Complex Neuroanatomy Reveals a Complex Sensorimotor Integration and Distribution Hub
    2020
    Co-Authors: Alastair J Loutit, Richard M. Vickery, Jason R. Potas
    Abstract:

    The Dorsal Column Nuclei complex (DCN-complex) includes the Dorsal Column Nuclei (DCN, referring to the gracile and cuneate Nuclei collectively), external cuneate, X, and Z Nuclei, and the median accessory nucleus. The DCN are organised by both somatotopy and modality, and have a diverse range of afferent inputs and projection targets. The functional organisation and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. To consolidate insights into their sensorimotor functions, this review examines the morphology, organisation, and connectivity of the DCN and their associated Nuclei. First, we briefly discuss the receptors, afferent fibres, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the remaining constituents of the DCN-complex. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the diencephalon, midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organisation and connectivity of the DCN-complex suggest that these Nuclei should be considered a complex integration and distribution hub for sensorimotor information.

  • The Dorsal Column Nuclei Complex Neuroanatomy Reveals a Complex Sensorimotor Integration and Distribution Hub
    2019
    Co-Authors: Alastair J Loutit, Richard M. Vickery, Jason R. Potas
    Abstract:

    The Dorsal Column Nuclei (DCN) are organised by both somatotopy and modality, and have a diverse range of afferent inputs and projection targets. The functional organisation and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. In this review, we examine the morphology, organisation, and connectivity of the DCN and their associated Nuclei, to improve understanding of their sensorimotor functions. First, we briefly discuss the receptors, afferent fibres, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the constituents of the Dorsal Column Nuclei complex (DCN-complex), which includes the gracile, cuneate, external cuneate, X, and Z Nuclei, and Bischoff’s nucleus. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organisation and connectivity of the DCN-complex suggest that these Nuclei should be considered a complex integration and distribution hub for sensorimotor information.

  • novel neural signal features permit robust machine learning of natural tactile and proprioception dominated Dorsal Column Nuclei signals
    bioRxiv, 2019
    Co-Authors: Alastair J Loutit, Jason R. Potas
    Abstract:

    Neural prostheses enable users to effect movement through a variety of actuators by translating brain signals into movement control signals. However, to achieve more natural limb movements from these devices, restoration of somatosensory feedback and advances in neural decoding of motor control-related brain signals are required. We used a machine-learning approach to assess signal features for their capacity to enhance decoding performance of neural signals evoked by natural tactile and proprioceptive somatosensory stimuli, recorded from the surface of the Dorsal Column Nuclei in urethane-anaesthetised rats. We determined signal features that are highly informative for decoding somatosensory stimuli, yet these appear underutilised in neuroprosthetic applications. We found that proprioception-dominated stimuli generalise across animals better than tactile-dominated stimuli, and we demonstrate how information that signal features contribute to neural decoding changes over a time-course of dynamic somatosensory events. These findings may improve neural decoding for various applications including novel neuroprosthetic design.

Angel Nuñez - One of the best experts on this subject based on the ideXlab platform.

  • Nociceptive stimuli induce changes in somatosensory responses of rat Dorsal Column Nuclei neurons
    Brain Research, 2004
    Co-Authors: Miguel Costa-garcia, Angel Nuñez
    Abstract:

    Accumulating evidence suggest that the Dorsal Column Nuclei (DCN) neurons play a role in nociception. To evaluate DCN neuronal responses to nociceptive stimuli, unit recordings were performed in urethane-anesthesized rats. Neurons selected for this analysis displayed a low spontaneous firing rate and some of them were antidromically activated by electrical stimulation of the ventral posterolateral thalamic nucleus. Formalin injections into receptive fields (RFs) of DCN cells, or applications of short-lasting and long-lasting thermal nociceptive stimuli were used. DCN neurons displayed smaller responses when long-lasting nociceptive thermal stimuli were applied to their RFs in comparison with values obtained from the innocuous cutaneous stimulation (5.2±1.0 and 4.0±0.6 spikes/stimuli, respectively; p=0.02). Formalin also decreased the responses to innocuous cutaneous stimuli when these stimuli were applied to the formalin injection site (2.6±0.3 spikes/stimuli in control conditions and 1.8±0.3 spikes/stimuli 20 min after formalin; p=0.002). In contrast, responses to sensory stimuli applied at the periphery of the RF after formalin injection increased (2.2±0.2 to 2.8±0.3 spikes/stimuli; p=0.005). In some cases, DCN neurons expanded their RF. Fiber input to the DCN did not modify their somatosensory responses when nociceptive stimuli were applied. Results demonstrate that thermal and formalin nociceptive stimuli modify the somatosensory responses of DCN neurons. Thus, decreasing somatosensory responses at the pain induction site or the generation of allodynia may be due to the activity of DCN neurons.

  • Rhythmic neuronal interactions and synchronization in the rat Dorsal Column Nuclei.
    Neuroscience, 2000
    Co-Authors: Angel Nuñez, Fivos Panetsos, Carlos Avendaño
    Abstract:

    Abstract Single-unit and multiunit activities were recorded from Dorsal Column Nuclei of anesthetized rats in order to study the characteristics of the oscillatory activity expressed by these cells and their neuronal interactions. On the basis of their firing rate characteristics in spontaneous conditions, two types of Dorsal Column Nuclei cell have been identified. Low-frequency cells (74%) were silent or displayed a low firing rate (1.9±0.48 spikes/s), and were identified as thalamic-projecting neurons because they were activated antidromically by medial lemniscus stimulation. High-frequency cells (26%) were characterized by higher discharge rates (27.2±5.1 spikes/s). None of them was antidromically activated by medial lemniscus stimulation. Low-frequency neurons showed a non-rhythmic discharge pattern spontaneously which became rhythmic under sensory stimulation of their receptive fields (48% of cases; 4.8±0.23 Hz). All high-frequency neurons showed a rhythmic discharge pattern at 13.8± 0.68 Hz either spontaneously or during sensory stimulation of their receptive fields. The shift predictor analysis indicated that oscillatory activity is not phase-locked to the stimulus onset in either type of cell, although the stimulus can reset the phase of the rhythmic activity of high-frequency cells. Cross-correlograms between pairs of low-frequency neurons typically revealed synchronized rhythmic activity when the overlapping receptive fields were stimulated. Rhythmic synchronization of high-frequency discharges was rarely observed spontaneously or under sensory stimulation. High-frequency neuronal firing could be correlated with the low-frequency neuronal activity or more often with the multiunit activity during sensory stimulation. Moreover, the presence of oscillatory activity modulated the sensory responses of Dorsal Column Nuclei cells, favoring their responses. These findings indicate that thalamic-projecting and non-projecting neurons in Dorsal Column Nuclei exhibited distinct oscillatory characteristics. However, both types of neuron may be entrained into an oscillatory rhythmic pattern when their overlapping receptive fields are stimulated, suggesting that in those conditions the Dorsal Column Nuclei generate a populational oscillatory output to the somatosensory thalamus which could modulate and amplify the effectiveness of the somatosensory transmission.

  • In vitro electrophysiological properties of rat Dorsal Column Nuclei neurons.
    The European journal of neuroscience, 1999
    Co-Authors: Angel Nuñez, Washington Buño
    Abstract:

    The Dorsal Column Nuclei include the gracile and cuneate Nuclei, which receive somatosensory information from the periphery and project to the ventroposterior nucleus of the contralateral thalamus. The aim of this study was to determine the electrophysiological and morphological characteristics of the neurons of the Dorsal Column Nuclei and to identify synaptic events evoked by electrical stimulation of the Dorsal Column, using an in vitro slice preparation. The results show two types of neurons, termed type I and II. A repolarizing sag distinguished type I cells during hyperpolarizing current injection, suggesting the activation of a Q-current. Moreover, type I cells, but not type II cells, were capable of maintaining spontaneous rhythmic activity at 9-15 Hz. Both types of cells displayed a delay in their return to the resting membrane potential following hyperpolarizing current pulses, indicating the existence of an A-current. Electrical stimuli applied to the Dorsal Column elicited brief EPSPs and IPSPs in both cell types. EPSPs were abolished by 6-cyano-7-nitroquinoxaline-2,3-dione, indicating that they were mediated through non-NMDA receptors. IPSPs were blocked by picrotoxin, implying the activation of GABAA receptors. Intracellular staining with carboxyfluoresceine revealed that type I neurons had elongated somas and primary dendrites that extended radially. Type II cells were smaller and had round somas with few primary dendrites, most of them emerging from one pole of the soma. The axon of many type I neurons was stained and could be followed running ventrally and in rostral direction.

  • Sensory information processing in the Dorsal Column Nuclei by neuronal oscillators
    Neuroscience, 1998
    Co-Authors: Fivos Panetsos, Angel Nuñez, Carlos Avendaño
    Abstract:

    The Dorsal Column Nuclei, a first relay station of the somatosensory system, express coherent oscillatory activity in the 4-22 Hz frequency range at single unit, multiunit and local field potential levels. This activity appears spontaneously (33% of the cases) or, more commonly (83%), during natural sensory stimulation of the receptive field. Such oscillations are not imposed upon the Dorsal Column Nuclei by incoming sensory afferents nor cortico-nuclear projections, which indicates that they are generated within the Dorsal Column Nuclei. We concluded that Dorsal Column Nuclei transform a non-rhythmic input from the periphery to a populational oscillatory output to the somatosensory thalamus during sensory stimulation.

Anders Blomqvist - One of the best experts on this subject based on the ideXlab platform.

  • Thalamic-projecting preprocholecystokinin messenger RNA-expressing neurons in the Dorsal Column Nuclei of the rat
    Neuroscience, 1997
    Co-Authors: S Farnebo, Ola Hermanson, Anders Blomqvist
    Abstract:

    This study aimed at investigating the expression of preprocholecystokinin messenger RNA among thalamic-projecting neurons in the Dorsal Column Nuclei of the rat. Thalamic-projecting neurons were identified by injection of cholera toxin subunit b into the ventroposterolateral nucleus. Following immunohistochemical detection of retrogradely transported tracer substance, the expression of preprocholecystokinin messenger RNA in the projection neurons of the Dorsal Column Nuclei was detected by in situ hybridization, using autoradiographic visualization of a 35S-labeled RNA probe complementary to preprocholecystokinin messenger RNA. Many preprocholecystokinin-expressing neurons were seen in the Dorsal Column Nuclei. A large proportion of these neurons were also labeled with cholera toxin. The double-labeled neurons, as well as neurons single-labeled with preprocholecystokinin messenger RNA or cholera toxin, were preferentially found within the middle region of the Dorsal Column Nuclei, located just caudal to the obex. These findings demonstrate that neurons in the Dorsal Column Nuclei express preprocholecystokinin messenger RNA, and show that these neurons provide a peptidergic projection from the Dorsal Column Nuclei to the ventroposterolateral nucleus of the thalamus. These observations suggest that cholecystokinin may be involved in the transmission of somatosensory (tactile) information from the Dorsal Column Nuclei to the thalamus.

  • Differential distribution of calcium-binding proteins in the Dorsal Column Nuclei of rats: a combined immunohistochemical and retrograde tract tracing study.
    Neuroscience, 1996
    Co-Authors: A. Magnusson, G. Dahlfors, Anders Blomqvist
    Abstract:

    This study aimed to investigate whether different calcium-binding proteins are present in morphologically and functionally separate cell groups in the Dorsal Column Nuclei of rats. Thalamic-projecting neurons were identified by iontophoretic injection of an intraaxonal tracer substance, choleragenoid, into the ventroposterolateral thalamic nucleus, which was localized by extracellular recordings of the responses to natural peripheral stimulation. The presence of the calcium-binding proteins calbindin and paravalbumin in the projection neurons was detected by a double-labelling immunofluorescent method. The vast majority of the thalamic-projecting neurons contained paravalbumin, but not all parvalbumin-immunoreactive cells were retrogradely labelled. Calbindin-immunoreactive neurons were also found in the Dorsal Column Nuclei, but only a small minority of these neurons projected to the thalamus. These findings are generally consistent with the notion that the different calcium-binding proteins represent functionally separate neuronal populations. Taken together with previous observations that parvalbumin is present in large Dorsal root ganglion cells, which project to the Dorsal Column Nuclei, and in the thalamocortical relay cells that receive Dorsal Column nuclear input, the present findings suggest that parvalbumin is associated with neurons that transmit modality-specific low-threshold mechanoreceptive information from the periphery to the somatosensory cortex. However, the presence of parvalbumin-immunoreactive cells that appeared not to project to the thalamus, as well as the occurrence of thalamic-projecting calbindin-immunoreactive neurons, indicate that parvalbumin and calbindin are present within several, functionally different, groups of neurons in the Dorsal Column Nuclei.

Joseph Wells - One of the best experts on this subject based on the ideXlab platform.

  • Peripherally evoked single unit responses in ventroposterolateral nucleus in the absence of the Dorsal Column Nuclei in rat
    Experimental brain research, 1991
    Co-Authors: W A Roberts, Joseph Wells
    Abstract:

    The present experiments were designed to determine the effects of removing the Dorsal Column Nuclei on the evoked responses of the ventroposterolateral nucleus (VPL) neurons in the rat. Previously, we have observed inhibitory interactions between forelimb and hindlimb inputs to VPL (Roberts and Wells 1990), and have also observed a synaptic recovery process within VPL following Dorsal Column Nuclei (DCN) lesions (Wells and Tripp 1987). In an attempt to describe any changes in VPL responses that correlate with the synaptic recovery in VPL following lesions to the DCN, we have studied the incidence of the inhibition process in VPL, the latency of activation of single unit VPL responses to peripheral nerve stimulation, the number of evoked unit responses observed per track studied and the somatotopy of responses in VPL. Dorsal Column Nuclei lesions did not alter the incidence or duration of the inhibitory interaction between forelimb and hindlimb inputs to VPL. Following DCN lesions, there was a significant increase in the latency to activation of VPL neurons by both forelimb and hindlimb inputs. This increase in latency returned to a non-significant difference from control over the same interval of time that is required for the structural recovery in VPL. There was a significant reduction in the number of evoked unit responses observed per track studied in the deafferented group at the twenty day post-lesion time course. This difference was no longer statistically significant in the sixty-four day post-lesion group. Finally, we have observed little change in the overall anatomic distribution of responses to forelimb or hindlimb stimulation in VPL following DCN lesions.(ABSTRACT TRUNCATED AT 250 WORDS)