Electrical Activity in the Optic Tectum and Colour Change in the Minnow (Phoxinus Phoxinus L.)

1. The electrical activity of the optic tectum was recorded from the minnow under various conditions to investigate its relationship to colour change. 2. The superficial E.E.G. was found to consist of two rhythms a 6-14 Hz (20-112 V) and a 18-24 Hz (6-18 µV). 3. When the fish were deeply anaesthetized the E.E.G. was reduced virtually to nothing. 4. Almost no activity was present in the optic tectum 30 min after bilateral blinding. There was an increase in activity after 5 h and this continued for 5 or more days but never returned to normal. 5. In darkness the activity of the superficial E.E.G. first increased and then decreased, and when the eyes were re-exposed to light the activity increased again. 6. The E.E.G. patterns were recorded and analysed from various depths and positions in the optic tectum during background reversal. In the stratum plexiformeet fibrosum externum, plexiforme internum and griseum internum no changes were observed. In the stratum fibrosum profundum and griseum periventriculare an increase in the high-frequency activity of approximately 10 Hz was observed on a black background.

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The Central Nervous Control of Colour Change in the Minnow (Phoxinus Phoxinus L.)

Journal of Experimental Biology ◽

10.1242/jeb.54.1.83 ◽

1971 ◽

Vol 54 (1) ◽

pp. 83-91

Author(s):

MICHAEL J. GENTLE

Keyword(s):

Optic Nerve ◽

Optic Tectum ◽

Posterior Part ◽

Colour Change ◽

Complete Removal ◽

The Other ◽

Nervous Control ◽

Phoxinus Phoxinus ◽

External Conditions

1. The colour of the minnow Phoxinus phoxinus L. and its ability to undergo colour change were studied after partial and complete blinding. The blinding was accomplished either by section of the optic nerve or by tectal ablation. 2. Following bilateral section of the optic nerve the blinded minnows darken. After the initial darkening, half of the fish pale and the other half remain dark. 3. The colour of the fish blinded by bilateral section of the optic nerve could not be affected by external conditions. 4. Following complete removal of the optic tectum the fish at first paled, but after 24 h they darkened to very variable tints. 5. Unilateral section of the optic nerve coupled with unilateral tectal removal on the same or opposite side did not affect the ability of the fish to change colour. 6. The bilateral removal of the anterior tectum from a blinded darkened fish did not affect its colour. 7. The bilateral removal of the posterior tectum of a darkened fish caused maximal pallor. 8. By a series of lesions an area in the dorsal posterior part of the optic tectum was found to cause darkening in the blinded fish because following its removal the fish paled. 9. It is suggested that the fibres from the tectum may act by exciting or inhibiting the neurones of the paling centre in the anterior medulla.

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The Central Nervous Control of Colour Change in the Minnow (Phoxinus Phoxinus L.)

Journal of Experimental Biology ◽

10.1242/jeb.54.1.93 ◽

1971 ◽

Vol 54 (1) ◽

pp. 93-102

Author(s):

MICHAEL J. GENTLE

Keyword(s):

Optic Tectum ◽

Colour Change ◽

The Other ◽

Dorsal Part ◽

Nervous Control ◽

Phoxinus Phoxinus ◽

Normal Fish

1. A series of ablations were carried out in the optic tectum of the minnow, Phoxinus phoxinus, in order to investigate its importance in colour change. 2. The presence of the anterior or posterior tectum alone one on or both sides caused persistent pallor in normal fish. 3. The presence of the anterior tectum on one side and the posterior on the other enabled the fish to adapt chromatically to its background. 4. Small bilateral removals from the dorsal part of the optic tectum did not effect colour change. Larger removals from the dorsal tectum reduced the extent of change and still larger removals caused the fish to pale on all backgrounds.

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The Eye and Colour Change in the Minnow (Phoxinus Phoxinus L)

Journal of Experimental Biology ◽

10.1242/jeb.57.3.701 ◽

1972 ◽

Vol 57 (3) ◽

pp. 701-707

Author(s):

MICHAEL J. GENTLE

Keyword(s):

Colour Change ◽

White Background ◽

Surgical Removal ◽

Phoxinus Phoxinus ◽

Black Background ◽

Temporal Field ◽

Dorsal Retina

1. Counts were made of the retinal receptors and observations were made of the colour of the minnow, Phoxinus phoxinus L., following the surgical removal of parts of the dorsal and ventral retina. 2. It was found that there were greater numbers of retinal receptors in the temporal field than in the rostral field of the eye. 3. There were very few triple and quadruple cones but a large number of double and single cones in the ventral retina compared to the dorsal. 4. Surgical removal of the dorsal retina or only part of it resulted in the fish being fully dark-adapted on a black or white background. 5. Surgical removal of the ventral retina resulted in the fish assuming an intermediate colour on a white background and a darker tint on a black background.

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Novel approach to modeling high-frequency activity data to assess therapeutic effects of analgesics in chronic pain conditions

Scientific Reports ◽

10.1038/s41598-021-87304-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Zekun Xu ◽

Eric Laber ◽

Ana-Maria Staicu ◽

B. Duncan X. Lascelles

Keyword(s):

High Frequency ◽

Activity Patterns ◽

Treatment Strategies ◽

Therapeutic Effects ◽

Activity Levels ◽

Activity Data ◽

Novel Approach ◽

High Frequency Activity ◽

Using Data ◽

Chronic Pain Conditions

AbstractOsteoarthritis (OA) is a chronic condition often associated with pain, affecting approximately fourteen percent of the population, and increasing in prevalence. A globally aging population have made treating OA-associated pain as well as maintaining mobility and activity a public health priority. OA affects all mammals, and the use of spontaneous animal models is one promising approach for improving translational pain research and the development of effective treatment strategies. Accelerometers are a common tool for collecting high-frequency activity data on animals to study the effects of treatment on pain related activity patterns. There has recently been increasing interest in their use to understand treatment effects in human pain conditions. However, activity patterns vary widely across subjects; furthermore, the effects of treatment may manifest in higher or lower activity counts or in subtler ways like changes in the frequency of certain types of activities. We use a zero inflated Poisson hidden semi-Markov model to characterize activity patterns and subsequently derive estimators of the treatment effect in terms of changes in activity levels or frequency of activity type. We demonstrate the application of our model, and its advance over traditional analysis methods, using data from a naturally occurring feline OA-associated pain model.

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