Molekuláris bionika és infobionika szakok tananyagának komplex

Neural Interfaces and Prostheses

György Karmos, Balázs 

Dombóvári, István Ulbert, Bálint 

Péter Kerekes 

Pázmány Péter Catholic University 

Faculty of Information Technology 

Budapest, Hungary 

[karmos,dombovari]@itk.ppke.hu,  

[e-mail],  

[e-mail]

Richárd Csercsa, Richárd 

Fiáth

Institute for Psychology 

Hungarian Academy of Sciences 

Budapest, Hungary 

[csercsa,fiath]@cogpsyphy.hu 

Ákos Kusnyerik 

Semmelweis University 

Dept. of Ophthalmology 

Budapest, Hungary 

[e-mail] 

The  course  makes  the  students  familiar 

with  the  new  developments  of  neural  engi-

neering in the field of neuroprosthetic devices 

that can substitute motor, sensory or cognitive 

functions that might have been damaged as a 

result of an injury or a disease. These devices 

make direct interfaces with the peripheral and 

central nervous system. Some of these devices 

are already routinely used in the clinical prac-

tice like the cochlear prostheses for restoring 

hearing others are still in the developmental or 

experimental phase. Neural interface is a con-

nection between the living tissue and a man-

made  device,  in  most  case  a  bioelectrode. 

Neuroprosthetic research is integrating differ-

ent  fields  of  medical  and  engineering  disci-

plines.  New  discoveries  in  this  field  are  al-

ways  the  result  of  close  collaboration  of  ex-

perts in most different areas of research. In the 

course we intend to give a survey of divergent 

areas of neuroprosthetics. 

In the first lectures of the course the basics 

of  bioelectrical  processes  of  nerve  cells  are 

summarized and the effects of electrical stim-

ulation  in  the  excitable  tissues  are  discussed. 

The electrical stimulation to activate peripher-

al nerves innervating muscles affected by pa-

ralysis  is  called  functional  electrical  stimula-

tion  (FES).  In  a  lecture  the  clinical  applica-

tions of FES combined by different forms of 

orthoses  are  discussed.  In  the  last  decade 

spectacular development was made in the neu-

ral control of limb prostheses. The nerve rein-

nervation  technique  resulted  in  the  develop-

ment of the “bionic arm” that is controlled by 

the intentions of the patient through myoelec-

tric signals.

Navigation  methods  like  stereotaxic  tech-

nique  and  frameless  neuronavigation  made 

possible minimal invasive neurosurgery. Neu-

ronavigation  is  based  on  fusion  of  CT,  MR, 

and angio images by a neurosurgical planning 

software. The planning software can precisely 

locate the size, shape and location of the brain 

tumor, lesion or abnormality. Modern “blood-

less  neurosurgery”  by  “Gamma  knife”  does 

not require the skull to be opened for perfor-

mance  of  the  operation.  Studies  demonstrate 

savings of more than 50% of direct costs as-

sociated with microsurgery. 

Stereotaxic  implantation  of  electrodes  in 

humans made possible the chronic deep brain 

stimulation  (DBS)  in  movement  disorders. 

The target area is also localized by recording 

of the neural activity along the electrode track. 

DBS is  a neurosurgical  treatment  involving 

the  implantation  of  a  battery-powered  neu-

rostimulator  which  sends  electrical  impulses 

to the target area of the brain through the im-

planted electrode. The neurostimulator is usu-

ally implanted under the skin of the chest and 

wires go under the skin to the electrodes. The 

patient  can  program  the  neurostimulator  by 

radiofrequency way. In the lecture the Parkin-

son’s  disease  is  used  as  an  example  since 

DBS  is  most  widely  and  most  successfully 

used  in  patients  suffering  in  medication  re-

sistant Parkinson’s disease. DBS is not a cure 

but suppresses the motor symptoms and high-

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ly improve the quality of life of the patients. 

In the last decade DBS also became generally 

accepted  as  treatment  in  dystonia,  essential 

tremor,  Tourette's  syndrome,  obsessive–

compulsive  disorder  and  depression.  The 

physiological mechanisms of the DBS are still 

not  clear.  The  different  hypotheses  are  dis-

cussed.  The  most  accepted  view  is  that  DBS 

has  a  suppressing  effect  on  the  pathological 

rhythm of the target area neuronal networks. 

A special noninvasive form of brain stimu-

lation is the transcranial magnetic stimulation 

(TMS).  TMS  apparatus  generate  rapidly 

changing magnetic field in a coil held close to 

the  head.  The  weak  electric  currents  induced 

by  this  magnetic  field  change  causes  excita-

tion or inhibition in the neurons of the stimu-

lated  area  of  the  brain.  TMS  causes minimal 

discomfort,  allowing  the  functioning  and  in-

terconnections of the brain to be studied. The 

TMS  lecture  deals  with  the  principles  and 

techniques of TMS and examples of possible 

clinical applications are mentioned. 

Sensory prostheses are the subjects of three 

lectures.  Two  of  them  deal  with  the  hearing 

aids. After a short introduction of the biology 

of hearing, the possibilities and types of audi-

tory  prostheses  will  be  detailed,  focusing 

mainly  on  cochlear  implants,  but  we  will

 show  other  solutions  too,  ranging  from  the 

middle  ear  implantable  hearing  devices  to 

methods in experimental stage like the audito-

ry  brainstem  implants  and  auditory  midbrain 

implants. The subjects of the third lecture are 

the visual prostheses. The retinal implants are 

discussed  in  more  detail  but  other  solutions 

like  stimulation  of  the  optic  nerve  and  the 

visual cortex are also mentioned. 

There  are  diseases  or  pathological  states 

when the muscle system of the patients is to-

tally paralyzed and they are unable keep con-

tact  with  their  environment.  A  special  group 

of  neuroprosthetic  devices,  the  “brain  com-

puter interfaces” (BCIs) give promise for the-

se  patients.  These  devices  translate  the  brain 

electrical signals for communication with the 

external world as well as for manipulation of 

technical  devices  such  prostheses  and  micro-

processors.  We  devoted  three  lectures  to  this 

topic giving detailed survey of both noninva-

sive and invasive BCIs. The present day BCI 

systems  are  in  experimental  phase but  some 

noninvasive  BCIs  are  already  commercially 

available.  A  new  area  of  BCI  application  is 

the  games  and  virtual  reality.  BCI  research 

became very popular in the recent years, new 

applications will emerge and the BCI systems 

will become part of our everyday life. 

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