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Allitt BJ, Johnstone VPA, Richards KL, Yan EB, Rajan R. Progesterone Sharpens Temporal Response Profiles of Sensory Cortical Neurons in Animals Exposed to Traumatic Brain Injury. Cell Transplant 2018; 26:1202-1223. [PMID: 28933224 PMCID: PMC5657734 DOI: 10.1177/0963689717714326] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Traumatic brain injury (TBI) initiates a cascade of pathophysiological changes that are both complex and difficult to treat. Progesterone (P4) is a neuroprotective treatment option that has shown excellent preclinical benefits in the treatment of TBI, but these benefits have not translated well in the clinic. We have previously shown that P4 exacerbates the already hypoactive upper cortical responses in the short-term post-TBI and does not reduce upper cortical hyperactivity in the long term, and we concluded that there is no tangible benefit to sensory cortex firing strength. Here we examined the effects of P4 treatment on temporal coding resolution in the rodent sensory cortex in both the short term (4 d) and long term (8 wk) following impact-acceleration–induced TBI. We show that in the short-term postinjury, TBI has no effect on sensory cortex temporal resolution and that P4 also sharpens the response profile in all cortical layers in the uninjured brain and all layers other than layer 2 (L2) in the injured brain. In the long term, TBI broadens the response profile in all cortical layers despite firing rate hyperactivity being localized to upper cortical layers and P4 sharpens the response profile in TBI animals in all layers other than L2 and has no long-term effect in the sham brain. These results indicate that P4 has long-term effects on sensory coding that may translate to beneficial perceptual outcomes. The effects seen here, combined with previous beneficial preclinical data, emphasize that P4 is still a potential treatment option in ameliorating TBI-induced disorders.
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Affiliation(s)
- Benjamin J Allitt
- 1 Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Victoria P A Johnstone
- 1 Department of Physiology, Monash University, Clayton, Victoria, Australia.,2 School of Anatomy, Physiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia
| | - Katrina L Richards
- 1 Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Edwin B Yan
- 1 Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Ramesh Rajan
- 1 Department of Physiology, Monash University, Clayton, Victoria, Australia
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2
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Bourke JL, Quigley AF, Duchi S, O'Connell CD, Crook JM, Wallace GG, Cook MJ, Kapsa RM. Three‐dimensional neural cultures produce networks that mimic native brain activity. J Tissue Eng Regen Med 2017; 12:490-493. [DOI: 10.1002/term.2508] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 06/14/2017] [Accepted: 06/29/2017] [Indexed: 01/15/2023]
Affiliation(s)
- Justin L. Bourke
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Department of Medicine, St Vincent's Hospital Melbourne University of Melbourne Fitzroy VIC Australia
| | - Anita F. Quigley
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Department of Medicine, St Vincent's Hospital Melbourne University of Melbourne Fitzroy VIC Australia
- Intelligent Polymer Research Institute University of Wollongong NSW Australia
| | - Serena Duchi
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Intelligent Polymer Research Institute University of Wollongong NSW Australia
- Department of Surgery University of Melbourne, St Vincent's Hospital Fitzroy VIC Australia
| | - Cathal D. O'Connell
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Intelligent Polymer Research Institute University of Wollongong NSW Australia
| | - Jeremy M. Crook
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Intelligent Polymer Research Institute University of Wollongong NSW Australia
| | - Gordon G. Wallace
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Intelligent Polymer Research Institute University of Wollongong NSW Australia
| | - Mark J. Cook
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Department of Medicine, St Vincent's Hospital Melbourne University of Melbourne Fitzroy VIC Australia
| | - Robert M.I. Kapsa
- Australian Research Council Centre of Excellence for Electromaterials Science Australia
- Department of Medicine, St Vincent's Hospital Melbourne University of Melbourne Fitzroy VIC Australia
- Intelligent Polymer Research Institute University of Wollongong NSW Australia
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3
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Allitt BJ, Alwis DS, Rajan R. Laminar-specific encoding of texture elements in rat barrel cortex. J Physiol 2017; 595:7223-7247. [PMID: 28929510 PMCID: PMC5709323 DOI: 10.1113/jp274865] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 09/06/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS For rats texture discrimination is signalled by the large face whiskers by stick-slip events. Neural encoding of repetitive stick-slip events will be influenced by intrinsic properties of adaptation. We show that texture coding in the barrel cortex is laminar specific and follows a power function. Our results also show layer 2 codes for novel feature elements via robust firing rates and temporal fidelity. We conclude that texture coding relies on a subtle neural ensemble to provide important object information. ABSTRACT Texture discrimination by rats is exquisitely guided by fine-grain mechanical stick-slip motions of the face whiskers as they encounter, stick to and slip past successive texture-defining surface features such as bumps and grooves. Neural encoding of successive stick-slip texture events will be shaped by adaptation, common to all sensory systems, whereby receptor and neural responses to a stimulus are affected by responses to preceding stimuli, allowing resetting to signal novel information. Additionally, when a whisker is actively moved to contact and brush over surfaces, that motion itself generates neural responses that could cause adaptation of responses to subsequent stick-slip events. Nothing is known about encoding in the rat whisker system of stick-slip events defining textures of different grain or the influence of adaptation from whisker protraction or successive texture-defining stick-slip events. Here we recorded responses from halothane-anaesthetized rats in response to texture-defining stimuli applied to passive whiskers. We demonstrate that: across the columnar network of the whisker-recipient barrel cortex, adaptation in response to repetitive stick-slip events is strongest in uppermost layers and equally lower thereafter; neither whisker protraction speed nor stick-slip frequency impede encoding of stick-slip events at rates up to 34.08 Hz; and layer 2 normalizes responses to whisker protraction to resist effects on texture signalling. Thus, within laminar-specific response patterns, barrel cortex reliably encodes texture-defining elements even to high frequencies.
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Affiliation(s)
| | - Dasuni S. Alwis
- Department of PhysiologyMonash UniversityClaytonVIC3800Australia
| | - Ramesh Rajan
- Department of PhysiologyMonash UniversityClaytonVIC3800Australia
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4
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Allitt BJ, Iva P, Yan EB, Rajan R. Hypo-excitation across all cortical laminae defines intermediate stages of cortical neuronal dysfunction in diffuse traumatic brain injury. Neuroscience 2016; 334:290-308. [PMID: 27530700 DOI: 10.1016/j.neuroscience.2016.08.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/06/2016] [Accepted: 08/08/2016] [Indexed: 01/18/2023]
Abstract
Traumatic brain injury (TBI) is a major cause of morbidity and mortality world-wide and can result in persistent cognitive, sensory and behavioral dysfunction. Understanding the time course of TBI-induced pathology is essential to effective treatment outcomes. We induced TBI in rats using an impact acceleration method and tested for sensorimotor skill and sensory sensitivity behaviors for two weeks to find persistently poor outcomes post-injury. At two weeks post-injury we made high resolution extracellular recordings from barrel cortex neurons, to simple and complex whisker deflections. We found that the supragranular suppression of neural firing (compared to normal) previously seen in the immediate post-TBI aftermath had spread to include suppression of input and infragranular layers at two weeks post-injury; thus, there was suppression of whisker-driven firing rates in all cortical layers to both stimulus types. Further, there were abnormalities in temporal response patterns such that in layers 3-5 there was a temporal broadening of response patterns in response to both whisker deflection stimulus types and in L2 a narrowing of temporal patterns in response to the complex stimulus. Thus, at two weeks post-TBI, supragranular hypo-excitation has evolved to include deep cortical layers likely as a function of progressive atrophy and neurodegeneration. These results are consistent with the hypothesis that TBI alters the delicate excitatory/inhibitory balance in cortex and likely contributes to temporal broadening of responses and restricts the ability to code for complex sensory stimuli.
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Affiliation(s)
- Benjamin J Allitt
- Department of Physiology, Monash University, Clayton, VIC, Australia.
| | - Pippa Iva
- Department of Physiology, Monash University, Clayton, VIC, Australia.
| | - Edwin B Yan
- Department of Physiology, Monash University, Clayton, VIC, Australia.
| | - Ramesh Rajan
- Department of Physiology, Monash University, Clayton, VIC, Australia.
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5
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Alwis DS, Yan EB, Johnstone V, Carron S, Hellewell S, Morganti-Kossmann MC, Rajan R. Environmental Enrichment Attenuates Traumatic Brain Injury: Induced Neuronal Hyperexcitability in Supragranular Layers of Sensory Cortex. J Neurotrauma 2016; 33:1084-101. [DOI: 10.1089/neu.2014.3774] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Dasuni Sathsara Alwis
- Department of Physiology, Monash University, Clayton, VIC, Australia
- National Trauma Research Institute, Alfred Hospital, Prahran, VIC, Australia
| | - Edwin Bingbing Yan
- National Trauma Research Institute, Alfred Hospital, Prahran, VIC, Australia
| | | | - Simone Carron
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - Sarah Hellewell
- National Trauma Research Institute, Alfred Hospital, Prahran, VIC, Australia
| | | | - Ramesh Rajan
- Department of Physiology, Monash University, Clayton, VIC, Australia
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6
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Allitt BJ, Johnstone VPA, Richards K, Yan EB, Rajan R. Progesterone Exacerbates Short-Term Effects of Traumatic Brain Injury on Supragranular Responses in Sensory Cortex and Over-Excites Infragranular Responses in the Long Term. J Neurotrauma 2015; 33:375-89. [PMID: 26258958 DOI: 10.1089/neu.2015.3946] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Progesterone (P4) has been suggested as a neuroprotective agent for traumatic brain injury (TBI) because it ameliorates many post-TBI sequelae. We examined the effects of P4 treatment on the short-term (4 days post-TBI) and long-term (8 weeks post-TBI) aftermath on neuronal processing in the rodent sensory cortex of impact acceleration-induced diffuse TBI. We have previously reported that in sensory cortex, diffuse TBI induces a short-term hypoexcitation that is greatest in the supragranular layers and decreases with depth, but a long-term hyperexcitation that is exclusive to the supragranular layers. Now, adult male TBI-treated rats administered P4 showed, in the short term, even greater suppression in neural responses in supragranular layers but a reversal of the TBI-induced suppression in granular and infragranular layers. In long-term TBI there were only inconsistent effects of P4 on the TBI-induced hyperexcitation in supragranular responses but infragranular responses, which were not affected by TBI alone, were elevated by P4 treatment. Intriguingly, the effects in the injured brain were almost identical to P4 effects in the normal brain, as seen in sham control animals treated with P4: in the short term, P4 effects in the normal brain were identical to those exercised in the injured brain and in the long term, P4 effects in the normal brain were rather similar to what was seen in the TBI brain. Overall, these results provide no support for any protective effects of P4 treatment on neuronal encoding in diffuse TBI, and this was reflected in sensorimotor and other behavior tasks also tested here. Additionally, the effects suggest that mechanisms used for P4 effects in the normal brain are also intact in the injured brain.
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Affiliation(s)
- Benjamin J Allitt
- 1 Department of Physiology, Monash University , Clayton VIC, Australia
| | - Victoria P A Johnstone
- 1 Department of Physiology, Monash University , Clayton VIC, Australia .,2 Current address: School of Anatomy, Physiology & Human Biology, The University of Western Australia , Crawley WA, Australia
| | - Katrina Richards
- 1 Department of Physiology, Monash University , Clayton VIC, Australia
| | - Edwin B Yan
- 1 Department of Physiology, Monash University , Clayton VIC, Australia
| | - Ramesh Rajan
- 1 Department of Physiology, Monash University , Clayton VIC, Australia
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7
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Johnstone VPA, Wright DK, Wong K, O'Brien TJ, Rajan R, Shultz SR. Experimental Traumatic Brain Injury Results in Long-Term Recovery of Functional Responsiveness in Sensory Cortex but Persisting Structural Changes and Sensorimotor, Cognitive, and Emotional Deficits. J Neurotrauma 2015; 32:1333-46. [PMID: 25739059 DOI: 10.1089/neu.2014.3785] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Traumatic brain injury (TBI) is a leading cause of death worldwide. In recent studies, we have shown that experimental TBI caused an immediate (24-h post) suppression of neuronal processing, especially in supragranular cortical layers. We now examine the long-term effects of experimental TBI on the sensory cortex and how these changes may contribute to a range of TBI morbidities. Adult male Sprague-Dawley rats received either a moderate lateral fluid percussion injury (n=14) or a sham surgery (n=12) and 12 weeks of recovery before behavioral assessment, magnetic resonance imaging, and electrophysiological recordings from the barrel cortex. TBI rats demonstrated sensorimotor deficits, cognitive impairments, and anxiety-like behavior, and this was associated with significant atrophy of the barrel cortex and other brain structures. Extracellular recordings from ipsilateral barrel cortex revealed normal neuronal responsiveness and diffusion tensor MRI showed increased fractional anisotropy, axial diffusivity, and tract density within this region. These findings suggest that long-term recovery of neuronal responsiveness is owing to structural reorganization within this region. Therefore, it is likely that long-term structural and functional changes within sensory cortex post-TBI may allow for recovery of neuronal responsiveness, but that this recovery does not remediate all behavioral deficits.
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Affiliation(s)
| | - David K Wright
- 2 Anatomy and Neuroscience, The University of Melbourne, Parkville VIC, Australia, and The Florey Institute of Neuroscience and Mental Health , Parkville, VIC, Australia
| | - Kendrew Wong
- 3 Department of Medicine, The Royal Melbourne Hospital, The Melbourne Brain Center, The University of Melbourne , Parkville, VIC, Australia
| | - Terence J O'Brien
- 3 Department of Medicine, The Royal Melbourne Hospital, The Melbourne Brain Center, The University of Melbourne , Parkville, VIC, Australia
| | - Ramesh Rajan
- 4 Department of Physiology, Monash University , Clayton VIC, Australia
| | - Sandy R Shultz
- 3 Department of Medicine, The Royal Melbourne Hospital, The Melbourne Brain Center, The University of Melbourne , Parkville, VIC, Australia
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8
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Johnstone VP, Shultz SR, Yan EB, O'Brien TJ, Rajan R. The acute phase of mild traumatic brain injury is characterized by a distance-dependent neuronal hypoactivity. J Neurotrauma 2014; 31:1881-95. [PMID: 24927383 PMCID: PMC4224042 DOI: 10.1089/neu.2014.3343] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The consequences of mild traumatic brain injury (TBI) on neuronal functionality are only now being elucidated. We have now examined the changes in sensory encoding in the whisker-recipient barrel cortex and the brain tissue damage in the acute phase (24 h) after induction of TBI (n=9), with sham controls receiving surgery only (n=5). Injury was induced using the lateral fluid percussion injury method, which causes a mixture of focal and diffuse brain injury. Both population and single cell neuronal responses evoked by both simple and complex whisker stimuli revealed a suppression of activity that decreased with distance from the locus of injury both within a hemisphere and across hemispheres, with a greater extent of hypoactivity in ipsilateral barrel cortex compared with contralateral cortex. This was coupled with an increase in spontaneous output in Layer 5a, but only ipsilateral to the injury site. There was also disruption of axonal integrity in various regions in the ipsilateral but not contralateral hemisphere. These results complement our previous findings after mild diffuse-only TBI induced by the weight-drop impact acceleration method where, in the same acute post-injury phase, we found a similar depth-dependent hypoactivity in sensory cortex. This suggests a common sequelae of events in both diffuse TBI and mixed focal/diffuse TBI in the immediate post-injury period that then evolve over time to produce different long-term functional outcomes.
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Affiliation(s)
| | - Sandy R. Shultz
- Department of Medicine, The Royal Melbourne Hospital, The Melbourne Brain Centre, The University of Melbourne, Parkville, Victoria, Australia
| | - Edwin B. Yan
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, The Royal Melbourne Hospital, The Melbourne Brain Centre, The University of Melbourne, Parkville, Victoria, Australia
| | - Ramesh Rajan
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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9
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Grady SK, Hoang TT, Gautam SH, Shew WL. Millisecond, micron precision multi-whisker detector. PLoS One 2013; 8:e73357. [PMID: 24023861 PMCID: PMC3759455 DOI: 10.1371/journal.pone.0073357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 07/24/2013] [Indexed: 11/29/2022] Open
Abstract
The neural mechanisms of somatosensory information processing in the rodent vibrissae system are a topic of intense debate and research. Certain hypotheses emphasize the importance of stick-slip whisker motion, high-frequency resonant vibrations, and/or the ability to decode complex textures. Other hypotheses focus on the importance of integrating information from multiple whiskers. Tests of the former require measurements of whisker motion that achieve high spatiotemporal accuracy without altering the mechanical properties of whiskers. Tests of the latter require the ability to monitor the motion of multiple whiskers simultaneously. Here we present a device that achieves both these requirements for two-dimensional whisker motion in the plane perpendicular to the whiskers. Moreover, the system we present is significantly less expensive (<$2.5 k) and simpler to build than alternative devices which achieve similar detection capabilities. Our system is based on two laser diodes and two linear cameras. It attains millisecond temporal precision and micron spatial resolution. We developed automated algorithms for processing the data collected by our device and benchmarked their performance against manual detection by human visual inspection. By this measure, our detection was successful with less than 10 µm deviation between the automated and manual detection, on average. Here, we demonstrate its utility in anesthetized rats by measuring the motion of multiple whiskers in response to an air puff.
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Affiliation(s)
- Stephen K. Grady
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Thanh T. Hoang
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Shree Hari Gautam
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Woodrow L. Shew
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, United States of America
- * E-mail:
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10
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Alwis DS, Rajan R. Environmental enrichment causes a global potentiation of neuronal responses across stimulus complexity and lamina of sensory cortex. Front Cell Neurosci 2013; 7:124. [PMID: 23964199 PMCID: PMC3737482 DOI: 10.3389/fncel.2013.00124] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 07/20/2013] [Indexed: 01/21/2023] Open
Abstract
Enriched social and physical housing produces many molecular, anatomical, electrophysiological and behavior benefits even in adult animals. Much less is known of its effects on cortical electrophysiology, especially in how sensory cortex encodes the altered environment, and extant studies have generally been restricted to neurons in input laminae in sensory cortex. To extend the understanding of how an enriched environment alters the way in which cortex views the world, we investigated enrichment-induced changes in neuronal encoding of sensory stimuli across all laminae of the rat barrel cortex receiving input from the face whisker tactile system. Animals were housed in Enriched (n = 13) or Isolated housing (n = 13) conditions for 8 weeks before extracellular recordings were obtained from barrel cortex in response to simple whisker deflections and whisker motions modeling movements seen in awake animals undertaking a variety of different tasks. Enrichment resulted in increases in neuronal responses to all stimuli, ranging from those modeling exploratory behavior through to discrimination behaviors. These increases were seen throughout the cortex from supragranular layers through to input Layer 4 and for some stimuli, in infragranular Layer 5. The observed enrichment-induced effect is consistent with the postulate that enrichment causes shift in cortical excitatory/inhibitory balance, and we demonstrate this is greatest in supragranular layers. However, we also report that the effects are non-selective for stimulus parameters across a range of stimuli except for one modeling the likely use of whiskers by the rats in the enriched housing.
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Affiliation(s)
- Dasuni S Alwis
- Department of Physiology, Monash University Clayton, VIC, Australia
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11
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Yan EB, Johnstone VPA, Alwis DS, Morganti-Kossmann MC, Rajan R. Characterising effects of impact velocity on brain and behaviour in a model of diffuse traumatic axonal injury. Neuroscience 2013; 248:17-29. [PMID: 23735754 DOI: 10.1016/j.neuroscience.2013.05.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 05/20/2013] [Accepted: 05/22/2013] [Indexed: 11/17/2022]
Abstract
The velocity of impact between an object and the human head is a critical factor influencing brain injury outcomes but has not been explored in any detail in animal models. Here we provide a comprehensive overview of the interplay between impact velocity and injury severity in a well-established weight-drop impact acceleration (WDIA) model of diffuse brain injury in rodents. We modified the standard WDIA model to produce impact velocities of 5.4, 5.85 and 6.15 m/s while keeping constant the weight and the drop height. Gradations in impact velocity produced progressive degrees of injury severity measured behaviourally, electrophysiologically and anatomically, with the former two methods showing greater sensitivity to changes in impact velocity. There were impact velocity-dependent reductions in sensorimotor performance and in cortical depth-related depression of sensory cortex responses; however axonal injury (demonstrated by immunohistochemistry for β-amyloid precursor protein and neurofilament heavy-chain) was discernible only at the highest impact velocity. We conclude that the WDIA model is capable of producing graded axonal injury in a repeatable manner, and as such will prove useful in the study of the biomechanics, pathophysiology and potential treatment of diffuse axonal injury.
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Affiliation(s)
- E B Yan
- Department of Physiology, Monash University, Monash, VIC 3800, Australia
| | - V P A Johnstone
- Department of Physiology, Monash University, Monash, VIC 3800, Australia
| | - D S Alwis
- Department of Physiology, Monash University, Monash, VIC 3800, Australia
| | - M-C Morganti-Kossmann
- Department of Epidemiology and Preventive Medicine, Monash University and Australian New Zealand Centre of Intensive Care Research, VIC, Australia
| | - R Rajan
- Department of Physiology, Monash University, Monash, VIC 3800, Australia.
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12
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Johnstone VPA, Yan EB, Alwis DS, Rajan R. Cortical hypoexcitation defines neuronal responses in the immediate aftermath of traumatic brain injury. PLoS One 2013; 8:e63454. [PMID: 23667624 PMCID: PMC3646737 DOI: 10.1371/journal.pone.0063454] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 04/03/2013] [Indexed: 11/19/2022] Open
Abstract
Traumatic brain injury (TBI) from a blow to the head is often associated with complex patterns of brain abnormalities that accompany deficits in cognitive and motor function. Previously we reported that a long-term consequence of TBI, induced with a closed-head injury method modelling human car and sporting accidents, is neuronal hyper-excitation in the rat sensory barrel cortex that receives tactile input from the face whiskers. Hyper-excitation occurred only in supra-granular layers and was stronger to complex than simple stimuli. We now examine changes in the immediate aftermath of TBI induced with same injury method. At 24 hours post-trauma significant sensorimotor deficits were observed and characterisation of the cortical population neuronal responses at that time revealed a depth-dependent suppression of neuronal responses, with reduced responses from supragranular layers through to input layer IV, but not in infragranular layers. In addition, increased spontaneous firing rate was recorded in cortical layers IV and V. We postulate that this early post-injury suppression of cortical processing of sensory input accounts for immediate post-trauma sensory morbidity and sets into train events that resolve into long-term cortical hyper-excitability in upper sensory cortex layers that may account for long-term sensory hyper-sensitivity in humans with TBI.
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Affiliation(s)
| | | | | | - Ramesh Rajan
- Department of Physiology, Monash University, Monash, VIC, Australia
- * E-mail:
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13
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Alwis DS, Yan EB, Morganti-Kossmann MC, Rajan R. Sensory cortex underpinnings of traumatic brain injury deficits. PLoS One 2012; 7:e52169. [PMID: 23284921 PMCID: PMC3528746 DOI: 10.1371/journal.pone.0052169] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/14/2012] [Indexed: 01/12/2023] Open
Abstract
Traumatic brain injury (TBI) can result in persistent sensorimotor and cognitive deficits including long-term altered sensory processing. The few animal models of sensory cortical processing effects of TBI have been limited to examination of effects immediately after TBI and only in some layers of cortex. We have now used the rat whisker tactile system and the cortex processing whisker-derived input to provide a highly detailed description of TBI-induced long-term changes in neuronal responses across the entire columnar network in primary sensory cortex. Brain injury (n = 19) was induced using an impact acceleration method and sham controls received surgery only (n = 15). Animals were tested in a range of sensorimotor behaviour tasks prior to and up to 6 weeks post-injury when there were still significant sensorimotor behaviour deficits. At 8–10 weeks post-trauma, in terminal experiments, extracellular recordings were obtained from barrel cortex neurons in response to whisker motion, including motion that mimicked whisker motion observed in awake animals undertaking different tasks. In cortex, there were lamina-specific neuronal response alterations that appeared to reflect local circuit changes. Hyper-excitation was found only in supragranular layers involved in intra-areal processing and long-range integration, and only for stimulation with complex, naturalistic whisker motion patterns and not for stimulation with simple trapezoidal whisker motion. Thus TBI induces long-term directional changes in integrative sensory cortical layers that depend on the complexity of the incoming sensory information. The nature of these changes allow predictions as to what types of sensory processes may be affected in TBI and contribute to post-trauma sensorimotor deficits.
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Affiliation(s)
- Dasuni S. Alwis
- Department of Physiology, Monash University, Clayton, Victoria, Australia
- National Trauma Research Institute, Alfred Hospital, Prahran, Victoria, Australia
| | - Edwin B. Yan
- National Trauma Research Institute, Alfred Hospital, Prahran, Victoria, Australia
| | | | - Ramesh Rajan
- Department of Physiology, Monash University, Clayton, Victoria, Australia
- * E-mail:
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14
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Davis DJ, Sachdev R, Pieribone VA. Effect of high velocity, large amplitude stimuli on the spread of depolarization in S1 "barrel" cortex. Somatosens Mot Res 2011; 28:73-85. [PMID: 22150170 DOI: 10.3109/08990220.2011.613177] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We examined the effect of large, controlled whisker movements, delivered at a high speed, on the amplitude and spread of depolarization in the anesthetized mouse barrel cortex. The stimulus speed was varied between 1500 and 6000°/s and the extent of movement was varied between 4° and 16°. The rate of rise of the response was linearly related to the rate of rise of the stimulus. The initial spatial extent of cortical activation was also related to the rate of rise of the stimulus: that is, the faster the stimulus onset, the faster the rate of rise of the response, the larger the extent of cortex activated initially. The spatial extent of the response and the rate of rise of the response were not correlated with changes in the deflection amplitude. However, slower, longer lasting stimuli produced an Off response, making the actual extent of activation larger for the slowest rising stimuli. These results indicate that the spread of cortical activation depends on stimulus features.
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Affiliation(s)
- Douglas J Davis
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT, USA
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Wolfe J, Hill DN, Pahlavan S, Drew PJ, Kleinfeld D, Feldman DE. Texture coding in the rat whisker system: slip-stick versus differential resonance. PLoS Biol 2008; 6:e215. [PMID: 18752354 PMCID: PMC2525689 DOI: 10.1371/journal.pbio.0060215] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 07/21/2008] [Indexed: 11/18/2022] Open
Abstract
Rats discriminate surface textures using their whiskers (vibrissae), but how whiskers extract texture information, and how this information is encoded by the brain, are not known. In the resonance model, whisker motion across different textures excites mechanical resonance in distinct subsets of whiskers, due to variation across whiskers in resonance frequency, which varies with whisker length. Texture information is therefore encoded by the spatial pattern of activated whiskers. In the competing kinetic signature model, different textures excite resonance equally across whiskers, and instead, texture is encoded by characteristic, nonuniform temporal patterns of whisker motion. We tested these models by measuring whisker motion in awake, behaving rats whisking in air and onto sandpaper surfaces. Resonant motion was prominent during whisking in air, with fundamental frequencies ranging from approximately 35 Hz for the long Delta whisker to approximately 110 Hz for the shorter D3 whisker. Resonant vibrations also occurred while whisking against textures, but the amplitude of resonance within single whiskers was independent of texture, contradicting the resonance model. Rather, whiskers resonated transiently during discrete, high-velocity, and high-acceleration slip-stick events, which occurred prominently during whisking on surfaces. The rate and magnitude of slip-stick events varied systematically with texture. These results suggest that texture is encoded not by differential resonant motion across whiskers, but by the magnitude and temporal pattern of slip-stick motion. These findings predict a temporal code for texture in neural spike trains.
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Affiliation(s)
- Jason Wolfe
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Dan N Hill
- Section on Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Sohrab Pahlavan
- Section on Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Patrick J Drew
- Section on Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - David Kleinfeld
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Daniel E Feldman
- Section on Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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