"From Simple Associations to Systematic Reasoning"

We are capable of drawing a variety of inferences effortlessly, spontaneously, and with remarkable efficiency --- as though these inferences are a reflex response of our cognitive apparatus. This remarkable human ability poses a challenge for cognitive science and computational neuroscience: How can a system of slow neuron-like elements represent a large body of systematic knowledge and perform a wide range of inferences with such speed?

SHRUTI attempts to address this challenge by demonstrating how a connectionist network can encode a large body of semantic and episodic facts, systematic rule-like mappings, knowledge about entities, and types, and yet perform a wide range of reflexive inferences within a few hundred milliseconds.

Relational structures (frames, schemas) are represented in SHRUTI by focal clusters of cells, and inference in SHRUTI corresponds to a transient propagation of rhythmic activity over such cell-clusters. Dynamic bindings between roles and entities are represented within such a rhythmic activity by the synchronous firing of appropriate role and entity cells. Rules correspond to high-efficacy links between cell-clusters, and long-term facts correspond to coincidence and coincidence-failure detector circuits. In particular, SHRUTI demonstrates that temporal synchrony in conjunction with structured neural representations suffices to support rather complex forms of relational information processing in the brain.

SHRUTI's representational machinery has been augmented to represent beliefs as well as utilities and actions (X-schemas). The resulting system propagates utilities and beliefs over a single underlying causal structure to make predictions, seek explanations, and identify actions that increase expected future utility. In on going work, neurally plausible mechanisms for control and decision-making are being developed for SHRUTI. The integration of these mechanisms with SHRUTI would lead to - SHRUTI-agent - a connectionist architecture capable of decision making, problem solving, and planning.

The SHRUTI project meshes with the NTL project on language acquisition and provides connectionist solutions for representational and computational issues arising in the project.


  • Lokendra Shastri      - Principal Investigator
  • Carter Wendelken    - graduate student
  • V. Ajjanagadde         - alumnus
  • D.R. Mani                  - alumnus
  • Dean J. Grannes        - alumnus
  • Publications:

    A list of publication may be found here

    External Collaboration:

    The reflexive reasoning abilities of SHRUTI can be integrated with a reflective (i.e., meta-cognitive) component resulting in a hybrid system capable of attention shifting, conflict detection, and the reflective evaluation of assumptions and alternate interpretations. This work was done in collaboration with Marvin Cohen and Bryan Thompson ; of Cognitive Technologies.

    Related Projects:

    SMRITI: Episodic Memory Formation in the Hippocampal System.

    Research Agents and Inferential Retrieval.


    Here are some demos generated using the SHRUTI simulator:

    Heading to the postoffice on President's Day.

    John fell in the hallway.

    View the SHRUTI submission to ACNN96

    ACNN'96 by clicking here.


    Research on SHRUTI has been supported by the following: NSF grants ECS-9970890, SBR-9720398 and IRI 88-05465, ONR grant N00014-93-1-1149, and DoD grant MDA904-96-C-1156. Subcontracts from Cognitive Technologies Inc. under ONR grant N00014-95-C-0182 and ARI Contract DASW01-97-C-0038. ARO grants DAA29-84-9-0027 and DAAL03-89-C-0031 to the AI Research Center, the University of Pennsylvania, DFG grant Schr 275/7-1 to V. Ajjanagadde, and ICSI general funds. Work on the CM-5 version of Shruti was supported by NSF Infrastructure Grant CDA-8722788 to L. Shastri.

    Why "SHRUTI"?

    "SHRUTI" is a Sanskrit word which refers to the oral tradition of communicating knowledge. In oral communication, knowledge is encoded as a transient and dynamic pattern of (acoustic) energy. This resonates with the functioning of SHRUTI where reasoning is the transient propagation of a rhythmic pattern of activity.