Shubo Chakrabarti

Publications (9) View all

• Article: Choosing goals, not rules: deciding among rule-based action plans.

  Christian Klaes, Stephanie Westendorff, Shubhodeep Chakrabarti, Alexander Gail
  [show abstract] [hide abstract]
  ABSTRACT: In natural situations, movements are often directed toward locations different from that of the evoking sensory stimulus. Movement goals must then be inferred from the sensory cue based on rules. When there is uncertainty about the rule that applies for a given cue, planning a movement involves both choosing the relevant rule and computing the movement goal based on that rule. Under these conditions, it is not clear whether primates compute multiple movement goals based on all possible rules before choosing an action, or whether they first choose a rule and then only represent the movement goal associated with that rule. Supporting the former hypothesis, we show that neurons in the frontoparietal reach areas of monkeys simultaneously represent two different rule-based movement goals, which are biased by the monkeys' choice preferences. Apparently, primates choose between multiple behavioral options by weighing against each other the movement goals associated with each option.
  Neuron 05/2011; 70(3):536-48. · 14.74 Impact Factor
• Article: Expert-like performance of an autonomous spike tracking algorithm in isolating and maintaining single units in the macaque cortex.

  Chakrabarti S, Hebert P, Wolf MT, Campos M, Burdick JW, Gail A.
  J Neurosci Methods. 01/2011;
• Article: Differential response patterns in the si barrel and septal compartments during mechanical whisker stimulation.

  Shubhodeep Chakrabarti, Kevin D Alloway
  [show abstract] [hide abstract]
  ABSTRACT: A growing body of evidence suggests that the barrel and septal regions in layer IV of rat primary somatosensory (SI) cortex may represent separate processing channels. To assess this view, pairs of barrel and septal neurons were recorded simultaneously in the anesthetized rat while a 4x4 array of 16 whiskers was mechanically stimulated at 4, 8, 12, and 16 Hz. Compared with barrel neurons, regular-spiking septal neurons displayed greater increases in response latencies as the frequency of whisker stimulation increased. Cross-correlation analysis indicated that the incidence and strength of neuronal coordination varied with the relative spatial configuration (within vs. across rows) and compartmental location (barrel vs. septa) of the recorded neurons. Barrel and septal neurons were strongly coordinated if both neurons were in close proximity and resided in the same row. Some barrel neurons were weakly coordinated, but only if they resided in the same row. By contrast, the strength of coordination among pairs of septal neurons did not vary with their spatial proximity or their spatial configuration within the arcs and rows of the barrel field. These differential responses provide further support for the view that the barrel and septal regions represent the cortical gateway for processing streams that encode specific aspects of the sensorimotor information associated with whisking behavior.
  Journal of Neurophysiology 07/2009; 102(3):1632-46. · 3.32 Impact Factor
• Article: MI neuronal responses to peripheral whisker stimulation: relationship to neuronal activity in si barrels and septa.

  Shubhodeep Chakrabarti, Mengliang Zhang, Kevin D Alloway
  [show abstract] [hide abstract]
  ABSTRACT: The whisker region in the rodent primary motor (MI) cortex receives dense projections from neurons aligned with the layer IV septa in the whisker region of the primary somatosensory (SI) cortex. To compare whisker-induced responses in MI with respect to the SI responses in the septa and adjoining barrel regions, we used several experimental approaches in anesthetized rats. Reversible inactivation of SI and the surrounding cortex suppressed the magnitude of whisker-induced responses in the MI whisker region by 80%. Subsequent laminar analysis of MI responses to electrical or mechanical stimulation of the whisker pad revealed that the most responsive MI neurons were located >or=1.0 mm below the pia. When layer IV neurons in SI were recorded simultaneously with deep MI neurons during low-frequency (2-Hz) deflections of the whiskers, the neurons in the SI barrels responded 2-6 ms earlier than those in MI. Barrel neurons displayed similar response latencies at all stimulus frequencies, but the response latencies in MI and the SI septa increased significantly when the whiskers were deflected at frequencies of 8 Hz. Finally, cross-correlation analysis of neuronal activity in SI and MI revealed greater amounts of time-locked coordination among septa-MI neuron pairs than among barrel-MI neuron pairs. These results suggest that the somatosensory corticocortical inputs to MI cortex convey information processed by the SI septal circuits.
  Journal of Neurophysiology 07/2008; 100(1):50-63. · 3.32 Impact Factor
• Article: Topography of cortical projections to the dorsolateral neostriatum in rats: multiple overlapping sensorimotor pathways.

  Kevin D Alloway, Li Lou, Fidel Nwabueze-Ogbo, Shubhodeep Chakrabarti
  [show abstract] [hide abstract]
  ABSTRACT: In rodents, the whisker representation in primary somatosensory (SI) cortex projects to the dorsolateral neostriatum, but the location of these projections has never been characterized with respect to layer IV barrels and their intervening septa. To address this issue, we injected a retrograde tracer into the dorsolateral neostriatum and then reconstructed the location of the labeled corticostriatal neurons with respect to the cytochrome oxidase (CO)-labeled barrels in SI. When the tracer was restricted to a small focal site in the neostriatum, the retrogradely labeled neurons formed elongated strips that were parallel to the curvilinear orientation of layer IV barrel rows. After larger tracer injections, labeled neurons were distributed uniformly across layer V and were aligned with both the barrel and septal compartments. Labeled projections from the contralateral SI barrel cortex, however, were much fewer in number and were disproportionately associated with the septal compartments. A comparison of the labeling patterns in the ipsilateral and contralateral hemispheres revealed symmetric, mirror-image distributions that extended across primary motor cortex (MI) and multiple somatosensory cortical regions, including the secondary somatosensory (SII) cortex, the parietal ventral (PV) and parietal rhinal (PR) areas, and the posteromedial (PM) region. Examination of the thalamus revealed labeled neurons in the intralaminar nuclei, in the medial part of the posterior nucleus (POm), and in the ventrobasal complex. These results indicate that the dorsolateral neostriatum integrates sensorimotor information from multiple sensorimotor representations in the thalamus and cortex.
  The Journal of Comparative Neurology 12/2006; 499(1):33-48. · 3.81 Impact Factor