Broadening of activity with flow across neural structures (Lytton et al. 2008)

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Accession:116830
"Synfire chains have long been suggested as a substrate for perception and information processing in the nervous system. However, embedding activation chains in a densely connected nervous matrix risks spread of signal that will obscure or obliterate the message. We used computer modeling and physiological measurements in rat hippocampus to assess this problem of activity broadening. We simulated a series of neural modules with feedforward propagation and random connectivity within each module and from one module to the next. ..."
Reference:
1 . Lytton WW, Orman R, Stewart M (2008) Broadening of activity with flow across neural structures. Perception 37:401-7 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism:
Cell Type(s):
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Temporal Pattern Generation; Spatio-temporal Activity Patterns;
Implementer(s): Lytton, William [billl at neurosim.downstate.edu];
: $Id: misc.mod,v 1.14 2005/03/25 13:16:35 billl Exp $
COMMENT
Misc. routines:
sassign() // assign a string from system
dassign()// assign a double
nokill() // chatch SIGHUP
prtime() // gives date/time
fspitchar(c,file) // sends single char to a file
spitchar(c)       // sends single char to stdout: eg c=1 => ^A
file_exist(file) // returns 1 if filename exists
hocgetc(file) // get single char from a file

  Note that with a SUFFIX equal to "nothing" these functions do not
have a suffix in hoc.  Thus to call sassign() in hoc use simply type
"sassign()" <- without the quotes.

    file_exist(filename)
        - returns 1 if filename exists

    sassign()  (string assign, written by Bill Lytton)
        - This routine is used to set a string in Hoc to something that has
          been returned by a system call.  sassign("name","shell_call ...")
          will produce a file called "sassign" in the cwd that will contain
          a hoc call that sets string 'name' to the result of shell_call 
          which should be a string.
        
    dassign()  (double assign, written and used by Bill Lytton)
        - This routine is used to set a variable in Hoc to something that has
          been returned by a system call.  sassign("name","shell_call ...")
          will produce a file called "dassign" in the cwd that will contain
          a hoc call that sets variable 'name' to the result of shell_call 
          which should be a number.

ENDCOMMENT
                           
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
    SUFFIX nothing
}

VERBATIM
#include <unistd.h>     /* F_OK     */
#include <errno.h>      /* errno    */
#include <signal.h>
#include <sys/types.h>         /* MUST REMEMBER THIS */
#include <time.h>
#include <stdio.h>
#include <limits.h>
ENDVERBATIM

:* FUNCTION file_exist()
FUNCTION file_exist() {
VERBATIM
    /* Returns TRUE if file exists, if file not exist the need to reset
       errno else will get a nrnoc error.  Seems to be a problem even
       if I don't include <errno.h> */

    char *gargstr(), *filename;

    filename = gargstr(1);

    if (*filename && !access(filename, F_OK)) {
        _lfile_exist = 1;

    } else {
        /* Errno set to 2 when file not found */
        errno = 0;

        _lfile_exist = 0;
    }
ENDVERBATIM
}

:* PROCEDURE sassign()
PROCEDURE sassign() {
VERBATIM
    FILE *pipein;
    char string[BUFSIZ], **strname, *syscall;
    char** hoc_pgargstr();

    strname = hoc_pgargstr(1);
    syscall = gargstr(2);

    if( !(pipein = popen(syscall, "r"))) {
        fprintf(stderr,"System call failed\n");
        return; 
    }
    
    if (fgets(string,BUFSIZ,pipein) == NULL) {
        fprintf(stderr,"System call did not return a string\n");
        pclose(pipein); return;
    }

    /*  assign_hoc_str(strname, string, 0); */
    hoc_assign_str(strname, string);

    pclose(pipein);
    errno = 0;
ENDVERBATIM
}

:* PROCEDURE dassign() 
PROCEDURE dassign() {
VERBATIM
    FILE *pipein, *outfile;
    char *strname, *syscall;
    double num;

    strname = gargstr(1);
    syscall = gargstr(2);

    if ( !(outfile = fopen("dassign","w"))) {
        fprintf(stderr,"Can't open output file dassign\n");
        return; 
    }

    if( !(pipein = popen(syscall, "r"))) {
        fprintf(stderr,"System call failed\n");
        fclose(outfile); return; 
    }
    
    if (fscanf(pipein,"%lf",&num) != 1) {
        fprintf(stderr,"System call did not return a number\n");
        fclose(outfile); pclose(pipein); return; 
    }

    fprintf(outfile,"%s=%g\n",strname,num);
    fprintf(outfile,"system(\"rm dassign\")\n");

    fclose(outfile); pclose(pipein);
    errno = 0;
ENDVERBATIM
}

:* PROCEDURE nokill() 
: nohup
PROCEDURE nokill() {
VERBATIM
  signal(SIGHUP, SIG_IGN);
ENDVERBATIM
}

:* FUNCTION prtime()
FUNCTION prtime () {
VERBATIM
  double prt;
  static double PRTIME;
  prt = (clock()-PRTIME)/CLOCKS_PER_SEC;
  // UINT_MAX for 32 bit machine -- see 'man clock'
  if (prt<0) prt += UINT_MAX/CLOCKS_PER_SEC; 
  PRTIME=clock();
  _lprtime = prt;
ENDVERBATIM
}

:* FUNCTION now ()
FUNCTION now () {
VERBATIM
  _lnow = time((time_t*)0);
  _lnow -= (12784) * 24*60*60; // time from the Epoch to 01/01/05
ENDVERBATIM
}

:* PROCEDURE sleepfor ()
PROCEDURE sleepfor (sec) {
VERBATIM
  struct timespec ts;
  ts.tv_sec = (time_t)_lsec;
  ts.tv_nsec = (long)0;
  nanosleep(&ts,(struct timespec*)0);
ENDVERBATIM
}

:* PROCEDURE fspitchar
PROCEDURE fspitchar(c) {
VERBATIM
{	
  FILE* f, *hoc_obj_file_arg();
  f = hoc_obj_file_arg(2);
  fprintf(f, "%c", (int)_lc);
}
ENDVERBATIM
}

:* PROCEDURE spitchar
PROCEDURE spitchar(c) {
VERBATIM
{	
  printf("%c", (int)_lc);
}
ENDVERBATIM
}

:* FUNCTION hocgetc
FUNCTION hocgetc() {
VERBATIM
{	
  FILE* f, *hoc_obj_file_arg();
  f = hoc_obj_file_arg(1);
  _lhocgetc = (double)getc(f);
}
ENDVERBATIM
}

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