Germund Hesslow - Academia.edu (original) (raw)

Uploads

Papers by Germund Hesslow

Research paper thumbnail of Bilateral disruption of conditioned responses after unilateral blockade of cerebellar output in the decerebrate ferret

The Journal of Physiology, 1997

Lesions of the cerebellar cortex can abolish classically conditioned eyeblink responses, but some... more Lesions of the cerebellar cortex can abolish classically conditioned eyeblink responses, but some recovery with retraining has been observed. It has been suggested that the recovered responses are generated by the intact contralateral cerebellar hemisphere. In order to investigate this suggestion, bilaterally acquired conditioned responses were studied after the unilateral blockade of cerebellar output. Decerebrate ferrets were trained with ipsilateral electrical forelimb stimulation (300 ms, 50 Hz, 1 mA) as the conditioned stimulus and bilaterally applied peri‐orbital stimulation (40 ms, 50 Hz, 3 mA) as the unconditioned stimulus. The conditioned and unconditioned eyeblink responses were monitored by EMG recordings from the orbicularis oculi muscle. The output from one cerebellar hemisphere was blocked either by injecting small amounts of lignocaine (lidocaine; 0.5‐1.0μl)) into the brachium conjunctivum, or by a restricted mechanical lesion of the brainstem rostral to the cerebellu...

Research paper thumbnail of Dendritic plateau potentials evoked in Purkinje cells by parallel fibre volleys in the cat

The Journal of Physiology, 1983

Responses evoked in Purkinje cell dendrites by parallel fibre volleys and climbing fibre impulses... more Responses evoked in Purkinje cell dendrites by parallel fibre volleys and climbing fibre impulses were investigated by intra‐ and extracellular recording from cat cerebellar cortex. The depth distribution of recording sites suggested that the intracellular recordings were predominantly from proximal dendrites whereas the extracellular recordings were predominantly from distal dendrites. Parallel fibre stimulation evoked monosynaptic excitation and disynaptic inhibition in the dendrites and, at higher strength, prolonged plateau‐like responses in distal dendrites but only rarely in proximal dendrites. However, when the inhibitory synapses were blocked with topically applied picrotoxin, parallel fibre volleys evoked plateau potentials also in proximal dendrites. The duration of the parallel‐fibre‐evoked plateau potentials in distal dendrites was prolonged by increasing the intensity of the eliciting stimulus or by increasing the number of stimuli. A similar prolongation in the duratio...

Research paper thumbnail of A closed-loop framework to investigate cerebellar learning in a decerebrated ferret preparation

Research paper thumbnail of Associative Self-Organizing Map

Research paper thumbnail of The transitivity of causation

Research paper thumbnail of The problem of causal selection

A positioning apparatus includes a master hydraulic positioning cylinder having a relatively long... more A positioning apparatus includes a master hydraulic positioning cylinder having a relatively long stroke capability and a train of additively connected, short-stroke pneumatic control cylinders for controlling the length of stroke of the master cylinder and thus the positioning of a variable-position tool such as a band saw. One end of the cylinder train is connected by a feedback rod to an extensible portion of the master cylinder. A connecting rod connects the opposite end of the train directly to the spool of a three-position servo valve which controls the flow of hydraulic fluid to and from opposite sides of the master cylinder. When air pressure is admitted to a selected side of a selected control cylinder, at least a portion of the train shifts initially in a direction to move the servo valve to an operating position to begin stroking the master cylinder in a desired direction. Stroking movement of the master cylinder is transmitted through the feedback rod to the train to stroke the selected control cylinder until its piston bottoms out, after which continued stroking of the master cylinder shifts the train to close the servo valve and stop the master cylinder when it has stroked through a distance corresponding to the full stroke of the selected control cylinder. The cylinder train includes a pair of "lost motion" cylinders enabling movement of the train beyond the limits of movement of the servo valve. This lost motion of the train activates a high-speed valve in the hydraulic circuit to stroke the master cylinder at high speed and a "final set" cylinder in the train to ensure that final stroking of the master cylinder to a selected setting always occurs from the same direction to eliminate setting errors from lost motion in the system. A lockout valve in the hydraulic system overrides the servo and high-speed valves when the controlled tool is in an operating condition to block flow to the master cylinder and prevent possible damage to the tool or positioning apparatus.

Research paper thumbnail of Changes in complex spike activity during classical conditioning

Frontiers in Neural Circuits, Aug 5, 2014

The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink c... more The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink conditioning. During conditioning, Purkinje cells acquire pause responses or "Purkinje cell CRs" to the conditioned stimuli (CS), resulting in disinhibition of the cerebellar nuclei (CN), allowing them to activate motor nuclei that control eyeblinks. This disinhibition also causes inhibition of the inferior olive (IO), via the nucleo-olivary pathway (N-O). Activation of the IO, which relays the unconditional stimulus (US) to the cortex, elicits characteristic complex spikes in Purkinje cells. Although Purkinje cell activity, as well as stimulation of the CN, is known to influence IO activity, much remains to be learned about the way that learned changes in simple spike firing affects the IO. In the present study, we analyzed changes in simple and complex spike firing, in extracellular Purkinje cell records, from the C3 zone, in decerebrate ferrets undergoing training in a conditioning paradigm. In agreement with the NO feedback hypothesis, acquisition resulted in a gradual decrease in complex spike activity during the conditioned stimulus, with a delay that is consistent with the long NO latency. Also supporting the feedback hypothesis, training with a short interstimulus interval (ISI), which does not lead to acquisition of a Purkinje cell CR, did not cause a suppression of complex spike activity. In contrast, observations that extinction did not lead to a recovery in complex spike activity and the irregular patterns of simple and complex spike activity after the conditioned stimulus are less conclusive.

Research paper thumbnail of Hjärnan och medvetandet

Research paper thumbnail of A closed-loop framework to investigate cerebellar learning in a decerebrated ferret preparation

Research paper thumbnail of Neural Network Architecture for Crossmodal Activation and Perceptual Sequences

A self-organizing neural network is described that can associate between different modalities and... more A self-organizing neural network is described that can associate between different modalities and also has the ability to learn perceptual sequences. This architecture is a step towards the development of a complete agent containing simplified versions of all major neural subsystems in a mammal. It aims at exploring as well as takes inspiration from the idea that cognitive function involves an internal simulation of perception and movement. We have tested the architecture in simulations as well as together with real sensors with very encouraging results. Perceptul activity in the brain is normally elicited from the sense organs, but it has recently been argued that a crucial aspect of cognitive function in biological organisms is the ability to simulate perception, that is, to elicit perceptual activity from other brain areas rather than via sensory afferents (Hesslow, 2002; Grush, 2004). Among other things, perceptual simulation could explain the appearance of an inner world (Hesslow and Jirenhed, 2007) and also how an organism could try out various courses of action 'in the mind'. One plausible source of simulated perceptual activity might be activity in another sensory modality. A familiar example is when the texture of an object that is felt in the pocket can evoke visual images/expectations of the object. A more dramatic biological illustration is the McGurk-MacDonald effect. If you hear a person making the sound /ba/ but the sound is superimposed on a video recording on which you do not see the lips closing, you may hear the sound /da/ instead (McGurk and MacDonald, 1976). Accordingly, a bio-inspired autonomous robot should be able to learn on its own and to automatically develop sensory representations of its different sensory modalities. These representations should also co-develop so that suitable activity in some modalities elicits appropriate activity in other sensory modalities as well. It would also be desirable with an ability to remember perceptual sequences, and that a corresponding sequence of activity evokes a suitable sequence of activity in the other modalities of the robot. With these traits a robot learning to navigate through an environment could remember a sequence of e.g. visual land

Research paper thumbnail of Effect of ethanol on the excitability of the inferior olive in decerebrate ferret

PubMed, May 1, 1996

Climbing fibers, which originate in the inferior olive and project to Purkinje cells and Golgi ce... more Climbing fibers, which originate in the inferior olive and project to Purkinje cells and Golgi cells in the cerebral cortex, were activated at low (0.4-Hz) and high (4-Hz) frequencies by periorbital stimulation in decerebrate ferrets. Climbing fiber responses were recorded as field potentials from the c3 zone of the cerebellar surface. When periorbital stimulation was applied at high frequency, the climbing fiber responses became strongly depressed within a few seconds. It has previously been shown that this high frequency depression (HFD) of climbing fiber responses is due to a cerebellar inhibition of the inferior olive, probably via the nucleo-olivary pathway. Acute administration of ethanol had small and variable effects on the amplitude of climbing fiber responses evoked by low-frequency stimulation. In contrast, medium concentrations (0.44-2.90 g/l) of ethanol led to a marked reduction of the HFD. Low ( < 0.44 g/l) systemic concentrations had no measurable effects on the HFD, whereas high concentrations ( > 2.90 g/l) caused either an increased HFD or a nonseptic reduction in olivary excitability. Because HFD has previously been shown to involve cerebello-olivary inhibition, the possibility of an interaction between ethanol and GABA-ergic responses in the interposito-olivary pathway is discussed.

Research paper thumbnail of Interaction between mossy fibre and climbing fibre responses in Purkinje cells

PubMed, 1983

A major problem in cerebellar physiology relates to the manner in which information from mossy fi... more A major problem in cerebellar physiology relates to the manner in which information from mossy fibres and climbing fibres is integrated in the efferent neurones of the cerebellar cortex, the Purkinje cells. Recent findings by Ekerot and Oscarsson [8] and by Ito, Sakurai and Tongroach [13] indicate that the important interaction between mossy fibres and climbing fibres takes place in the dendrites rather than in the Purkinje cell somata. It has been demonstrated that impulses in climbing fibres evoke not only the so-called "complex spikes" in the somata but also plateau-like depolarizations in the distal dendrites which may have durations of hundreds of ms. The plateau potentials are presumably produced by a voltage dependent calcium conductance increase which, under physiological conditions, is triggered off exclusively by the large synaptic potentials generated by climbing fibre impulses. The spread of the plateau potentials to the distal dendrites and their long duration would facilitate spatial and temporal interaction between the mossy fibre and climbing fibre inputs. The findings suggest two kinds of interaction. (1) The duration of the plateau potentials in individual dendritic branches is modulated by the local mossy fibre/parallel fibre input. Thus, it might be postulated that dendritic branches act as independent integrators of mossy fibre and climbing fibre inputs. (2) It has been suggested that interaction between mossy fibres and climbing fibres forms the basis of learning processes in the cerebellum mediated through plastic changes in the synapses between parallel fibres and Purkinje cell dendrites. The plateau potentials would influence parallel fibre synapses by increasing the intradendritic calcium which, in turn, would lastingly depress the sensitivity of the postsynaptic receptors of the parallel fibre synapses that are activated in conjunction with the climbing fibres.

Research paper thumbnail of Kir3 channel blockade in the cerebellar cortex suppresses performance of classically conditioned Purkinje cell responses

Scientific Reports, Sep 24, 2020

Research paper thumbnail of Internal Simulation in a Bimodal System

Research paper thumbnail of Blind Adaptive Behavior Based on Internal Simulation of Perception

This paper presents experiments, based on a neuroscientific hypothesis, exploring the possibility... more This paper presents experiments, based on a neuroscientific hypothesis, exploring the possibility of an&amp;amp;#x27;inner world&amp;amp;#x27;based on internal simulation of perception rather than an explicit representational world model. First a series of initial experiments is discussed, in which ...

Research paper thumbnail of The inner world of a simple robot

Research paper thumbnail of Associative Self-Organizing Map

InTech eBooks, Jan 21, 2011

Research paper thumbnail of Bilateral control of the orbicularis oculi muscle by one cerebellar hemisphere in the ferret

PubMed, Sep 1, 1993

Reports that lesions of the anterior interpositus nucleus in the cerebellum or of the cerebellar ... more Reports that lesions of the anterior interpositus nucleus in the cerebellum or of the cerebellar cortex abolish classically conditioned eyeblink responses were originally taken to indicate that the cerebellum is the locus of learning. This interpretation has recently been questioned by reports that conditioned responses may recover after ipsilateral cerebellar lesions. It cannot be excluded, however, that the recovered responses were produced by the intact contralateral hemisphere. In order to determine if cerebellar outflow to the orbicularis oculi muscle is bilateral, we stimulated both the brachium conjunctivum and a cortical area in the c3 zone of the cerebellar cortex which controls eyeblink. Both kinds of stimulation elicited EMG activity in both the ipsi- and the contralateral eyelids. The results thus show that there is a bilateral control of eyeblink from each cerebellar hemisphere and they raise the possibility that recovery of conditioning after ipsilateral cerebellar lesions is due to the intact hemisphere. Reports of such recovery after unilateral lesions are therefore inconclusive.

Research paper thumbnail of Feedback control of Purkinje cell activity by the cerebello-olivary pathway

European Journal of Neuroscience, Dec 2, 2004

Research paper thumbnail of The secondary spikes of climbing fibre responses recorded from Purkinje cell somata in cat cerebellum

The Journal of Physiology, Aug 1, 1986

1. Extracellularly recorded climbing fibre responses in Purkinje cell somata in the cerebellar co... more 1. Extracellularly recorded climbing fibre responses in Purkinje cell somata in the cerebellar cortex were investigated in cats deeply anaesthetized with barbiturate. The effects on the amplitude of initial and secondary spikes of (a) preceding climbing fibre activation, (b) on-beam parallel fibre activation and (c) off-beam parallel fibre activation were studied. 2. When a climbing fibre response was preceded by climbing fibre activation there was a decrease in the amplitude of the initial spike of the second response at intervals up to 25 ms and little effect at longer intervals. Secondary spike amplitude was greatly increased at intervals up to 100 ms. 3. When a complex spike was preceded by on-beam parallel fibre activation there was a decrease in the initial spike amplitude at short intervals and an increase in the amplitude at long intervals. Secondary spike amplitude was increased up to 150 ms after an on-beam parallel fibre volley. 4. When a complex spike was preceded by off-beam parallel fibre stimulation there was an increase in initial spike amplitude at intervals up to about 200 ms and a decrease in secondary spike amplitude at intervals up to about 150 ms. 5. The results show that the amplitude of the secondary spikes can be modified by a preceding input to the Purkinje cell. The results also suggest that the secondary spikes are generated in the Purkinje cell dendrites and the initial spike in the soma.

Research paper thumbnail of Bilateral disruption of conditioned responses after unilateral blockade of cerebellar output in the decerebrate ferret

The Journal of Physiology, 1997

Lesions of the cerebellar cortex can abolish classically conditioned eyeblink responses, but some... more Lesions of the cerebellar cortex can abolish classically conditioned eyeblink responses, but some recovery with retraining has been observed. It has been suggested that the recovered responses are generated by the intact contralateral cerebellar hemisphere. In order to investigate this suggestion, bilaterally acquired conditioned responses were studied after the unilateral blockade of cerebellar output. Decerebrate ferrets were trained with ipsilateral electrical forelimb stimulation (300 ms, 50 Hz, 1 mA) as the conditioned stimulus and bilaterally applied peri‐orbital stimulation (40 ms, 50 Hz, 3 mA) as the unconditioned stimulus. The conditioned and unconditioned eyeblink responses were monitored by EMG recordings from the orbicularis oculi muscle. The output from one cerebellar hemisphere was blocked either by injecting small amounts of lignocaine (lidocaine; 0.5‐1.0μl)) into the brachium conjunctivum, or by a restricted mechanical lesion of the brainstem rostral to the cerebellu...

Research paper thumbnail of Dendritic plateau potentials evoked in Purkinje cells by parallel fibre volleys in the cat

The Journal of Physiology, 1983

Responses evoked in Purkinje cell dendrites by parallel fibre volleys and climbing fibre impulses... more Responses evoked in Purkinje cell dendrites by parallel fibre volleys and climbing fibre impulses were investigated by intra‐ and extracellular recording from cat cerebellar cortex. The depth distribution of recording sites suggested that the intracellular recordings were predominantly from proximal dendrites whereas the extracellular recordings were predominantly from distal dendrites. Parallel fibre stimulation evoked monosynaptic excitation and disynaptic inhibition in the dendrites and, at higher strength, prolonged plateau‐like responses in distal dendrites but only rarely in proximal dendrites. However, when the inhibitory synapses were blocked with topically applied picrotoxin, parallel fibre volleys evoked plateau potentials also in proximal dendrites. The duration of the parallel‐fibre‐evoked plateau potentials in distal dendrites was prolonged by increasing the intensity of the eliciting stimulus or by increasing the number of stimuli. A similar prolongation in the duratio...

Research paper thumbnail of A closed-loop framework to investigate cerebellar learning in a decerebrated ferret preparation

Research paper thumbnail of Associative Self-Organizing Map

Research paper thumbnail of The transitivity of causation

Research paper thumbnail of The problem of causal selection

A positioning apparatus includes a master hydraulic positioning cylinder having a relatively long... more A positioning apparatus includes a master hydraulic positioning cylinder having a relatively long stroke capability and a train of additively connected, short-stroke pneumatic control cylinders for controlling the length of stroke of the master cylinder and thus the positioning of a variable-position tool such as a band saw. One end of the cylinder train is connected by a feedback rod to an extensible portion of the master cylinder. A connecting rod connects the opposite end of the train directly to the spool of a three-position servo valve which controls the flow of hydraulic fluid to and from opposite sides of the master cylinder. When air pressure is admitted to a selected side of a selected control cylinder, at least a portion of the train shifts initially in a direction to move the servo valve to an operating position to begin stroking the master cylinder in a desired direction. Stroking movement of the master cylinder is transmitted through the feedback rod to the train to stroke the selected control cylinder until its piston bottoms out, after which continued stroking of the master cylinder shifts the train to close the servo valve and stop the master cylinder when it has stroked through a distance corresponding to the full stroke of the selected control cylinder. The cylinder train includes a pair of "lost motion" cylinders enabling movement of the train beyond the limits of movement of the servo valve. This lost motion of the train activates a high-speed valve in the hydraulic circuit to stroke the master cylinder at high speed and a "final set" cylinder in the train to ensure that final stroking of the master cylinder to a selected setting always occurs from the same direction to eliminate setting errors from lost motion in the system. A lockout valve in the hydraulic system overrides the servo and high-speed valves when the controlled tool is in an operating condition to block flow to the master cylinder and prevent possible damage to the tool or positioning apparatus.

Research paper thumbnail of Changes in complex spike activity during classical conditioning

Frontiers in Neural Circuits, Aug 5, 2014

The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink c... more The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink conditioning. During conditioning, Purkinje cells acquire pause responses or "Purkinje cell CRs" to the conditioned stimuli (CS), resulting in disinhibition of the cerebellar nuclei (CN), allowing them to activate motor nuclei that control eyeblinks. This disinhibition also causes inhibition of the inferior olive (IO), via the nucleo-olivary pathway (N-O). Activation of the IO, which relays the unconditional stimulus (US) to the cortex, elicits characteristic complex spikes in Purkinje cells. Although Purkinje cell activity, as well as stimulation of the CN, is known to influence IO activity, much remains to be learned about the way that learned changes in simple spike firing affects the IO. In the present study, we analyzed changes in simple and complex spike firing, in extracellular Purkinje cell records, from the C3 zone, in decerebrate ferrets undergoing training in a conditioning paradigm. In agreement with the NO feedback hypothesis, acquisition resulted in a gradual decrease in complex spike activity during the conditioned stimulus, with a delay that is consistent with the long NO latency. Also supporting the feedback hypothesis, training with a short interstimulus interval (ISI), which does not lead to acquisition of a Purkinje cell CR, did not cause a suppression of complex spike activity. In contrast, observations that extinction did not lead to a recovery in complex spike activity and the irregular patterns of simple and complex spike activity after the conditioned stimulus are less conclusive.

Research paper thumbnail of Hjärnan och medvetandet

Research paper thumbnail of A closed-loop framework to investigate cerebellar learning in a decerebrated ferret preparation

Research paper thumbnail of Neural Network Architecture for Crossmodal Activation and Perceptual Sequences

A self-organizing neural network is described that can associate between different modalities and... more A self-organizing neural network is described that can associate between different modalities and also has the ability to learn perceptual sequences. This architecture is a step towards the development of a complete agent containing simplified versions of all major neural subsystems in a mammal. It aims at exploring as well as takes inspiration from the idea that cognitive function involves an internal simulation of perception and movement. We have tested the architecture in simulations as well as together with real sensors with very encouraging results. Perceptul activity in the brain is normally elicited from the sense organs, but it has recently been argued that a crucial aspect of cognitive function in biological organisms is the ability to simulate perception, that is, to elicit perceptual activity from other brain areas rather than via sensory afferents (Hesslow, 2002; Grush, 2004). Among other things, perceptual simulation could explain the appearance of an inner world (Hesslow and Jirenhed, 2007) and also how an organism could try out various courses of action 'in the mind'. One plausible source of simulated perceptual activity might be activity in another sensory modality. A familiar example is when the texture of an object that is felt in the pocket can evoke visual images/expectations of the object. A more dramatic biological illustration is the McGurk-MacDonald effect. If you hear a person making the sound /ba/ but the sound is superimposed on a video recording on which you do not see the lips closing, you may hear the sound /da/ instead (McGurk and MacDonald, 1976). Accordingly, a bio-inspired autonomous robot should be able to learn on its own and to automatically develop sensory representations of its different sensory modalities. These representations should also co-develop so that suitable activity in some modalities elicits appropriate activity in other sensory modalities as well. It would also be desirable with an ability to remember perceptual sequences, and that a corresponding sequence of activity evokes a suitable sequence of activity in the other modalities of the robot. With these traits a robot learning to navigate through an environment could remember a sequence of e.g. visual land

Research paper thumbnail of Effect of ethanol on the excitability of the inferior olive in decerebrate ferret

PubMed, May 1, 1996

Climbing fibers, which originate in the inferior olive and project to Purkinje cells and Golgi ce... more Climbing fibers, which originate in the inferior olive and project to Purkinje cells and Golgi cells in the cerebral cortex, were activated at low (0.4-Hz) and high (4-Hz) frequencies by periorbital stimulation in decerebrate ferrets. Climbing fiber responses were recorded as field potentials from the c3 zone of the cerebellar surface. When periorbital stimulation was applied at high frequency, the climbing fiber responses became strongly depressed within a few seconds. It has previously been shown that this high frequency depression (HFD) of climbing fiber responses is due to a cerebellar inhibition of the inferior olive, probably via the nucleo-olivary pathway. Acute administration of ethanol had small and variable effects on the amplitude of climbing fiber responses evoked by low-frequency stimulation. In contrast, medium concentrations (0.44-2.90 g/l) of ethanol led to a marked reduction of the HFD. Low ( < 0.44 g/l) systemic concentrations had no measurable effects on the HFD, whereas high concentrations ( > 2.90 g/l) caused either an increased HFD or a nonseptic reduction in olivary excitability. Because HFD has previously been shown to involve cerebello-olivary inhibition, the possibility of an interaction between ethanol and GABA-ergic responses in the interposito-olivary pathway is discussed.

Research paper thumbnail of Interaction between mossy fibre and climbing fibre responses in Purkinje cells

PubMed, 1983

A major problem in cerebellar physiology relates to the manner in which information from mossy fi... more A major problem in cerebellar physiology relates to the manner in which information from mossy fibres and climbing fibres is integrated in the efferent neurones of the cerebellar cortex, the Purkinje cells. Recent findings by Ekerot and Oscarsson [8] and by Ito, Sakurai and Tongroach [13] indicate that the important interaction between mossy fibres and climbing fibres takes place in the dendrites rather than in the Purkinje cell somata. It has been demonstrated that impulses in climbing fibres evoke not only the so-called "complex spikes" in the somata but also plateau-like depolarizations in the distal dendrites which may have durations of hundreds of ms. The plateau potentials are presumably produced by a voltage dependent calcium conductance increase which, under physiological conditions, is triggered off exclusively by the large synaptic potentials generated by climbing fibre impulses. The spread of the plateau potentials to the distal dendrites and their long duration would facilitate spatial and temporal interaction between the mossy fibre and climbing fibre inputs. The findings suggest two kinds of interaction. (1) The duration of the plateau potentials in individual dendritic branches is modulated by the local mossy fibre/parallel fibre input. Thus, it might be postulated that dendritic branches act as independent integrators of mossy fibre and climbing fibre inputs. (2) It has been suggested that interaction between mossy fibres and climbing fibres forms the basis of learning processes in the cerebellum mediated through plastic changes in the synapses between parallel fibres and Purkinje cell dendrites. The plateau potentials would influence parallel fibre synapses by increasing the intradendritic calcium which, in turn, would lastingly depress the sensitivity of the postsynaptic receptors of the parallel fibre synapses that are activated in conjunction with the climbing fibres.

Research paper thumbnail of Kir3 channel blockade in the cerebellar cortex suppresses performance of classically conditioned Purkinje cell responses

Scientific Reports, Sep 24, 2020

Research paper thumbnail of Internal Simulation in a Bimodal System

Research paper thumbnail of Blind Adaptive Behavior Based on Internal Simulation of Perception

This paper presents experiments, based on a neuroscientific hypothesis, exploring the possibility... more This paper presents experiments, based on a neuroscientific hypothesis, exploring the possibility of an&amp;amp;#x27;inner world&amp;amp;#x27;based on internal simulation of perception rather than an explicit representational world model. First a series of initial experiments is discussed, in which ...

Research paper thumbnail of The inner world of a simple robot

Research paper thumbnail of Associative Self-Organizing Map

InTech eBooks, Jan 21, 2011

Research paper thumbnail of Bilateral control of the orbicularis oculi muscle by one cerebellar hemisphere in the ferret

PubMed, Sep 1, 1993

Reports that lesions of the anterior interpositus nucleus in the cerebellum or of the cerebellar ... more Reports that lesions of the anterior interpositus nucleus in the cerebellum or of the cerebellar cortex abolish classically conditioned eyeblink responses were originally taken to indicate that the cerebellum is the locus of learning. This interpretation has recently been questioned by reports that conditioned responses may recover after ipsilateral cerebellar lesions. It cannot be excluded, however, that the recovered responses were produced by the intact contralateral hemisphere. In order to determine if cerebellar outflow to the orbicularis oculi muscle is bilateral, we stimulated both the brachium conjunctivum and a cortical area in the c3 zone of the cerebellar cortex which controls eyeblink. Both kinds of stimulation elicited EMG activity in both the ipsi- and the contralateral eyelids. The results thus show that there is a bilateral control of eyeblink from each cerebellar hemisphere and they raise the possibility that recovery of conditioning after ipsilateral cerebellar lesions is due to the intact hemisphere. Reports of such recovery after unilateral lesions are therefore inconclusive.

Research paper thumbnail of Feedback control of Purkinje cell activity by the cerebello-olivary pathway

European Journal of Neuroscience, Dec 2, 2004

Research paper thumbnail of The secondary spikes of climbing fibre responses recorded from Purkinje cell somata in cat cerebellum

The Journal of Physiology, Aug 1, 1986

1. Extracellularly recorded climbing fibre responses in Purkinje cell somata in the cerebellar co... more 1. Extracellularly recorded climbing fibre responses in Purkinje cell somata in the cerebellar cortex were investigated in cats deeply anaesthetized with barbiturate. The effects on the amplitude of initial and secondary spikes of (a) preceding climbing fibre activation, (b) on-beam parallel fibre activation and (c) off-beam parallel fibre activation were studied. 2. When a climbing fibre response was preceded by climbing fibre activation there was a decrease in the amplitude of the initial spike of the second response at intervals up to 25 ms and little effect at longer intervals. Secondary spike amplitude was greatly increased at intervals up to 100 ms. 3. When a complex spike was preceded by on-beam parallel fibre activation there was a decrease in the initial spike amplitude at short intervals and an increase in the amplitude at long intervals. Secondary spike amplitude was increased up to 150 ms after an on-beam parallel fibre volley. 4. When a complex spike was preceded by off-beam parallel fibre stimulation there was an increase in initial spike amplitude at intervals up to about 200 ms and a decrease in secondary spike amplitude at intervals up to about 150 ms. 5. The results show that the amplitude of the secondary spikes can be modified by a preceding input to the Purkinje cell. The results also suggest that the secondary spikes are generated in the Purkinje cell dendrites and the initial spike in the soma.