scholarly journals Stimulus Parameters Influence Characteristics of Optical Intrinsic Signal Responses in Somatosensory Cortex

1995 ◽  
Vol 15 (6) ◽  
pp. 1109-1120 ◽  
Author(s):  
Anne J. Blood ◽  
Sanjiv M. Narayan ◽  
Arthur W. Toga
Keyword(s):  
Barrel Cortex ◽  
Stimulus Frequency ◽  
Onset Time ◽  
Absolute Number ◽  
Regions Of Interest ◽  
Response Magnitude ◽  
Intrinsic Signal ◽  
Time To Peak ◽  
Optical Intrinsic Signal ◽  
Signal Response

Optical imaging of intrinsic signals was performed in the barrel cortex of the rat during whisker deflections of varying frequencies (1 to 20 Hz) and durations (0.1 to 5 s). A dose–response relationship was shown between these stimuli and the characteristics of the optically recorded intrinsic signal response. At constant frequencies, longer stimulus durations increased response magnitude, as defined by mean pixel value in statistically determined regions of interest. At constant durations, higher stimulus frequencies increased response magnitude. Response magnitude was also increased by greater numbers of deflections. When stimulus number was constant, there were no differences in response magnitude, regardless of stimulus frequency and duration. Spatial extent of responses, as defined by number of pixels in regions of interest, did not differ between stimulus frequencies, durations, or numbers. Comparison of the time to reach peak intrinsic signal response after stimulus onset (“time-to-peak”) suggested that higher frequencies were associated with faster time-to-peak. Registration of intrinsic signal responses with cytochrome oxidase-stained whisker barrels demonstrated that responses were located over the barrel corresponding to the stimulated whisker. In summary, we have shown that the absolute number of stimuli delivered to the system is, at least for short stimulus periods (≤5 s), a determining factor for the magnitude of these responses, whereas stimulus frequency appears to influence time-to-peak response.

scholarly journals Temporally Staggered Forelimb Stimulation Modulates Barrel Cortex Optical Intrinsic Signal Responses to Whisker Stimulation

2002 ◽  
Vol 88 (1) ◽  
pp. 422-437 ◽  
Author(s):  
Anne J. Blood ◽  
Nader Pouratian ◽  
Arthur W. Toga
Keyword(s):  
Response Time ◽  
Time Course ◽  
Barrel Cortex ◽  
Functional Neuroimaging ◽  
Stimulus Onset ◽  
Response Magnitude ◽  
Intrinsic Signal ◽  
Time To Peak ◽  
Optical Intrinsic Signal ◽  
Whisker Stimulation

Characterization of neurovascular relationships is critical to accurate interpretation of functional neuroimaging data. We have previously observed spatial uncoupling of optical intrinsic signal imaging (OIS) and evoked potential (EP) responses in rodent barrel cortex following simultaneous whisker and forelimb stimulation, leading to changes in OIS response magnitude. To further test the hypothesis that this uncoupling may have resulted from “passive” overspill of perfusion-related responses between functional regions, we conducted the present study using temporally staggered rather than simultaneous whisker and forelimb stimulation. This paradigm minimized overlap of neural responses in barrel cortex and forelimb primary somatosensory cortex (SI), while maintaining overlap of vascular response time courses between regions. When contrasted with responses to 1.5-s lone-whisker stimulation, staggered whisker and forelimb stimulation resulted in broadening of barrel cortex OIS response time course in the temporal direction of forelimb stimulation. OIS response peaks were also temporally shifted toward the forelimb stimulation period; time-to-peak was shorter (relative to whisker stimulus onset) when forelimb stimulation preceded whisker stimulation and longer when forelimb stimulation followed whisker stimulation. In contrast with OIS and EP magnitude decreases previously observed during simultaneous whisker/forelimb stimulation, barrel cortex OIS response magnitude increased during staggered stimulation and no detectable changes in underlying EP activity were observed. Spatial extent of barrel cortex OIS responses also increased during staggered stimulation. These findings provide further evidence for spatial uncoupling of OIS and EP responses, and emphasize the importance of temporal stimulus properties on the effects of this uncoupling. It is hypothesized that spatial uncoupling is a result of passive overspill of perfusion-related responses into regions distinct from those which are functionally active. It will be important to consider potential influences of this uncoupling when designing and interpreting functional imaging studies that use hemodynamic responses to infer underlying neural activity.

scholarly journals Optical Intrinsic Signal Imaging Responses Are Modulated in Rodent Somatosensory Cortex during Simultaneous Whisker and Forelimb Stimulation

1998 ◽  
Vol 18 (9) ◽  
pp. 968-977 ◽  
Author(s):  
Anne J. Blood ◽  
Arthur W. Toga
Keyword(s):  
Evoked Potentials ◽  
Barrel Cortex ◽  
Response Magnitude ◽  
Response Patterns ◽  
Response Modulation ◽  
Intrinsic Signal ◽  
Optical Intrinsic Signal ◽  
Individual Trial ◽  
Cortical Responses ◽  
Different Response

Optical intrinsic signal imaging(OIS) was used to investigate physiologic interactions between spatially and functionally distinct cortical somatosensory systems. The OIS response magnitude was evaluated after simultaneous stimulation of single whiskers and forelimb digits. Whisker C1 was deflected at a frequency of 10 Hz for 2 seconds while low- or high-intensity vibratory stimuli were applied to forelimb digits. The OIS responses to simultaneous whisker and forelimb stimulation were compared with lone whisker stimulated controls. Overall, addition of a second stimulus caused decreases in barrel cortex response magnitude. Three different response patterns were detected within individual trial sets. Modulation of barrel cortex evoked potentials provided evidence that changes in OIS responses observed here may be partially influenced by vascular responses to changes in neuronal activity. However, OIS responses in the barrel region during lone forelimb stimulation that were unaccompanied by evoked potentials suggested the possibility of independent vascular dynamic influences on response modulation. This study demonstrates that cortical responses at the level of primary sensory processing may be significantly influenced by activity in adjacent regions. Furthermore, it reveals that vascular and neuronal characteristics of interregional modulation do not co-localize and may produce responses in which one component increases while the other decreases.

scholarly journals Spatial Integration of Vascular Changes with Neural Activity in Mouse Cortex

2002 ◽  
Vol 22 (3) ◽  
pp. 353-360 ◽  
Author(s):  
Joseph P. Erinjeri ◽  
Thomas A. Woolsey
Keyword(s):  
Real Time ◽  
Barrel Cortex ◽  
Brain Regions ◽  
Histochemical Staining ◽  
Spatial Integration ◽  
Intrinsic Signals ◽  
Intrinsic Signal ◽  
Cortical Columns ◽  
Optical Intrinsic Signal ◽  
Mouse Cortex

The authors evaluated representations of discretely activated, neighboring brain regions using real-time optical intrinsic signals by transcranial imaging with 540-nm and 610-nm broadband illumination of the mouse barrel cortex. Iron filings were glued to two neighboring whiskers (C2 + D2) that were stimulated magnetically, singly and together. Real-time images were collected, averaged, and analyzed statistically. Postmortem filling of arteries with fluorescent beads was shown in relation to histochemical staining of barrels to accurately relate surface changes to functional cortical columns. Significant optical intrinsic signal changes are related to overlapping distributions of arterioles that feed the two separate areas. Activation of adjacent and interacting cortical columns leads not only to increased magnitude of vascular responses in those columns, but also to wider spatial extent of absorption changes occurring principally in areas of cortex fed by vessels upstream of the active cortex. The localization of changing hemoglobin absorption around upstream blood vessels and their vascular domains suggests that propagated vasodilation of upstream parent vessels is greater when vasodilatory signals from separate areas of active cortex converge on common arterioles that feed them.

scholarly journals Encoding of Stimulus Frequency and Sensor Motion in the Posterior Medial Thalamic Nucleus

2008 ◽  
Vol 100 (2) ◽  
pp. 681-689 ◽  
Author(s):  
Radi Masri ◽  
Tatiana Bezdudnaya ◽  
Jason C. Trageser ◽  
Asaf Keller
Keyword(s):  
Barrel Cortex ◽  
Stimulus Frequency ◽  
Response Duration ◽  
Stimulation Frequency ◽  
Response Latencies ◽  
Medial Nucleus ◽  
Anesthetized Rats ◽  
Reticular Activating System ◽  
Parallel Streams ◽  
Posterior Medial Nucleus

In all sensory systems, information is processed along several parallel streams. In the vibrissa-to-barrel cortex system, these include the lemniscal system and the lesser-known paralemniscal system. The posterior medial nucleus (POm) is the thalamic structure associated with the latter pathway. Previous studies suggested that POm response latencies are positively correlated with stimulation frequency and negatively correlated with response duration, providing a basis for a phase locked loop-temporal decoding of stimulus frequency. We tested this hypothesis by analyzing response latencies of POm neurons, in both awake and anesthetized rats, to vibrissae deflections at frequencies between 0.3 and 11 Hz. We found no significant, systematic correlation between stimulation frequency and the latency or duration of POm responses. We obtained similar findings from recording in awake rats, in rats under different anesthetics, and in anesthetized rats in which the reticular activating system was stimulated. These findings suggest that stimulus frequency is not reliably reflected in response latency of POm neurons. We also tested the hypothesis that POm neurons respond preferentially to sensor motion, that is, they respond to whisking in air, without contacts. We recorded from awake, head-restrained rats while monitoring vibrissae movements. All POm neurons responded to passive whisker deflections, but none responded to noncontact whisking. Thus like their counterparts in the trigeminal ganglion, POm neurons may not reliably encode whisking kinematics. These observations suggest that POm neurons might not faithfully encode vibrissae inputs to provide reliable information on vibrissae movements or contacts.

Active force during hypoxia of hypertrophied rabbit right ventricular trabeculae

1987 ◽  
Vol 252 (5) ◽  
pp. H945-H952 ◽  
Author(s):  
M. A. Capeless ◽  
B. B. Hamrell
Keyword(s):  
Stimulus Frequency ◽  
Oxygen Demand ◽  
Peak Stress ◽  
Ringer Solution ◽  
Myocardial Oxygen Demand ◽  
Cross Sectional ◽  
Time To Peak ◽  
Hypertrophied Myocardium ◽  
Pulmonary Artery Constriction ◽  
Ventricular Trabeculae

Hypertrophy is often accompanied by increased myocardial oxygen demand, but any unique effects of hypoxia on contraction in hypertrophy are unknown. Trabeculae from normal [n = 9; 0.119 +/- 0.014 mm2 (means +/- SE) cross-sectional area] and hypertrophied (pulmonary artery constriction; n = 7; 0.108 +/- 0.028 mm2) rabbit right ventricles were subjected to graded hypoxia (Krebs-Ringer solution, 28 degrees C, 1 Hz stimulus frequency). During normoxia, peak active isometric (Pmax) and resting stress (Prest) at optimum length and peak rate of stress development (dP/dt) in hypertrophy were the same as normal and time to peak stress was longer than normal. Time to peak stress and dP/dt decreased with hypoxia, but time to peak stress remained longer than normal in hypertrophy; Prest was unchanged. The ratio of peak active stress (P) during hypoxia to Pmax decreased linearly with superfusate PO2, but the hypertrophy relationship (y = 4.00 X 10(-3) x + 0.084) is the same as normal (y = 3.70 X 10(-3) x + 0.154; p greater than 0.05). Therefore, a normal level of P was preserved in hypertrophied myocardium and prolonged time to peak stress might have been important for that preservation.

scholarly journals Plastic Change along the Intact Crossed Pathway in Acute Phase of Cerebral Ischemia Revealed by Optical Intrinsic Signal Imaging

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Xiaoli Guo ◽  
Yongzhi He ◽  
Hongyang Lu ◽  
Yao Li ◽  
Xin Su ◽  
...  
Keyword(s):  
Acute Phase ◽  
Response Pattern ◽  
Compensatory Response ◽  
Intrinsic Signal ◽  
Optical Intrinsic Signal ◽  
Somatosensory Input ◽  
Strong Stimulation ◽  
Photothrombotic Stroke ◽  
Plastic Change ◽  
Depressed Response

The intact crossed pathway via which the contralesional hemisphere responds to the ipsilesional somatosensory input has shown to be affected by unilateral stroke. The aim of this study was to investigate the plasticity of the intact crossed pathway in response to different intensities of stimulation in a rodent photothrombotic stroke model. Using optical intrinsic signal imaging, an overall increase of the contralesional cortical response was observed in the acute phase (≤48 hours) after stroke. In particular, the contralesional hyperactivation is more prominent under weak stimulations, while a strong stimulation would even elicit a depressed response. The results suggest a distinct stimulation-response pattern along the intact crossed pathway after stroke. We speculate that the contralesional hyperactivation under weak stimulations was due to the reorganization for compensatory response to the weak ipsilateral somatosensory input.

Blood volume and optical intrinsic signal imaging of cortical spreading depression

NeuroImage ◽  
2000 ◽  
Vol 11 (5) ◽  
pp. S770
Author(s):  
A.M. O'Farrell ◽  
D.E. Rex ◽  
A. Muthialu ◽  
G.K. Wong ◽  
N. Pouratian ◽  
...  
Keyword(s):  
Blood Volume ◽  
Cortical Spreading Depression ◽  
Spreading Depression ◽  
Intrinsic Signal ◽  
Optical Intrinsic Signal
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