Geoff Horseman - Academia.edu (original) (raw)

Papers by Geoff Horseman

Research paper thumbnail of Some Aspects of the Auditory Pathway and Audition in the European Mole, <i>Talpa europaea</i&gt

Brain Behavior and Evolution, 1982

The structure of the lower auditory pathway and certain responses to sounds were studied in the E... more The structure of the lower auditory pathway and certain responses to sounds were studied in the European mole (Talpa europaea). While the animal possesses a structurally normal cochlear nuclear complex and auditory midbrain, the medial superior olive, although small, is prominent and the lateral superior olive is lacking. This characteristic has been observed in other species with essentially low frequency hearing. Behavioural and electrophysiological responses to sound were evoked between 0.1 and 15 kHz, and moles were apparently at least sensitive to tones of 5-8 kHz as they were to low tones. In general, evidence is presented for the mole having essentially normal mammalian auditory characteristics.

Research paper thumbnail of Involvement of the suboesophageal and thoracic ganglia in the control of antennal movements in crickets

Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, Aug 19, 1997

In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal gang... more In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal ganglia (SOG) and thoracic ganglia to the generation of antennal movements during visual tracking, walking and ight was investigated by the transection of connectives. Transection of one circumoesophageal connective abolished the movements and postures of the antenna ipsilateral to the lesion, while the contralateral antenna behaved normally. Simple antennal re¯exes remained. Transection of one neck connective reduced fast components of antennal movements during tracking and walking. During¯ight the ipsilateral antenna could not be maintained in a prolonged forward position. Antennal movements during tracking and walking appeared normal after transection of one connective between proand mesothoracic ganglia. However, the antennal¯ight posture required uninterrupted connections between brain and mesothoracic ganglion. The ablation of more posterior ganglia had no eect on the antennal behaviours investigated. Recordings from an antennal motor nerve revealed a unilateral net excitation relayed via the SOG to the brain. Two ascending interneurones with activity closely correlated with antennal movements are candidates for such a relay function. The data show that the brain is not sucient to generate antennal movements and postures as integral parts of several behaviours. The SOG and the thoracic ganglia are required in addition. Key words Insect á Antennae á Motor control á Brain á Lesion experiments Abbreviations TG1 prothoracic ganglion á TG2 mesothoracic ganglion á TG3 metathoracic ganglion

Research paper thumbnail of Some Aspects of the Auditory Pathway and Audition in the European Mole, Talpa europaea

Brain, Behavior and Evolution, 1982

The structure of the lower auditory pathway and certain responses to sounds were studied in the E... more The structure of the lower auditory pathway and certain responses to sounds were studied in the European mole (Talpa europaea). While the animal possesses a structurally normal cochlear nuclear complex and auditory midbrain, the medial superior olive, although small, is prominent and the lateral superior olive is lacking. This characteristic has been observed in other species with essentially low frequency hearing. Behavioural and electrophysiological responses to sound were evoked between 0.1 and 15 kHz, and moles were apparently at least sensitive to tones of 5-8 kHz as they were to low tones. In general, evidence is presented for the mole having essentially normal mammalian auditory characteristics.

Research paper thumbnail of RESEARCH ARTICLE Neuronal processing of translational optic flow in the visual system of the shore crab Carcinus maenas

SUMMARY This paper describes a search for neurones sensitive to optic flow in the visual system o... more SUMMARY This paper describes a search for neurones sensitive to optic flow in the visual system of the shore crab Carcinus maenas using a procedure developed from that of Krapp and Hengstenberg. This involved determining local motion sensitivity and its directional selectivity at many points within the neurone’s receptive field and plotting the results on a map. Our results showed that local preferred directions of motion are independent of velocity, stimulus shape and type of motion (circular or linear). Global response maps thus clearly represent real properties of the neurones’ receptive fields. Using this method, we have discovered two families of interneurones sensitive to translational optic flow. The first family has its terminal arborisations in the lobula of the optic lobe, the second family in the medulla. The response maps of the lobula neurones (which appear to be monostratified lobular giant neurones) show a clear focus of expansion centred on or just above the horizon,...

Research paper thumbnail of PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection

Journal of Neuroscience Methods, 2002

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of... more A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. 9120°. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Research paper thumbnail of Computer-aided studies of vision in crabs

Marine and Freshwater Behaviour and Physiology, 2002

A system for the back projection of computer-generated visual images onto a screen or screens tha... more A system for the back projection of computer-generated visual images onto a screen or screens that cover 240 of the horizontal visual field is described. Its applicability for the study of crab vision is tested by comparing the frequency response of the optokinetic response of the land crab, Cardisoma guanhumi, to sinusoidal oscillation of computer-generated striped patterns and a real striped drum. Significant differences were observed only at the low end of the frequency spectrum. The flexibility of computer-generated visual stimulation and its advantages for the study of optic flow are illustrated by experiments that: (a) demonstrate how well crabs separate the translational and rotational components of optic flow by showing compensatory eye movements to only the latter; (b) show that the ability to compensate for rotation is not impaired by combinations of rotation and translation; (c) show that motion parallax cues are used in addition to previously-described global cues for making the distinction between rotation and translation. Finally, the use of these methods in a successful search for visual interneurones sensitive to optic flow stimuli is demonstrated for the shore crab, Carcinus maenas.

Research paper thumbnail of Involvement of the suboesophageal and thoracic ganglia in the control of antennal movements in crickets

Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology, 1997

In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal gang... more In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal ganglia (SOG) and thoracic ganglia to the generation of antennal movements during visual tracking, walking and ight was investigated by the transection of connectives. Transection of one circumoesophageal connective abolished the movements and postures of the antenna ipsilateral to the lesion, while the contralateral antenna behaved normally. Simple antennal re¯exes remained. Transection of one neck connective reduced fast components of antennal movements during tracking and walking. During¯ight the ipsilateral antenna could not be maintained in a prolonged forward position. Antennal movements during tracking and walking appeared normal after transection of one connective between proand mesothoracic ganglia. However, the antennal¯ight posture required uninterrupted connections between brain and mesothoracic ganglion. The ablation of more posterior ganglia had no eect on the antennal behaviours investigated. Recordings from an antennal motor nerve revealed a unilateral net excitation relayed via the SOG to the brain. Two ascending interneurones with activity closely correlated with antennal movements are candidates for such a relay function. The data show that the brain is not sucient to generate antennal movements and postures as integral parts of several behaviours. The SOG and the thoracic ganglia are required in addition. Key words Insect á Antennae á Motor control á Brain á Lesion experiments Abbreviations TG1 prothoracic ganglion á TG2 mesothoracic ganglion á TG3 metathoracic ganglion

Research paper thumbnail of The Detection and Analysis of Optic Flow by Crabs: from Eye Movements to Electrophysiology

The Crustacean Nervous System, 2002

Research paper thumbnail of Neuronal processing of translational optic flow in the visual system of the shore crab Carcinus maenas

Journal of Experimental Biology, 2011

Research paper thumbnail of PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection

Journal of Neuroscience Methods, 2002

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of... more A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. +/-120 degrees. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Research paper thumbnail of The effects of l-glutamate on cultured insect neurones

Neurosci Lett, 1988

The effects of L-glutamate on insect cultured neurones were studied under current and voltage-cla... more The effects of L-glutamate on insect cultured neurones were studied under current and voltage-clamp conditions using conventional and whole-cell patch-clamp techniques. Brief pressure or iontophoretic application of e-glutamate produced either a depolarisation or hyperpolarisation. The current underlying the depolarisation was inwardly directed and reversed at around 0 mV while the hyperpolarisation was caused by an outward current that reversed between -60 and -80 mV. Single channel currents underlying the depolarisation were readily recorded from cell attached patches and showed multiple conductance states. Channel activity corresponding to the hyperpolarising response has not yet been observed.

Research paper thumbnail of PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection

Journal of Neuroscience Methods, 2002

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of... more A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. +/-120 degrees. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Research paper thumbnail of Computer-aided studies of vision in crabs

Marine and Freshwater Behaviour and Physiology, 2002

A system for the back projection of computer-generated visual images onto a screen or screens tha... more A system for the back projection of computer-generated visual images onto a screen or screens that cover 240 of the horizontal visual field is described. Its applicability for the study of crab vision is tested by comparing the frequency response of the optokinetic response of the land crab, Cardisoma guanhumi, to sinusoidal oscillation of computer-generated striped patterns and a real striped drum. Significant differences were observed only at the low end of the frequency spectrum. The flexibility of computer-generated visual stimulation and its advantages for the study of optic flow are illustrated by experiments that: (a) demonstrate how well crabs separate the translational and rotational components of optic flow by showing compensatory eye movements to only the latter; (b) show that the ability to compensate for rotation is not impaired by combinations of rotation and translation; (c) show that motion parallax cues are used in addition to previously-described global cues for making the distinction between rotation and translation. Finally, the use of these methods in a successful search for visual interneurones sensitive to optic flow stimuli is demonstrated for the shore crab, Carcinus maenas.

Research paper thumbnail of Some Aspects of the Auditory Pathway and Audition in the European Mole, <i>Talpa europaea</i&gt

Brain Behavior and Evolution, 1982

The structure of the lower auditory pathway and certain responses to sounds were studied in the E... more The structure of the lower auditory pathway and certain responses to sounds were studied in the European mole (Talpa europaea). While the animal possesses a structurally normal cochlear nuclear complex and auditory midbrain, the medial superior olive, although small, is prominent and the lateral superior olive is lacking. This characteristic has been observed in other species with essentially low frequency hearing. Behavioural and electrophysiological responses to sound were evoked between 0.1 and 15 kHz, and moles were apparently at least sensitive to tones of 5-8 kHz as they were to low tones. In general, evidence is presented for the mole having essentially normal mammalian auditory characteristics.

Research paper thumbnail of Involvement of the suboesophageal and thoracic ganglia in the control of antennal movements in crickets

Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, Aug 19, 1997

In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal gang... more In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal ganglia (SOG) and thoracic ganglia to the generation of antennal movements during visual tracking, walking and ight was investigated by the transection of connectives. Transection of one circumoesophageal connective abolished the movements and postures of the antenna ipsilateral to the lesion, while the contralateral antenna behaved normally. Simple antennal re¯exes remained. Transection of one neck connective reduced fast components of antennal movements during tracking and walking. During¯ight the ipsilateral antenna could not be maintained in a prolonged forward position. Antennal movements during tracking and walking appeared normal after transection of one connective between proand mesothoracic ganglia. However, the antennal¯ight posture required uninterrupted connections between brain and mesothoracic ganglion. The ablation of more posterior ganglia had no eect on the antennal behaviours investigated. Recordings from an antennal motor nerve revealed a unilateral net excitation relayed via the SOG to the brain. Two ascending interneurones with activity closely correlated with antennal movements are candidates for such a relay function. The data show that the brain is not sucient to generate antennal movements and postures as integral parts of several behaviours. The SOG and the thoracic ganglia are required in addition. Key words Insect á Antennae á Motor control á Brain á Lesion experiments Abbreviations TG1 prothoracic ganglion á TG2 mesothoracic ganglion á TG3 metathoracic ganglion

Research paper thumbnail of Some Aspects of the Auditory Pathway and Audition in the European Mole, Talpa europaea

Brain, Behavior and Evolution, 1982

The structure of the lower auditory pathway and certain responses to sounds were studied in the E... more The structure of the lower auditory pathway and certain responses to sounds were studied in the European mole (Talpa europaea). While the animal possesses a structurally normal cochlear nuclear complex and auditory midbrain, the medial superior olive, although small, is prominent and the lateral superior olive is lacking. This characteristic has been observed in other species with essentially low frequency hearing. Behavioural and electrophysiological responses to sound were evoked between 0.1 and 15 kHz, and moles were apparently at least sensitive to tones of 5-8 kHz as they were to low tones. In general, evidence is presented for the mole having essentially normal mammalian auditory characteristics.

Research paper thumbnail of RESEARCH ARTICLE Neuronal processing of translational optic flow in the visual system of the shore crab Carcinus maenas

SUMMARY This paper describes a search for neurones sensitive to optic flow in the visual system o... more SUMMARY This paper describes a search for neurones sensitive to optic flow in the visual system of the shore crab Carcinus maenas using a procedure developed from that of Krapp and Hengstenberg. This involved determining local motion sensitivity and its directional selectivity at many points within the neurone’s receptive field and plotting the results on a map. Our results showed that local preferred directions of motion are independent of velocity, stimulus shape and type of motion (circular or linear). Global response maps thus clearly represent real properties of the neurones’ receptive fields. Using this method, we have discovered two families of interneurones sensitive to translational optic flow. The first family has its terminal arborisations in the lobula of the optic lobe, the second family in the medulla. The response maps of the lobula neurones (which appear to be monostratified lobular giant neurones) show a clear focus of expansion centred on or just above the horizon,...

Research paper thumbnail of PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection

Journal of Neuroscience Methods, 2002

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of... more A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. 9120°. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Research paper thumbnail of Computer-aided studies of vision in crabs

Marine and Freshwater Behaviour and Physiology, 2002

A system for the back projection of computer-generated visual images onto a screen or screens tha... more A system for the back projection of computer-generated visual images onto a screen or screens that cover 240 of the horizontal visual field is described. Its applicability for the study of crab vision is tested by comparing the frequency response of the optokinetic response of the land crab, Cardisoma guanhumi, to sinusoidal oscillation of computer-generated striped patterns and a real striped drum. Significant differences were observed only at the low end of the frequency spectrum. The flexibility of computer-generated visual stimulation and its advantages for the study of optic flow are illustrated by experiments that: (a) demonstrate how well crabs separate the translational and rotational components of optic flow by showing compensatory eye movements to only the latter; (b) show that the ability to compensate for rotation is not impaired by combinations of rotation and translation; (c) show that motion parallax cues are used in addition to previously-described global cues for making the distinction between rotation and translation. Finally, the use of these methods in a successful search for visual interneurones sensitive to optic flow stimuli is demonstrated for the shore crab, Carcinus maenas.

Research paper thumbnail of Involvement of the suboesophageal and thoracic ganglia in the control of antennal movements in crickets

Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology, 1997

In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal gang... more In crickets (Gryllus campestris, Gryllus bimaculatus) the contribution of the suboesophageal ganglia (SOG) and thoracic ganglia to the generation of antennal movements during visual tracking, walking and ight was investigated by the transection of connectives. Transection of one circumoesophageal connective abolished the movements and postures of the antenna ipsilateral to the lesion, while the contralateral antenna behaved normally. Simple antennal re¯exes remained. Transection of one neck connective reduced fast components of antennal movements during tracking and walking. During¯ight the ipsilateral antenna could not be maintained in a prolonged forward position. Antennal movements during tracking and walking appeared normal after transection of one connective between proand mesothoracic ganglia. However, the antennal¯ight posture required uninterrupted connections between brain and mesothoracic ganglion. The ablation of more posterior ganglia had no eect on the antennal behaviours investigated. Recordings from an antennal motor nerve revealed a unilateral net excitation relayed via the SOG to the brain. Two ascending interneurones with activity closely correlated with antennal movements are candidates for such a relay function. The data show that the brain is not sucient to generate antennal movements and postures as integral parts of several behaviours. The SOG and the thoracic ganglia are required in addition. Key words Insect á Antennae á Motor control á Brain á Lesion experiments Abbreviations TG1 prothoracic ganglion á TG2 mesothoracic ganglion á TG3 metathoracic ganglion

Research paper thumbnail of The Detection and Analysis of Optic Flow by Crabs: from Eye Movements to Electrophysiology

The Crustacean Nervous System, 2002

Research paper thumbnail of Neuronal processing of translational optic flow in the visual system of the shore crab Carcinus maenas

Journal of Experimental Biology, 2011

Research paper thumbnail of PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection

Journal of Neuroscience Methods, 2002

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of... more A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. +/-120 degrees. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Research paper thumbnail of The effects of l-glutamate on cultured insect neurones

Neurosci Lett, 1988

The effects of L-glutamate on insect cultured neurones were studied under current and voltage-cla... more The effects of L-glutamate on insect cultured neurones were studied under current and voltage-clamp conditions using conventional and whole-cell patch-clamp techniques. Brief pressure or iontophoretic application of e-glutamate produced either a depolarisation or hyperpolarisation. The current underlying the depolarisation was inwardly directed and reversed at around 0 mV while the hyperpolarisation was caused by an outward current that reversed between -60 and -80 mV. Single channel currents underlying the depolarisation were readily recorded from cell attached patches and showed multiple conductance states. Channel activity corresponding to the hyperpolarising response has not yet been observed.

Research paper thumbnail of PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection

Journal of Neuroscience Methods, 2002

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of... more A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. +/-120 degrees. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Research paper thumbnail of Computer-aided studies of vision in crabs

Marine and Freshwater Behaviour and Physiology, 2002

A system for the back projection of computer-generated visual images onto a screen or screens tha... more A system for the back projection of computer-generated visual images onto a screen or screens that cover 240 of the horizontal visual field is described. Its applicability for the study of crab vision is tested by comparing the frequency response of the optokinetic response of the land crab, Cardisoma guanhumi, to sinusoidal oscillation of computer-generated striped patterns and a real striped drum. Significant differences were observed only at the low end of the frequency spectrum. The flexibility of computer-generated visual stimulation and its advantages for the study of optic flow are illustrated by experiments that: (a) demonstrate how well crabs separate the translational and rotational components of optic flow by showing compensatory eye movements to only the latter; (b) show that the ability to compensate for rotation is not impaired by combinations of rotation and translation; (c) show that motion parallax cues are used in addition to previously-described global cues for making the distinction between rotation and translation. Finally, the use of these methods in a successful search for visual interneurones sensitive to optic flow stimuli is demonstrated for the shore crab, Carcinus maenas.