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Deviance detection by a P3-like response in rat posterior parietal cortex  [PDF]
Allicia Imada,Allyn Morris,Michael C. Wiest
Frontiers in Integrative Neuroscience , 2013, DOI: 10.3389/fnint.2012.00127
Abstract: To better understand sensory processing in frontal and parietal cortex of the rat, and to further assess the rat as a model of human frontal-parietal processing, we recorded local field potentials (LFPs) from microelectrode arrays implanted in medio-dorsal frontal, and posterior parietal cortex of awake rats as they were presented with a succession of frequent “standard” tones and infrequent “oddball” tones. Extending previous results from surface recordings we found, after controlling for the frequencies of the standard and oddball tones, that rat frontal and parietal-evoked LFPs (eLFPs) exhibit significantly larger N1 (~40 ms latency), P2 (~100 ms), N2 (~160 ms), P3E (~200–240 ms), and P3L (~300–500 ms) amplitudes after an oddball tone. These neural oddball effects could contribute to the automatic allocation of attention to rare stimuli. To determine whether these enhanced responses to rare stimuli could be accounted for in terms of stimulus-specific neural adaptation (SSA), we also recorded during single-tone control sessions involving frequent standard, or infrequent oddball beeps alone. We compared the difference between rare-tone and frequent-tone response amplitudes in the two-tone context (oddball effect) or single-tone context which isolates the contribution of SSA (SSA effect). An analysis of variance (ANOVA) revealed a significant main effect of tone context on rare-tone response enhancements, showing that the rare-tone enhancements were stronger in the two-tone context than the single-tone context. This difference between tone contexts was greatest at the early P3E peak (200–240 ms post-beep) in parietal cortex, suggesting true deviance detection by this evoked response component, which cannot be accounted for in terms of simple models of SSA.
Asymmetric Multisensory Interactions of Visual and Somatosensory Responses in a Region of the Rat Parietal Cortex  [PDF]
Michael T. Lippert, Kentaroh Takagaki, Christoph Kayser, Frank W. Ohl
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063631
Abstract: Perception greatly benefits from integrating multiple sensory cues into a unified percept. To study the neural mechanisms of sensory integration, model systems are required that allow the simultaneous assessment of activity and the use of techniques to affect individual neural processes in behaving animals. While rodents qualify for these requirements, little is known about multisensory integration and areas involved for this purpose in the rodent. Using optical imaging combined with laminar electrophysiological recordings, the rat parietal cortex was identified as an area where visual and somatosensory inputs converge and interact. Our results reveal similar response patterns to visual and somatosensory stimuli at the level of current source density (CSD) responses and multi-unit responses within a strip in parietal cortex. Surprisingly, a selective asymmetry was observed in multisensory interactions: when the somatosensory response preceded the visual response, supra-linear summation of CSD was observed, but the reverse stimulus order resulted in sub-linear effects in the CSD. This asymmetry was not present in multi-unit activity however, which showed consistently sub-linear interactions. These interactions were restricted to a specific temporal window, and pharmacological tests revealed significant local intra-cortical contributions to this phenomenon. Our results highlight the rodent parietal cortex as a system to model the neural underpinnings of multisensory processing in behaving animals and at the cellular level.
Visual categorization and the parietal cortex  [PDF]
Sruthi K. Swaminathan,David J. Freedman
Frontiers in Integrative Neuroscience , 2012, DOI: 10.3389/fnint.2012.00018
Abstract: The primate brain is adept at rapidly grouping items and events into functional classes, or categories, in order to recognize the significance of stimuli and guide behavior. Higher cognitive functions have traditionally been considered the domain of frontal areas. However, increasing evidence suggests that parietal cortex is also involved in categorical and associative processes. Previous work showed that the parietal cortex is highly involved in spatial processing, attention, and saccadic eye movement planning, and more recent studies have found decision-making signals in lateral intraparietal area (LIP). We recently found that a subdivision of parietal cortex, LIP, reflects learned categories for multiple types of visual stimuli. Additionally, a comparison of categorization signals in parietal and frontal areas found stronger and earlier categorization signals in parietal cortex arguing that, in trained animals, parietal abstract association or category signals are unlikely to arise via feedback from prefrontal cortex (PFC).
C-fos protein expression in the parietal cortex and olfactory tubercle in the hypoxic rat brain
Pu?ka? Laslo,Pu?ka? Nela,Babovi? Sini?a S.,Velicki Lazar
Medicinski Pregled , 2007, DOI: 10.2298/mpns0704128p
Abstract: Introduction. We have attempted to identify which parts of the brain react to ischemic attack using the four-vessel occlusion model in rats. Material and methods. We have monitored the expression of c-fos protein in the parietal cortex (R3 and T3) and in the olfactory tubercle (R4 and T4), regions which are supplied with blood by different arteries. The four-vessel occlusion was performed using the Pulsinelli’s method and rats were divided into two groups: total ischemia (ligation of four blood vessels or coagulation of the vertebral artheries with bilateral ligation of carotid arteries - R group) and transient ischemic attack (ligation of four blood vessels or coagulation of the vertebral arteries with bilateral repeated ligation of carotid arteries - T group of rats, the so- called preconditioned group). Each of these groups had a control group. Results and conclusion. The results showed pronounced expression of c-fos neurons in T group of rats which can explain longer survival of neurons. We believe that this model can serve as a good starting point to developing new approaches to the therapy of brain ischemia.
Efectos de la exposición prenatal a paraquat sobre el desarrollo de la transmisión sináptica aminoacídica en la corteza cerebral parietal del ratón Effects of prenatal expossure to paraquat on the development of amino acid synaptic transmission in mouse cerebral parietal cortex
Pedro Benítez-Díaz,Leticia Miranda-Contreras
Investigación Clínica , 2009,
Abstract: Se estudiaron los efectos de la exposición prenatal al paraquat (PQ), sobre el desarrollo postnatal de la transmisión sináptica aminoacídica de la corteza cerebral parietal del ratón. Las ratonas NMRI pre adas del grupo experimental recibieron 5 dosis de 10mg/kg de peso corporal de PQ, entre el día de gestación (G)12 y G20, y el grupo control recibió solución salina. Mediante HPLC, se determinaron los niveles de aspartato, glutamato, glicina, GABA y taurina de las crías, entre la edad postnatal (P)1 y P30. Entre P3 y P15, se observó un incremento significativo de los neurotransmisores excitatorios, aspartato y glutamato, en los ratones expuestos a PQ. Con respecto a la neurotransmisión inhibidora, los cambios más importantes se observaron en glicina: sus niveles se mantuvieron significativamente por debajo del grupo control entre P1 y P7, y significativamente por encima en P11 y P15. Para taurina, entre P1 y P7 sus niveles se mantuvieron significativamente altos con respecto al grupo control. En P30, los niveles de todos los neurotransmisores se encontraron significativamente por debajo del grupo control. En conclusión, podríamos decir que la exposición prenatal a PQ tuvo efectos tóxicos que se reflejaron en una alteración de los niveles basales de los neurotransmisores aminoacídicos durante el desarrollo postnatal de la corteza parietal del ratón, predominando la excitación sobre la inhibición durante todo el período estudiado. Estas alteraciones podrían indicar la ocurrencia de importantes da os corticales, tales como la disminución de algunas poblaciones neuronales, la inadecuada formación de los circuitos corticales y alteraciones en el proceso de sinaptogénesis. The effects of prenatal expossure to paraquat (PQ) were studied on postnatal development of mouse parietal cerebral cortex, in particular, the ontogenesis of amino acid synaptic transmission. Pregnant NMRI mice were separated into two groups: the experimental group received 5 doses of 10mg PQ/kg body weight, between days of gestation (G)12 and G20, whereas the control group received physiological saline solution. Levels of neurotransmitter amino acids: Asp, Glu, Gly, GABA and Tau were determined by HPLC between postnatal (P) days P1 and P30. Between P3 and P15, a significant increment in the levels of excitatory amino acids, Asp and Glu, were observed in mice exposed to PQ, as compared with the control group. With respect to the inhibitory neurotransmitter levels, in the group exposed to PQ, the more important changes were observed in Gly between P1 and P15. In relation to taurine, its leve
Representation of numerosity in posterior parietal cortex  [PDF]
Jamie D. Roitman,Elizabeth M. Brannon,Michael L. Platt
Frontiers in Integrative Neuroscience , 2012, DOI: 10.3389/fnint.2012.00025
Abstract: Humans and animals appear to share a similar representation of number as an analog magnitude on an internal, subjective scale. Neurological and neurophysiological data suggest that posterior parietal cortex (PPC) is a critical component of the circuits that form the basis of numerical abilities in humans. Patients with parietal lesions are impaired in their ability to access the deep meaning of numbers. Acalculiac patients with inferior parietal damage often have difficulty performing arithmetic (2 + 4?) or number bisection (what is between 3 and 5?) tasks, but are able to recite multiplication tables and read or write numerals. Functional imaging studies of neurologically intact humans performing subtraction, number comparison, and non-verbal magnitude comparison tasks show activity in areas within the intraparietal sulcus (IPS). Taken together, clinical cases and imaging studies support a critical role for parietal cortex in the mental manipulation of numerical quantities. Further, responses of single PPC neurons in non-human primates are sensitive to the numerosity of visual stimuli independent of low-level stimulus qualities. When monkeys are trained to make explicit judgments about the numerical value of such stimuli, PPC neurons encode their cardinal numerical value; without such training PPC neurons appear to encode numerical magnitude in an analog fashion. Here we suggest that the spatial and integrative properties of PPC neurons contribute to their critical role in numerical cognition.
Spatio-Temporal Updating in the Left Posterior Parietal Cortex  [PDF]
Makoto Wada, Kouji Takano, Shiro Ikegami, Hiroki Ora, Charles Spence, Kenji Kansaku
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0039800
Abstract: Adopting an unusual posture can sometimes give rise to paradoxical experiences. For example, the subjective ordering of successive unseen tactile stimuli delivered to the two arms can be affected when people cross them. A growing body of evidence now highlights the role played by the parietal cortex in spatio-temporal information processing when sensory stimuli are delivered to the body or when actions are executed; however, little is known about the neural basis of such paradoxical feelings resulting from such unusual limb positions. Here, we demonstrate increased fMRI activation in the left posterior parietal cortex when human participants adopted a crossed hands posture with their eyes closed. Furthermore, by assessing tactile temporal order judgments (TOJs) in the same individuals, we observed a positive association between activity in this area and the degree of reversal in TOJs resulting from crossing arms. The strongest positive association was observed in the left intraparietal sulcus. This result implies that the left posterior parietal cortex may be critically involved in monitoring limb position and in spatio-temporal binding when serial events are delivered to the limbs.
Involvement of the hippocampus, amygdala, entorhinal cortex and posterior parietal cortex in memory consolidation
Brazilian Journal of Medical and Biological Research , 1997, DOI: 10.1590/S0100-879X1997000200012
Abstract: a total of 182 young adult male wistar rats were bilaterally implanted with cannulae into the ca1 region of the dorsal hippocampus and into the amygdaloid nucleus, the entorhinal cortex, and the posterior parietal cortex. after recovery, the animals were trained in a step-down inhibitory avoidance task. at various times after training (0, 30, 60 or 90 min) the animals received a 0.5-μl microinfusion of vehicle (saline) or 0.5 μg of muscimol dissolved in the vehicle. a retention test was carried out 24 h after training. retention test performance was hindered by muscimol administered into both the hippocampus and amygdala at 0 but not at 30 min posttraining. the drug was amnestic when given into the entorhinal cortex 30, 60 or 90 min after training, or into the parietal cortex 60 or 90 min after training, but not before. these findings suggest a sequential entry operation, during the posttraining period, of the hippocampus and amygdala, the entorhinal cortex, and the posterior parietal cortex in memory processing
Involvement of the hippocampus, amygdala, entorhinal cortex and posterior parietal cortex in memory consolidation  [cached]
Zanatta M.S.,Quillfeldt J.H.,Schaeffer E.,Schmitz P.K.
Brazilian Journal of Medical and Biological Research , 1997,
Abstract: A total of 182 young adult male Wistar rats were bilaterally implanted with cannulae into the CA1 region of the dorsal hippocampus and into the amygdaloid nucleus, the entorhinal cortex, and the posterior parietal cortex. After recovery, the animals were trained in a step-down inhibitory avoidance task. At various times after training (0, 30, 60 or 90 min) the animals received a 0.5-μl microinfusion of vehicle (saline) or 0.5 μg of muscimol dissolved in the vehicle. A retention test was carried out 24 h after training. Retention test performance was hindered by muscimol administered into both the hippocampus and amygdala at 0 but not at 30 min posttraining. The drug was amnestic when given into the entorhinal cortex 30, 60 or 90 min after training, or into the parietal cortex 60 or 90 min after training, but not before. These findings suggest a sequential entry operation, during the posttraining period, of the hippocampus and amygdala, the entorhinal cortex, and the posterior parietal cortex in memory processing
Parietal Cortex Signals Come Unstuck in Time  [PDF]
Erik P. Cook,Christopher C. Pack
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1001414
Abstract: Humans and other animals are surprisingly adept at estimating the duration of temporal intervals, even without the use of watches and clocks. This ability is typically studied in the lab by asking observers to indicate their estimate of the time between two external sensory events. The results of such studies confirm that humans can accurately estimate durations on a variety of time scales. Although many brain areas are thought to contribute to the representation of elapsed time, recent neurophysiological studies have linked the parietal cortex in particular to the perception of sub-second time intervals. In this Primer, we describe previous work on parietal cortex and time perception, and we highlight the findings of a study published in this issue of PLOS Biology, in which Schneider and Ghose [1] characterize single-neuron responses during performance of a novel “Temporal Production” task. During temporal production, the observer must track the passage of time without anticipating any external sensory event, and it appears that the parietal cortex may use a unique strategy to support this type of measurement.
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