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Neuroscience |
Current projects
Research group
Selected publications
Nucleo-olivary inhibition
This project concerns the function of the projection from
the deep nuclei of the cerebellum to the inferior olive. It was shown with
direct stimulation of the nucleo-olivary fibres (Hesslow 1986) and by indirect methods in collaboration with
Gert Andersson and Martin Garwicz (Andersson & Hesslow, 1987; Andersson, Garwicz & Hesslow, 1988) that
this pathway is inhibitory and GABA-ergic. Nelson, Barmack and Mugnaini showed that
the neurones contain GABA. We suggested that the cerebellar inhibition of the
olive is a negative feed-back mechanism, controlling both synapse-specific
cerebellar plasticity and general excitability of Purkinje and deep nuclear
cells. The first assumption was tested and confirmed by Hesslow
& Ivarsson (1996) and Fredrik Bengtsson
(2004) and the second assumption was
confirmed by Fredrik Bengtsson (2006). He has shown
that blocking the nucleo-olivary pathway causes an
increase in climbing fibre acitivity that is
sufficient to silence spontaneous activity in Purkinje cells. Anders Rasmussen,
Riccardo Zucca and Pär Svensson are currently working
on more subtle aspects of this control system.
Classical conditioning in cerebellar neurones
The third body of work, mainly done together with
Magnus Ivarsson and Pär Svensson, has addressed the role of the cerebellum in
classical conditioning. Hesslow (1994a,b) and (Ivarsson, Svensson & Hesslow, 1997) showed the role of several microzones in the cerebellar cortex in bilateral control of
conditioned eye-blink responses. Hesslow & Ivarsson (1996) supported the hypothesis that conditioned
responses via nucleo-olivary inhibition provides a
negative feed-back signal to the inferior olive. Recordings from Purkinje cells
(Hesslow & Ivarsson,1994) support the cerebellar
model of classical conditioning (Yeo and Hesslow, 1998). The most recent work has concerned the role
of the mossy fibre system as a pathway for the conditioned stimulus information
to the cerebellum (Svensson, Ivarsson
and Hesslow, 1997; Hesslow,
Svensson and Ivarsson,
1999).
Classical conditioning (popular account)
Classical conditioning in humans
We are currently pursuing a project for
studying human eyeblink conditioning. We are using a setup developed in Chris
de Zeeuw’s lab in Rotterdam by Bas Koekkokk, Henk-Jan Boele and Jan-Willem Potters for training humans with tone
and airpuffs. Blinks are monitored by measuring
changes in the magnetic field generated by a small magnet fastened on the
eyelid. The PhD student Karolina Löwgren is using the
setup for studying children with speech and language disabilities. The working
hypothesis is that the underlying problem for some of these children is a
cerebellar dysfunction.
Internal simulation of behaviour and perception
This is a theoretical project concerning possible
brain mechanisms for generating the inner world of consciousness and thinking. Hesslow (1994c, 2002) (and some papers listed under
Philosophy) suggest that the inner world arises as a consequence of the brain's
ability to generate its own input. A ’simulation’ theory of cognitive
function is developed. It is based on three core hypotheses about brain
function. First, it is assumed that behaviour can be simulated by activating
motor structures as during an overt action, but suppressing its execution. The
second assumption is that perception can be simulated by internal activation of
sensory cortex as during normal perception of external stimuli. Third, it is
assumed that both overt and covert actions can elicit perceptual simulation of
their normal consequences. A large body of evidence supports these assumptions.
It is argued that the simulation mechanism can explain many of the traditional
problems concerning consciousness and the inner world. The basic idea has now
been implemented in robot simulations by Dan-Anders Jirenhed, Magnus Johnsson and Tom Ziemke.
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The group descends from the research group headed by
Olov Oscarsson who was a
PhD student of Anders Lundberg and later worked under J.C. Eccles in |
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The research is mainly funded by The Swedish Medical
Research Council, Åhlenstiftelsen, Gyllenstierna-Krapperupstifelsen. |
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Members of the research group: |
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Germund Hesslow, Professor Fredrik Johansson, PhD student Karolina Löwgren, PhD
student Riccardo Zucca, PhD student
(Currently at Pompeu Fabra
University in Barcelona) |
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Hesslow G (1986), Inhibition of inferior olivary transmission by mesencephalic
stimulation in the cat, Neurosci Lett 63:76-80. |
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Andersson G, Hesslow G (1987),
Inferior olive excitability after high frequency climbing fibre activation in
the cat, Experimental Brain Research 67:523-532. |
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Andersson G, Garwicz M, Hesslow G (1988), Evidence for GABA-mediated cerebellar
inhibition of the inferior olive in the cat, Experimental Brain Research
72:450-456. |
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Hesslow G. (1994a) Correspondence between climbing fibre input and motor output in eyeblink related areas in cat cerebellar cortex. J Physiol 476:229-244. |
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Hesslow G (1994b). Inhibition of conditioned eye-blink responses by stimulation of the cerebellar cortex in the cat. J Physiol 476:245-256 . |
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Hesslow, G. (1994c) Will neuroscience explain consciousness? Journal of Theoretical Biology . 171:29-39 |
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Hesslow G. (1995). Classical conditioning of eyeblink in
decerebrate cats and ferrets. In Ferrell and Proske
(ed.) Neural Control of Movement. Plenum Press. pp 117-122. |
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Hesslow G, Ivarsson M (1994). Suppression of cerebellar Purkinje cells during conditioned responses in ferrets. Neuroreport 5:649-652. |
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Hesslow G, Ivarsson M (1996). Inhibition of the inferior olive during conditioned responses in the decerebrate ferret. Exp Brain Res, 10:36-46. |
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Svensson P, Ivarsson M and Hesslow G (1997). Effect of Varying the Intensity and Train Frequency of Forelimb and Cerebellar Mossy Fiber Conditioned Stimuli on the Latency of Conditioned Eye-Blink Responses in Decerebrate Ferrets. Learning & Memory, 4: 105-115. |
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Ivarsson M, Svensson P and Hesslow G (1997). Bilateral disruption of conditioned responses after unilateral blockade of cerebellar output in the decerebrate ferret. J Physiol , 502: 189-201. |
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Yeo CH and Hesslow G (1998).
Cerebellum and conditioned reflexes. Trends in Cognitive Sciences
, 2: 322-330. |
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Hesslow G, Svensson P and Ivarsson M (1999). Learned Movements Elicited by Direct Stimulation of Cerebellar Mossy Fiber Afferents. Neuron, 24: 179-185. |
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Hesslow, G. (2001) Medvetande som simulering av beteende och perception. I H. Lagercrantz (red) Hjärnan och medvetandet. Nya Doxa, Nora |
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Hesslow, G (2001) Lost in thought. Review of Rodolfo Llinás book I of the Vortex: From Neurons to Self |
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Hesslow, G. (2001) New lecture on consciousness. Powerpoint presentation. |
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Hesslow, G. (2002) Thinking as Simulation of Behaviour: an Associationist View of Cognitive Function |
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Hesslow, G. and Yeo, C.H. (2002)
The Functional Anatomy of Skeletal Conditioning. In Moore, J.W. (ed) A Neuroscientist's Guide to Classical Conditioning.
Springer, |
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Hesslow, G. (2002) Conscious thought as simulation of behaviour and perception. Trends in Cognitive Sciences, 6:242-247 |
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Bengtsson, F., Svensson, P and Hesslow, G. (2004) Feedback control of Purkinje cell activity by the cerebello-olivary pathway. European Journal of Neuroscience 20: 2999–3005 |
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Svensson, P, Bengtsson, F and Hesslow, G (2006) Cerebellar inhibition of inferior olivary transmission in the decerebrate ferret. Experimental Brain Research 168: 241-53 |
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Bengtsson F & Hesslow G (2006). Cerebellar Control of the Inferior Olive. Cerebellum 5: 7-14. |
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Jirenhed D-A, Bengtsson F, & Hesslow G (2007). Acquisition, Extinction, and Reacquisition of a Cerebellar Cortical Memory Trace. J Neurosci 27: 2493-2502 |
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Bengtsson F, Jirenhed D-A, Svensson P & Hesslow G (2007).
Extinction of conditioned blink responses by cerebello-olivary
pathway stimulation. NeuroReport 18: 1479-82 |
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Hesslow, G. (2007) Hjärnan och medvetandet. Hjärnan. K. Österberg (red.), Karolinska University Press, Stockholm. See under Philosophy |
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Rasmussen, A, Jirenhed, D.-A, Hesslow, G. (2008). Simple and Complex Spike Firing Patterns in Purkinje cells During Classical Conditioning. Cerebelllum. 7:563-566 |
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Svensson
P, Jirenhed DA, Bengtsson
F, Hesslow G (2010) Effect of Conditioned Stimulus
Parameters on Timing of Conditioned Purkinje Cell Responses. Journal of Neurophysiology
103:1329-1336. |
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Jirenhed D-A, Hesslow G (2011)
Learning Stimulus Intervals – Adaptive Timing of Conditioned Purkinje Cell
Responses. Cerebellum 10: 523-535 |
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Jirenhed D-A, Hesslow G (2011)
Time Course of Classically Conditioned Purkinje Cell Response is Determined
by Initial Part of Conditioned Stimulus.
Journal of Neuroscience. 31: 9070 –9074 |
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Johnsson, M., Martinsson, M., Gil,
D. and Hesslow, G. (2011). Associative
Self-Organizing Map. In Mwasiagi, J.I. (Ed), Self
Organising Maps - Applications and Novel Algorithm
Design, INTECH, 603-626. ISBN: 978-953-307-546-4 |
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Johnsson, M., Gil, D., Hesslow, G.
and Balkenius C. (2011). Internal Simulation in a
Bimodal System. Scandinavian Conference
on Artificial Intelligence (SCAI 2011), Norwegian University of Science
and Technology, Trondheim, Norway. |
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Bengtsson,F. and Hesslow,G.
(2012). Feedback control in the olivo-cerebellar
loop. In Manto M, Gruol
D, Schmahmann J, Koibuchi
N and Rossi F. (eds), The Handbook of the Cerebellum and Cerebellar Disorders. Springer. |
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Hesslow,G. (2012) Current status of the simulation theory of cognition. Brain Research 1428:71-79. |
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Current posters |
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