Constant light environment suppresses maturation and reduces complexity of new born neuron processes in the hippocampus and caudal nidopallium of a diurnal corvid: Implication for impairment of the learning and cognitive performance

Illuminated night alters hippocampal gene expressions and induces depressive‐like responses in diurnal corvids

“…A similar impairment of response to NOE was found in zebra finches ( Taeniopygia guttata ) under LL (Jha & Kumar, ). We argue that dLAN‐induced depressive mood response was not because of an insufficient light during the daytime as reported in diurnal grass rat (Leach, Adidharma, & Yan, ), since house crows on same daytime light did not show any such effect under an LD; in fact, crows showed normal behaviour and cognitive performance with similar (150 lux) illumination during the light phase of 12L:12D (Taufique et al., ).…”

“…LAN negatively affected neural plasticity as shown by decreased spine density, altered dendritic morphology, and suppressed neurogenesis in HP of both nocturnal and diurnal rodents (Bedrosian, Fonken, Walton, Haim, & Nelson, ; Fonken et al., ; Fujioka et al., ). Similar decline in neurogenesis, dendritic complexity of newborn neurons, and neuronal activity of HP and NC (caudal nidopallium) was also found in Indian house crows under LL (Taufique & Kumar, ; Taufique, Prabhat, & Kumar, ). Hippocampal neurogenesis correlated with the cognitive performance, particularly spatial learning, and episodic memory in many species including birds (Lieberwirth, Pan, Liu, Zhang, & Wang, ; Taufique et al., ).…”

“…Similar decline in neurogenesis, dendritic complexity of newborn neurons, and neuronal activity of HP and NC (caudal nidopallium) was also found in Indian house crows under LL (Taufique & Kumar, ; Taufique, Prabhat, & Kumar, ). Hippocampal neurogenesis correlated with the cognitive performance, particularly spatial learning, and episodic memory in many species including birds (Lieberwirth, Pan, Liu, Zhang, & Wang, ; Taufique et al., ). It was also implicated in the regulation of mood; e.g., antidepressant drugs enhanced neurogenesis in rodent HP (Vollmayr, Mahlstedt, & Henn, ).…”

“…The activity records were graphed (actogram) and presented in 48 hr time scale in which successive days were plotted sideways and underneath to show a better visual illustration of 24 hr pattern and timing of activity and rest. We defined a period of three consecutive 10‐min intervals with <10 activity counts as the rest period (Taufique et al., ); hence, 10‐min intervals with ≥10 activity counts were the activity periods. This was also used to define activity onsets and offsets relative to the times of light onset and offset, respectively, and to show the relationship of 24 hr activity pattern with prevailing LD condition.…”

“…We used one bin (every sixth) section for double‐labelled IHC of DCX and BDNF, as per procedure described in our previous publication (Taufique et al., ). Briefly, PBS‐washed sections were treated with 2.5% bovine serum albumin solution (in PBS with 0.3% Triton X‐100; PBSBT) for 30 min to block the non‐specific binding.…”