another Dognitive Science seminar

[Gary Cottrell]

                                      SEMINAR

                            Oscillations in Dog Cortex:
                                   A new approach

                                Garrison W. Cottrell
                             Department of Dog Science
                      Southern California Condominium College


          Recent work (Blackie & Wolf, 1990) has shown that when  a  canine  is
     attending  a  stimulus,  the  neurons  representing  that stimulus fire in
     synchrony.  It has been suggested that  this is the mechanism by which the
     stimulus features are bound together in the dog's brain.  It has also been
     suggested that whole object recognition occurs in  the  Inferior  Temporal
     (IT) Cortex of  the  dog[1].   The  question  then  arises:  How  are  the
     oscillations  in  one  part  of  the  brain used by the object recognition
     system in another part? If IT is indeed an  inferior  temporal  processor,
     how could it possibly make use of such temporal information?

          Part of the problem in studying such  phenomena  is  that  the  brain
     processes  things  so  fast, it is difficult to measure recognition events
     among the blooming, buzzing confusion in the  cortex.   Hence  we  suggest
     that  the  ideal  subjects for studying such processes are older dogs, who
     appear to have far fewer neurons[2], and those that remain run at  a  much
     more leisurely pace.  A second reason for studying elderly  dogs  is  that
     they  sleep  a great deal, and this is an ideal time to study the baseline
     activity of recognition system.  If the Boltzdogg machine model (Hilton  &
     Slugowski,  1986)  is  correct,  the  oscillations  observed  during sleep
     reflect the structure of the system in isolation from the environment.

          There are many difficulties in assessing brain activity.  Single cell
     recordings  are  at  too  low  a level to asses symbolic activity.  Evoked
     potential studies are good at  temporal  resolution  but  poor  at  source
     identification.   PET  studies  are  useful for localization but have poor
     temporal resolution[3].  We have discovered a non-invasive  technique  for
     studying  oscillations  in dog brains that also gives us the sources in an
     unambiguous way.  We have found that,  contrary  to  popular  belief,  leg
     locomotion  during  sleep  does  not mean that dogs are chasing rabbits in
     their dreams.  Rather, neuromodulators released during  sleep  rewire  the
     output  of  the  recognition system to the leg musculature.  Thus, the leg
     twitches are a direct reflection of  cortical  oscillations  in  the  four
     complex object recognition regions[4] in  the  dog  brain.   An  immediate
     observation is that the food & master (left &  right  rear  legs)  regions
     oscillate 180 degrees out of phase with the sex & cat face regions (left &
     right front legs).  Thus one can observe right away that representation is
     a  process,  since  just  like  a  computer  process,  this  one runs, and
     eventually halts.  The major difference is that  this  process  runs  when
     asleep (cf. Unix(tm) sleep(1)).

     This is a great new instrument for assessing the behavior  of  the  brain,
     since  we avoid problems with animal rights people by using a non-invasive
     technique.  Since the older dog is asleep so much, he presents a  terrific
     wealth  of  data  on  brain  activity.   On  a more philosophical note, it
     suggests that meaning representations are oscillations all the way down  -
     suggesting  that  West Coast researchers that are into "getting the vibes"
     are not that  far  off  in  their  approach.   The  dogleg  technology  is
     certainly  giving  Dognitive  Science  a leg up on what's happening in the
     dog's brain.

     A live demonstration of leg twitching during sleep will  be  presented  at
     the talk.
     ------------
        [1]It is unclear why this part of cortex  is  deemed  to  be  inferior,
     since  it plays such an important role.  Some have suggested that the name
     means that it is bad at temporal processing, and makes up for this lack by
     being good at spatial processing.
        [2]Some  believe  that  older dogs' grandmother cells have gone to rest
     homes.  And, although researchers can't agree whether  these  neurons  are
     simply  decaying  or  are  being actively suppressed, it must be true that
     they can't have all checked out, since Jellybean at 15;10 still recognizes
     his  food.   However,  he also recognizes grass, dirt, and rotting logs as
     food, which suggests a degraded distributed representation.
        [3]Aside from the fact that they do not record activity, CAT scans  are
     obviously an inappropriate tool for studying dognition.
        [4]It  is  generally accepted that the four recognition systems are di-
     vided modularly into the FOOD, OPPOSITE SEX, MASTER and CAT FACES regions.
     However,  there  is some argument whether the latter region is recognizing
     cat faces, upside down monkey faces, or paint brushes (Parrot, 1989).