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Biomedical subjects

B J McCabe

Publications and source records attributed to B J McCabe.

52 records · Page 3Linked to original sources
PubMed1985

Noradrenaline and learning: effects of the noradrenergic neurotoxin DSP4 on imprinting in the domestic chick.

The effects of the noradrenergic neurotoxin DSP4 on imprinting in domestic chicks were investigated. Chicks received either DSP4 or distilled water and were trained 60 hr after hatching by exposing them to either a rotating red box or a stuffed jungle fowl. Noradrenaline concentration was determined in Wulst and medial and basal forebrain samples. The medial forebrain sample comprised mainly the intermediate part of the medial hyperstriatum ventrale, a region previously shown to be intimately involved in imprinting. The DSP4 treatment reduced forebrain noradrenaline levels by about 65%. DSP4 profoundly impaired imprinting in box-trained chicks but not in fowl-trained chicks. In box-trained chicks, the strength of imprinting was positively correlated with noradrenaline concentration in both medial and basal forebrain samples. It is suggested on the basis of these and previous studies that some of the neural structures and mechanisms involved in imprinting on the fowl differ from those involved in imprinting on the box.

Animals↗
PubMed1985

Changes in the structure of synapses associated with learning.

Two experiments were conducted to investigate the effects of training on a region of the chick brain known to be critically involved in imprinting, the intermediate and medial extent of the hyperstriatum ventrale (IMHV). In the first experiment, three groups of chicks were used: (i) dark-reared (n = 9), (ii) trained for 20 min (n = 17), and (iii) trained for 140 min (n = 7). Chicks were trained by exposing them when they were approximately 21 hr old to a flashing red light. Chicks were killed when they were approximately 30 hr old and blocks of tissue were removed from the right and left IMHV. Stereological techniques were used to measure from electron micrographs the numerical density of dendritic spine and shaft synapses and the length of the postsynaptic density of these synaptic junctions. There was a significant effect of training only in the left IMHV and on only one measure, the overall mean length of the postsynaptic density of spine synapses, SPL. This measure was significantly greater by 17.2% in chicks trained for 140 min than in dark-reared controls. There was no significant effect of training for 20 min. In the second experiment one group of chicks (n = 15) was exposed to a rotating red box for a total of 3 hr. Another group of chicks was dark-reared (n = 15). The chicks were killed when they were approximately 46 hr old. Samples from the hyperstriatum accessorium and IMHV of the right and left sides were analyzed. Training was associated with a significant change, an increase, only of SPL in the left IMHV.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1983

Imprinting in the domestic chick: the role of each side of the hyperstriatum ventrale in acquisition and retention.

Previous experiments have shown that the acquisition of a preference through imprinting is impaired if part (IMHV) of the hyperstriatum ventrale is destroyed bilaterally before chicks are exposed to a visually conspicuous (training) object. The present experiments were undertaken to determine (i) whether the acquisition of a preference for the training object is possible with only one IMHV intact and, if acquisition is possible, (ii) whether destruction of this IMHV impairs retention. Chicks were hatched and reared in darkness to congruent to 12 h posthatch. The chicks were then anaesthetised and a lesion placed in (i) the left IMHV (N = 12 chicks), (ii) the right IMHV (N = 12), (iii) the left hyperstriatum accessorium (HA) (N = 12) or (iv) the right HA (N = 12). There were 48 sham operated controls. Approximately 24 h after the operation chicks were exposed to the training stimulus. Their approach to this stimulus and to a second, novel stimulus were then measured and a preference score calculated. All five groups of chicks preferred the training stimulus and the magnitude of the preference was similar in all groups. To determine whether the IMHV region which had been intact during training was essential for retention, all chicks were anaesthetised for a second time, congruent to 20 h after the end of training. The remaining IMHV region was then destroyed. Approximately 28 h later the chicks' preferences were again measured. The sham operated and HA lesioned chicks continued strongly to prefer the training stimulus, but the birds lesioned in IMHV showed no such retention, the preference score of the IMHV chicks being significantly lower than that of the sham operated and HA lesioned chicks. The order in which the right and left sides were destroyed did not significantly influence the preference score; this result was true both for IMHV and for HA chicks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Changes in telencephalic catecholamine levels in the domestic chick. Effects of age and visual experience.

The concentrations of adrenaline, dopamine and noradrenaline were measured in 3 regions of the domestic chick telencephalon: (a) the Wulst; (b) a medial forebrain sample comprising mainly the intermediate part of the medial hyperstriatum ventrale (IMHV); and (c) a basal forebrain sample comprising mainly paleostriatum augmentatum. There was no significant left/right hemispheric asymmetry in the concentration of any of these catecholamines in any region studied. Adrenaline was undetectable in the Wulst and medial forebrain samples and only trace amounts were found in the basal forebrain samples of 1-day-old, light-reared chicks. Dopamine concentrations of 9.13 +/- 1.13 (S.E.M.) ng/g were present in the Wulst, 16.66 +/- 2.56 ng/g in the medial forebrain and 121.19 +/- 33.06 ng/g in the basal forebrain samples at hatching. These levels did not alter with age or with visual experience of an imprinting stimulus during the first 50 h post-hatch. At hatching, noradrenaline concentrations of 35.83 +/- 8.61 ng/g were present in the Wulst, 26.09 +/- 3.75 ng/g in the medial forebrain and 53.13 +/- 7.85 in the basal forebrain samples. The noradrenaline concentrations in the Wulst and medial forebrain samples increased significantly over the first 50 h post-hatch in dark-reared chicks. Visual experience increased noradrenaline levels in all 3 regions of the telencephalon studied.

Aging↗
PubMed1981

Effects of restricted lesions of the chick forebrain on the acquisition of filial preferences during imprinting.

The effects of placing bilateral lesions in that part of the chick brain (IMHV) which was previously been implicated in imprinting, was studied in young domestic chicks. Twenty-four dark-reared chicks were matched in pairs on the basis of their approach activity during a 30 min period of exposure to one of two visual imprinting stimuli. Both members of the chick pair were then anaesthetized and bilateral lesions were made by radio-frequency coagulation in the IMHV of one chick; the other chick served as a sham-operated control. On the following day each chick was exposed for 2.5 h to the imprinting stimulus to which it had previously been exposed. After training, the preferences of all chicks were measured by comparing their approach to the training stimulus with that to the second stimulus. Sham-operated chicks showed a strong preference for the training stimulus; lesioned chicks showed none. Subsequently the latency of each chick to approach and accurately peck a shiny rod was measured. The two groups of chicks did not differ significantly in this test of visuomotor coordination. The area of tissue damaged by the lesion was reconstructed: IMHV was severely damaged with relatively little damage to other areas of the brain.

Animals↗
PubMed1979

An autoradiographic study of the chick brain after imprinting.

On the first day after hatching domestic chicks were exposed to an imprinting stimulus, a horizontal yellow slit of light moving upwards in a window and presented at a rate of 4 slits/sec. Chicks were exposed for either 45 min (undertrained) or 180 min (overtrained) on the first day of hatching (60 or 240 min in the case of 1 pair). On the second day all birds were exposed for a further 63 min. Twenty birds were matched in pairs and each chick received 1.1 muCi [14C]uracil/g body weight injected into the heart region before exposure on day 2. At 150 min after the injection the chicks were decapitated and serial coronal sections of their brains cut; alternate pairs of sections were prepared for autoradiography. The optical density for a number of major anatomical regions was measured. The measurements for each region were averaged over congruent to 0.6 mm 'slabs' of brain and expressed as a percentage of the mean of all measurements for that brain. Standardized mean optical density was significantly greater in undertrained chicks than in overtrained chicks in a part of the medial region of hyperstriatum ventrale (MHV) which extended across two adjacent slabs. The slabs were slightly posterior to the mid-point between anterior and posterior poles of the brain. In the next two, adjacent, anterior slabs the variances for MHV were significantly greater in undertrained chicks than in overtrained chicks. There were no other significant differences between brain regions. Taken together with previous studies these results suggest that the intermediate and medial part of hyperstriatum ventrale is intimately linked with the imprinting process.

Animals↗
PubMed1979

Effects of rhythmic hyperstriatal stimulation on chicks' preferences for visual flicker.

Chicks' preferences for the frequency of a flashing light can be modified by electrically stimulating the medial part of the hyperstriatum ventrale with trains of shocks at that frequency. Chicks stimulated with 1.5 pulse trains s-1 preferred a light flashing at 1.5 s-1 and chicks stimulated at 4.5 trains s-1 preferred a light flashing at 4.5 s-1. Three behavioural measures taken during the preference test, namely measures of movement, latency to approach and distress calls were not significantly influenced by the frequency of brain stimulation.

Animals↗